Radiation-activated tetravalent platinum complexes and uses thereof

Abstract

The present disclosure provides a complex of general formula (I), wherein M is a tetravalent platinum; L is independently neutral ligand or anionic ligand at each occurrence; x is an integer of 1-5; P is a precursor ligand, which refers to a ligand of tetravalent platinum ion, which can be released from the complex after irradiation and converted into a functional molecule D to realize the functions of medicine, fluorescence detection or functional materials, etc. x M—P (I).

Description

Technical Field

[0001] This disclosure relates to the field of radiation chemistry, specifically to a radiation-activated tetravalent platinum complex and its uses. Background Technology

[0002] Cancer is the second leading cause of death. Currently, chemotherapy is the primary treatment for cancer in clinical practice. Platinum-based drugs, with their highly effective and broad-spectrum anti-cancer activity, have become important first-line chemotherapy drugs, widely used in the treatment of common malignant tumors such as lung cancer, bladder cancer, ovarian cancer, cervical cancer, esophageal cancer, gastric cancer, colorectal cancer, and head and neck tumors. First-generation platinum-based anticancer drugs are represented by cisplatin; second-generation drugs include carboplatin, nedaplatin, and cycloplatin; and third-generation drugs include oxaliplatin and lobaplatin. These platinum-based anticancer drugs are mainly complexes of divalent platinum. Tetravalent platinum compounds themselves have low killing ability against cancer cells, but they can exert anticancer activity by being reduced and releasing divalent platinum under physiological conditions. This retains the broad-spectrum and highly effective anticancer advantages of traditional divalent platinum drugs, while also bringing unique advantages due to the different coordination structure of tetravalent platinum compared to divalent platinum. Tetravalent platinum has d 2 sp 3 The six-coordinate structure of tetravalent platinum offers greater stability than divalent platinum, resulting in higher blood stability. The axial direction of tetravalent platinum complexes provides two additional ligands, offering more design options for platinum-based drugs. Tetravalent platinum can be structurally modified not only on the lateral ligands but also on the axial ligands, for example, by introducing functional groups such as lipid-water tuning, enzyme-targeting, DNA-targeting, and serum albumin-targeting groups into the axial ligands.

[0003] Extensive research has been conducted on platinum-based compounds, but their drawbacks, such as strong toxicity, low absorption, poor targeting, and severe drug resistance, have become apparent. Therefore, the development of novel platinum-based compounds remains necessary. However, there are currently no reports of incorporating radiation-responsive molecules into the ligands of tetravalent platinum-based compounds.

[0004] Furthermore, no reports have been found of using radiation to release functional molecules from the ligands of tetravalent platinum compounds to achieve functions such as medicine, fluorescence detection, and functional materials. Summary of the Invention

[0005] One aspect of this disclosure provides a metal complex of general formula (I),

[0006] L x ——M——P(I)

[0007] Where M is tetravalent platinum; L is either a neutral ligand or an anionic ligand each time it appears; x is an integer from 1 to 5; P is a precursor ligand, which refers to a ligand of tetravalent platinum ions that can be released from the complex and converted into functional molecule D after irradiation.

[0008] In some embodiments, the functional molecule D is selected from drug molecules, fluorescent molecules, and functional material molecules. In some preferred embodiments, the functional molecule D is an anticancer drug molecule. In some more preferred embodiments, the functional molecule D is an anticancer drug molecule, and at least one L has a group that targets tumor cells. For example, the L with the group that targets tumor cells includes a sugar transporter targeting group, a glutamine receptor targeting group, a phosphate ester receptor targeting group, an epidermal growth factor receptor targeting group, an integrin targeting group, an energy metabolism enzyme targeting group, a mitochondrial targeting group, a serum albumin targeting group, an inflammatory factor targeting group, a DNA targeting group, a histone deacetylase (HDAC) targeting group, a p53 gene activator group, a microtubule inhibitor group, a cyclin-dependent kinase inhibitor group, or an indoleamine 2,3-dioxygenase inhibitor group.

[0009] In some embodiments, the functional molecule D is selected from methylaurestatin E, methylaurestatin F, ibrutinib, acalabrutinib, zanubrutinib, doxorubicin, mitomycin-C, mitomycin-A, daunorubicin, aminopterin, actinomycin, bleomycin, 9-aminocamptothecin, N8-acetylspermethyleneamine, 1-(2-chloroethyl)-1,2-dimethylsulfonylhydrazine, yunnanmycin, gemcitabine, cytarabine, dolalastatin, dacarbazine, 5-fluorouracil; paclitaxel, docetaxel, gemcitabine, cytarabine; 6-mercaptopurine. In some preferred embodiments, the functional molecule D is methylaurestatin E, methylaurestatin F, or 5-fluorouracil.

[0010] In some embodiments, at least one ligand L is selected from: NH3, ethylenediamine, F - Cl - Oxalate, Malonate, 1,2-Diaminocyclohexane, 1,2-Diaminobenzene, 2-Aminopropane, Aminocyclohexane, 1,1-Dicarboxylate cyclobutane, Hydroxyacetate, Lactate, Aminocyclohexane, 2-Isopropyl-4,5-Di(aminomethyl)-1,3-Dioxacyclopentane, 5-Triphenylphosphonium-pentanoate, Succinate, N-Formate pentyl-butenediamide, Porphyrin, Acetate, Propionate.

[0011] In some implementations, a ligand L is an axial ligand that, upon irradiation, can be released from the complex and converted into a functional molecule, which may be the same as or different from the functional molecule D.

[0012] In some implementations, P is an axial ligand.

[0013] In some implementations, P is -OC(=O)-XY, where

[0014] X is -NH-, -NR-, -O-, or -S-, and R is an optional substituted C. 1-10 Alkyl groups, HXY constitute functional molecule D; or

[0015] X is -CH2-, -CRH-, or -CR2-, and R is an independently substituted C each time it appears. 1-10 Alkyl groups, or two R atoms together with their attached carbon atoms to form a 5- or 6-membered ring, constitute the functional molecule D.

[0016] Another aspect of this disclosure also provides the application of the metal complex of the above general formula (I) in the fields of medicine, detection or functional materials, wherein the metal complex of general formula (I) releases functional molecules from the ligand after irradiation to achieve functions such as medicine, fluorescence detection or functional materials. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit the invention.

[0018] Figure 1 The ligand release ratio of 10 μM tetravalent platinum complex 19-31 after irradiation with 60 Gy of X-rays is shown.

[0019] Figure 2 The diagram shows the reaction schematic, fluorescence change graph, and UPLC change graph for screening tetravalent platinum compounds 32, 33, and 34 that are stable in vivo.

[0020] Figure 3 The results of in vivo activation experiments of tetravalent platinum compound 35, based on oxaliplatin, are shown.

[0021] Figure 4 The results of the activation experiment of the radiation-responsive antibody-drug conjugate with platinum as a linker are shown. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0023] This invention may be implemented in other specific forms without departing from its essential attributes. It should be understood that, without conflict, any and all embodiments of this invention can be combined with technical features of any or more other embodiments to obtain further embodiments. This invention includes such combinations to obtain further embodiments.

[0024] All publications and patents mentioned in this disclosure are incorporated herein by reference in their entirety. In the event of any conflict between the use or terminology used in any publications and patents incorporated by reference and the use or terminology used in this disclosure, the use and terminology of this disclosure shall prevail.

[0025] The chapter titles used in this article are for organizational purposes only and should not be construed as limiting the subject matter.

[0026] Unless otherwise specified, all technical and scientific terms used herein have their usual meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0027] Unless otherwise stated, when disclosing or claiming protection for any type of range (e.g., the number of ligands), the intent to separately disclose or claim protection for each possible value that range may reasonably cover, including any subranges included therein. For example, the numerical range of ligand L in this document, such as 1 to 5, indicates integers within that range, where 1-5 should be understood to include 1, 2, 3, 4, 5, as well as the ranges of 1-4 and 1-3.

[0028] This disclosure should be interpreted as consistent with the laws and principles of chemical bonding. In some cases, a hydrogen atom may be removed to accommodate a substituent at a given position.

[0029] As used herein, the words “comprising,” “containing,” or “including” mean that the element preceding the word encompasses the elements listed following the word and their equivalents, without excluding elements not described. The terms “containing” or “comprising (including)” as used herein can be open-ended, semi-closed, or closed-ended. In other words, the terms also include “consistently composed of” or “composed of”.

[0030] The terms “part,” “structural part,” “chemical part,” “group,” and “chemical group” used in this article refer to specific segments or functional groups within a molecule. A chemical part is generally considered to be a chemical entity embedded in or attached to a molecule.

[0031] It should be understood that the singular form used in this disclosure (such as "a") may include plural references unless otherwise specified.

[0032] Unless otherwise specified, this disclosure employs standard nomenclature and standard laboratory procedures and techniques of analytical chemistry, organic synthetic chemistry, and coordination chemistry. Unless otherwise stated, this disclosure employs conventional methods of mass spectrometry and elemental analysis, and the steps and conditions can be referred to conventional operating procedures and conditions in the art.

[0033] The reagents and raw materials used in this disclosure are commercially available or can be prepared by conventional chemical synthesis methods.

[0034] The term "optional" is used herein to describe a situation that may or may not occur. For example, "optionally fused with a ring" means that it is fused with a ring or not fused with a ring. For example, the term "optionally substituted" as used herein means unsubstituted or having at least one non-hydrogen substituent that does not impair the desired properties possessed by the unsubstituted analogue.

[0035] In this disclosure, unless otherwise specified, the number of "substitutes" may be one or more; when there are multiples, there may be two, three, or four. Furthermore, when there are multiple "substitutes," the "substitutes" may be the same or different.

[0036] In this disclosure, the position of "replace" may be arbitrary unless otherwise specified.

[0037] The term "axial ligand" used in this article refers to the d-ligand of tetravalent platinum. 2 sp 3 The two axial ligands in the six-coordinate structure detach from the complex after irradiation reduction.

[0038] The term "lateral ligand" used in this article refers to the d-ligand of tetravalent platinum. 2 sp 3 The four transverse ligands in the six-coordinate structure can remain coordinated with divalent platinum ions after the complex is irradiated and reduced, or they can detach from the complex.

[0039] The term “neutral ligand” or “anionic ligand” as used in this article refers to a ligand that can coordinate with platinum, which is generally uncharged or negatively charged, but may have local cations such as triphenylphosphonium or ammonium groups.

[0040] The term "C1-C" used in this article 10"Alkyl" refers to a straight-chain or branched alkane chain containing 1 to 10 carbon atoms. Representative examples of C1-C6 alkyl groups include, but are not limited to, methyl (C1), ethyl (C2), n-propyl (C3), isopropyl (C3), n-butyl (C4), tert-butyl (C4), sec-butyl (C4), isobutyl (C4), n-pentyl (C5), 3-pentyl (C5), neopentyl (C5), 3-methyl-2-butyl (C5), tert-pentyl (C5), and n-hexyl (C6). The term "lower alkyl" refers to a straight-chain or branched alkyl group having 1 to 4 carbon atoms. "Substituted alkyl" refers to an alkyl group substituted at any available linker with one or more substituents, preferably 1 to 4 substituents. The term "haloalkyl" refers to an alkyl group having one or more halogen substituents, including but not limited to groups such as -CH2Br, -CH2I, -CH2Cl, -CH2F, -CHF2, and -CF3.

[0041] As used herein, the term "alkylene" refers to a divalent hydrocarbon group having two connection points, as described above for "alkyl". For example, methylene is a -CH2- group, and ethylene is a -CH2-CH2- group.

[0042] As used herein, the terms “alkoxy” and “alkylthio” refer to the alkyl group as described above, which is connected via an oxygen bond (-O-) or a sulfur bond (-S-), respectively. The terms “substituted alkoxy” and “substituted alkylthio” refer to the substituted alkyl group, which is connected via an oxygen bond or a sulfur bond, respectively. “Lower alkoxy” is the group OR, where R is a lower alkyl group (an alkyl group containing 1 to 4 carbon atoms).

[0043] The term "halogen" as used in this article refers to fluorine, chlorine, iodine, or bromine.

[0044] The radiation source disclosed herein may be alpha, beta, or gamma rays produced by the decay of radioactive nuclides. X-rays, gamma rays, high-energy electrons, protons, heavy ions, and alpha particles produced by boron neutron capture therapy (BNCT), as well as other possible exogenous or endogenous radiation, produced by external radiation sources may also be applicable to this disclosure.

[0045] The high-energy rays used in radiotherapy possess high spatiotemporal resolution, high tissue penetration capability, and are highly clinically relevant. Utilizing high-energy rays in radiotherapy to activate precursor molecules and initiate chemical reactions in vivo has both basic research value and clinical application value.

[0046] High-energy ray-activated chemical reactions involve the radiation of water to produce a large number of reactive substances, which then react with the target substrate. Among the products of water radiation, the compounds with the highest yields are hydroxyl radicals and hydrated electrons.

[0047] Living organisms generally exist in a reducing environment, where substances such as glutathione and vitamin C quench hydroxyl radicals and increase the production of hydrated electrons. Therefore, utilizing hydrated electrons in chemical reactions would be a major breakthrough in living chemistry.

[0048] High-energy radiation (such as X-rays and gamma rays) can be used as external stimuli to induce chemical reactions in complexes containing precursor ligands, releasing functional molecules. Due to the high penetrating power and high spatiotemporal resolution of radiation, precursor ligands can be activated very effectively by radiotherapy equipment. For example, X-ray irradiation, as an external trigger for activating precursor ligands, allows for precise control of the area, time, and dose at which such precursor ligands are converted to their active forms, because the radiation-induced chemical reactions can be controlled spatially and temporally.

[0049] This disclosure provides a metal complex of general formula (I),

[0050] L x ——M——P(I)

[0051] Where M is tetravalent platinum; L is either a neutral ligand or an anionic ligand each time it appears; x is an integer from 1 to 5; P is a precursor ligand, which refers to a ligand of tetravalent platinum ions that can be released from the complex and converted into functional molecule D after irradiation.

[0052] L can be an axial ligand and / or a transverse ligand in a tetravalent platinum complex. Ligand L is a ligand capable of coordinating with tetravalent or divalent platinum. In a preferred embodiment, the ligand L is a ligand capable of forming a stable complex with tetravalent or divalent platinum. In a more preferred embodiment, the ligand L, as a transverse ligand, retains its ability to form a stable complex with platinum ions after irradiation.

[0053] The choice of x ensures that all L and P ligands satisfy the requirement of a total of six coordinations. When x is 2-5, the x L ligands in the complex can be the same or different. In some embodiments, both L and P are ligands with one coordination, and x is 5. In some embodiments, L is a ligand with one coordination and P is a ligand with two coordinations, and x is 4.

[0054] In some embodiments, the functional molecule D includes, but is not limited to, drug molecules, fluorescent molecules, or functional material molecules. The tetravalent platinum ion complexes of this disclosure are unique in that at least one axial ligand detaches from the complex after irradiation to form the functional molecule. In one embodiment, both axial ligands detach from the complex after irradiation.

[0055] In some embodiments, the functional molecule D is an anticancer drug molecule. In some preferred embodiments, the functional molecule D is an anticancer drug molecule, and at least one L has a group that targets tumor cells. For example, the L with the group that targets tumor cells includes a sugar transporter targeting group, a glutamine receptor targeting group, a phosphate receptor targeting group, an epidermal growth factor receptor targeting group, an integrin targeting group, an energy metabolism enzyme targeting group, a mitochondrial targeting group, a serum albumin targeting group, an inflammatory factor targeting group, a DNA targeting group, a histone deacetylase (HDAC) targeting group, a p53 gene activator group, a microtubule inhibitor group, a cyclin-dependent kinase inhibitor group, or an indoleamine 2,3-dioxygenase inhibitor group.

[0056] In some embodiments, the functional molecule D is selected from methylaurestatin E, methylaurestatin F, ibrutinib, acalabrutinib, zanubrutinib, doxorubicin, mitomycin-C, mitomycin-A, daunorubicin, aminopterin, actinomycin, bleomycin, 9-aminocamptothecin, N8-acetylspermethyleneamine, 1-(2-chloroethyl)-1,2-dimethylsulfonylhydrazine, yunnanmycin, gemcitabine, cytarabine, dolalastatin, dacarbazine, 5-fluorouracil; paclitaxel, docetaxel, gemcitabine, cytarabine; 6-mercaptopurine. In some preferred embodiments, the functional molecule D is methylaurestatin E, methylaurestatin F, or 5-fluorouracil.

[0057] In some embodiments, at least one ligand L is selected from: NH3, ethylenediamine, F - Cl - Oxalate, Malonate, 1,2-Diaminocyclohexane, 1,2-Diaminobenzene, 2-Aminopropane, Aminocyclohexane, 1,1-Dicarboxylate cyclobutane, Hydroxyacetate, Lactate, Aminocyclohexane, 2-Isopropyl-4,5-Di(aminomethyl)-1,3-Dioxacyclopentane, 5-Triphenylphosphonium-pentanoate, Succinate, N-Formate pentyl-butenediamide, Porphyrin, Acetate, Propionate.

[0058] In some implementations, a ligand L is an axial ligand that, upon irradiation, can be released from the complex and converted into a functional molecule, which may be the same as or different from the functional molecule D.

[0059] In some implementations, P is an axial ligand.

[0060] In some implementations, P is - OC(=O)-XY, where

[0061] X is -NH-, -NR-, -O-, or -S-, and R is an optional substituted C. 1-10 Alkyl groups, HXY constitute functional molecule D; or

[0062] X is -CH2-, -CRH-, or -CR2-, and R is an independently substituted C each time it appears. 1-10 Alkyl groups, or two R atoms together with their attached carbon atoms to form a 5- or 6-membered ring, constitute the functional molecule D.

[0063] In one implementation, the optional replacement of C 1-10 Alkyl group is C 1-10 Alkyl groups or C groups substituted with one or more substituents 1-10 Alkyl groups, wherein the substituents include, but are not limited to, halogens, -R1, -NR1R2, -CN, -NO2, -N3, -OR1, -SR1, -NHCOR1, -O-COR1, -CH=CR1R2, -C(=O)-R1, -C(=O)-OR1, -C(=O)-Cl, -C(=O)-NH2, -C(=O)-NH-R1, and -C(=O)-NR1R2, wherein R1 and R2 are independently selected from H, C1-C6 alkyl, C1-C6 haloalkyl, C2-C6 alkenyl, C3-C 10 cycloalkyl, C6-C 20 The aryl group or a heteroaryl group having 5-20 ring atoms, wherein the alkyl, alkenyl, cycloalkyl, aryl, and heteroaryl groups described with respect to the substituents are optionally replaced by one or more halogens, hydroxyl groups, mercapto groups, -NH2, -CN, -NO2, -N3, -NHCOH, -OC(=O)H, -C(=O)H, -C(=O)-OH, -C(=O)-Cl, -C(=O)-NH2, -C(=O)-NH-CH3, -C(=O)-CH3, -C(=O)-OCH3, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 haloalkyl, C2-C6 alkenyl, C3-C 10 cycloalkyl, C6-C 20 Aryl or heteroaryl substitution with 5-20 ring atoms.

[0064] Another aspect of this disclosure also provides the application of the metal complex of the above general formula (I) in the fields of medicine, detection or functional materials, wherein the metal complex of general formula (I) releases functional molecules from the ligand after irradiation to achieve functions such as medicine, fluorescence detection or functional materials.

[0065] In some embodiments, the tetravalent platinum complex of this disclosure serves as a precursor to a divalent platinum drug, which is reduced by hydrated electrons generated by irradiation to obtain a divalent platinum product that has pharmacological activity, such as anticancer activity. On the other hand, one or two axial ligand molecules of the tetravalent platinum complex undergo a chemical reaction upon irradiation to release one or two functional molecules, which synergistically exert pharmacological activity with the divalent platinum product. This reduces the effective dosage of the tetravalent platinum complex and thus reduces the toxic side effects of the drug.

[0066] In some embodiments, the tetravalent platinum complexes of this disclosure may incorporate targeting groups into the axial or transverse ligands, thereby enhancing the targeting of the platinum compounds. For example, targeting groups such as sugar transporter targeting, glutamine receptor targeting, phosphate receptor targeting, epidermal growth factor receptor targeting, integrin targeting, energy metabolism enzyme targeting, mitochondrial targeting, serum albumin targeting, inflammatory factor targeting, DNA targeting, histone deacetylase (HDAC) targeting, p53 gene activator, tubulin inhibitor, cyclin-dependent kinase inhibitor, and indoleamine 2,3-dioxygenase inhibitor may be incorporated into the axial or transverse ligands of the tetravalent platinum complexes to enhance targeting. For details, please refer to the entire contents of the journal Progress in Chemistry, 2018, Vol. 30(6), pp. 831-846, which are incorporated herein by reference.

[0067] In one embodiment, an antibody molecule or peptide is introduced into a lateral or axial ligand of tetravalent platinum. For example, see Green Chem., 2020, 22, 2203–2212 for details on introducing antibody molecules or peptides into ligands.

[0068] In one embodiment, Herceptin is introduced into the axial or transverse ligand of the tetravalent platinum complex. In a preferred embodiment, Herceptin is introduced into the axial ligand of the tetravalent platinum complex.

[0069] In one embodiment, the targeting ligand may contain a maleimide group, wherein the maleimide group is linked to an antibody or peptide thiol group.

[0070] In one embodiment, the targeting ligand may contain a succinimide group, wherein the succinimide group is linked to an antibody or peptide amino group.

[0071] In one implementation, the ligand that performs the targeting function can be a peptide molecule with targeting function, such as prostate-specific membrane antigen (PSMA), arginine (R)-glycine (G)-aspartic acid (D) tripeptide, chemokine receptor (CXCR4), etc.

[0072] In one embodiment, the targeting ligand is a lateral ligand or an axial ligand. In a preferred embodiment, the targeting ligand is an axial ligand.

[0073] In some embodiments, the metal complex of general formula (I) is a tetravalent platinum complex as shown below.

[0074]

[0075] H-OC(O)-XY or HXY are functional molecules.

[0076] Axial ligand L5 is also a leaving group, which can be divided into three categories: 1. Non-functional capping agents, such as acetic acid and other molecules that do not have therapeutic or targeting effects; 2. Molecules that have targeting effects, which can be maleimide-containing molecules used to link with antibody or peptide thiol groups; molecules containing succinimide used to link with antibody or peptide amino groups; or molecules that have targeting effects and are directly linked to peptide molecules, such as PSMA, RGD, CXCR4, etc.; 3. Molecules that have therapeutic effects, which are the same as or different from another axial ligand and can play a synergistic role with two drugs.

[0077] In one embodiment, ligand P in the complex is obtained by the reaction shown below.

[0078]

[0079] The target product is obtained by stirring hydroxylated tetravalent platinum and an equimolar amount of the active ester in dimethyl sulfoxide at room temperature (e.g., room temperature) for 24 hours. The solid is then lyophilized in a solvent and purified by washing it sequentially with an organic solvent such as diethyl ether and ethanol. The active ester can be commercially available or prepared using conventional organic chemical synthesis methods. For example, the active ester can be prepared by the following methods.

[0080] Where X is NH, NR, O or S.

[0081] Y-XH was dissolved in dichloromethane, and an equivalent amount of disuccinimide carbonate was added, followed by an equivalent amount of diisopropylethylamine (DIPEA). The mixture was reacted for 12 hours, and the active ester was obtained by purification by silica gel column chromatography.

[0082] Where X is CH2, CRH or CR2.

[0083] Dissolve carboxylic acid YX-COOH in dichloromethane, add two equivalents of diisopropylethylamine, add an equivalent amount of condensing agent 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI), and then add N-hydroxysuccinimide. React for 12 hours, and the active ester can be obtained by purification by silica gel column chromatography.

[0084] In one embodiment, this disclosure uses a drug containing a primary or secondary amine as the functional molecule. In a preferred embodiment, this disclosure uses an anticancer drug containing a primary or secondary amine as the functional molecule. Drugs containing primary or secondary amines include, for example, ibrutinib, acalatinib, zanubrutinib, doxorubicin, mitomycin-C, mitomycin-A, daunorubicin, aminopterin, actinomycin, bleomycin, 9-aminocamptothecin, N8-acetylspermine, 1-(2-chloroethyl)-1,2-dimethylsulfonylhydrazine, yunnanmycin, gemcitabine, cytarabine, dolalastatin, dacarbazine, 5-fluorouracil, and derivatives thereof. Drugs containing primary or secondary amines also include amino derivatives of drugs that naturally do not contain an amino group. In other words, drugs that originally did not contain an amino group can be chemically modified to have an amino group, and then an active ester can be prepared from the primary or secondary amine and then reacted with hydroxylated tetravalent platinum to obtain... - Tetravalent platinum coordinated with O(O)CXY ligands.

[0085] In a preferred embodiment, the functional molecule is methylauratestatin E.

[0086] In one embodiment, this disclosure uses a hydroxyl-containing drug as the functional molecule. In a preferred embodiment, this disclosure uses a hydroxyl-containing anticancer drug as the functional molecule. Examples of hydroxyl-containing functional molecules include paclitaxel, docetaxel, gemcitabine, and cytarabine. Hydroxyl-containing functional molecules also include hydroxyl derivatives of naturally occurring drugs that do not contain hydroxyl groups. In other words, a drug that originally does not contain hydroxyl groups can be chemically modified to have hydroxyl groups, and then an active ester can be prepared from the hydroxyl groups and reacted with hydroxylated tetravalent platinum to obtain... - Tetravalent platinum coordinated with O(O)CXY ligands.

[0087] In one embodiment, this disclosure uses a thiol-containing drug as the functional molecule. In a preferred embodiment, this disclosure uses a thiol-containing anticancer drug as the functional molecule. Thiol-containing functional molecules include, for example, 6-mercaptopurine. Thiol-containing functional molecules also include thiol derivatives of drugs that do not naturally contain thiol groups. In other words, a drug that originally did not contain thiol groups can be chemically modified to have thiol groups, and then an active ester can be prepared from the thiol group and reacted with hydroxylated tetravalent platinum to obtain... - Tetravalent platinum coordinated with O(O)CXY ligands.

[0088] Similar to drug molecules, other functional molecules can also be used to prepare active esters, which are then reacted with hydroxylated tetravalent platinum to obtain... - Tetravalent platinum coordinated with O(O)CXY ligands.

[0089] Example

[0090] The starting materials used in the examples were commercially available and / or could be prepared using various methods well known to those skilled in the art of organic synthesis. Those skilled in the art of organic synthesis will appropriately select the reaction conditions (including solvent, reaction atmosphere, reaction temperature, duration of the experiment, and post-treatment) from the synthetic methods described below. Those skilled in the art of organic synthesis will understand that the functional groups present on the various parts of the molecule should be compatible with the proposed reagents and reactions. NMR was recorded using a Bruker AVANCE 400MHz spectrometer. High-resolution mass spectrometry was performed using a Bruker Fourier Transform Ion Cyclotron resonance mass spectrometer. The liquid chromatography-mass spectrometry used was a Waters e2695 system equipped with a Waters 2995PDA and a Waters Acquity QDA mass spectrometer.

[0091] Changes in the valence state of metal ions involve electron transfer. We first conducted high-energy ray-driven chemical reaction studies on a large number of metal ions and metal complexes.

[0092] The following metal salts and metal complexes were screened:

[0093]

[0094] Experimental Procedure: The compound was dissolved in ultrapure water to prepare a 100 μM metal compound solution, while oxygen was removed from the solution by purging with nitrogen for 15 minutes. The deoxygenated metal solution was then irradiated with X-rays from a radiotherapy instrument (RAD·SOURCE, model RS 2000-225, irradiation parameter 4 Gy / min) at doses ranging from 0 to 1000 Gy. Finally, the amount of raw material remaining was measured, the concentration of reactant disappearance was calculated, and the radiation yield was calculated (radiation yield = concentration of reactant disappearance / radiation dose).

[0095] Table 1. Yields of metal compounds reduced by irradiation

[0096] Sample code and sample name Production (nM / Gy) 1 (Sodium chloride) -(No metal cation reduction reaction occurs) 2 (potassium chloride) -(No metal cation reduction reaction occurs) 3 (Dicopotassium hydrogen phosphate) -(No metal cation reduction reaction occurs) 4 (Magnesium chloride) -(No metal cation reduction reaction occurs) 5 (ferric chloride) 578 6 566 7 572 8 (potassium permanganate) 64 9 (potassium dichromate) 87 10 (nickel chloride) 347 11 655 12 478 13 (Copper sulfate) 209 14 (Silver Nitrate) 576 15 (Vitamin B12) 553 16 (Iron Porphyrin) 598 17 575 18 427

[0097] Summarizing the above results, it was found that compounds with two or more stable valence states in aqueous solution can be reduced. Furthermore, the experiments revealed that for metal complexes, the reduction of metal ions usually leads to changes in the complex structure, and may even release ligand compounds.

[0098] Molecular synthetic route:

[0099] Molecules 1 through 17 are all commercially available compounds.

[0100] General synthetic route for molecules 19–28:

[0101]

[0102] Commercially available divalent platinum (1 mmol) was reacted with 3 mL of hydrogen peroxide for 3 hours, and the mixture was filtered to obtain dihydroxylated tetravalent platinum. The target compound was obtained by reacting the tetravalent platinum with the active ester of triphenylphosphonium (2.2 mmol).

[0103] Mass spectrometry detection of compound 19: 511.62 (carrying two positive charges)

[0104] Mass spectrometry detection of compound 20: 547.66 (with two positive charges)

[0105] Mass spectrometry detection of compound 21: 560.67 (carrying two positive charges)

[0106] Mass spectrometry detection of compound 22: 513.65 (with two positive charges)

[0107] Mass spectrometry detection of compound 23: 560.69 (carrying two positive charges)

[0108] Mass spectrometry detection of compound 24: 597.69 (carrying two positive charges)

[0109] Mass spectrometry detection of compound 25: 551.65 (with two positive charges)

[0110] Mass spectrometry detection of compound 26: 553.67 (with two positive charges)

[0111] Mass spectrometry detection of compound 27: 553.16 (carrying two positive charges)

[0112] Mass spectrometry detection of compound 28: 511.62 (carrying two positive charges)

[0113] General synthetic route for molecules 29-31:

[0114] The target product 29-31 is obtained by reacting hydroxylated tetravalent platinum with an equivalent amount of active ester and then adding two equivalents of succinic anhydride.

[0115]

[0116] Mass spectrometry detection of compound 29: 675.06 (with a negative charge)

[0117] Mass spectrometry detection of compound 30: 747.16 (with a negative charge)

[0118] Mass spectrometry detection of compound 31: 773.17 (with a negative charge)

[0119] General synthetic route for molecules 32-34:

[0120]

[0121] The target product 32-34 is obtained by reacting hydroxylated tetravalent platinum with an equivalent amount of active carbamate and then adding two equivalents of succinic anhydride.

[0122] Mass spectrometry detection of compound 32: 633.01 (with a negative charge)

[0123] Mass spectrometry detection of compound 33: 705.10 (with a negative charge)

[0124] Mass spectrometry detection of compound 34: 731.11 (carrying a negative charge)

[0125] Synthetic steps of molecule 35

[0126]

[0127]

[0128] Oxaliplatin is oxidized to obtain tetravalent platinum, which is then reacted with an equivalent amount of active ester, and then reacted with an equivalent amount of active carbamate to obtain product 35.

[0129] Molecular 35 mass spectrometry detection: 1047.35 (carrying a positive charge)

[0130] Synthesis of molecules 36-38

[0131]

[0132] Commercially available oxaliplatin (10 mmol) was reacted with 30 mL of hydrogen peroxide for 3 hours, and the mixture was filtered to obtain dihydroxylated tetravalent platinum.

[0133] Compound 37 was obtained by reacting tetravalent platinum with the active ester of maleimide (12 mmol) in 10 mL DMF for 12 hours. The compound was then purified by silica gel column chromatography with DCM:MeOH = 9:1 as the eluent.

[0134] Compound 37 was dissolved in DMF, and succinimide carbonate (24 mmol) was added. After reacting for 6 hours, compound 38 was obtained. The compound was then purified and separated by silica gel column chromatography with DCM:MeOH = 20:1 as the eluent.

[0135] Compound 38 was dissolved in DMF, and 10 mmol of MMAE was added. After reacting for 24 hours, compound 36 was obtained. It was then purified and separated by silica gel column chromatography with DCM:MeOH = 20:1 as the eluent.

[0136] Mass spectrometry detection of molecule 37: 625.14 (plus a positive ion peak of hydrogen).

[0137] Mass spectrometry detection of molecule 38: 766.15 (plus a positive ion peak of hydrogen).

[0138] Molecular 36 mass spectrometry detection: 1368.62 (plus a positive ion peak of hydrogen).

[0139] We investigated the feasibility of this radiation-activated mechanism in vivo using platinum complexes. First, we irradiated the tetravalent platinum complexes with high-energy rays, demonstrating that the reaction has a broad spectrum for platinum-based drugs. The results are as follows: Figure 1 As shown.

[0140] Experimental Procedure: A 10 μM solution of the tetravalent platinum complex was prepared by dissolving it in ultrapure water, while nitrogen gas was purged to remove oxygen. The deoxygenated tetravalent platinum complex solution was then subjected to X-ray irradiation using a radiotherapy instrument (RAD·SOURCE, model RS 2000-225, irradiation parameters 4 Gy / min), receiving X-ray doses ranging from 0 to 60 Gy. The peak area of ​​the newly formed axial ligand was detected by ultra-high performance liquid chromatography (UHPLC), and the release amount of axial ligand during irradiation was determined using a standard curve of peak area versus concentration of the pure ligand in UHPLC.

[0141] The experimental results of ligand release ratio (actual amount of axial ligands released after reaction / theoretically complete amount of axial ligands released) of 10 μM tetravalent platinum complex 19-31 after irradiation with 60 Gy of X-rays are as follows: Figure 1 As shown. Radiation activation detection of molecules 19 to 31 confirmed the widespread applicability of reducing tetravalent platinum metal complexes with high-energy rays and releasing axial ligands.

[0142] To apply this radiation-activated chemical reaction in vivo, a key issue must be addressed: ensuring the stability of the complex in the reducing environment of the tumor. Among the FDA-approved platinum-based drugs—cisplatin, carboplatin, and oxaliplatin—are there any tetravalent platinum precursors that specifically stabilize the tumor's reducing environment in vivo? Furthermore, is this approach limited to releasing carboxyl ligands? Since many drugs contain amino groups, compounds 32, 33, and 34 were used for stability screening. The results are as follows: Figure 2 As shown.

[0143] Experimental Procedure: Compounds 32, 33, and 34 were dissolved in pure water to prepare 10 μM solutions, while nitrogen gas was passed through to remove oxygen. The deoxygenated tetravalent platinum complex solutions were then subjected to X-ray irradiation using a radiotherapy instrument (RAD·SOURCE, model RS 2000-225, irradiation parameters 4 Gy / min) at doses ranging from 0 to 60 Gy. The release of axial ligands was detected by ultra-high performance liquid chromatography (UHPLC). The results of the compounds' response to high-energy radiation were thus obtained.

[0144] Compounds 32, 33, and 34 were dissolved in pure water to prepare 10 μM solutions. Oxygen was removed from the solutions, and then endogenous reducing agent vitamin C was added to achieve a vitamin C concentration of 2 mM. The solutions were incubated for 24 hours, and the release of axial ligands at different time points was measured. This determined the stability of the compounds in a reducing environment.

[0145] Oxaliplatin was used as the parent tetravalent platinum complex to prepare a 10 μM solution. After removing oxygen from the solution, various types of endogenous reducing agents (cysteine, glutathione, and reduced nicotinamide adenine dinucleotide phosphate) at different concentrations were added. The stability of the compound against endogenous reducing agents in both cellular and in vivo environments was then determined.

[0146] Figure 2 Experimental results were obtained to screen tetravalent platinum compounds 32, 33, and 34 for in vivo stability. Figure 2 In the diagram, (A) shows the structures of the three platinum compounds used in the study; (B), (G), and (I) are schematic diagrams of the reactions of these three tetravalent platinum compounds; (C) is a fluorescence change diagram after molecule 34 is co-incubated with Vc, showing that molecule 34 is relatively stable in the presence of Vc and no reduction reaction occurs; (D) is a fluorescence change diagram after molecule 34 is irradiated, showing that the relative fluorescence intensity is linearly correlated with the irradiation dose; (E) is a UPLC change diagram after molecule 34 is co-incubated with Vc, showing that no new coumarin peak is generated after molecule 34 is co-incubated with Vc; (F) is a UPLC change diagram after molecule 34 is irradiated, showing that the axial ligand coumarin is gradually released as the irradiation dose increases during the irradiation process; (H) is a fluorescence change diagram after molecule 32 is co-incubated with Vc; and (J) is a fluorescence change diagram after molecule 33 is co-incubated with Vc.

[0147] After confirming the stability of compounds with oxaliplatin as the parent molecule and their in vitro activation by high-energy radiation, the feasibility of this activation mechanism in vivo was investigated. Molecule 35 was designed; its activation releases ligands that emit near-infrared fluorescence, which can be used for non-destructive determination of axial ligand release at the in vivo level. Experimental results are as follows... Figure 3 As shown.

[0148] Experimental steps:

[0149] Test tube experiment: A 10 μM solution of molecule 35 was prepared by dissolving it in pure water, while simultaneously removing oxygen from the solution. The deoxygenated tetravalent platinum complex solution was then irradiated with X-rays from a radiotherapy device (RAD·SOURCE, model RS 2000-225, irradiation parameters 4 Gy / min), receiving doses ranging from 0 to 60 Gy. Changes in the fluorescence signal of the solution were then detected using a small animal imaging system.

[0150] Cellular experiments: A 10 μM solution of molecule 35 was prepared by dissolving it in HBSS buffer, while simultaneously removing oxygen from the solution. Cells were then co-incubated with the buffer and subsequently irradiated with X-rays from a radiotherapy device at doses ranging from 0 to 16 Gy. The fluorescence signal of the cells was detected using confocal microscopy.

[0151] In vivo experiments: A 20 mM stock solution was prepared by dissolving molecule 35 in DMSO. 20 μL of a phosphate buffer solution (pH = 7.4) containing 1% DMSO was injected into the tumor area of ​​mice, with a 35 concentration of 200 μM. The tumor area was then irradiated with X-rays at doses of 0, 4, and 12 Gy. The fluorescence pattern of the tumor area was then detected using a small animal imaging system.

[0152] Figure 3 This study investigated the in vivo activation of tetravalent platinum, with oxaliplatin as the parent compound. Figure 3 In the image, (A) is a schematic diagram of the structure and activation of molecule 35; (B) is a schematic diagram of the release of axial ligands from molecule 35 in a test tube; (C) is a confocal image of molecule 35 activated in a cellular environment; and (D) is a small animal imaging image of molecule 35 activated in a mouse tumor model.

[0153] Experimental results show that molecule 35 can be reduced and released in vivo by high-energy rays in vitro, in cells, and in mouse models, and this release strategy has been conceptually proven.

[0154] Activating chemotherapy drugs through radiotherapy aligns with the goals of precision medicine, and antibody-drug conjugates (ADCs) can achieve this goal. Oxaliplatin was used as a linker to prepare the prodrug compound 36. 36 was then linked to the antibody Herceptin to prepare the ADC. Mouse therapeutic experiments were conducted on this ADC, and the results are as follows... Figure 4 As shown.

[0155]

[0156] Experimental steps:

[0157] Preparation of antibody-drug conjugates (ADCs): Add 200 μL of phosphate buffer solution to a 1.5 mL centrifuge tube, followed by 100 μL of 50 mg / mL Herceptin solution, and then 75 μL of 1 mM TECP. React for 1.5 h to open disulfide bonds. Next, add 35 μL of 10 mM DMSO solution of compound 36 to the reaction mixture and react for 1 h. Remove unreacted small molecules by ultrafiltration and centrifugation to obtain the antibody-drug conjugate complex.

[0158] In vitro release assay of antibody-drug conjugates: The prepared antibody-drug conjugates were diluted to 50 nM and irradiated with 0–16 Gy of X-rays (RAD·SOURCE, model RS 2000-225, irradiation parameters 4 Gy / min). The mass spectrometry signal intensity of the functional molecule MMAE was detected by mass spectrometry, and the release amount of MMAE was determined by the external standard curve, i.e., the MMAE concentration-mass spectrometry signal intensity curve.

[0159] Cytotoxicity assay: Cells were incubated with different concentrations of antibody-drug conjugates and irradiated with different doses of X-rays to determine the half-maximal inhibitory concentration of the antibody-drug conjugates against cancer cells under different conditions.

[0160] Animal treatment experiment: Mice were divided into four groups. The first group was injected with PBS solution only; the second group was injected with PBS and then irradiated with X-rays; the third group was injected with platinum antibody-drug conjugate only; and the fourth group was injected with antibody-drug conjugate and then irradiated with X-rays. Tumor volume was measured.

[0161] Figure 4 This is a radiation-responsive antibody-drug conjugate using platinum as a linker. Figure 4 In the image, (A) is a schematic diagram of the activation and release of MMAE by antibody-drug conjugate (ADC); (B) is an in vitro release experiment of 50 nM antibody-drug conjugate; (C) is an antibody-drug conjugate cytotoxicity experiment; (D) is a mouse body weight change curve; (E) is a mouse tumor growth curve; (F) is a tumor image on day 24; and (G) is a tumor mass graph on day 24.

[0162] This treatment method can significantly inhibit tumor growth and has extremely high clinical application value.

[0163] The embodiments of this disclosure illustrate in principle the feasibility of a strategy for releasing functional molecules from irradiated tetravalent platinum complexes. Furthermore, the embodiments of this disclosure use MMAE functional molecules as a model to illustrate the feasibility of a strategy for releasing drug molecules from irradiated tetravalent platinum complexes. The embodiments of this disclosure also demonstrate a good linear relationship between the concentration of functional molecules released from the complex and the dose.

[0164] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the scope of protection of the present invention, which is determined by the appended claims.

Claims

1. A metal complex, wherein the metal complex is selected from... or The metal complex releases axial ligands after being irradiated and reduced, wherein the irradiation is X-rays or gamma rays.

Images