Antibiotic compounds, formulations and methods of use

Abstract

Antibiotic compound Formula (I): JPEG2025505237000064.jpg61132[In the formula, R A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether; β-carboxyl or γ-carboxyl, branched or linear C optionally substituted by aromatic or heteroaromatic substituents; 1 -C 4 Denotes alkyl; R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 is -NH 2 or -N(H)-COCH 2 NH 2 R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O, or N. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof. Compositions comprising such compounds are provided, as well as such compounds or formulations for use as pharmaceuticals, and such compounds or formulations for use in treating bacterial infections.

Description

[Technical field]

[0001] The present invention relates to novel antibiotic compounds, particularly a novel class of polymyxins, which have activity against gram-negative bacteria. The present invention also provides methods for producing said novel antibiotic compounds. The present invention further relates to formulations containing the novel antibiotic compounds. Also provided are methods of using such antibiotic compounds and such formulations to treat bacterial infections. [Background technology]

[0002] Globally, the emergence of multidrug-resistant bacteria is on the rise while the pipeline of novel antibiotics in development is nearly exhausted, a problem that is most pronounced in the scarcity of new antibiotics targeting Gram-negative species.

[0003] Polymyxins are a clinically established class of antibiotics that have been commercially available since 1960. They are mostly active only against difficult-to-treat gram-negative pathogens. As resistance to many other antibiotics continues to increase and gram-negative bacteria are essentially difficult to treat with current antibiotics, polymyxins have become the clinician's drug of last resort. The clinically used members of the polymyxin family are polymyxin B and its closely related analog, polymyxin E (also known as colistin).

[0004] Structurally, polymyxins contain a macrocyclic heptapeptide ring-closed by the side chains of 2,4-diaminobutyric acid (Dab) residues at the C-terminus and position 4 of the peptide, and an exocyclic tripeptide acylated at the N-terminus with a fatty acid tail. The only difference between polymyxin B and colistin is that the amino acid residue at position 6 is D-Phe in polymyxin B and D-Leu in colistin. Like other amphipathic cationic antibacterial membrane-active compounds, polymyxins selectively target bacterial membranes over mammalian membranes.

[0005] Despite their potent antibacterial activity, polymyxins have significant drawbacks: their clinical application is dose-limited due to well-documented nephrotoxicity, an effect that has historically limited their widespread use in the treatment of infections (see, e.g., Akajagbor, DS et al.;. Higher Incidence of Acute Kidney Injury With Intravenous Colistimethate Sodium Compared With Polymyxin B in Critically Ill Patients at a Tertiary Care Medical Center. Clin. Infect. Dis. 2013, 57 (9), 1300-1303; and P., ZA; L., NR Nephrotoxicity of Polymyxins: Is There Any Difference between Colistimethate and Polymyxin B? Antimicrob. Agents Chemother. 2017, 61 (3), e02319-16).

[0006] Renal failure is a common reason for discontinuing antibacterial treatment. The toxic effects of polymyxins are driven primarily by their tendency to accumulate in renal tubular cells. However, due to the rise in MDR Gram-negative pathogens, the use of polymyxin therapy is increasing (see, e.g., Evans, ME et al.; Polymyxin B Sulfate and Colistin: Old Antibiotics for Emerging Multiresistant Gram-Negative Bacteria. Ann. Pharmacother. 1999, 33 (9), 960-967). Therefore, there is a growing demand for safer variants.

[0007] To date, two approaches have attracted attention as ways to expand the therapeutic range of polymyxins: either increasing antibacterial activity, preferably without increasing toxicity, or decreasing toxicity, preferably without losing antibacterial activity.

[0008] Several approaches have been explored to evaluate more active or less toxic polymyxin analogues, resulting in the discovery of several analogues with low acute toxicity but high nephrotoxicity. However, because the molecular basis of polymyxin toxicity is not fully understood, it is difficult to find polymyxin analogues that are both effective against Gram-negative bacteria and exhibit acceptable nephrotoxicity.

[0009] It is therefore an object of the present invention to provide compounds useful for the treatment of infections caused by Gram-negative bacteria.A further object is to provide a novel class of polymyxins which exhibit a toxicity similar to, but preferably less than, polymyxin B and colistin, while at the same time exhibiting very good antibacterial activity similar to polymyxin B and colistin.

[0010] Yet a further object is to provide a novel class of polymyxins that can be produced in a cost-effective and environmentally friendly manner.Finally, it is an object to provide a method for modifying polymyxin analogues, preferably polymyxin B or E analogues, to reduce nephrotoxicity while still acting against bacterial pathogens. Summary of the Invention

[0011] Thus, in a first aspect, the present invention provides compounds useful for treating bacterial infections.For example, the compounds may be useful for treating infections caused by gram-negative bacteria.The compounds of the present invention are polymyxin scaffolds that contain lipid side chains, preferably disulfide-containing lipid side chains.

[0012] Thus, in a first aspect, the present invention provides a compound of formula (I): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O or N. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0013] As used herein, the bond XX may represent CC, CS, CO, CN, SS, SC, SO, SN, OO, OC, OS, ON, NN, NC, NS or NO, preferably CC, SS, CS, SC, CO or OC, more preferably CC or SS, and most preferably SS.

[0014] The term "side chain of a natural or unnatural α-amino acid" refers to a group of the formula NH2-CH(R x )-COOH in natural or unnatural amino acids x (i.e., R A ;R B ;R C ;R D ;R E ; and / or R F ) However, those in which the sulfur or oxygen substituents are directly attached to the amino acid backbone, e.g., NH2-CH(OR')-COOH or NH2-CH(SR')-COOH, are not preferred because reduced biological activity has been observed.

[0015] Preferably, the compound of formula (Ia): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety, preferably methyl. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0016] Preferably, in the compound of formula (Ia), R 1 denotes one of the following structures: [ka]

[0017] Preferably, in the compound of formula (Ia), R 5 and R 6 each independently represents hydrogen.

[0018] Further preferred compounds have the formula (II): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0019] Preferably, the compound of formula (IIa): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety, preferably methyl. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0020] Preferably, in the compound of formula (IIa), R 1denotes one of the following structures: [ka] Preferably, in the compound of formula (IIa), R 5 and R 6 each independently represents hydrogen.

[0021] Preferably, the compound of formula (IIb): [ka] [In the formula, R 1 represents an optionally substituted straight or branched chain alkyl, alkenyl, alkynyl or alkylene moiety having up to 20 carbon atoms; optionally substituted with an aryl or heteroaryl moiety; R 2 represents hydrogen, hydroxymethyl, 2-aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 represents -NH2 or -N(H)-COCH2NH2; and R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, an optionally substituted aryl moiety, or an optionally substituted arylalkyl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0022] Preferably, in the compound of formula (IIb), R 1 denotes one of the following structures: [ka]

[0023] Further preferred compounds have the formula (III): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0024] Preferably, the compound of formula (IIIa): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety, preferably methyl. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0025] Preferably, in the compound of formula (IIIa), R 1 denotes one of the following structures: [ka] Preferably, in the compound of formula (IIIa), R 5 and R 6 each independently represents hydrogen.

[0026] In a second embodiment of the present invention, a compound of formula (IV): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferablyA ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof is provided.

[0027] Preferably, the compound of formula (IVa): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety, preferably methyl. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0028] Preferably, in the compound of formula (IVa), R 1 denotes one of the following structures: [ka] Preferably, in the compound of formula (IVa), R 5 and R 6 each independently represents hydrogen.

[0029] In a third aspect of the present invention, a compound of formula (V): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R Fare each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, in particular β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, in particular benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 4 represents an optionally substituted alkyl moiety; an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof is provided.

[0030] Preferably, the compound of formula (Va): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 4 represents an optionally substituted alkyl moiety; an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0031] Preferably, in the compound of formula (Va), R1 denotes one of the following structures: [ka]

[0032] In a fourth embodiment of the present invention, a compound of formula (VI): [ka] [In the formula, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, in particular β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, in particular benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 4 represents an optionally substituted alkyl moiety; an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof is provided.

[0033] Preferably, the compound of formula (VIa): [ka] [In the formula, R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 4 represents an optionally substituted alkyl moiety; an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety. or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0034] Preferably, in the compound of formula (VIa), R 1 denotes one of the following structures: [ka]

[0035] A fifth aspect of the invention provides methods of making the compounds of the invention.

[0036] The sixth aspect of the present invention provides a composition of the present invention, comprising a compound of the present invention and a pharma- ceutically acceptable carrier.The composition can be a parenteral formulation or an oral formulation.The formulation can be a parenteral formulation, for example an intravenous formulation.

[0037] A seventh aspect provides a compound or composition of the invention for use as a medicament.

[0038] An eighth aspect provides a compound or composition of the invention for use in treating a bacterial infection. The bacterial infection may be an infection by a gram-negative bacterium. The gram-negative bacterium may be from at least one of the following families:

[0039] A ninth aspect provides a method of treating a bacterial infection in a patient, comprising administering to said patient an effective amount of a compound of the invention or a composition of the invention.

[0040] Thus, in further aspects, the present invention also encompasses one or more methods of preparing said compounds; pharmaceutical uses of the compounds or compositions of the present invention; pharmaceutical compositions comprising the compounds or compositions of the present invention together with a pharma- ceutically acceptable diluent or carrier; use of the compounds or compositions of the present invention in the preparation of a medicament for treating or preventing septic shock; and a method of treating or preventing septic shock comprising administering a therapeutically or prophylactically effective amount of a compound or composition of the present invention to an individual in need thereof.

[0041] A compound or composition according to the invention may be advantageously administered to a mammal, preferably a human, when a gram-negative bacterial infection is diagnosed, e.g. a gram-negative bacterial infection that may lead to endotoxemia, bacterial sepsis and / or septic shock. Gram-negative bacteria that may cause these fatal disorders include, but are not limited to, N. meningitidis, E. coli, Salmonella typhi, Bordetella pertussis, and Pseudomonas aeruginosa. The compounds or compositions of the present invention may be administered to an individual in need thereof by a systemic route, preferably an intravenous route. The dosage depends on various factors, including, but not limited to, the age, weight, physiological state, and infection state of the patient. It may be administered once or several times until the risk of a fatal event is averted.

[0042] The present invention provides a novel class of polymyxins that exhibit reduced toxicity compared to polymyxin B and colistin, while at the same time exhibiting excellent antibacterial activity similar to polymyxin B and colistin. Moreover, these polymyxins can be produced in a cost-effective and environmentally friendly manner. [Brief description of the drawings]

[0043] Embodiments of the invention are further described below with reference to the accompanying drawings, in which:

[0044] [Figure 1] FIG. 1 illustrates the synthesis scheme 1.

[0045] [Diagram 2] FIG. 2 illustrates synthetic scheme 2.

[0046] [Diagram 3] FIG. 3 illustrates the synthetic scheme 3.

[0047] [Figure 4] FIG. 4 illustrates synthetic scheme 4.

[0048] [Diagram 5] FIG. 5 illustrates synthetic scheme 5.

[0049] [Figure 6] FIG. 6 illustrates Synthetic Scheme 6.

[0050] [Figure 7] FIG. 7 illustrates Synthetic Scheme 7.

[0051] [Figure 8] FIG. 8 illustrates synthetic scheme 8.

[0052] [Figure 9] FIG. 9 illustrates synthetic scheme 9.

[0053] Detailed Description Throughout the description and claims of this specification, the words "comprise" and "contain" and variations thereof mean "including, but not limited to," and are not intended to (and do not) exclude other moieties, additives, components, integers, or steps. Throughout the description and claims of this specification, the singular includes the plural, unless the context requires otherwise. In particular, when the indefinite article is used, the specification is understood to contemplate the plural as well as the singular, unless the context requires otherwise.

[0054] It is understood that any feature, integer, property, compound, chemical moiety or group described in connection with a particular aspect, embodiment or example of the invention is also applicable to other aspects, embodiments or examples described herein, except where inconsistent therewith. All of the features disclosed herein (including the accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed herein (including the accompanying claims, abstract and drawings), or any novel one, or any novel combination of the steps of any method or process so disclosed.

[0055] The reader is directed to all papers and documents in connection with this application that have been filed contemporaneously or prior to this application and that are in the public domain herewith, and the contents of all such papers and documents are hereby incorporated by reference.

[0056] All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.

[0057] definition The following explanations of terms and methods are provided to better describe the present disclosure and to guide those of skill in the art in the practice of the present disclosure.

[0058] There is an increasing number of Gram-negative bacteria that are resistant to aminoglycosides, β-lactams and fluoroquinolone antibiotics. These bacteria are often only sensitive to polymyxins and related peptides that have antibacterial properties. As a result, there is renewed interest in the use of polymyxins for the treatment of multidrug-resistant Gram-negative bacterial infections in humans.

[0059] Peptides such as polymyxin B and colistin, also known as polymyxin E, have been administered to humans as antibacterial agents. However, their use has been limited so far due to toxicity. Thus, there is a need for novel peptide compounds that have antibacterial properties similar to those of polymyxin B and an improved therapeutic index, as well as methods for producing such antibacterial compounds.

[0060] The present invention is particularly concerned with the treatment of disease. The term "treatment" and the treatment encompassed by the present invention includes the following and combinations thereof: (1) preventing, e.g., delaying, the onset and / or progression of an event, condition, disorder or symptom, e.g., preventing, reducing, or delaying the development of an event, condition, disorder or symptom, or its recurrence in the case of maintenance of treatment or secondary prevention, or at least one clinical or subclinical sign thereof; (2) preventing or delaying the appearance of the clinical signs of an event, condition, disorder or symptom that develops in an animal (e.g., a human) that is afflicted with or susceptible to a condition, disorder or symptom, but has not yet experienced or exhibited the clinical or subclinical signs of the condition, disorder or symptom; and / or (3) alleviating and / or curing an event, condition, disorder or symptom (e.g., resolving the event, condition, disorder or symptom, or at least one clinical or subclinical sign thereof, curing the patient, or putting the patient into remission). The benefit to the treated patient may be statistically significant or at least perceptible to the patient or physician. It will be understood that a medicament does not necessarily produce a clinical effect in each patient to whom it is administered. The benefit to the treated patient may be statistically significant or at least perceptible to the patient or physician. It will be understood that a medicament does not necessarily produce a clinical effect in each patient to whom it is administered. Thus, in an individual patient, or even in a particular patient population, treatment may only partially fail or succeed, and the meaning of the terms "treatment" and "prevention", as well as similar terms, should be understood accordingly. The compositions and methods described herein are used for the treatment and / or prevention of the above-mentioned conditions.

[0061] The term "prevention" includes reference to treatment therapies aimed at maintaining health or inhibiting or delaying the onset and / or progression of an event, condition, disorder or symptom, e.g., reducing the likelihood of an event, condition, disorder or symptom occurring. The outcome of prevention is, for example, maintaining health or delaying the onset and / or progression of an event, condition, disorder or symptom. It should be remembered that treatment may fail in individual patients or even in certain patient populations, and this paragraph should be interpreted accordingly.

[0062] The term "antibiotic" refers to a compound that inhibits the growth of or destroys microorganisms, such as bacteria (such as gram-positive or gram-negative bacteria). An "antibacterial agent" is an antibiotic that has activity against bacteria. The compounds of the present invention are antibacterial, particularly active against gram-negative bacteria.Gram-positive bacteria include Staphylococcus (e.g., S. aureus, S. epidermidis, S. saprophyticus), Streptococcus (e.g., Strep. pyogenes, Strep. agalactiae, Strep. viridans, Strep. pneumonia), Enterococcus, Bacillus, Clostridia, Listeria and Corynebacterium.

[0063] The term "alkyl" as used herein includes reference to straight or branched chain alkyl moieties having up to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) carbon atoms. The term includes reference to, for example, methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl, sec-butyl or tert-butyl), pentyl, hexyl, and the like. In particular, alkyl refers to "C1-C 10 "C1-C6 alkyl", i.e., alkyl having 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms; "C1-C6 alkyl", i.e., alkyl having 1, 2, 3, 4, 5 or 6 carbon atoms; "C1-C4 alkyl", i.e., alkyl having 1, 2, 3 or 4 carbon atoms; "C1-C6 alkyl", i.e., alkyl having 1, 2, 3, 4, 5 or 6 carbon atoms; or "C1-C3 alkyl", i.e., alkyl having 1, 2 or 3 carbon atoms. The term "lower alkyl" includes reference to alkyl groups having 1, 2, 3 or 4 carbon atoms.

[0064] The term "alkenyl" as used herein includes reference to straight or branched chain alkenyl moieties having up to 20 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) carbon atoms. The term includes reference to, for example, ethenyl, propenyl, butenyl, pentenyl, hexenyl, and the like. In particular, alkenyl refers to "C2-C 10"Alkenyl", i.e., alkenyl having 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms; "C2-C6 alkyl", i.e., alkenyl having 2, 3, 4, 5 or 6 carbon atoms; "C2-C4 alkyl", i.e., alkenyl having 2, 3 or 4 carbon atoms, and the term "lower alkenyl" includes reference to alkyl groups having 2, 3 or 4 carbon atoms. Alkenyl can be monounsaturated (i.e., containing a single carbon-carbon double bond) or polyunsaturated (i.e., containing two or more carbon-carbon double bonds, e.g., containing two, three or four carbon-carbon double bonds). For example, alkenyl can be alkadienyl, alkatrienyl, and the like.

[0065] The term "alkylene" by itself or as part of another substituent means a divalent radical derived from alkyl, exemplified by, but not limited to, -CH2CH2CH2CH2-. Typically, an alkyl (or alkylene) group will have from 1 to 24 carbon atoms, with those groups having 10 or fewer carbon atoms being preferred in the present invention. A "lower alkyl" or "lower alkylene" is a shorter chain alkyl or alkylene group, generally having 8 or fewer carbon atoms.

[0066] The term "cycloalkyl" as used herein includes references to alicyclic moieties having 3, 4, 5 or 6 carbon atoms. The group may be a bridged or polycyclic ring system. More often, cycloalkyl groups are monocyclic. This term includes references to groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.

[0067] The term "heteroalkyl," by itself or in combination with other terms, means, unless otherwise specified, a stable linear or branched chain, or cyclic hydrocarbon radical, or combinations thereof, consisting of at least one carbon atom and at least one heteroatom selected from the group consisting of O, N, P, Si, and S, where the nitrogen and sulfur atoms may be optionally oxidized and the nitrogen heteroatom may be optionally quaternized. The heteroatom O, N, P, S, and Si may be placed at any interior position of the heteroalkyl group or at the position at which the alkyl group is attached to the remainder of the molecule. Examples include, but are not limited to, -CH2-CH2-O-CH3, -CH2-CH2-NH-CH3, -CH2-CH2-N(CH3)-CH3, -CH2-S-CH2-CH3, -CH2-CH2, -S(O)-CH3, -CH2-CH2-S(O)2-CH3, -CH=CH-O-CH3, -Si(CH3)3, -CH2-CH=N-OCH3, -CH=CH-N(CH3)-CH3, O-CH3, -O-CH2-CH3 and -CN. Up to two heteroatoms may be consecutive, such as, for example, -CH2-NH-OCH3 and -CH2-O-Si(CH3)3. Similarly, the term "heteroalkylene" by itself or as part of another substituent refers to a divalent radical derived from heteroalkyl, exemplified, but not limited to, -CH-CH-S-CH-CH- and -CH-S-CH-CH-NH-CH-. In the case of heteroalkylene groups, heteroatoms can also occupy either or both of the chain termini (e.g., alkyleneoxy, alkylenedioxy, alkyleneamino, alkylenediamino, etc.). Furthermore, in the case of alkylene and heteroalkylene linking groups, no orientation of the linking group is implied by the direction in which the formula of the linking group is written. For example, the formula -C(O)R'- denotes both -C(O)R'- and -R'C(O)-. As noted above, heteroalkyl groups as used herein include groups that are attached to the remainder of the molecule through a heteroatom, such as, for example, -C(O)R', -C(O)NR', ​​-NR'R'', -OR', -SR' and / or -SOR'.When "heteroalkyl" is described followed by a specific heteroalkyl group, such as -NR'R'', it will be understood that the terms heteroalkyl and -NR'R'' are not redundant or mutually exclusive. Rather, the specific heteroalkyl group is described to add clarity. Thus, the term "heteroalkyl" should not be construed herein as excluding specific heteroalkyl groups, such as -NR'R''.

[0068] The term "heterocycloalkyl" as used herein includes references to saturated heterocyclic moieties having 3, 4, 5, 6 or 7 ring carbon atoms and 1, 2, 3, 4 or 5 ring heteroatoms selected from nitrogen, oxygen, phosphorus and sulfur. For example, heterocycloalkyl can include 3, 4 or 5 ring carbon atoms and 1 or 2 ring heteroatoms selected from nitrogen and oxygen. The group can be a polycyclic ring system, but is often monocyclic. This term includes references to groups such as azetidinyl, pyrrolidinyl, tetrahydrofuranyl, piperidinyl, oxiranyl, pyrazolidinyl, imidazolyl, indolizidinyl, piperazinyl, thiazolidinyl, morpholinyl, thiomorpholinyl, quinolizidinyl, etc.

[0069] As used herein, the term "halo" or "halogen" includes reference to F, Cl, Br or I, e.g., F, Cl or Br. In a particular class of embodiments, the halogen is F or Cl, with F being more common.

[0070] The term "halo" or "halogen", by itself or as part of another substituent, means a fluorine, chlorine, bromine, or iodine atom, unless otherwise specified. Additionally, terms such as "haloalkyl" are meant to include monohaloalkyl and polyhaloalkyl. For example, the term "haloalkyl" means an alkyl group in which one or more hydrogen atoms are replaced by the corresponding number of halogens. For example, the term "halo(C1-C4)alkyl" is meant to include, but is not limited to, trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, and the like.

[0071] The term "alkoxy" as used herein includes reference to -O-alkyl, where alkyl is straight or branched and contains 1, 2, 3, 4, 5, or 6 carbon atoms. In one embodiment, alkoxy has 1, 2, 3, or 4 carbon atoms, e.g., 1, 2, or 3 carbon atoms. This term includes reference to, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, pentoxy, hexoxy, and the like. The term "lower alkoxy" includes reference to alkoxy groups having 1, 2, 3, or 4 carbon atoms.

[0072] The term "haloalkoxy," as used herein, refers to an alkoxy group in which one or more hydrogen atoms are replaced by the corresponding number of halogens.

[0073] The term "aryl" refers to a fused or covalently linked polyunsaturated, aromatic, hydrocarbon substituent that may be a single ring or multiple rings (preferably 1-3 rings), unless otherwise specified. The term "heteroaryl" refers to an aryl group (or ring) containing 1-4 heteroatoms selected from N, O and S, in which the nitrogen and sulfur atoms are optionally oxidized and the nitrogen atom(s) are optionally quaternized. Heteroaryl groups can be attached to the remainder of the molecule through a carbon or heteroatom. Non-limiting examples of aryl and heteroaryl groups include phenyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, 3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl, Examples include 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl, 4-pyrimidyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl, 1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl, 3-quinolyl, and 6-quinolyl. Substituents for each of the above noted aryl and heteroaryl ring systems are selected from the group of acceptable substituents described below. "Arylene" and "heteroarylene" refer to a divalent radical derived from aryl and heteroaryl, respectively.

[0074] The term "lipid" as used herein with respect to a substituent typically refers to a moiety that is hydrophobic. A lipid may comprise substituted or unsubstituted alkyl, alkenyl, cycloalkyl, bridged cycloalkyl, (alkyl)cycloalkyl, (alkyl)bridged cycloalkyl, (alkyl)cycloalkenyl and / or alkylaryl groups. For example, a lipid may comprise substituted or unsubstituted alkyl, alkenyl, (alkyl)cycloalkyl, (alkyl)cycloalkenyl and / or alkylaryl groups. Exemplary substituents include -OH, =O, -CN, -halo, -NH2, -NH(C1-C6 alkyl), -N(C1-C4 alkyl)2, -phenyl, -phenyl-halo; for example, -OH, =O, -CN, -halo, -NH2, -NH(C1-C6 alkyl), -N(C1-C4 alkyl)2. The backbone of a substituted or unsubstituted lipid may also be interrupted by disulfide bonds (-SS-), thioether bonds (-S-), ether bonds -O- or esters (-C(O)O-).

[0075] Each of the above terms (e.g., "alkyl," "cycloalkyl," "heteroalkyl," "aryl" and "heteroaryl") are meant to include both substituted and unsubstituted forms of the specified radical, unless otherwise specified. x -substituted alkyl, where "x" is an integer), the substituent may be optionally substituted with one or more R groups where permitted by different chemical valence rules (e.g., R x -substituted alkyl is each R x Multiple R groups, each of which may be different x (The radical may include an alkyl group.) Examples of substituents for each type of radical are provided below.

[0076] The term "substituted" as used herein with respect to a moiety means that one or more, particularly up to 5, more particularly 1, 2 or 3 hydrogen atoms of said moiety are replaced independently of each other by the corresponding number of listed substituents. Unless otherwise specified, exemplary substituents include -OH, -CN, -NH, -NH(C1-C6 alkyl), -N(C1-C4 alkyl), =O, -halo, -C1-C6 alkyl, -C2-C6 alkenyl, -C1-C6 haloalkyl, -C1-C6 haloalkoxy and -C2-C6 haloalkenyl, -C1-C6 alkyl carboxylic acid (e.g. -CH3COOH or -COOH). When the substituent is -C1-C6 alkyl or -C1-C6 haloalkyl, the C1-C6 chain is optionally interrupted by an ether bond (-O-) or an ester bond (-C(O)O-). Exemplary substituents for substituted alkyl include -OH, -CN, -NH, =O, -halo, -COH, -C1-C6 haloalkyl, -C1-C6 haloalkoxy and -C2-C6 haloalkenyl, -C1-C6 alkylcarboxylic acid (e.g., -CH3COOH or -COOH). For example, exemplary substituents for alkyl include -OH, -CN, -NH, =O, -halo.

[0077] The term "side chain of a natural or unnatural α-amino acid" refers to a group of the formula NH2-CH(R x )-COOH in natural or unnatural amino acids A ~R F It means either:

[0078] Examples of side chains of natural α-amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, histidine, 5-hydroxylysine, 4-hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, α-aminoadipic acid, -amino-n-butyric acid, 3,4-dihydroxyphenylalanine, homoserine, α-methylserine, ornithine, pipecolic acid, and thyroxine.

[0079] Naturally occurring α-amino acids containing functional substituents in their characteristic side chains, such as amino, carboxyl, hydroxy, mercapto, guanidyl, imidazolyl or indolyl groups, include arginine, lysine, glutamic acid, aspartic acid, tryptophan, histidine, serine, threonine, tyrosine and cysteine. A ~R F When either of these is one of these side chains, said functional group may optionally be protected.

[0080] The term "protected" as used with reference to functional substituents in the side chains of natural α-amino acids refers to derivatives of such substituents that are substantially non-functional. For example, carboxyl groups can be esterified, amino groups can be converted to amides or carbamates, hydroxyl groups can be converted to ethers or esters, and thiol groups can be converted to thioethers or thioesters.

[0081] Examples of side chains of unnatural α-amino acids include R A ~R F Salts of the compounds used in the present invention include physiologically acceptable acid addition salts, such as hydrochloride, hydrobromide, sulfate, methanesulfonate, p-toluenesulfonate, phosphate, acetate, citrate, succinate, lactate, tartrate, fumarate and maleate. Salts with bases, such as sodium, potassium, magnesium, calcium salts, etc., may also be formed.

[0082] The compounds used in accordance with the present invention have multiple chiral centers due to the presence of asymmetric carbon atoms which gives rise to a number of diastereomers with R or S, or D and L stereochemistry at each chiral center.

[0083] Of course, it is understood that the substituents are present only in chemically possible positions, and that a person skilled in the art can determine (experimentally or theoretically) whether a particular substituent is possible without undue effort. For example, an amino group or a hydroxy group having free hydrogen may be unstable when bonded to a carbon atom having an unsaturated (e.g., olefinic) bond. Furthermore, it is understood that the substituents described herein may themselves be substituted by any substituent, subject to the above-mentioned restrictions on suitable substituents as recognized by a person skilled in the art.

[0084] When steric considerations dictate the configuration of substituents on a group, the isomer with the lowest conformational energy may be favored.

[0085] When a compound, moiety, method, or article is described as "optionally" having a certain feature, the disclosure includes compounds, moieties, methods, or articles that have that feature and compounds, moieties, methods, or articles that do not have that feature. Thus, when a moiety is described as "optionally substituted," the disclosure includes the unsubstituted moiety as well as the substituted moiety.

[0086] When two or more moieties are described as being "independently" or "each independently" selected from a list of atoms or groups, this means that the moieties can be the same or different, and thus the identity of each moiety is independent of the identity of one or more other moieties.

[0087] As used herein, the term "pharmacologically acceptable" includes reference to compounds, materials, compositions, and / or dosage forms that are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human or animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio. The term includes acceptability for both human and veterinary purposes.

[0088] The term "pharmaceutically acceptable salts" is meant to include salts of active compounds prepared using relatively non-toxic acids or bases, depending on the specific substituents found on the compounds described herein.When a compound of the present invention contains a relatively acidic functionality, a base addition salt can be obtained by contacting a neutral form of such a compound with a sufficient amount of a desired base in a neat or suitable inert solvent.Examples of pharmaceutically acceptable base addition salts include sodium salts, potassium salts, calcium salts, ammonium salts, organic amino salts or magnesium salts, or similar salts.When a compound of the present invention contains a relatively basic functionality, an acid addition salt can be obtained by contacting a neutral form of such a compound with a sufficient amount of a desired acid in a neat or suitable inert solvent. Examples of pharma- ceutically acceptable acid addition salts include those derived from inorganic acids such as hydrochloric, hydrobromic, nitric, carbonic, monohydrogencarbonic, phosphoric, monohydrogenphosphate, dihydrogenphosphate, sulfuric, monohydrogensulfuric, hydroiodic or phosphoric acid, and also those derived from relatively non-toxic organic acids such as acetic, propionic, isobutyric, maleic, malonic, benzoic, succinic, suberic, fumaric, lactic, mandelic, phthalic, benzenesulfonic, p-tolylsulfonic, citric, tartaric, methanesulfonic, etc. Also included are salts of amino acids such as arginates, and salts of organic acids such as glucuronic and galacturonic acids (see, e.g., Berge et al., “Pharmaceutical Salts”, Journal of Pharmaceutical Science, 1977, 66, 1-19). Certain compounds of the present invention contain both basic and acidic functionalities that allow the compounds to be converted into either base or acid addition salts.

[0089] The neutral forms of the compounds are preferably regenerated by contacting the salt with a base or acid and isolating the parent compound in the conventional manner. The parent form of the compound differs from the various salt forms in certain physical properties, such as solubility in polar solvents.

[0090] Certain compounds of the present invention can exist not only in unsolvated form but also in solvated form, including hydrated form.In general, solvated form is equivalent to unsolvated form and is included in the scope of the present invention.Certain compounds of the present invention can exist in multiple crystalline or amorphous forms.In general, all physical forms are equivalent for the use contemplated by the present invention and are intended to be within the scope of the present invention.

[0091] Certain compounds of the present invention possess asymmetric carbon atoms (optical centers) or double bonds; the racemates, diastereomers, tautomers, geometric isomers and individual isomers are encompassed within the scope of the present invention. Compounds of the present invention do not include those known in the art to be too unstable to synthesize and / or isolate.

[0092] symbol: [ka] indicates the point of attachment of a moiety to the remainder of the compound.

[0093] The term "prodrug" as used herein refers to a compound that is converted into a parent compound or other active compound in vivo, for example, by hydrolysis in blood. An example of such a prodrug is a pharma- ceutically acceptable ester of a carboxylic acid. A thorough discussion is provided in T. Higuchi and V. Stella, Pro-drugs as Novel Delivery Systems, Vol. 14 of the ACS Symposium Series, Edward B. Roche, ed., Bioreversible Carriers in Drug Design, American Pharmaceutical Association and Pergamon Press, 1987; H Bundgaard, ed., Design of Prodrugs, Elsevier, 1985; and Judkins, et al. Synthetic Communications, 26(23), 4351-4367 (1996); and The organic chemistry of drug design and drug action by Richard B Silverman in particular, pages 497-546, each of which is incorporated herein by reference.

[0094] The term "pharmaceutical preparation" as used herein includes reference to preparation that contains at least one active compound and optionally one or more additional pharmaceutically acceptable components, such as pharmaceutically acceptable carriers.When pharmaceutical preparation contains two or more active compounds, or contains at least one active compound and one or more additional pharmaceutically acceptable components, said pharmaceutical preparation is also pharmaceutical composition.Unless otherwise indicated by context, all references to "preparation" in this specification refer to pharmaceutical preparation.

[0095] As used herein, the term "product" or "product of the invention" includes reference to any product containing a compound of the invention. In particular, the term product relates to compositions and formulations that contain a compound of the invention, such as pharmaceutical compositions.

[0096] As used herein, the term "therapeutically effective amount" means an amount of a drug or pharmaceutical agent calculated, within the scope of sound pharmacological judgment, to provide (or will provide) a desired therapeutic response in a mammal (animal or human), which serves, for example, to cure, delay the progression of, or prevent a disease, disorder, or condition.

[0097] Preferably, R 1 is C1-C 10 Alkyl moiety, C2-C 10 , preferably a monounsaturated alkenyl moiety, or an optionally substituted benzyl moiety. More preferably, R 1 denotes one of the following structures: [ka] Preferably, R 2 represents aminoethyl or aminomethyl.

[0098] Preferably, R 4 represents a cycloalkyl moiety having 4 to 20 carbon atoms, preferably an alicyclic moiety containing 5, 6 or 7 carbon atoms, wherein said moiety is preferably a monocyclic, bridged or polycyclic ring selected from the group consisting of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl; or a pharma- ceutically acceptable salt, solvate or prodrug thereof. More preferably, R 4 represents an optionally substituted arylalkyl moiety, an optionally substituted aryl moiety, or a biphenyl moiety.

[0099] Preferably, the (*) indicates the stereochemistry at the designated carbon atom, each of which may independently be L or D.

[0100] The invention also relates to a method for preparing a compound according to the invention, comprising the steps of: a) removing the side chains from polymyxin B by enzymatic digestion with ficin to obtain a polymyxin nonapeptide macrocyclic ring comprising a side chain with a free N-terminal amine group; b) protecting the amino functions of the ring and leaving the N-terminal amine unprotected to obtain a polymyxin nonapeptide macrocyclic ring comprising four protected amine groups and a free N-terminal amine group; c) coupling the free N-terminal amine group with a disulfide-containing compound to obtain a disulfide-coupled polymyxin nonapeptide macrocyclic ring comprising four protected amine groups; and d) removing the protecting groups and isolating the compound of formula (I).

[0101] The invention also relates to a process for preparing a compound according to the invention, comprising the steps of protecting the amino functions of polymyxin B to obtain N-protected polymyxin B; removing the complete side chain from the N-protected polymyxin B by enzymatic digestion with savine to obtain a tri-N-protected polymyxin B heptameric macrocycle having a single free amino group; coupling the free amino group with a disulfide lipidated tripeptide or an N-terminal amide or carbamate linked building block to obtain a disulfide-coupled polymyxin nonapeptide macrocycle containing three protected amine groups, and removing the protecting groups to isolate the compound of formula (I).

[0102] The present invention also relates to a process for preparing a compound according to the invention, wherein the protecting group is a tert-butyloxycarbonyl (BOC) protecting group.

[0103] The present invention also relates to a method for preparing a compound according to the invention, wherein a lipidated tripeptide building block, preferably a disulfide lipidated tripeptide building block, is prepared using solid phase peptide synthesis.

[0104] The present invention also relates to a method for preparing a compound according to the invention, wherein the disulfide lipidated N-terminal amide or carbamate linked building block has a structure according to formula (VIIa) or (VIIb): [ka]

[0105] The present invention also provides a method for preparing a compound according to the invention, comprising the steps of: a) removing the side chains from polymyxin by enzymatic digestion with an enzyme capable of breaking the bond between the exocyclic amino acid closest to the fatty acid tail and the middle exocyclic amino acid to obtain a polymyxin nonapeptide macrocycle containing a side chain with a free N-terminal amine group; b) protecting the amino functionality of the ring and leaving the N-terminal amine unprotected to obtain a polymyxin nonapeptide macrocyclic ring containing a protected amine group and a free N-terminal amine group; c) coupling the free N-terminal amine group with a compound to obtain a coupled polymyxin nonapeptide macrocycle containing a protected amine group; and d) removing the protecting group and isolating the resulting compound of formula (I), (Ia), (II), (IIa), (IIb), (III), (IIIa), (IV), (V) or (VI), respectively; Including, Preferably, wherein said polymyxin nonapeptide macrocycle contains four protected amine groups and a free N-terminal amine group, and said coupled polymyxin nonapeptide macrocycle contains four or five protected amine groups; and / or Preferably, step c relates to a method comprising coupling the free N-terminal amine group with a disulfide-containing compound to obtain a disulfide-coupled polymyxin nonapeptide macrocycle containing four or five protected amine groups.

[0106] The present invention also provides a method for preparing a compound according to the invention, comprising the steps of: a) protecting the amino functions of polymyxin to obtain N-protected polymyxin; b) removing the complete side chain by enzymatic digestion with an enzyme capable of breaking the bond between the exocyclic amino acid closest to the cyclic heptapeptide and said cyclic heptapeptide to obtain an N-protected polymyxin heptameric macrocycle with a single free amino group; c) coupling said free amino group with a lipidated tripeptide or an N-terminal amide or carbamate linked building block to obtain a coupled polymyxin peptide macrocycle containing a protected amine group; and d) removing the protecting group and isolating the compound of formula (I), formula (Ia), formula (II), formula (IIa), formula (IIb), formula (III), formula (IIIa), formula (IV), formula (V), formula or formula (VI); Including, Preferably, wherein said N-protected polymyxin heptameric macrocycle is tri-N-protected and said coupled polymyxin peptide macrocycle contains 3, 4 or 5, preferably 4 or 5, or preferably 3 protected amine groups; and / or Preferably, step c comprises coupling said free amino group with a disulfide lipidated tripeptide or an N-terminal amide or carbamate linked building block to obtain a disulfide-coupled polymyxin nonapeptide macrocycle containing three protected amine groups.

[0107] Preferably, the coupled polymyxin peptide macrocycle is a coupled polymyxin nonapeptide or a coupled polymyxin decapeptide.

[0108] 1-8, it is understood herein that the term "polymyxin nonapeptide macrocycle" means that the polymyxin compound comprises nine amino acids and a macrocycle. For the avoidance of doubt, this does not mean that the macrocycle comprises the nine amino acids incorporated into the macrocycle, but rather refers to the total number of amino acids.

[0109] Thus, with reference to Figures 5-8, the term "polymyxin decapeptide macrocycle" as used herein is understood to mean that the polymyxin compound contains 10 amino acids and a macrocycle.

[0110] The present invention also relates to a method for preparing a compound according to the invention, wherein the polymyxin is polymyxin B or polymyxin E.

[0111] The present invention also relates to a process for preparing the compounds according to the invention, wherein the enzyme is a hydrolase, preferably a proteolytic enzyme, more preferably ficin, savinase or subtilisin.

[0112] Preferably, in the method according to the invention, said bond is a peptide bond.

[0113] The present invention also provides a method for preparing a compound according to the present invention, wherein the disulfide-containing compound has the structure BXXIII or BXXIV: [ka] wherein R represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety, preferably where R is an optionally substituted alkyl moiety or an optionally substituted aryl moiety. The present invention relates to a method having a structure according to the present invention.

[0114] The present invention also relates to a method for preparing a compound according to the invention, wherein the disulfide lipidated N-terminal amide or carbamate linked building block has the structure BXXV or BXXVI: [ka] wherein R represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety, preferably wherein R is an optionally substituted alkyl moiety or an optionally substituted aryl moiety; where R' represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl, or 5-(2-amino)pentanoic acid. The present invention relates to a method having the structure:

[0115] Preferably, R 1 together with the carbonyl group and the nitrogen alpha to the carbon to which it is attached, represents D-phenylalanine or D-leucine. More preferably, R 1 together with the carbonyl group and the nitrogen alpha to the carbon to which it is attached, preferably denotes D-phenylalanine. In what follows and above, when referring to amino acids, these are represented by the substituent R 1 ~R 4 and the adjacent atoms that form the amino acid moiety. For example, R 1 When R, together with the carbonyl group and the nitrogen α of the carbon to which it is attached, represents D-phenylalanine, 1 represents a benzyl group, in which the amino acid residue found at position 6 of Formula I, Formula Ia, Formula II, Formula IIa, Formula III, Formula IV, Formula V or Formula VI is D-Phe: [ka] Shows. R 1 When combined with a carbonyl group and the nitrogen alpha to the carbon to which it is attached, R 1indicates an isopropyl group, in which the amino acid residue found at position 6 is D-Leu in Formula I, Formula Ia, Formula II, Formula IIa, Formula III, Formula IV, Formula V or Formula VI, and has the following structure: [ka]

[0116] compound In one aspect, the present invention provides compounds of formula (I) as hereinbefore described or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0117] In another aspect, the present invention provides a compound of formula (II) as hereinbefore described or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0118] In another aspect, the present invention provides compounds of formula (III) as hereinbefore described, or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0119] In yet another aspect, the present invention provides a compound of formula (IV) as hereinbefore described or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0120] In yet another aspect, the present invention provides a compound of formula (V) as hereinbefore described, or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof. In yet another aspect, the present invention provides a compound of formula (VI) as hereinbefore described, or a pharma- ceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

[0121] Formulation and Administration According to a further aspect of the invention there is provided a pharmaceutical formulation or composition comprising a compound of the invention, optionally in admixture with at least one pharma- ceutically acceptable adjuvant, diluent or carrier.

[0122] The formulation or composition may be a parenteral formulation or an oral formulation. The formulation may be a parenteral formulation, such as an intravenous formulation. The formulation may be an oral formulation.

[0123] The compounds, preparations or compositions of the present invention can be administered orally, topically, intravenously, subcutaneously, buccal, rectal, transdermal, nasal, tracheal, bronchial or other parenteral routes, as oral or nasal sprays, or by inhalation.The compounds can be administered in the form of pharmaceutical preparations in pharma-ceutically acceptable dosage forms, including the compounds as free compounds or as addition salts, for example, of pharma-ceutically acceptable non-toxic organic or inorganic acids or bases.The compositions can be administered in various doses, depending on the disorder and patient to be treated, and the route of administration.

[0124] Typically, therefore, the pharmaceutical compounds of the present invention can be administered parenterally (as used herein, "parenterally" refers to modes of administration including intravenous, intramuscular, intraperitoneal, intrasternal, subcutaneous and intraarticular injection and infusion) or orally to a host to obtain an antibacterial effect. For example, the pharmaceutical compounds of the present invention can be administered by intravenous injection or infusion. In the case of large animals such as humans, the compounds of the present invention can be administered alone or as a composition in combination with a pharma- ceutical acceptable diluent, excipient or carrier.

[0125] The actual dosage levels of the active ingredients in the pharmaceutical formulations and compositions of the present invention can be varied to obtain an amount of the active compound effective to achieve the desired therapeutic response for a particular patient, composition and mode of administration. The selected dosage level will depend on the activity of the particular compound, the route of administration, the severity of the condition being treated, and the condition and medical history of the patient being treated. However, it is within the skill of the art to begin administering the compound at a level lower than that required to obtain the desired therapeutic effect and gradually increase the dosage until the desired effect is obtained. Suitable dosages are generally in the range of 0.01 to 100 mg / kg / day, for example, 0.1 to 50 mg / kg / day.

[0126] The pharmaceutical preparation or composition of the present invention for parenteral (e.g., intravenous) injection may include pharma- ceutically acceptable sterile aqueous or non-aqueous solutions, dispersions, suspensions or emulsions, as well as sterile powders for reconstitution into sterile injectable solutions or dispersions immediately before use. Examples of suitable aqueous and non-aqueous carriers, diluents, solvents or vehicles include water, ethanol, polyols (such as glycerol, propylene glycol, polyethylene glycol, etc.), and suitable mixtures thereof, vegetable oils (such as olive oil), and injectable organic esters such as ethyl oleate. The appropriate fluidity can be maintained, for example, by using coating materials such as lecithin, by maintaining the required particle size in the case of dispersions, and by using surfactants. The preparation or composition for parenteral injection may represent the preferred preparation or composition of the present invention.

[0127] These compositions may also contain adjuvants such as preservatives, wetting agents, emulsifying agents, and dispersing agents. Prevention of microbial action can be ensured by including various antibacterial and antifungal agents, such as parabens, chlorobutanol, or phenol sorbic acid. It may also be desirable to include isotonic agents, such as sugars or sodium chloride. Prolonged absorption of injectable pharmaceutical forms can be brought about by including agents that delay absorption, such as aluminum monostearate and gelatin.

[0128] Solid dosage forms for oral administration include capsules, tablets, pills, powders and granules. In such solid dosage forms, the active compound is usually mixed with at least one inert, pharma- ceutically acceptable excipient or carrier, such as sodium citrate or dicalcium phosphate, and / or one or more of the following: a) fillers or extenders, such as starch, lactose, sucrose, glucose, mannitol and silicic acid; b) binders, such as carboxymethylcellulose, alginates, gelatin, polyvinylpyrrolidone, sucrose and acacia; c) humectants, such as glycerol; d) disintegrants, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates and sodium carbonate; e) solution retarders. f) absorption enhancers, such as quaternary ammonium compounds; g) wetting agents, such as cetyl alcohol and glycerol monostearate; h) absorbents, such as kaolin and bentonite clay; i) lubricants, such as talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof. In the case of capsules, tablets, and pills, the dosage form may also include buffering agents. Solid compositions of a similar type may also be used as fillers in soft and hard-filled gelatin capsules, using such excipients as lactose or milk sugar and high molecular weight polyethylene glycols.

[0129] The oral formulation may contain a solubilizing agent. Examples of the solubilizing agent include nonionic surfactants, such as sucrose fatty acid esters, glycerol fatty acid esters, sorbitan fatty acid esters (e.g., sorbitan trioleate), polyethylene glycol, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, methoxypolyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene alkylthioethers, polyoxyethylene polyoxypropylene copolymers, polyoxyethylene glycerol fatty acid esters, pentaerythritol fatty acid esters, propylene glycol mono fatty acid esters, polyoxyethylene propylene glycol mono fatty acid esters, polyoxyethylene sorbitol fatty acid esters, fatty acid alkylolamides, and alkylamine oxides. oxide); bile acids and their salts (e.g., chenodeoxycholic acid, cholic acid, deoxycholic acid, dehydrocholic acid and their salts, and glycine or its taurine conjugates); ionic surfactants such as sodium lauryl sulfate, fatty acid soaps, alkyl sulfonates, alkyl phosphates, ether phosphates, fatty acid salts of basic amino acids; triethanolamine soaps, and alkyl quaternary ammonium salts; and amphoteric surfactants such as betaines and amino carboxylates.

[0130] The solid dosage forms of tablets, dragees, capsules, pills and granules can be prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical formulation art. They can optionally contain opacifying agents and can be of a composition that releases the active ingredient only, or preferentially, and / or in a delayed manner in a certain part of the intestinal tract. Examples of embedding compositions include polymeric substances and waxes.

[0131] The active compounds can also be in microencapsulated form, if appropriate, with one or more of the above-mentioned excipients.

[0132] The active compound may be in finely divided form, for example micronized.

[0133] The liquid dosage form for oral administration includes pharma- ceutically acceptable emulsions, solutions, suspensions, syrups and elixirs.In addition to active compounds, liquid dosage forms may contain inert diluents commonly used in the art, such as water or other solvents, solubilizers and emulsifiers, such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, dimethylformamide, oils (especially cottonseed oil, peanut oil, corn oil, germ oil, olive oil, castor oil and sesame oil), glycerol, tetrahydrofurfuryl alcohol, polyethylene glycol and fatty acid esters of sorbitan and mixtures thereof.In addition to inert diluents, oral compositions may also contain adjuvants, such as wetting agents, emulsifiers and suspending agents, sweeteners, flavorings and aromatics. Suspensions may contain, in addition to the active compound, suspending agents such as ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar, and tragacanth, and mixtures thereof.

[0134] Compositions for rectal or vaginal administration may be in the form of suppositories which can be prepared by mixing the compounds of the present invention with a suitable non-irritating excipient or carrier such as cocoa butter, polyethylene glycol or a suppository wax which is solid at room temperature but liquid at body temperature and therefore will melt in the rectum or vaginal cavity and release the active compound.

[0135] The topical administration dosage form of the compound of the present invention includes powder, spray, cream, foam, gel, ointment and inhalant.The active compound is mixed under sterile conditions with a pharma- ceutically acceptable carrier and any necessary preservative, buffer or propellant that may be required.Ophthalmic preparations, eye ointments, powders and solutions are also considered to be within the scope of the present invention.

[0136] Liquid (e.g., aqueous) formulations and compositions, whether intended for parenteral or oral use, may contain additional compound(s) that help prevent precipitation of active compounds. The compounds of the present invention are glycopeptide derivatives. Precipitation of such compounds in aqueous solutions can be avoided or minimized by including monosaccharides in the solution. For example, aqueous formulations or compositions may contain glucose. In particular, parenteral (e.g., intravenous) formulations or compositions may contain the compounds of the present invention, water for injection, and glucose.

[0137] Formulations or compositions according to the present subject matter may contain other active agents, particularly those intended for use in treating bacterial infections, so long as they do not interfere with the activity of the compound.

[0138] The formulation according to the present subject matter can contain inactive ingredients.Suitable inactive ingredients are well known in the art and are described in standard textbooks, such as Goodman and Gillman: The Pharmacological Bases of Therapeutics, 13th Ed., Brunton et al., Eds. McGraw-Hill Education (2017), and Remington's Pharmaceutical Sciences, 17th Ed., Mack Publishing Co., Easton, Pa. (1990) (both of which are incorporated herein by reference in their entirety).

[0139] The formulation may be used in combination with additional pharmaceutical dosage forms to improve efficacy in treating any of the disorders described herein.In this regard, the formulation may be administered as part of a regimen that additionally includes any other medicament and / or pharmaceutical dosage form known in the art to be effective in treating any of these disorders.

[0140] use The compounds of the present invention are a novel class of polymyxins or polymyxin derivatives. Polymyxins, particularly polymyxin B and colistin, are antibiotics that are active against gram-negative bacteria.

[0141] The compounds provided herein represent antibiotics, particularly antibiotics useful in treating conditions associated with infections caused by gram-negative bacteria.The compounds of the present invention may provide similar or better activity while exhibiting lower nephrotoxicity. The compounds are preferably used to treat bacterial infections, which may be caused by gram-negative or gram-positive bacteria. For example, the bacterial infection may be caused by bacteria from one or more (e.g., at least one) of the following genera: Clostridium, Pseudomonas, Escherichia, Klebsiella, Enterococcus, Enterobacter, Serratia, Stenotrophomonas, Aeromonas, Morganella, or Escherichia. organella, Yersinia, Salmonella, Proteus, Pasteurella, Haemophilus, Citrobacter, Burkholderia, Brucella, Moraxella, Mycobacterium, Streptococcus or Staphylococcus. Specific examples include Clostridium, Pseudomonas, Escherichia, Klebsiella, Enterococcus, Enterobacter, Streptococcus, and Staphylococcus.The bacterial infection may be, for example, Moraxella catarrhalis, Brucella abortus, Burkholderia cepacia, Citrobacter species, Escherichia coli, Haemophilus pneumonia, Klebsiella pneumonia, Pasteurella multocida, Proteus mirabilis, Salmonella typhimurium, Clostridium difficile, Yersinia enterocolitica, or any combination thereof. The infection may be caused by one or more bacteria selected from Mycobacterium tuberculosis, Staphylococcus aureus, group B streptococci, Streptococcus pneumoniae, and Streptococcus pyogenes.

[0142] The compounds of the present invention are particularly useful in the treatment of bacterial infections caused by gram-negative bacteria.

[0143] Assay The compounds of the present invention can be evaluated for biological activity using any suitable assay that would be known to one of skill in the art. Exemplary assays useful for evaluating the compounds of the present invention are provided in the following paragraphs.

[0144] The antibacterial activity of the compounds was tested against a bacterial panel including gram-negative bacteria. The structures and potencies of the resulting compound panel are summarized in Tables A-C below. Particularly preferred compounds include those shown in Tables 1-6 below:

[0145] [Table 1]

[0146] [Table 2]

[0147] [Table 3]

[0148] [Table 4]

[0149] [Table 5]

[0150] [Table 6]

[0151] Particularly preferred compounds include those shown in Table 7 below. [Table 7-1] [Table 7-2]

[0152] The example compounds in Table 7 can be described as having the following features: 1. diaminopropionic acid (Dap) at P3, 2. diaminobutyric acid (Dab) at P3, 3. diaminopropionic acid (Dap) at P3, 4. diaminobutyric acid (Dab) at P3, 5. all-carbon lipid variant with Dap at P3, 6. all-carbon lipid variant with Dab at P3, 7. lipid with substituents adjacent to the disulfide motif and a Dap at P3.

[0153] Synthesis of compounds The compounds of the present invention can be prepared according to the reaction schemes depicted herein below: Scheme 1 (Figure 1) shows a general preparation procedure via the polymyxin nonapeptide, i.e., starting from any polymyxin species, by synthesis of the polymyxin analogue via the polymyxin nonapeptide.

[0154] In Figure 1, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety; Each X independently represents C, S, O or N.

[0155] Additionally, "PG" denotes a protected group, i.e., the protected amine side chain of RA; RB; RC; RD; RE; or RF. Exemplary building blocks are outlined below.

[0156] The enzymatic degradation in Scheme 1 can be carried out by an enzyme capable of cleaving polymyxin between positions 1 and 2, preferably the enzyme is a hydrolase, preferably the enzyme is ficin.

[0157] Scheme 2 (FIG. 2) shows a specific preparation procedure via polymyxin B nonapeptide (PMBN), i.e., preparation by starting from polymyxin B and synthesizing a polymyxin B analogue via polymyxin B nonapeptide.

[0158] In Figure 2, R 2 R represents aminoethyl; 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; R 5 and R 6each independently represents hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O, or N.

[0159] Exemplary building blocks are outlined below. Scheme 3 (FIG. 3) shows a specific preparation procedure via polymyxin E nonapeptide (PMEN), i.e., preparation by starting from polymyxin E and synthesizing a polymyxin E analogue via polymyxin E nonapeptide.

[0160] In Figure 3, R 2 R represents aminoethyl; 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O, or N.

[0161] Exemplary building blocks are outlined below. Scheme 4 (Figure 4) shows the preparation by synthesis of polymyxin analogues containing disulfide tails starting from commercially available polymyxin B.

[0162] The synthesis of these polymyxin analogues according to any one of Schemes 1-4 required a number of building blocks. As exemplified below, the first series of disulfide-containing building blocks prepared consisted of simple aliphatic groups, derivatives of either D-cysteine ​​(D-Cys) or L-cysteine ​​(L-Cys). A wide range of variations in the lipophilic alkyl tail and the level of substitution on the amine were observed. Both Boc-protected compounds (BI-BIV) and compounds with an additional Gly motif (BV-BVIII) were prepared.

[0163] The following compounds are cysteine-based disulfide building blocks with aliphatic tails, and are useful disulfide lipidated tripeptide building blocks with structures BI-BIX, where any polymyxin species can be enzymatically degraded to a nonapeptide and then coupled to an amine side chain protected one (e.g. PMEN(Boc)4 or PMBN(Boc)4) according to any one of Schemes 1-4: [ka]

[0164] Additionally, compounds bearing aromatic substituted tails on the Cys scaffold according to structures BIX-BXV (bottom row, top left to right) were synthesized: [ka]

[0165] Here, the aromatic moiety and the linker between the aromatic moiety and the thiol were varied, either directly attached, as in 4-phenoxybenzenethiol, or attached via an extra methylene linker, as in 4-phenoxyphenyl)methanethiol.

[0166] Analogs that do not contain disulfides were prepared similarly, as well as analogs that have D-penicillamine (D-Pen) in place of D-Cys (BXVI and BXVII): [ka]

[0167] Schemes 1-4 are used to generate the so-called first generation compounds.

[0168] Scheme 5 (Figure 5) shows another general synthetic route of the compounds according to the invention via the polymyxin heptapeptide containing P3 variations, i.e., preparation by synthesizing polymyxin analogues via the polymyxin heptapeptide starting from any polymyxin species.

[0169] In Figure 5, R A ;R B ;R C ;R D ;R E ; and R F each individually represents the side chain of a natural or unnatural α-amino acid, in which any functional groups are protected, preferably A ;R B ;R C ;R D ;R E ; and R F are each individually hydrogen, optionally hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, preferably β-carboxyl or γ-carboxyl, aromatic or heteroaromatic substituents, preferably benzyl, guanidinium or imidazolium, and / or amino groups, preferably ε-NH + represents a branched or linear C1-C4 alkyl group, optionally substituted by R 1 represents an optionally substituted alkyl moiety, an optionally substituted benzyl moiety; R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety; Each X independently represents C, S, O or N.

[0170] Additionally, "PG" refers to a protected group, i.e., R A ;R B ;R C ;R D ;R E ; or R F The protected amine side chain of

[0171] The enzymatic degradation in Scheme 5 may be carried out by an enzyme capable of cleaving polymyxin between positions 3 and 4, preferably wherein said enzyme is a hydrolase, preferably said enzyme is savinase. The term "savinase" is a trademark. Savinase is known by several names, e.g. subtilisin, and is indexed by the International Union of Biochemistry and Molecular Biology (IUBMB) as EC 3.4.21.62.

[0172] The compounds are prepared starting from commercially available polymyxin: after protection and enzymatic cleavage of the amine side chains, a protected polymyxin heptapeptide is obtained, which is further conjugated to separately synthesized building blocks in a convergent synthesis (see FIG. 9, which shows Scheme 9 as an example for its preparation).

[0173] The building blocks can be synthesized using solid-phase peptide synthesis, as shown in FIG. 9 / Scheme 9, which shows a representative synthesis of a trimeric peptide building block used in the preparation of an exemplary second-generation polymyxin analog. The CTC resin is substituted with the desired amino acid and conjugated via its carboxylic acid. Standard solid-phase peptide synthesis (SPPS) methods provide the desired peptide on the resin. This allows for convenient variation of the P3 amino acid, as well as the optional introduction of a disulfide-linked lipid tail. In this set of lipidated tripeptides, the N-terminal cysteine ​​is D-Cys. The lipid or disulfide lipid used in the synthesis of the second-generation analog can be selected from the compounds described above for the first-generation compounds.

[0174] Scheme 6 (FIG. 6) shows a specific preparation procedure via polymyxin B heptapeptide (PMBH) containing P3 variations, i.e., by synthesizing polymyxin B analogs via polymyxin B heptapeptide starting from polymyxin B.

[0175] In Figure 6, R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O, or N.

[0176] The compounds are prepared starting from commercially available polymyxin B. After bocylation and enzymatic digestion with savinase, a tri-Boc protected polymyxin B heptapeptide (PMBH(Boc)3) is obtained, which is further conjugated to separately synthesized building blocks in a convergent synthesis. See FIG. 9 showing scheme 9 for an example of its preparation.

[0177] These so-called second generation analogues are prepared as shown in Scheme 6. Commercially available polymyxin B is first treated with Boc-anhydride to give polymyxins with all free amines Boc-protected. This protected species is subjected to enzymatic digestion with the industrial enzyme savinase to give the heptameric macrocycle PMBH(Boc)3. Methods for the preparation of PMBH(Boc)3 are well known in the literature. Subsequent coupling to a building block, preferably a lipidated tripeptide building block or a building block containing two amino acids attached to a lipid tail bearing an α-amine, followed by global deprotection and purification, gives the second generation analogue.

[0178] The lipidated building blocks were synthesized using solid-phase peptide synthesis, as shown in FIG. 9 / Scheme 9, which shows a representative synthesis of the trimeric peptide building blocks used in the preparation of exemplary second-generation polymyxin analogs. The CTC resin is substituted with the desired amino acid and conjugated via its carboxylic acid. Standard solid-phase peptide synthesis (SPPS) procedures yield the desired peptide on the resin. This allows for variation of the P3 amino acid and the optional introduction of a disulfide-linked lipid tail. In this set of lipidated tripeptides, the N-terminal cysteine ​​is D-Cys. The lipid or disulfide lipid used in the synthesis of the second-generation analogs can be selected from the compounds shown above for the first-generation compounds.

[0179] Scheme 7 (Figure 7) shows a specific preparation procedure via polymyxin E heptapeptide (PMEH) containing P3 variations, i.e., preparation by starting from polymyxin E and synthesizing polymyxin E analogues via polymyxin E heptapeptide.

[0180] In Figure 7, R 2 represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid; R 3 indicates -NH2 or -N(H)-COCH2NH2; R4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; R 5 and R 6 each independently represents hydrogen or an optionally substituted alkyl moiety; each X independently represents C, S, O, or N.

[0181] The compound is prepared starting from commercially available polymyxin E. After boc-ylation and enzymatic digestion with savinase, a tri-Boc-protected polymyxin E heptapeptide (PMEH(Boc)3) is obtained, which is further conjugated to separately synthesized building blocks in a convergent synthesis (see FIG. 9 showing scheme 9 for an example of its preparation).

[0182] These so-called second generation analogues are prepared as shown in Scheme 7 above. Commercially available polymyxin E is first treated with Boc anhydride to obtain a polymyxin species in which all free amines are Boc-protected. This protected species is subjected to enzymatic digestion with the industrial enzyme savinase to obtain the heptameric macrocycle PMEH(Boc)3. The preparation of PMEH(Boc)3 is well known from the literature. Subsequent coupling to a building block, preferably a lipidated tripeptide building block or a building block containing two amino acids attached to a lipid tail bearing an α-amine, followed by global deprotection and purification, gives the second generation analogue.

[0183] The lipidated tripeptide building blocks are synthesized using solid-phase peptide synthesis, as shown in FIG. 9 / Scheme 9, which shows a representative synthesis of the trimeric peptide building blocks used in the preparation of exemplary second-generation polymyxin analogs. The CTC resin is substituted with the desired amino acid and conjugated via its carboxylic acid. Standard solid-phase peptide synthesis (SPPS) procedures yield the desired peptide on the resin. This allows for variation of the P3 amino acid and the optional introduction of a disulfide-linked lipid tail. In this set of lipidated tripeptides, the N-terminal cysteine ​​is D-Cys. The lipid or disulfide lipid used in the synthesis of the second-generation analogs can be selected from the compounds shown above for the first-generation compounds.

[0184] Scheme 8 shows a specific synthetic route for disulfide-linked polymyxins, including P3 variants. In FIG. 8, scheme 8, i.e., the synthesis of disulfide-containing polymyxin variants with a non-standard residue at the designated P3 position, is shown. The compound is prepared starting from commercially available polymyxin B. After boc-ylation and enzymatic digestion with savinase, a tri-Boc-protected polymyxin B heptapeptide (PMBH(Boc)3) is obtained, which is further conjugated to separately synthesized building blocks in a convergent synthesis (see FIG. 9 showing scheme 9 for an example of its preparation).

[0185] These so-called second generation analogues were prepared as shown in Scheme 2. Commercially available polymyxin B is first treated with Boc-anhydride to give polymyxins with all free amines Boc-protected. This protected species is subjected to enzymatic digestion with the industrial enzyme savinase to give the heptameric macrocycle PMBH(Boc)3, the preparation of which is well known in the literature. Subsequent coupling to the required lipidated tripeptide building block, followed by overall global deprotection and purification, gives the second generation analogue.

[0186] As shown in FIG. 9 / Scheme 9, which shows a representative synthesis of trimeric peptide building blocks used in the preparation of second generation polymyxin analogs, the required lipidated tripeptide building blocks were synthesized using solid phase peptide synthesis. The CTC resin was substituted with the desired amino acid and conjugated via its carboxylic acid. The desired peptide was obtained on the resin by standard solid phase peptide synthesis (SPPS) procedures. This allowed for convenient variation of the P3 amino acid and the introduction of the desired disulfide-linked lipid tail. In this set of lipidated tripeptides, the N-terminal cysteine ​​is D-Cys. The disulfide lipids used in the synthesis of the second generation analogs were selected from those compounds shown above for the first generation compounds.

[0187] The second generation compounds have the structure BXX [ka] This includes compounds according to the invention.

[0188] These so-called second generation analogues were prepared as shown in Figure 8. Commercially available polymyxin B is first treated with Boc anhydride to give a polymyxin species in which all free amines are Boc-protected. This protected species is subjected to enzymatic digestion with the industrial enzyme savinase to give the heptameric macrocycle PMBH(Boc)3. The preparation of PMBH(Boc)3 is well known from the literature. Subsequent coupling to the required lipidated tripeptide building block, followed by global deprotection and purification, gives the second generation analogue.

[0189] The requisite lipidated tripeptide building blocks were synthesized using solid phase peptide synthesis (Scheme 9).

[0190] In addition, a series of analogs, designated third generation compounds, were prepared that contain non-amino acid based linkers connecting the nonapeptide and the acyl tail. These analogs share the following linker structure: [ka]

[0191] When substitution of an amino acid at P3 was desired, the compounds were prepared either via PMBN(Boc)4 according to Scheme 2 or Scheme 4 or via PMBH(Boc)3 according to Scheme 6 or Scheme 8. The building blocks were the respective carboxylic acids (for amide formation) (Structure BXXIII) or chloroformates (for carbamate formation) (Structure BXXIV). Preferably, preparation via PMBH(Boc)3 according to Scheme 6 or 8 involves a building block bearing a carboxylic acid or hydroxyl group, preferably a carboxylic acid group, at the point of attachment of the building block to the protected, enzymatically digested polymyxin (Structure BXXV or BXXVI) prior to coupling.

[0192] Structures BXXIII, BXXIV, BXXV and BXXVI are [ka] wherein R represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety, preferably wherein R is an optionally substituted alkyl moiety or an optionally substituted aryl moiety; R' represents hydrogen, hydroxymethyl, aminoethyl, aminomethyl or 5-(2-amino)pentanoic acid. It is.

[0193] Similarly, these third generation compounds can be prepared starting from any polymyxin species according to Scheme 1 or, if substitution of an amino acid at P3 is desired, according to Scheme 5. The building blocks can be the respective carboxylic acids (for amide formation) (Structure BXXIII) or chloroformates (for carbamate formation) (Structure BXXIV). Preferably, the preparation for Scheme 5 involves a building block bearing a carboxylic acid or hydroxyl group, preferably a carboxylic acid group, at the point of attachment of the building block (Structure BXXV or BXXVI) to the protected, enzymatically digested polymyxin prior to coupling.

[0194] Additionally, these third generation compounds can also be prepared via either PMEN(Boc)4 according to Scheme 3 or PMEH(Boc)3 according to Scheme 7. The building blocks can be the respective carboxylic acids (for amide formation) (Structure BXXIII) or chloroformates (for carbamate formation) (Structure BXXIV). Preferably, preparation via PMEH(Boc)3 according to Scheme 7 involves a building block bearing a hydroxyl group at the attachment point of the building block to a protected, enzymatically digested polymyxin (Structure BXXV or BXXVI) prior to coupling.

[0195] In addition, R A -R F Polymyxin analogues with variations in the positions are well known in the literature. In addition, stereochemical variants have also been reported. Such polymyxin analogues are accessible by synthetic means described in the prior art (e.g., ACS Cent Sci. 2021, 7, 126-134. DOI: 10.1021 / acscentsci.0c01135; and Nature 2022, 601, 606-611. DOI: 10.1038 / s41586-021-04264-x). EXAMPLES

[0196] Synthesis of compounds according to the invention Compounds were prepared according to schemes 2, 3, 4, 6, 7 or 8 above, and various sets of compounds with different substitution patterns were prepared. All prepared polymyxin analogues were tested for antibacterial activity against relevant Gram-negative strains (Table B). Polymyxin B and PMBN were used as references. In addition, toxicity on renal proximal tubule epithelial cells (PTEC) was evaluated.

[0197] result Compounds according to the following compound family are hereinafter referred to as first generation compounds and have the general structure (BXIX): [ka] has.

[0198] For clarity, as disclosed above, first generation compounds do not necessarily contain disulfide bonds and need not be based solely on the polymyxin B structure. Tables A, A' and A'' show the MIC values ​​[ug / mL] and relative toxicity values ​​of first generation disulfide-containing polymyxins. Abbreviations used herein are: PMBN: polymyxin B nonapeptide; PTEC: proximal tubular epithelial cells.

[0199] [Table 8]

[0200] [Table 9]

[0201] [Table 10]

[0202] The second generation compound has the structure BXX: [ka] This includes compounds according to the invention.

[0203] An example of a BXX and two examples of BXX in which the acyl tail contains a carbon-carbon bond instead of a disulfide bond are shown in Table B. Table B shows the MIC values ​​[ug / mL] and relative toxicity values ​​of second generation polymyxins. Abbreviations: Dab: diamino-butyric acid; Dap: diaminopropionic acid; PMBN: polymyxin B nonapeptide; PTEC: proximal renal tubule epithelial cells.

[0204] [Table 11-1] [Table 11-2]

[0205] The third generation compounds were also tested for their antibacterial activity against relevant Gram-negative strains (Table C). Polymyxin B and PMBN were used as references. In addition, toxicity against renal proximal tubule epithelial cells (PTEC) was evaluated (see Table C).

[0206] The compounds in Table C were prepared via PMBN(Boc)4 according to Scheme 4, or via PMBH(Boc)3 according to Scheme 8 if amino acid substitution at P3 was desired. The building blocks were the respective carboxylic acids (for amide formation) or chloroformates (for carbamate formation).

[0207] [Table 12]

[0208] The above examples demonstrate that compounds according to the invention demonstrate an excellent relationship between toxicity and antibacterial efficacy, thereby allowing for significant improvements in the usefulness of polymyxin compounds in treating patients.

Claims

1. Formula (III): 【Chemistry 1】 [In the formula, R A ;R B ;R C ;R D ;R E and R F each individually represents the side chain of a natural or unnatural α-amino acid, with any functional groups protected; R 1 represents an optionally substituted alkyl moiety or an optionally substituted benzyl moiety; R 2 represents hydrogen, aminomethyl or 5-(2-amino)pentanoic acid; R 3 is -NH 2 or -N(H)-COCH 2 NH 2 indicates; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety. or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

2. The compound of claim 1, or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, wherein RA; RB; RC; RD; RE; and RF each independently represent hydrogen, branched or straight-chain C1-C4 alkyl optionally substituted by hydroxyl, sulfhydryl, alkylthiol ether, carboxyl, aromatic or heteroaromatic substituents, and / or amino groups.

3. R 1 is 【Chemistry 2】 indicates; R 2 represents aminomethyl; R 3 represents —NH 2 or —N(H)—COCH 2 NH 2 ; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; 2. The compound of claim 1, or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, wherein R5 and R6 each independently represent hydrogen.

4. Formula (IIIa): 【Transformation 3】 [In the formula, R 1 represents an optionally substituted alkyl moiety or an optionally substituted benzyl moiety; R 2 represents hydrogen, aminomethyl or 5-(2-amino)pentanoic acid; R 3 is -NH 2 or -N(H)-COCH 2 NH 2 indicates; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety; or an optionally substituted aryl moiety; R 5 and R 6 each independently represents a hydrogen or an optionally substituted alkyl moiety.

2. The compound of claim 1, or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

5. R 1 is 【Chemistry 4】 indicates; R 2 represents aminomethyl; R 3 represents —NH 2 or —N(H)—COCH 2 NH 2 ; R 4 represents an optionally substituted alkyl moiety, an optionally substituted cycloalkyl moiety, or an optionally substituted aryl moiety; 5. The compound of claim 4, or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, wherein R5 and R6 each independently represent hydrogen.

6. R 1 But C 1 -C 10 Alkyl moiety, C 2 -C 10 or an optionally substituted benzyl moiety: or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

7. R 4 represents a cycloalkyl moiety having from 4 to 20 carbon atoms, wherein said moiety is a monocyclic, bridged, or polycyclic ring, or a pharmaceutically acceptable salt, stereoisomer, solvate, or prodrug thereof.

8. R 4 represents an optionally substituted arylalkyl moiety, an optionally substituted aryl moiety, or a biphenyl moiety, or a pharmaceutically acceptable salt, stereoisomer, solvate, or prodrug thereof.

9. 2. The compound of claim 1, or a pharmaceutically acceptable salt, stereoisomer, solvate, or prodrug thereof, wherein (*) indicates the stereochemistry at the designated carbon atom, each of which may independently be L or D.

10. A pharmaceutical comprising the compound according to any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

11. A pharmaceutical for treating a bacterial infection, comprising a compound according to any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

12. 10. An antibacterial composition comprising a compound according to any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, and a pharmaceutically acceptable carrier.

13. A method for preparing a compound according to any one of claims 1 to 9, comprising: a) removing the side chains from polymyxin by enzymatic digestion with an enzyme capable of breaking the bond between the exocyclic amino acid closest to the fatty acid tail and the middle exocyclic amino acid to obtain a polymyxin nonapeptide macrocycle containing a side chain with a free N-terminal amine group; b) protecting the amino functionality of said ring and leaving the N-terminal amine unprotected to obtain a polymyxin nonapeptide macrocycle containing a protected amine group and a free N-terminal amine group; c) coupling the free N-terminal amine group with a compound to obtain a coupled polymyxin nonapeptide macrocycle containing a protected amine group; and d) removing the protecting group and isolating the resulting compound of formula (III) or formula (IIIa), respectively; A method comprising:

14. A method for preparing a compound according to any one of claims 1 to 9, comprising: a) protecting the amino functional groups of polymyxin to obtain N-protected polymyxin; b) removing the complete side chain from the N-protected polymyxin by enzymatic digestion with an enzyme capable of breaking the bond between the exocyclic amino acid closest to the cyclic heptapeptide and said cyclic heptapeptide to obtain an N-protected polymyxin heptameric macrocycle with a single free amino group; c) coupling the free amino group with a lipidated tripeptide or an N-terminal amide or carbamate linked building block to obtain a coupled polymyxin peptide macrocycle containing a protected amine group; and d) removing the protecting group and isolating the resulting compound of formula (III) or formula (IIIa), respectively; A method comprising:

15. 14. The method of claim 13, wherein the polymyxin is polymyxin B or polymyxin E, the enzyme is a hydrolytic enzyme, and / or the bond is a peptide bond.

16. The method of claim 14, wherein the polymyxin is polymyxin B or polymyxin E, the enzyme is a hydrolytic enzyme, and / or the bond is a peptide bond.

17. The method of claim 13, wherein the polymyxin nonapeptide macrocycle contains four protected amine groups and a free N-terminal amine group, and the coupled polymyxin nonapeptide macrocycle contains four or five protected amine groups.

18. 15. The method of claim 14, wherein the coupled polymyxin peptide macrocycle is a coupled polymyxin nonapeptide or polymyxin decapeptide.

19. A pharmaceutical formulation comprising the compound of any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof.

20. A pharmaceutical composition comprising a compound according to any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, and a pharmaceutically acceptable diluent or carrier.

21. A pharmaceutical formulation or composition for treating a bacterial infection, comprising a compound according to any one of claims 1 to 9 or a pharmaceutically acceptable salt, stereoisomer, solvate or prodrug thereof, wherein the pharmaceutical composition further comprises a pharmaceutically acceptable diluent or carrier.

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