Camphor modified peptides, methods of making and using the same

Abstract

Provided are camosol-modified peptide compounds, preparation methods, pharmaceutical compositions, and uses thereof, the compounds being prepared by chemical coupling of camosol and a polypeptide. The compounds can dissolve thrombus and have the use of brain ischemia protection.

Description

Technical Field

[0001] This disclosure pertains to the field of biomedicine and relates to various camphor-modified peptide compounds, their preparation methods, and their applications in pharmaceutical manufacturing and disease treatment. Background Technology

[0002] In recent years, the incidence of thrombotic diseases, especially ischemic stroke, has been gradually increasing. Recurrence of stroke can lead to aggravation of existing neurological dysfunction, disability, and a significant increase in mortality, seriously threatening human health. Therefore, drug treatment of thrombotic diseases is a key focus and hot topic in the treatment of ischemic stroke.

[0003] Ischemic stroke, also known as apoplexy, develops through multiple mechanisms, including the activation of glutamate receptors, which facilitates glutamate release and calcium ion influx, thereby activating nitric oxide, cysteine ​​proteases, and other proteases. This leads to inflammation, free radical production, and protein damage that causes neuronal apoptosis (Rogalewski et al., 2006). Other key features of stroke include blood-brain barrier (BBB) ​​damage, oxidative stress, cytokine-mediated toxicity, excitotoxicity, and neuronal dysfunction (Kuriakose and Xiao, 2020). The simultaneous activation of multiple pathways makes the treatment of ischemic stroke and neurological impairment challenging. Therefore, ischemic protection is of great value in the treatment of thrombotic diseases, and there is an urgent need for compounds suitable for thrombotic diseases to provide ischemic protection. Summary of the Invention

[0004] This disclosure provides camphenol-modified peptide compounds that have cerebral ischemia-protective applications, which can alleviate or reduce neurological symptoms and brain tissue damage caused by cerebral ischemia.

[0005] A first aspect of this disclosure provides a compound or its prodrug, tautomer, optical isomer, geometric isomer, solvate or pharmaceutically acceptable salt thereof, comprising a camphene moiety and a polypeptide moiety coupled to said camphene, said polypeptide moiety comprising Pro-Ala-Lys (PAK), Ala-Lys-Pro (AKP) or Lys-Ala-Pro (KAP).

[0006] In some embodiments, the compound has a structure as shown in Formula I: Formula I Where L represents the connector, P 1 This indicates the polypeptide portion.

[0007] In some embodiments, the polypeptide portion of the compound is derived from a polypeptide having thrombolytic activity and / or free radical scavenging activity.

[0008] In some embodiments, the linker L of the compound is connected to the polypeptide moiety P. 1 The N-terminal covalent connection.

[0009] In some embodiments, the linker L of the compound is linked to the hydroxyl group of camphene alcohol by an ester bond.

[0010] In some embodiments, the camphene in the compound is dextrocamphene.

[0011] In some embodiments, the compound has a structure as shown in Formula II: Formula II Where 0 and 1 represent the number of H atoms; when the number of H atoms is 1, -NH- represents the imino group at the N-terminus of the polypeptide moiety; when the number of H atoms is 0, N represents the cyclic nitrogen atom at the N-terminus of the polypeptide moiety. P indicates the polypeptide moiety excluding the N-terminus -N(H). 0,1 - Other polypeptide residues.

[0012] In some embodiments, the polypeptide moiety includes one, two, or three repeating sequence peptides with at least one of Pro-Ala-Lys, Ala-Lys-Pro, and Lys-Ala-Pro as structural units.

[0013] In some embodiments, the polypeptide portion of the compound is a tripeptide, tetrapeptide, pentapeptide, hexapeptide, heptapeptide, octapeptide, nonapeptide, decapeptide, or undecapeptide.

[0014] In some embodiments, the polypeptide moiety includes a dipeptide fragment β-Ala-His, Arg-Gly located at the N-terminus of the Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro fragment, or a His-β-Ala, Arg-Gly located at the C-terminus.

[0015] In some embodiments, the polypeptide portion further includes a Lys residue covalently linked to a linker, optionally with the C-terminus of the Lys residue linked to an Arg-Gly-Asp-Ser or Ile-Glu-Ser-Asp-Val fragment.

[0016] In some embodiments, a peptide fragment including Lys-Ala-Pro is linked to the Lys residue.

[0017] In some embodiments, one or more sites of the C-terminus, N-terminus, and intermediate residues of the polypeptide moiety are modified with polyethylene glycol (PEG), optionally, the PEG is selected from one or more of PEG2 to PEG24.

[0018] In some embodiments, the N-terminal residues of the polypeptide moiety include a PEG modification selected from PEG2, PEG4, PEG8, PEG12 or PEG24, and optionally, the PEG modification is linked to a linker.

[0019] In some embodiments, the polypeptide of the compound comprises one or more of the following polypeptide fragments: Pro-Ala-Lys, Lys-Ala-Pro, β-Ala-His-Lys-Ala-Pro, β-Ala-His-Pro-Ala-Lys, Gly-Arg-Pro-Ala-Lys, PEG4-Pro-Ala-Lys, Lys(Lys-Ala-Pro)-Arg-Gly-Asp-Ser, Lys(Lys-Ala-Pro-His-β- Ala)-Arg-Gly-Asp-Ser, Lys(Lys-Ala-Pro-Arg-Gly)-Arg-Gly-Asp-Ser, Lys(Lys-Ala-Pro)-Ile-Glu-Ser-Asp- Val, Lys(Lys-Ala-Pro-His-Ala-β)-Ile-Glu-Ser-Asp-Val or Lys(Lys-Ala-Pro-Arg-Gly)-Ile-Glu-Ser-Asp-Val.

[0020] The second aspect of this disclosure provides a method for preparing the aforementioned compound, comprising: preparing an intermediate including an ester bond by reacting camphene with a coupling agent under reaction conditions, wherein the intermediate is sequentially bonded to a corresponding amino acid, and purified to obtain the compound.

[0021] A third aspect of this disclosure provides a pharmaceutical composition comprising the aforementioned compound or a compound prepared by the aforementioned methods, and one or more pharmaceutically acceptable excipients.

[0022] This disclosure provides, in its fourth aspect, the use of the aforementioned compounds, compounds prepared by the aforementioned methods, or pharmaceutical compositions in the preparation of thrombolytic, free radical scavenging, or anti-inflammatory drugs.

[0023] In some embodiments, the application includes the use of the compound or pharmaceutical composition in the preparation of a cerebral ischemia-protective drug.

[0024] In some embodiments, the compound or pharmaceutical composition has use in the preparation of a medicament for treating thrombotic diseases.

[0025] In some embodiments, the thrombotic diseases include ischemic stroke, myocardial infarction, stroke, venous thrombosis, pulmonary embolism, peripheral arterial occlusive disease, ductus venosus obstruction, arteriovenous fistula and shunt obstruction, and carotid artery stenosis.

[0026] The fifth aspect of this disclosure provides a method for treating a subject suffering from a thrombotic disease, comprising administering to the subject an effective amount of the aforementioned compound, the compound prepared by the aforementioned method, or the aforementioned pharmaceutical composition.

[0027] The sixth aspect of this disclosure provides a method for improving cerebral ischemia, cerebral thrombosis, free radical status, or inflammatory status in a subject, comprising administering to the subject in need an effective amount of the aforementioned compound, the compound prepared by the aforementioned method, or the aforementioned pharmaceutical composition. Attached Figure Description

[0028] Figure 1 The mass spectrum of camphene-linker-Pro-Ala-Lys in Example 2 is shown. Figure 2 The mass spectrum of camphene-linker-Lys-Ala-Pro in Example 3 is shown. Figure 3 The mass spectrum of camphene-linker-β-Ala-His-Lys-Ala-Pro in Example 4 is shown. Figure 4 The mass spectrum of camphene-linker-β-Ala-His-Pro-Ala-Lys in Example 5 is shown. Figure 5 The mass spectrum of camphene-linker-Gly-Arg-Pro-Ala-Lys in Example 6 is shown. Figure 6 The mass spectrum of camphene-linker-PEG4-Pro-Ala-Lys in Example 7 is shown. Figure 7 The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro)-Arg-Gly-Asp-Ser in Example 8 is shown. Figure 8 The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro-His-β-Ala)-Arg-Gly-Asp-Ser in Example 9 is shown. Figure 9 The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Arg-Gly-Asp-Ser in Example 10 is shown. Figure 10 The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro)-Ile-Glu-Ser-Asp-Val in Example 11 is shown. Figure 11The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro-His-Ala-β)-Ile-Glu-Ser-Asp-Val in Example 12 is shown. Figure 12 The mass spectrum of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Ile-Glu-Ser-Asp-Val in Example 13 is shown. Figure 13 The effect of the test drug in Example 14 on the neurological symptom scores of MCAO rats is shown. Detailed Implementation

[0029] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification.

[0030] Unless otherwise stated, all figures used in this specification and claims to represent content, concentration, proportion, mass, volume, time, temperature, thickness, technical effect, etc., should in any instance be understood to be modified by the terms “about” or “approximately”. Therefore, unless indicated to the contrary, the numerical parameters listed in the following specification and appended claims are approximate values. They can vary for those skilled in the art depending on the desired properties and effects sought through this disclosure, and each numerical parameter should be interpreted according to the number of significant figures and conventional rounding methods or in a manner understood by those skilled in the art.

[0031] Although the numerical ranges and parameters described in this disclosure are approximate, the values ​​presented in the specific embodiments are provided as precisely as possible. However, any numerical value will inherently contain some errors, which are necessarily caused by the standard deviation found in its corresponding test measurements. Each numerical range given in this specification will include every narrower numerical range falling within that wider range, as if these narrower numerical ranges were explicitly stated herein.

[0032] In this application, the term "comprising" generally means including, encompassing, containing, or including. In some cases, it also means "to be" or "composed of".

[0033] When used in this document, the expression “A and / or B” includes three cases: (1) A; (2) B; and (3) A and B. The expression “A, B and / or C” includes seven cases: (1) A; (2) B; (3) C; (4) A and B; (5) A and C; (6) B and C; and (7) A, B and C. The meanings of similar expressions can be deduced by analogy.

[0034] Unless otherwise stated, all figures used in this specification and claims to represent content, concentration, proportion, mass, volume, time, temperature, thickness, technical effect, etc., should in any instance be understood to be modified by the terms “about” or “approximately”. Therefore, unless indicated to the contrary, the numerical parameters listed in the following specification and appended claims are approximate values. They can vary for those skilled in the art depending on the desired properties and effects sought through this disclosure, and each numerical parameter should be interpreted according to the number of significant figures and conventional rounding methods or in a manner understood by those skilled in the art.

[0035] Although the numerical ranges and parameters described in this disclosure are approximate, the values ​​presented in the specific embodiments are provided as precisely as possible. However, any numerical value will inherently contain some errors, which are necessarily caused by the standard deviation found in its corresponding test measurements. Each numerical range given in this specification will include every narrower numerical range falling within that wider range, as if these narrower numerical ranges were explicitly stated herein.

[0036] [Compound] Treatment of thrombotic diseases, especially those originating in the brain, is complex. The blood-brain barrier prevents many thrombolytic drugs from crossing it to reach the brain. Furthermore, the large number of free radicals generated during cerebral ischemia-reperfusion can damage brain tissue and impair brain function. Therefore, compounds that can cross the blood-brain barrier and possess neuroprotective properties are crucial for the treatment of cerebral thrombotic diseases.

[0037] Generally, the "blood-brain barrier" refers to the barrier between blood plasma and brain cells formed by the walls of brain capillaries and glial cells, and the barrier between blood plasma and cerebrospinal fluid formed by the choroid plexus. These barriers can prevent certain substances from entering brain tissue from the blood.

[0038] This application provides a camphenol-modified peptide compound or its prodrug, tautomer, optical isomer, geometric isomer, solvate or pharmaceutically acceptable salt thereof that can be used for thrombotic diseases, the compound comprising a camphenol moiety and a polypeptide moiety covalently coupled (chemically covalently linked) to said camphenol.

[0039] In this article, the term "peptide" refers to a compound formed by the dehydration condensation of three or more amino acids linked together by peptide bonds. Peptides can be prepared through chemical synthesis or through protein hydrolysis. The types of amino acids in a peptide may include, but are not limited to, natural or non-natural amino acids such as L-amino acids, D-amino acids, α-amino acids, or β-amino acids.

[0040] In some embodiments, the compound has a structure as shown in Formula I: Formula I Where L represents the connector, P 1 This indicates the polypeptide portion.

[0041] Existing research indicates that inflammation is a potential therapeutic target for ischemic stroke. It can interact with factors such as excitotoxicity and oxidative stress to form a vicious cycle, which can aggravate damage and lead to enlargement of the infarct, nerve cell damage, and cerebral edema.

[0042] Camphor (or borneol) is a small-molecule bicyclic monoterpenoid compound with good lipid solubility, allowing it to easily cross the blood-brain barrier and enter the brain to exert its anti-inflammatory and neuroprotective effects. The camphor moiety in the compound shown in Formula I can improve the lipid solubility of the compound, facilitating its crossing of the blood-brain barrier and enabling it to exert its anti-inflammatory and neuroprotective effects.

[0043] In some embodiments, the camphor is levonorgestrel. In some embodiments, the camphor is dextroborneol, which can inhibit the expression of inflammatory cytokines such as TNF-α (Tumor Necrosis Factor-α) and IL-1β (Interleukin-1β) and pro-inflammatory proteins such as COX-2 (Cyclooxygenase-2) and iNOS (inducible nitric oxide sythase) during cerebral ischemia-reperfusion, and activate γ-aminobutyric acid type A receptor (GABAa) receptor, blocking the above vicious cycle pathway, thereby reducing cell apoptosis and cell necrosis, protecting the blood-brain barrier, alleviating cerebral edema, and thus reducing ischemia-reperfusion injury.

[0044] The linker is used to connect the camphene moiety and the polypeptide moiety. In some embodiments, the camphene is linked to the polypeptide moiety via a cleavable or non-cleavable linker L. In some embodiments, the camphene is linked to the polypeptide moiety via a cleavable linker L, and under suitable cleavage conditions, the compound represented by Formula I cleaves to release free camphene and / or polypeptide, thereby exerting a therapeutic effect.

[0045] In some embodiments, the camphene is bonded to the linker L via an ester bond. In some embodiments, the linker L is bonded to the hydroxyl group of the camphene via an ester bond. In some embodiments, the linker L is bonded to the N-terminus of the polypeptide moiety via an amide bond.

[0046] In some embodiments, the connector L is -C(=O)-.

[0047] In some embodiments, the compound has the structural formula shown in Formula II: Formula II Where 0 and 1 represent the number of H atoms; when the number of H atoms is 1, -NH- represents the imino group at the N-terminus of the polypeptide moiety; when the number of H atoms is 0, N represents the cyclic nitrogen atom at the N-terminus of the polypeptide moiety; P represents the polypeptide moiety excluding the N-terminus -N(H). 0,1 - Other polypeptide residues.

[0048] In the compounds disclosed herein, the polypeptide portion is derived from polypeptides having thrombolytic activity and / or free radical scavenging activity. The term "derivative" refers to the treatment of atoms or groups in a source substance (or compound) through at least one of substitution, removal, condensation, and addition reactions to form a more complex or simpler product with chemical bond changes compared to the source substance.

[0049] In some embodiments, the polypeptide moiety has thrombolytic activity. In some embodiments, the polypeptide moiety has free radical scavenging activity. In some embodiments, the polypeptide moiety has both thrombolytic and free radical scavenging activities, and in vivo, it synergizes with borneol to simultaneously achieve thrombolytic, anti-inflammatory, and free radical scavenging effects.

[0050] In some embodiments, the polypeptide portion includes a polypeptide fragment that is Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro from the N-terminus to the C-terminus.

[0051] In this document, a "fragment" of a polypeptide includes both complete, separable polypeptide segments and non-separable polypeptide residue segments covalently bonded to other molecules, such as P in this application. 1 Those skilled in the art can easily understand and distinguish the specific meanings referred to by fragments under different conditions.

[0052] This article uses standard three-letter or single-letter coding rules to represent amino acids. Specifically, alanine-Ala (A), cysteine-Cys (C), aspartic acid-Asp (D), glutamic acid-Glu (E), phenylalanine-Phe (F), glycine-Gly (G), histidine-His (H), isoleucine-Ile (I), lysine-Lys (K), leucine-Leu (L), methionine-Met (M), asparagine-Asn (N), proline-Pro (P), glutamine-Gln (Q), arginine-Arg (R), serine-Ser (S), threonine-Thr (T), valine-Val (V), tryptophan-Trp (W), and tyrosine-Tyr (Y).

[0053] In the camphene-modified peptide compounds provided in this disclosure, the polypeptide moiety may include one, two, three, four, five, six or more repetitive sequence peptides with at least one of Pro-Ala-Lys, Ala-Lys-Pro, and Lys-Ala-Pro as structural units. The structural units may be distributed continuously or intermittently.

[0054] In some embodiments, the polypeptide moiety comprises one, two, or three repeating sequence peptides with Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro as structural units.

[0055] In some embodiments, the polypeptide moiety comprises a repeating sequence peptide with Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro as structural units.

[0056] In this document, the polypeptide moiety can be a tripeptide, tetrapeptide, pentapeptide, hexapeptide, heptapeptide, octapeptide, nonapeptide, decapeptide, or undecapeptide, or more. In some embodiments, the polypeptide moiety is a tripeptide, tetrapeptide, pentapeptide, hexapeptide, heptapeptide, octapeptide, nonapeptide, decapeptide, or undecapeptide.

[0057] In this article, "tripeptide" refers to a peptide fragment formed by three natural or non-natural amino acids linked by peptide bonds, which can be a straight-chain peptide fragment or a branched peptide fragment. It can be understood that dipeptide, tetrapeptide, pentapeptide, hexapeptide, heptapeptide, octapeptide, nonapeptide, decapeptide, and undecapeptide have a similar meaning.

[0058] In some embodiments, the N-terminus or C-terminus of the Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro fragment in the polypeptide fragment is connected to β-Ala-His, His-β-Ala, or Arg-Gly.

[0059] In some embodiments, the polypeptide moiety includes a dipeptide fragment β-Ala-His, Arg-Gly located at the N-terminus of the Pro-Ala-Lys, Ala-Lys-Pro, or Lys-Ala-Pro fragment, or a His-β-Ala, Arg-Gly located at the C-terminus.

[0060] In some embodiments, the polypeptide moiety may further include a polypeptide fragment of Arg-Gly-Asp-Ser or Ile-Glu-Ser-Asp-Val from the N-terminus to the C-terminus.

[0061] In some embodiments, the polypeptide moiety further includes a Lys residue covalently linked to a linker, optionally with an Arg-Gly-Asp-Ser or Ile-Glu-Ser-Asp-Val fragment linked to its C-terminus. In some embodiments, the polypeptide moiety includes a polypeptide fragment with an N-terminus to C-terminus of Lys-Arg-Gly-Asp-Ser or Lys-Ile-Glu-Ser-Asp-Val.

[0062] In some embodiments, the polypeptide moiety includes a peptide fragment comprising Lys-Ala-Pro linked to the Lys residue. In this case, the peptide fragment may exist as a branched peptide fragment. For example, the polypeptide moiety includes a Lys(Lys-Ala-Pro)- peptide fragment, wherein the peptide fragment Lys-Ala-Pro within the parentheses represents a branched peptide chain and is covalently linked to the Lys residue immediately to the left of the parentheses.

[0063] In some embodiments, the polypeptide moiety comprises a polypeptide fragment of Lys(Lys-Ala-Pro-His-β-Ala)- or Lys(Lys-Ala-Pro-Arg-Gly)-. It is understood that other polypeptide moiety having branched peptide chains in this disclosure have a similar understanding and meaning.

[0064] In the compounds disclosed herein, the amino acids (or amino acid residues) of the polypeptide moiety may be natural or chemically modified, including but not limited to phosphorylation, acetylation, methylation, glycosylation, ubiquitination, succinylation, crotonylation, 2-hydroxyisobutyrylation, lactation, and polyethylene glycol (PEG) modification. In some embodiments, the amino acids (or amino acid residues) of the polypeptide moiety, including one or more sites at the C-terminus, N-terminus, and intermediate residues of the polypeptide moiety, are modified with polyethylene glycol PEG, glycosylation, or phosphorylation.

[0065] In some embodiments, one or more sites at the C-terminus, N-terminus, or intermediate residues of the polypeptide moiety are modified with polyethylene glycol (PEG). In some embodiments, the N-terminal residue of the polypeptide moiety includes PEG modification. Optionally, the PEG is selected from any one or more of PEG2 to PEG24, including but not limited to PEG2, PEG4, PEG8, PEG12, and PEG24. In some embodiments, the N-terminal residue of the polypeptide moiety includes PEG4 modification. The PEG modification can prolong the half-life of the compound or polypeptide moiety provided in this application in vivo, reduce or eliminate immunogenicity, and reduce toxic side effects.

[0066] In some embodiments, the PEG modification is covalently linked to the linker. In some embodiments, one end of the PEG contains a carboxyl group and / or an amino group. In some embodiments, the PEG used in the PEG modification is NH2-PEG4-COOH, wherein the amino group forms an amide bond with the linker, and the carboxyl group forms an amide bond with the N-terminal amino group of the amino acid.

[0067] In some embodiments, the polypeptide portion includes or has one or more of the following groups (1) to (12): (1) Pro-Ala-Lys; (2) Lys-Ala-Pro; (3) β-Ala-His-Lys-Ala-Pro; (4) β-Ala-His-Pro-Ala-Lys; (5) Gly-Arg-Pro-Ala-Lys; (6) PEG4-Pro-Ala-Lys; (7) Lys(Lys-Ala-Pro)-Arg-Gly-Asp-Ser; (8) Lys(Lys-Ala-Pro-His-β-Ala)-Arg-Gly-Asp-Ser; (9) Lys(Lys-Ala-Pro-Arg-Gly)-Arg-Gly-Asp-Ser; (10) Lys(Lys-Ala-Pro)-Ile-Glu-Ser-Asp-Val; (11) Lys(Lys-Ala-Pro-His-Ala-β)-Ile-Glu-Ser-Asp-Val; (12) Lys(Lys-Ala-Pro-Arg-Gly)-Ile-Glu-Ser-Asp-Val.

[0068] The polypeptide moieties of groups (1) to (12) above have the main chain and branch chain structures shown in the table below:

[0069] The camphor-modified peptide compounds disclosed herein possess suitable physical properties, allowing them to cross the blood-brain barrier effectively. They can also self-degrade in the brain to release camphor and thrombolytic peptides, thereby exerting thrombolytic, anti-inflammatory, and free radical scavenging effects. The synergistic effect of these two substances reduces cell necrosis and tissue damage, thus providing protection against cerebral ischemia.

[0070] [Preparation Method] This disclosure provides a method for preparing the aforementioned compound, comprising: preparing an intermediate including an ester bond from camphene and a coupling agent under reaction conditions, wherein the intermediate is sequentially bonded to a corresponding amino acid, and purified to obtain the compound.

[0071] In this article, the term "coupling agent" refers to a class of substances having at least two reactive groups that can participate in chemical reactions and form chemical bonds, thereby combining two substances together.

[0072] In some embodiments, the coupling agent may be phenyl 4-nitrochloroformate.

[0073] In some embodiments, solid-phase peptide synthesis techniques can be used to sequentially bond intermediates to corresponding amino acids. Solid-phase peptide synthesis techniques are well known and skillfully practiced by those skilled in the art. In this method, the synthesis of peptides in the compounds disclosed herein can be carried out by sequentially adding the desired amino acid residues one at a time to the growing peptide chain, according to the general principles of solid-phase methods. These methods are disclosed in several references, including Merrifield, RB, Solid phase synthesis (Nobel lecture). Angew Chem 24:799-810 (1985); and Barany et al., The Peptides, Analysis, Synthesis and Biology, Vol. 2, edited by Gross, E. and Meienhofer, J., Academic Press 1-284 (1980).

[0074] In the chemical synthesis of peptides, reactive side chain groups of each amino acid residue are protected with appropriate protecting groups to prevent chemical reactions at that site before the protecting groups are removed. For example, when reacting at the carboxyl group of an amino acid or fragment, the α-amino group (e.g., 9-fluorenylmethoxycarbonyl (Fmoc), tert-butoxycarbonyl (Boc)) is protected with a protecting group, and then the α-amino protecting group is selectively removed, thereby allowing subsequent reactions at that site.

[0075] Orthogonal protecting groups can be used as appropriate to prepare peptides containing side chains, such as Fmoc-Ser(tBu)-OH, Fmoc-Glu(OtBu)-OH, Fmoc-Lys(Boc)‐OH, and Fmoc-Arg(pbf)‐OH.

[0076] The compound can be cleaved from the solid phase using any suitable reagent, such as a combination of trifluoroacetic acid (TFA), triisopropylsilane (TIS), and water. The final product is precipitated by adding cold ether and collected by filtration.

[0077] Purification can be performed using any known method in the prior art, such as reverse-phase high-performance liquid chromatography.

[0078] Although the synthesis is described primarily with reference to solid-phase peptide synthesis methods, it should be understood that other chemical and synthetic methods may be used to prepare the compounds of this invention.

[0079] [Pharmaceutical Composition] This disclosure provides a pharmaceutical composition comprising the aforementioned compound or a compound prepared by the aforementioned methods, and further comprising pharmaceutically acceptable excipients.

[0080] The pharmaceutical compositions disclosed herein can be formulated in any manner known in the art, including but not limited to dosage forms such as tablets, capsules, small capsules, suspensions, powders, lyophilized preparations, suppositories, eye drops, skin patches, oral soluble preparations, sprays, aerosols, and other solid, semi-solid, or liquid systems.

[0081] The pharmaceutical composition may be an immediate-release and / or modified-release formulation, including delayed-release, sustained-release, pulsatile-release, controlled-release, targeted-release, and programmed-release formulations.

[0082] In this document, "pharmaceuticalally acceptable excipients" refers to components in a pharmaceutical composition other than the active ingredient that are non-toxic to the subject. Pharmaceutically acceptable excipients include, but are not limited to, excipients (e.g., diluents, carriers, etc.) and additives (e.g., stabilizers, preservatives, solubilizers, buffers, etc.). Excipients may include polyvinylpyrrolidone, gelatin, hydroxypropyl cellulose (HPC), gum arabic, polyethylene glycol, mannitol, sodium chloride, and sodium citrate. For injectable formulations or other liquid dosage forms, water containing at least one or more buffering components is preferred, and stabilizers, preservatives, and solubilizers may also be used. For solid dosage forms, any of a variety of thickeners, fillers, extenders, and carrier additives may be used, such as starch, sugars, cellulose derivatives, fatty acids, etc. For topical dosage forms, any of a variety of creams, ointments, gels, lotions, etc., may be used. For most pharmaceutical formulations, the inactive ingredient may constitute a significant portion of the formulation by weight or volume. For pharmaceutical formulations, this also covers any of a variety of dose-release, sustained-release or continuous-release formulations and additives, such that a dose can be formulated to deliver the compounds of this disclosure over a period of time.

[0083] The compounds disclosed herein may be administered via mucosal, buccal, oral, transdermal, inhalation, nasal, urethral, ​​vaginal, intravenous, subcutaneous, intramuscular, or intraperitoneal injection routes. The excipients in the pharmaceutical compositions are adapted to their route of administration.

[0084] In some embodiments, the compounds of this disclosure can be delivered orally, for example, in tablets or capsules. The compounds can be packaged in an intestinal protectant, preferably such that the compound is not released before the tablets or capsules are delivered to the stomach and optionally further to a portion of the small intestine.

[0085] In some embodiments, the compounds of this disclosure can be administered by injection. Suitable pharmaceutical forms for injection include sterile aqueous solutions or dispersions and sterile powders for the immediate preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and its flowability must allow it to be administered via a syringe. The form must be stable under the conditions of preparation and storage and must be preserved to prevent contamination by microorganisms such as bacteria and fungi. The carrier may be a solvent or dispersion medium containing, for example, water, ethanol, polyols (e.g., glycerol, propylene glycol, or liquid polyethylene glycol), suitable mixtures thereof, and vegetable oils.

[0086] Therapeutic administration can also be achieved through injection of sustained-release formulations, such as those that allow for subcutaneous injection, including: nanospheres / microspheres, liposomes, emulsions, gels, insoluble salts, or suspensions.

[0087] In some embodiments, the compounds of this disclosure can be administered intranasally. The pharmaceutical compositions may be in aqueous solution form, such as a solution comprising saline, citrate, or other commonly used excipients or preservatives. They may also be in dry formulation or powder form.

[0088] [use] This disclosure provides the use of the aforementioned compounds, compounds prepared by the aforementioned methods, or the aforementioned pharmaceutical compositions in the preparation of thrombolytic, free radical scavenging, or anti-inflammatory drugs.

[0089] The camphor moiety and the thrombolytic peptide moiety in the compound help the compound cross the blood-brain barrier, exerting the anti-inflammatory effect of camphor and the thrombolytic and free radical scavenging effects of the peptide.

[0090] Furthermore, this disclosure provides the use of the aforementioned compounds, compounds prepared by the aforementioned methods, or the aforementioned pharmaceutical compositions in the preparation of drugs for protecting against cerebral ischemia.

[0091] Thrombotic diseases can cause cerebral ischemia-reperfusion injury, leading to cerebral ischemia-reperfusion injury. After crossing the blood-brain barrier and entering the brain, the compound self-cleaves to release camphene and thrombolytic peptides. Camphene inhibits the expression of inflammatory cytokines and proteins, activates GABAa receptors, reduces apoptosis and necrosis, and alleviates cerebral edema and ischemia-reperfusion injury. Meanwhile, the peptides can dissolve thrombi in the brain and scavenge free radicals generated during cerebral ischemia-reperfusion, reducing cerebral ischemia and ischemia-reperfusion injury. Together, these factors protect ischemic sites in the brain.

[0092] Furthermore, this disclosure provides the use of the aforementioned compounds, compounds prepared by the aforementioned methods, or the aforementioned pharmaceutical compositions in the preparation of medicaments for treating thrombotic diseases.

[0093] In this article, the term "thrombotic disease" refers to diseases in humans and animals during their lifetime caused by the formation of abnormal blood clots in the blood vessels.

[0094] The thrombotic diseases mentioned include, but are not limited to: ischemic stroke, myocardial infarction, stroke, venous thrombosis, pulmonary embolism, peripheral arterial occlusive disease, venous duct obstruction, arteriovenous fistula and shunt obstruction, and carotid artery stenosis.

[0095] On the other hand, this application provides a method for treating a subject suffering from thrombotic disease, the method comprising: administering to the subject an effective amount of the aforementioned compound, the compound prepared by the aforementioned method, or the aforementioned pharmaceutical composition.

[0096] On the other hand, this application provides a method for improving cerebral ischemia, cerebral thrombosis, free radical status, or inflammatory status in a subject, the method comprising: administering to the subject an effective amount of the aforementioned compound, the compound prepared by the aforementioned method, or the aforementioned pharmaceutical composition.

[0097] In this article, "effective amount" means an amount that is sufficient to elicit the desired therapeutic effect when administered by any of the methods described above or by any other means known in the art.

[0098] Generally, the actual amount of the compound disclosed herein administered to a patient can vary within a wide range, depending on the route of administration, patient condition (including weight, sex, health status and diet), formulation used and expected response.

[0099] The compounds disclosed herein have good biological activity. For example, depending on the specific compound selected, the desired therapeutic response, the route of administration, the formulation, and other factors known to those skilled in the art, the compounds can be administered at about 0.1, 0.5, 1, 5, 50, 100, 500, 1000, or 5000 μg / kg body weight (as a single dose or as separate daily doses).

[0100] The various embodiments and preferences disclosed above can be combined with each other (as long as they are not inherently contradictory), and all embodiments formed by such combinations are considered as part of the disclosure of this application.

[0101] The technical solutions of this disclosure will be illustrated more clearly and explicitly below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0102] Example The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0103] The Chinese explanations of the abbreviations or full English names used in this application are shown in Table 1 below: Table 1 provides a Chinese translation of the abbreviations or full English names used.

[0104] The resin raw material used in Examples 2 to 12 was 2-chlorotrimethylbenzene resin (CTC Resin) with a substitution constant of 0.5 mmol / g.

[0105] Example 1: Synthesis of Camphenol-Linker

[0106] 9.65 g (48 mmol) of phenyl 4-nitrochloroformate and 6.16 g (40 mmol) of camphenol were weighed into a 250 mL flask. Dichloromethane was added for dissolution, and 5.5 mL (40 mmol) of triethylamine was added dropwise under ice bath conditions. The mixture was allowed to rise naturally to room temperature (25 ± 5 °C) for 3 h. After the reaction was complete, the reaction solution was concentrated to dryness under reduced pressure, dissolved in petroleum ether, stirred with silica gel, and purified by column chromatography to obtain 9.31 g (73% yield) of the camphenol-linker target compound, [M+H]. + 319.08. The 1H-NMR analysis is shown in Table 2.

[0107] Table 2: Camphor-linker target compounds 1 H-NMR analysis

[0108] Example 2: Synthesis of Camphenol-Linker-PAK (PDC-1)

[0109] (1) Synthesis of Fmoc-Lys(Boc)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.47 g (1 mmol) of Fmoc-Lys(Boc)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0110] (2) Synthesis of Fmoc-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0111] (3) Synthesis of Fmoc-Pro-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method mentioned in step (2), connect Fmoc-Pro-OH. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0112] (4) Synthesis of camphenol-linker-Pro-Ala-Lys(Boc)-CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and then 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then vacuum dried to obtain the peptide resin.

[0113] (5) Synthesis of camphenol-linker-Pro-Ala-Lys The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a rate of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether and then dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0114] (6) Purification of camphene-linker-Pro-Ala-Lys The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by mass spectrometry (MS). The correct product fraction was collected and lyophilized to obtain the final product. Purity: 95.1% (HPLC, 220 nm, C18, linear gradient); [M+H] + : 495.3, [2M+H] + :990.6, see Figure 1 .

[0115] Example 3: Synthesis of Camphenol-Linker-KAP (PDC-2)

[0116] (1) Synthesis of Fmoc-Pro-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.34 g (1 mmol) of Fmoc-Pro-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction mixture for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction mixture for 1 h.

[0117] (2) Synthesis of Fmoc-Ala-Pro-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in an appropriate amount of DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0118] (3) Synthesis of Fmoc-Lys(Boc)-Ala-Pro-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc‐Lys(Boc)‐OH. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0119] (4) Synthesis of camphenol-linker-Lys(Boc)-Ala-Pro-CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and then 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then vacuum dried to obtain the peptide resin.

[0120] (5) Synthesis of camphenol-linker-Lys-Ala-Pro The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0121] (6) Purification of camphene-linker-Lys-Ala-Pro The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.9% (HPLC, 220 nm, C18, linear gradient); [M+H] + : 495.3, see Figure 2 .

[0122] Example 4: Synthesis of camphene-linker-β-AHKAP (PDC-3)

[0123] (1) Synthesis of Fmoc-Pro-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.34 g (1 mmol) of Fmoc-Pro-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction mixture for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction mixture for 1 h.

[0124] (2) Synthesis of Fmoc-Ala-Pro-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0125] (3) Synthesis of Fmoc-β-Ala-His(trt)-Lys(Boc)-Ala-Pro-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, in the same way as in step (2), connect Fmoc-Lys(Boc)-OH, Fmoc-His(trt)-OH, and Fmoc-β-Ala-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0126] (4) Synthesis of camphenol-linker-β-Ala-His(trt)-Lys(Boc)-Ala-Pro-CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and then 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then vacuum dried to obtain the peptide resin.

[0127] (5) Synthesis of camphenol-linker-β-Ala-His-Lys-Ala-Pro The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether and then dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0128] (6) Purification of camphene-linker-β-Ala-His-Lys-Ala-Pro The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.1% (HPLC, 220 nm, C18, linear gradient); [M+H] + : 704.4, [M+2H] 2+ 352.3, see Figure 3 .

[0129] Example 5: Synthesis of camphene-linker-β-AHPAK (PDC-4)

[0130] (1) Synthesis of Fmoc-Lys(Boc)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.47 g (1 mmol) of Fmoc-Lys(Boc)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0131] (2) Synthesis of Fmoc-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0132] (3) Synthesis of Fmoc-β-Ala-His(trt)-Pro-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Pro-OH, Fmoc-His(trt)-OH, and Fmoc-β-Ala-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0133] (4) Synthesis of camphenol-linker-β-Ala-His(trt)-Pro-Ala-Lys(Boc)-CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and then 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then vacuum dried to obtain the peptide resin.

[0134] (5) Synthesis of camphenol-linker-β-Ala-His-Pro-Ala-Lys The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether. The tubes were then dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0135] (6) Purification of camphene-linker-β-Ala-His-Pro-Ala-Lys The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.8% (HPLC, 220 nm, C18, linear gradient); [M+H] + : 703.4, [M+2H] 2+ 352.4, see Figure 4 .

[0136] Example 6: Synthesis of Camphenol-Linker-GRPAK (PDC-5)

[0137] (1) Synthesis of Fmoc-Lys(Boc)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.47 g (1 mmol) of Fmoc-Lys(Boc)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0138] (2) Synthesis of Fmoc-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0139] (3) Synthesis of Fmoc-Gly-Arg(pbf)-Pro-Ala-Lys(Boc) CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Pro-OH, Fmoc-Arg(pbf)-OH, and Fmoc-Gly-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0140] (4) Synthesis of camphenol-linker-Gly-Arg(pbf)-Pro-Ala-Lys(Boc) CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and then 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then vacuum dried to obtain the peptide resin.

[0141] (5) Synthesis of camphene-linker-Gly-Arg-Pro-Ala-Lys The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0142] (6) Purification of camphene-linker-Gly-Arg-Pro-Ala-Lys The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 98.5% (HPLC, 220 nm, C18, linear gradient); [M+H] + 709.4, [M+2H] 2+ 354.8, see Figure 5 .

[0143] Example 7: Synthesis of Camphenol-Linker-PEG4-PAK (PDC-6)

[0144] (1) Synthesis of Fmoc-Lys(Boc)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.47 g (1 mmol) of Fmoc-Lys(Boc)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0145] (2) Synthesis of Fmoc-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 0.93 g (3 mmol) of Fmoc-Ala-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0146] (3) Synthesis of Fmoc-PEG4-Pro-Ala-Lys(Boc)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Pro-OH and Fmoc-NH-PEG4-COOH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0147] (4) Synthesis of camphene-linker-PEG4-Pro-Ala-Lys(Boc)-CTC Resin 25% 4-methylpiperidine / DMF (volume ratio) was added to the resin to remove the N-terminal Fmoc group. Then, 0.64 g (2 mmol) of camphene-linker was added, and an appropriate amount of DCM was added to dissolve it. Then, 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times in sequence. Then, it was dried under vacuum to obtain the peptide resin.

[0148] (5) Synthesis of camphene-linker-PEG4-Pro-Ala-Lys The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0149] (6) Purification of camphene-linker-PEG4-Pro-Ala-Lys The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 98.6% (HPLC, 220 nm, C18, linear gradient); [M+H] + 742.4, see Figure 6 .

[0150] Example 8: Synthesis of Camphenol-Linker-K(KAP)RGDS (PDC-7)

[0151] (1) Synthesis of Fmoc-Ser(tBu)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.38 g (1 mmol) of Fmoc-Ser(tBu)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0152] (2) Synthesis of Fmoc-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0153] (3) Synthesis of Fmoc-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method mentioned in step (2), connect Fmoc-Gly-OH and Fmoc-Arg(pbf)-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0154] (4) Synthesis of Alloc-Lys(Fmoc)-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0155] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTCResin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, following the method in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, and Fmoc‐Pro‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0156] (6) Synthesis of camphenol-linker-Lys[Lys(Boc)-Ala-Pro]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0157] (7) Synthesis of camphenol-linker-Lys(Lys-Ala-Pro)-Arg-Gly-Asp-Ser The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a rate of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and methyl tert-butyl ether (MTBE) was added. The collected filtrate was then poured into the MTBE, and the mixture was stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with MTBE, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0158] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro)-Arg-Gly-Asp-Ser The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 95.66% (HPLC, 220 nm, C18, linear gradient); [M+H] + 1039.5, [M+2H] 2+ 519.8, [M+3H] 3+ 347.0, see Figure 7 .

[0159] Example 9: Synthesis of Camphenol-Linker-K(KAPHA-β)RGDS (PDC-8)

[0160] (1) Synthesis of Fmoc-Ser(tBu)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.38 g (1 mmol) of Fmoc-Ser(tBu)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0161] (2) Synthesis of Fmoc-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0162] (3) Synthesis of Fmoc-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Gly-OH and Fmoc-Arg(pbf)-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0163] (4) Synthesis of Alloc-Lys(Fmoc)-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0164] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro-His(trt)-β-Ala]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method used in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, Fmoc‐Pro‐OH, Fmoc-His(trt)‐OH, and Fmoc-β‐Ala‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0165] (6) Synthesis of camphenol-linker-Lys[Lys(Boc)-Ala-Pro-His(trt)-β-Ala]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0166] (7) Synthesis of camphenol-linker-Lys(Lys-Ala-Pro-His-β-Ala)-Arg-Gly-Asp-Ser The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a rate of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether and then dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0167] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro-His-β-Ala)-Arg-Gly-Asp-Ser The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.4% (HPLC, 220 nm, C18, linear gradient); [M+H] + 1246.6, [M+2H] 2+ 623.9, [M+3H] 3+ :416.4, see Figure 8 .

[0168] Example 10: Synthesis of Camphenol-Linker-K(KAPRG)RGDS (PDC-9)

[0169] (1) Synthesis of Fmoc-Ser(tBu)-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, then add 0.38 g (1 mmol) of Fmoc-Ser(tBu)-OH and 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0170] (2) Synthesis of Fmoc-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0171] (3) Synthesis of Fmoc-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method used in step (2), connect Fmoc-Gly-OH and Fmoc-Arg(pbf)-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0172] (4) Synthesis of Alloc-Lys(Fmoc)-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0173] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro-Arg(pbf)-Gly-Boc]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method used in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, Fmoc‐Pro‐OH, Fmoc-Arg(pbf)‐OH, and Fmoc-Gly‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0174] (6) Synthesis of camphene-linker-Lys[Lys(Boc)-Ala-Pro-Arg(pbf)-Gly-Boc]-Arg(pbf)-Gly-Asp(OtBu)-Ser(tBu)-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0175] (7) Synthesis of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Arg-Gly-Asp-Ser The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and methyl tert-butyl ether (MTBE) was added. The collected filtrate was then poured into the MTBE, and the mixture was stirred until peptides precipitated. The mixture was centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tube was washed twice with MTBE, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0176] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Arg-Gly-Asp-Ser The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.2% (HPLC, 220 nm, C18, linear gradient); [M+H] + : 1252.1, [M+2H] 2+ 626.5, [M+3H] 3+ :418.1, see Figure 9 .

[0177] Example 11: Synthesis of Camphenol-Linker-K(KAP)IESDV (PDC-10)

[0178] (1) Synthesis of Fmoc-Val-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, add 0.34 g (1 mmol) of Fmoc-Ser(tBu)-OH, add 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0179] (2) Synthesis of Fmoc-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0180] (3) Synthesis of Fmoc-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method used in step (2), connect Fmoc-Ser(tBu)-OH, Fmoc-Glu(OtBu)-OH and Fmoc-Ile-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0181] (4)Alloc-Lys(Fmoc)-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0182] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method used in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, and Fmoc‐Pro‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0183] (6) Synthesis of camphene-linker-Lys[Lys(Boc)-Ala-Pro-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0184] (7) Synthesis of camphene-linker-Lys(Lys-Ala-Pro)-Ile-Glu-Ser-Asp-Val The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and icy methyl tert-butyl ether was added. The collected filtrate was then poured into the methyl tert-butyl ether and stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with methyl tert-butyl ether. The tubes were then dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0185] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro)-Ile-Glu-Ser-Asp-Val The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.6% (HPLC, 220 nm, C18, linear gradient); [M+H] + 1167.6, [M+2H] 2+ 584.0, see Figure 10 .

[0186] Example 12: Synthesis of Camphenol-Linker-K(KAPHA-β)IESDV (PDC-11)

[0187] (1) Synthesis of Fmoc-Val-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, add 0.34 g (1 mmol) of Fmoc-Ser(tBu)-OH, add 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0188] (2) Synthesis of Fmoc-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0189] (3) Synthesis of Fmoc-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Ser(tBu)-OH, Fmoc-Glu(OtBu)-OH and Fmoc-Ile-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0190] (4) Synthesis of Alloc-Lys(Fmoc)-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0191] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro-His(trt)-Ala-β-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu) -Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, following the method in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, Fmoc‐Pro‐OH, Fmoc-His(trt)‐OH, and Boc-β-Ala‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0192] (6) Synthesis of camphene-linker-Lys[Lys(Boc)-Ala-Pro-His(trt)-Ala-β-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0193] (7) Synthesis of camphene-linker-Lys(Lys-Ala-Pro-His-Ala-β)-Ile-Glu-Ser-Asp-Val The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a ratio of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and methyl tert-butyl ether (MTBE) was added. The collected filtrate was then poured into the MTBE, and the mixture was stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with MTBE, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0194] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro-His-Ala-β)-Ile-Glu-Ser-Asp-Val The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS analysis. The correct product fraction was collected and lyophilized to obtain the final product. Purity: 98.9% (HPLC, 220 nm, C18, linear gradient); [M+H] + 1380.7, [M+2H] 2+ 690.5, [M+3H] 3+ :460.8, see Figure 11 .

[0195] Example 13: Synthesis of Camphenol-Linker-K(KAPRG)IESDV (PDC-12)

[0196] (1) Synthesis of Fmoc-Val-CTC Resin Weigh 1.0 g of 2-CTC Resin into a reactor, add 10 ml of DMF to allow swelling for 1 h, add 0.34 g (1 mmol) of Fmoc-Ser(tBu)-OH, add 0.25 ml (2 mmol) of DIEA, and shake the reaction for 1 h. Remove the solvent, wash the resin alternately with DMF and DCM three times each, then add 20% methanol-dichloromethane solution and 0.25 ml of DIEA, and shake the reaction for 1 h.

[0197] (2) Synthesis of Fmoc-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.23 g (3 mmol) of Fmoc-Asp(OtBu)-OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0198] (3) Synthesis of Fmoc-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Ser(tBu)-OH, Fmoc-Glu(OtBu)-OH and Fmoc-Ile-OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0199] (4) Synthesis of Alloc-Lys(Fmoc)-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to remove the N-terminal Fmoc group of the resin and react for 30 min. Remove the solvent and wash the resin alternately with DMF and DCM, three times each. Weigh 1.27 g (3 mmol) of Alloc-Lys(Fmoc)‐OH and 1.14 g (3 mmol) of HATU, dissolve them in DMF, and add them to the resin. Then add 0.75 ml (6 mmol) of DIEA to start the reaction. Determine the reaction endpoint by ninhydrin detection. If the detection result shows that the reaction is complete, remove the reaction solution and wash the resin alternately with DMF and DCM, three times each.

[0200] (5) Synthesis of Alloc-Lys[Lys(Boc)-Ala-Pro-Arg(pbf)-Gly-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu) -Val-CTC Resin Add 25% 4-methylpiperidine / DMF (volume ratio) to the resin to remove the Fmoc group at the N-terminus of the resin. Then, according to the synthesis method in step (2), connect Fmoc-Lys(Boc)‐OH, Fmoc‐Ala‐OH, Fmoc‐Pro‐OH, Fmoc-Arg(pbf)‐OH and Fmoc-Gly‐OH in sequence. After the reaction is completed, add DMF and DCM to the resin and wash the resin alternately, washing each three times.

[0201] (6) Synthesis of camphene-linker-Lys[Lys(Boc)-Ala-Pro-Arg(pbf)-Gly-Boc]-Ile-Glu(OtBu)-Ser(tBu)-Asp(OtBu)-Val-CTC Resin A 20% tetra(triphenylphosphine)palladium solution in dichloromethane was added to the resin. 10 mmol of benzylsilane was used to remove the N-terminal Alloc group of the resin. Then, 0.64 g (2 mmol) of camphene-linker was added, dissolved in DCM, and 0.5 ml (4 mmol) of DIEA was added to start the reaction. After the reaction was complete (the endpoint was detected by ninhydrin), the reaction solution was removed. The resin was washed sequentially with DMF 3 times, methanol 2 times, DCM 2 times, and methanol 2 times, and then dried under vacuum to obtain the peptide resin.

[0202] (7) Synthesis of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Ile-Glu-Ser-Asp-Val The dried peptide resin was added to the reactor, along with lysis buffer (TFA: TIS: H2O = 95: 2.5: 2.5), at a rate of 10 mL per gram of peptide resin. The mixture was stirred at room temperature for 2 h. The resulting mixture was filtered, and the filtrate was collected. The resin was washed twice with a small amount of TFA. Centrifuge tubes were prepared, and methyl tert-butyl ether (MTBE) was added. The collected filtrate was then poured into the MTBE, and the mixture was stirred until the peptide precipitated. The tubes were centrifuged, and the supernatant was discarded. The white substance at the bottom of the centrifuge tubes was washed twice with MTBE, and then the tubes were dried in a vacuum desiccator for at least 12 hours to obtain the crude product.

[0203] (8) Purification of camphene-linker-Lys(Lys-Ala-Pro-Arg-Gly)-Ile-Glu-Ser-Asp-Val The crude product was dissolved in acetonitrile and water, and the solution was loaded onto a reverse-phase high-performance liquid chromatography column for gradient elution. The location of the product was confirmed by MS (mass spectrometry). The correct product fraction was collected and lyophilized to obtain the final product. Purity: 99.5% (HPLC, 220 nm, C18, linear gradient); [M+H] +1375.7, [M+2H] 2+ 688.0, [M+3H] 3+ : 459.0, see Figure 12 .

[0204] Example 14: Detection of the therapeutic effect of camphenol polypeptide conjugate on stroke in rats 14.1 Drugs and Solvents 14.1.1 Test drug: Positive control drug: Edaravone and dexborneol (4:1) in combination. Test samples: PDC-1, PDC-2, PDC-3, PDC-4, PDC-5, and PDC-6 prepared in Examples 2-7, respectively. Solvent: 20% propylene glycol aqueous solution 14.1.2 Preparation method: Positive control drug: Edaravone 40 mg and dexborneol 10 mg were added to 3.0 mL of propylene glycol and completely dissolved. Water for injection was then slowly added to a final volume of 15.0 mL to obtain the positive control drug solution. The final concentration of edaravone was 2.67 mg / mL, and the final concentration of dexborneol was 0.67 mg / mL.

[0205] Test sample: Similar to the preparation method of the positive control drug, PDC-1, PDC-2, PDC-3, PDC-4, PDC-5, and PDC-6 were dissolved in propylene glycol, and then slowly diluted with 4 times the volume of water for injection to obtain the test sample's administration solution. The final concentrations were: PDC-1 0.82 mg / mL, PDC-2 1.17 mg / mL, PDC-3 0.82 mg / mL, PDC-4 1.17 mg / mL, PDC-5 1.24 mg / mL, and PDC-6 1.18 mg / mL.

[0206] 14.2 Experimental Consumables and Reagents Triphenyltetrazolium chloride (TTC): Purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd.), prepared as a 2% TTC solution with physiological saline, and stored protected from light. Isoflurane inhalation anesthesia, MCAO suture: Purchased from Beijing Xinong Technology Co., Ltd.; 0.36mm series, A2636-A4 suitable for 250-280g rats, suture length approximately 45mm, head diameter 0.36±0.02mm.

[0207] 14.3 Laboratory Animals Adult male SD rats, SPF grade (specific pathogen-free animals, laboratory animals not carrying major potential infections or opportunistic pathogens or pathogens that significantly interfere with scientific experiments), weight: maintained at 260-280g during the experiment; source: Beijing Vital River Laboratory Animal Technology Co., Ltd. Environmental acclimatization period: at least 2 days, with researchers conducting cage-side observations once daily during the acclimatization period.

[0208] 14.4 Rearing conditions No more than 5 animals per cage. Record the environmental parameters of the animal housing during the rearing period. No other species of animals should be kept in the same room during the experiment. Temperature: 18~24°C; Relative humidity: 40%~70%; Ventilation: at least 8 air changes per hour, using an IVC independent air supply system (independent ventilation cage system); Lighting: automatic lighting, alternating between light and dark every 12 hours, lights off at 8:00 AM and on again at 8:00 AM the following day.

[0209] 14.5 Dosage Design Table 3 Dosage Design Table

[0210] Dosage = Concentration × Quantity 14.6 Experimental Methods A MCAO (middle cerebral artery occlusion) reperfusion model was established using the Longa method. Rats were fasted for 12 hours preoperatively, but allowed free access to water. Anesthesia was administered via isoflurane inhalation. A midline cervical incision was made to expose the common carotid artery (CCA), external carotid artery (ECA), and pterygopalatine artery. A specially purchased suture (Beijing Xinong, A2636-A4, suitable for 250-280g rats) was inserted into all rats through the right ECA incision, and marked at a 20mm length. The pterygopalatine artery was briefly clamped to prevent accidental insertion. The suture length was approximately 18-20mm from the CCA bifurcation, depending on the animal's weight. The right middle cerebral artery was embolized, and the skin was then sutured, with the tail end of the suture fixed to the skin. After 2 hours of ischemia, the suture was carefully removed, thus initiating reperfusion. The sham-operated group underwent the same procedure as the surgical group without suture insertion. Body temperature was maintained at (37±0.5)℃ during ischemia and for 2 hours after reperfusion. The successful model was defined as the appearance of left-sided limb paralysis, unsteady standing, and circling to one side when the tail was lifted after the rats regained consciousness from surgical anesthesia. After recovery, the rats were scored using the Zea-Longa 5-point scale: 0 points represented no neurological deficits; 1 point represented inability to fully extend the contralateral forelimb; 2 points represented circling to the paralyzed side when walking; 3 points represented falling to the paralyzed side when walking; 4 points represented inability to walk spontaneously and impaired consciousness; 5 points represented death. A score of 1 or higher was considered a successful model; any rat scoring 5 points, or with subarachnoid hemorrhage found during autopsy, or without neurological deficits (0 points), was considered a failed model.

[0211] Rats were randomly divided into groups based on their scores, with at least 8 animals in each group. One hour after ischemia, rats in each group were administered 20% propylene glycol aqueous solution, a positive control drug (edaravone 8 mg / kg + dexborneol 2 mg / kg), and the test sample at 5 μmol / kg via tail vein injection. Twenty-four hours after administration, the animals were assessed for neurological deficits using the Zea-Longa five-point scale to evaluate drug efficacy. The infarct volume was determined using 2,3,5-triphenyltetrazolium chloride (TTC) staining. Animals were euthanized by decapitation after excessive carbon dioxide inhalation, and the brains were quickly removed and placed in ice-cold saline for 10 minutes. Brain slices, uniformly cut into 2 mm thick sections from the coronal plane of the cerebral sulcus, were quickly stained in 2% TTC solution (37℃) for 30 minutes, and then fixed with 4% polyformic acid. 24 hours later, photos were taken with a digital camera, input into a computer, and the infarct area was calculated using image processing software (Adobe, Photoshop). The pink area represents normal brain tissue, and the white area represents the infarct area. To reduce the influence of hemispheric edema on the results, the infarct volume was calculated by subtracting the volume of normal tissue on the ipsilateral side from the volume of normal tissue on the contralateral side of the injury. The result was expressed as a percentage of infarct volume. Infarction rate = (Volume of normal tissue on the contralateral side - Volume of normal tissue on the ipsilateral side) / Volume of normal tissue on the contralateral side × 100%. All statistical procedures were performed using GraphPad Prism software.

[0212] 14.7 Experimental Results 14.7.1. Effects of the test drug on neurological symptoms and behavior in rats with acute cerebral ischemia Following cerebral ischemia, anesthetized rats exhibited varying degrees of focal neurological dysfunction upon awakening, manifesting as weakness in the left hind limb, circling to the left when walking with extended limbs, and in severe cases, falling to the left or being unable to walk, eventually leading to altered consciousness. When the tail was lifted, the left forelimb was flexed and adducted, while the hind limb was extended and rotated to the right. Animals in the model group showed significant neurological damage symptoms after cerebral ischemia, with significantly elevated neurological function scores (P<0.05). Table 4 shows the number of surviving animals and their behavioral scores after the experiment. It can be seen that compared to the solvent group, the behavioral scores of the test group were significantly lower, indicating that the test product could significantly improve the neurological behavioral function of rats with acute cerebral ischemia. The behavioral scores of compounds PDC-1 and PDC-3 were basically equivalent to those of the positive control group, indicating that PDC-1 and PDC-3 could significantly improve the neurological behavioral function of rats with acute cerebral ischemia.

[0213] 14.7.2. Effect of the test drug on the infarct volume in rats with acute cerebral ischemia After staining, normal brain tissue appeared entirely rose-red, while infarcted tissue appeared white with clear boundaries. Except for the sham-operated group, all other groups of rats showed obvious infarct foci in their brains. Table 4 shows the cerebral infarction rate in the experimental animals. Compared to the solvent group, the cerebral infarction rate in the test sample group was significantly lower, indicating that the test sample could significantly reduce the infarct volume in rats. The cerebral infarction rates of compounds PDC-1 and PDC-4 were lower than those in the positive control group, indicating that PDC-1 and PDC-4 significantly improved cerebral infarction and were more effective than the positive control drug.

[0214] Table 4

[0215] Numerical values ​​are expressed as mean ± SD. One-way ANOVA and Dunnett's multiple comparisonstest were used to analyze the results compared to the sham surgery group. P<0.05; compared with the solvent group, #P<0.05.

[0216] In summary, compound PDC-1 can effectively prevent motor dysfunction and cerebral infarction in rats with cerebral ischemia.

[0217] Example 15: Detection of the therapeutic effect of camphenol polypeptide conjugate on stroke rats after continuous administration The method for establishing the MCAO reperfusion rat model and the model scoring criteria are basically the same as in Example 14, except that: the ischemia time is 1 hour, and the drug is administered via the tail vein. After 2 hours of ischemia, the embolic suture is carefully removed, thus forming reperfusion.

[0218] Animals were randomly grouped according to their model scores. The animal groups and administration methods are shown in Table 5 below. Table 5

[0219] One hour after ischemia, rats in each group were administered the first dose via tail vein injection of 20% propylene glycol aqueous solution, the positive control drug (edaravone 8 mg / kg + dexborneol 2 mg / kg), and the test sample at 5 μmol / kg. This administration continued for 5 days. Neurological deficits were assessed using the Zea-Longa five-point scale one hour after modeling (d0, initial score). Scoring was repeated at the same time points on day 1 (d1, 24 hours after reperfusion), day 2 (d2), day 3 (d3), day 4 (d4), day 5 (d5), and day 6 (d6) after modeling. The rate of decrease in Zea-Longa score at the experimental endpoint was calculated to assess efficacy.

[0220] Figure 13The effects of the test drugs on the neurological symptoms and behaviors of rats with acute cerebral ischemia were shown. Among them, PDC-1, PDC-2, PDC-7 and PDC-10 showed a decrease of 0.58, 0.64, 0.89 and 0.92 in the initial score of the solvent group, respectively, at the endpoint, indicating a trend of improving the neurological symptoms and behaviors of rats.

[0221] In addition, the same method as in Example 14 was used to stain rat brain tissue and calculate the cerebral infarction rate to investigate the effect of the test drug on the cerebral infarction volume in rats with acute cerebral ischemia. The results are shown in Table 6. It can be seen that obvious infarct foci appeared in the brains of all rats after modeling, and the cerebral infarction rate in the solvent group was significantly higher than that in the sham-operated group. After 5 days of continuous treatment, the positive control drug, PDC-1, and PDC-2 effectively reduced the cerebral infarction volume, and the difference was statistically significant (P<0.05).

[0222] Table 6

[0223] Numerical values ​​are expressed as mean ± SD. One-way ANOVA and Dunnett's multiple comparisonstest were used to analyze the results compared to the solvent group. P<0.05.

[0224] The results show that the compounds disclosed herein can significantly improve and enhance the neurological and behavioral functions of rats with acute cerebral ischemia, significantly reduce the volume of cerebral infarction, and demonstrate a good protective effect against cerebral ischemia. They also show excellent efficacy in the treatment of stroke and have good prospects for clinical application.

Claims

1. A compound or its solvate, or a pharmaceutically acceptable salt thereof, characterized in that, The compound is selected from: The camphor group in the compound is dextrocamphor.

2. A method for preparing the compound of claim 1 or its solvates, or pharmaceutically acceptable salts, characterized in that, include: Camphor and a coupling agent are reacted under reaction conditions to prepare an intermediate containing an ester bond. The intermediate is then sequentially bonded to the corresponding amino acid, purified, and the compound shown or its solvate or pharmaceutically acceptable salt is obtained.

3. A pharmaceutical composition, characterized in that, It includes the compound of claim 1 or the compound prepared by the method of claim 2 or a solvate thereof, a pharmaceutically acceptable salt, and a pharmaceutically acceptable excipient.

4. The use of the compound of claim 1 or its solvate, a pharmaceutically acceptable salt thereof, the compound of claim 2 prepared by the method thereof, a pharmaceutically acceptable salt thereof, or the pharmaceutical composition of claim 3 in the preparation of a cerebral ischemia-protective drug.

5. The application according to claim 4, characterized in that, Ischemic brain diseases include ischemic stroke.

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