A polypeptide with anticancer activity and its preparation method and application

Abstract

The application belongs to the technical fields of medicinal chemistry and antitumor drugs, and discloses a polypeptide with anticancer activity, a preparation method and application thereof. The polypeptide is a Bathiapeptide F analogue containing a thiazole or dithiazole skeleton, and the molecular structure of the polypeptide contains independently changeable amino acid residue or peptide residue substituents. The application designs and synthesizes a new polypeptide analogue containing a thiazole or dithiazole skeleton by taking Bathiapeptide F as a parent structure. The preparation method includes the steps of amination reaction, sulfuration reaction, thiazole ring formation reaction, amide condensation reaction, ester hydrolysis, and removal of an amino protecting group. Experimental results show that the polypeptide has obvious inhibitory effect on Huh7 liver cancer cells, MDA-MB-231 breast cancer cells and A375 melanoma cells, and can be used for preparing anticancer drugs, and has good drug development prospects.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical chemistry and anti-tumor drug technology, specifically relating to a polypeptide with anti-cancer activity, its preparation method, and its application. Background Technology

[0002] Cancer is a major disease characterized by uncontrolled cell proliferation, with high incidence, high mortality, and significant treatment challenges. Although existing treatments such as surgery, radiotherapy, chemotherapy, targeted therapy, and immunotherapy are widely used in clinical practice, problems such as tumor drug resistance, severe side effects, insufficient selectivity, and limited efficacy for some cancer types remain prominent. Therefore, the development of novel anticancer drugs with novel structures and well-defined activities remains of great importance.

[0003] Peptides are an important type of natural product, attracting widespread attention in anticancer drug research due to their high targeting, selectivity, and biocompatibility. Natural peptides typically originate from microorganisms, marine organisms, or higher plants, exhibiting diverse primary structures and spatial conformations. They can exert antitumor effects by regulating protein-protein interactions, inducing apoptosis in cancer cells, or inhibiting cancer cell proliferation. Furthermore, peptide molecules have numerous modifiable sites, facilitating structural modifications to improve their stability, membrane permeability, and resistance to enzymatic degradation. However, natural peptides also face challenges such as limited sources, low content, unstable supply, difficulties in extraction and purification, and insufficient solubility, in vivo stability, and bioavailability in some compounds, limiting their further development.

[0004] Bathiapeptides are a class of novel natural peptides with a characteristic bithiazole backbone and exhibit good antitumor activity. However, the natural abundance of these compounds is extremely low, and structural modification and activity development around their bithiazole backbone remain insufficient. Summary of the Invention

[0005] To address the shortcomings mentioned in the background art, the present invention aims to provide a polypeptide with anticancer activity, its preparation method, and its applications. The polypeptide is a polypeptide analog obtained based on the characteristic bithiazole backbone of Bathiapeptide F, and its structure contains thiazole or bithiazole units and amino acid residues. The preparation method includes steps such as amination, sulfidation, thiazole cyclization, amide condensation, ester hydrolysis, and removal of amino protecting groups. Experiments show that the polypeptide has inhibitory effects on Huh7 liver cancer cells, MDA-MB-231 breast cancer cells, and A375 melanoma cells, and can be used to prepare anticancer drugs.

[0006] The objective of this invention can be achieved through the following technical solutions: A polypeptide with anticancer activity, said polypeptide being a compound having the structure shown in formula (I), or a pharmaceutically acceptable salt thereof:

[0007] Ⅰ In formula (I), R1 and R2 are each independently selected from amino acid residues, combined amino acid residues linked by amide bonds, hydroxyl groups or hydrogen, R is a thiazole ring, or R is absent and its two sides are directly connected.

[0008] More preferably, the amino acid residue is selected from one of glycine residue, alanine residue, valine residue, isoleucine residue, leucine residue, normal valine residue, phenylalanine residue, tyrosine residue, cyclopropylglycine residue, and tertiary leucine residue; the combined amino acid residues linked by amide bonds are dipeptide residues or tripeptide residues formed by linking two or three amino acids selected from glycine, alanine, valine, isoleucine, leucine, normal valine, phenylalanine, tyrosine, cyclopropylglycine, and tertiary leucine through amide bonds.

[0009] More preferably, the polypeptide is selected from one of polypeptide 1, polypeptide 2, polypeptide 3, polypeptide 4, polypeptide 5, polypeptide 6, polypeptide 7, polypeptide 8, polypeptide 9, polypeptide 10, polypeptide 11, polypeptide 12, polypeptide 13, polypeptide 14, polypeptide 15, polypeptide 16 and polypeptide 17, or a pharmaceutically acceptable salt thereof, and its structural formula is as follows:

[0010] .

[0011] More preferably, the polypeptide is selected from one of polypeptide 1 and polypeptide 2, or a pharmaceutically acceptable salt thereof.

[0012] A method for preparing a polypeptide with anticancer activity, characterized by comprising the following steps: (1) Amino acid ester starting materials are subjected to an ammoniation reaction to obtain amide intermediates; (2) The amide intermediate is subjected to a sulfidation reaction to obtain a thioamide intermediate; (3) The thioamide intermediate is subjected to a thiazole cyclization reaction, and the ammoniation, sulfidation and thiazole cyclization reactions are repeated according to the target polypeptide structure to obtain a thiazole monomer or a bithiazole monomer. (4) The thiazole monomer or bithiazole monomer is subjected to amino protecting group removal or ester hydrolysis to obtain a condensable intermediate; (5) The condensable intermediate is subjected to an amide condensation reaction with a protected amino acid or an amino acid ester salt to obtain a polypeptide intermediate; (6) The polypeptide intermediate is subjected to ester hydrolysis, removal of amino protecting groups or a combination thereof, and purified to obtain the polypeptide with anticancer activity.

[0013] More preferably, in step (1), the amination reaction uses methanol or ethanol as a solvent and ammonia water as an amination reagent, and the volume ratio of methanol or ethanol to ammonia water is (2~5):(1~3).

[0014] More preferably, in step (2), the sulfidation reaction uses Lawson's reagent as the sulfidation reagent, and the molar ratio of Lawson's reagent to the amide intermediate is (0.5~1.2):1.

[0015] More preferably, in step (3), the thiazole cyclization reaction uses DME as a solvent and adds potassium bicarbonate, ethyl bromopyruvate, 2,6-dimethylpyridine and trifluoroacetic anhydride. The molar ratio of the thioamide intermediate, potassium bicarbonate, ethyl bromopyruvate, 2,6-dimethylpyridine and trifluoroacetic anhydride is 1:(6~12):(2~5):(4~8):(2~5).

[0016] More preferably, in step (5), the amide condensation reaction uses HATU as the condensing agent and DIPEA as the organic base, and the molar ratio of the protected amino acid or amino acid ester salt, HATU and DIPEA is 1:(1.0~1.5):(2~5); in step (6), the ester hydrolysis is carried out using tetrahydrofuran, water and lithium hydroxide solution, the volume ratio of tetrahydrofuran to water is (2~5):1, and the removal of the amino protecting group is carried out using dichloromethane and trifluoroacetic acid, the volume ratio of dichloromethane to trifluoroacetic acid is (0.5~2):1.

[0017] The application of peptides with anticancer activity in the preparation of anticancer drugs, which are used to inhibit the proliferation of Huh7 liver cancer cells, MDA-MB-231 breast cancer cells or A375 melanoma cells.

[0018] The beneficial effects of this invention are: This invention uses the characteristic thiazole or bithiazole backbone of Bathiapeptide F as the structural design basis. By simplifying the natural polypeptide backbone and modifying amino acid residues, a novel class of structurally well-defined anticancer polypeptide analogs is obtained. Compared with naturally derived Bathiapeptides, the polypeptides of this invention can be prepared by chemical synthesis, reducing dependence on natural extraction sources and avoiding problems such as low content of natural products, difficult separation and purification, and poor batch stability, which is beneficial for subsequent scale-up preparation and quality control. While retaining the important active structural unit of the thiazole or bithiazole backbone, this invention introduces different amino acid residues or peptide residues, making the compound structure tunable and providing a foundation for further structure-activity relationship studies and structural optimization. The preparation method employs steps such as amination, sulfidation, thiazole cyclization, amide condensation, ester hydrolysis, and removal of amino protecting groups. The route is clear, the raw materials are readily available, and it is suitable for the preparation of various analogs. Experimental results show that the representative peptides of this invention have significant inhibitory effects on Huh7 liver cancer cells, MDA-MB-231 breast cancer cells, and A375 melanoma cells, indicating that these peptides have good anti-cancer activity and certain broad-spectrum tumor-suppressing potential. Attached Figure Description

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a synthetic route diagram of the polypeptide of the present invention; Figure 2 The 1H NMR spectrum of peptide 2 (400MHz). Figure 3 The 13C NMR spectrum (100MHz) of peptide 2 is shown. Figure 4 The 1H NMR spectrum of peptide 7 (400MHz). Figure 5 The 13C NMR spectrum (100MHz) of peptide 7 is shown. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: Preparation of polypeptide 1 (1) Synthesis of thiazole monomers ① Ammoniation reaction: Dissolve 25g of the starting material Boc-D-alanine methyl ester in 120ml of methanol, add 80ml of ammonia water to obtain the reaction solution, concentrate under reduced pressure, and dry to obtain 23g of white solid. ② Sulfation reaction: Compound 1 was dissolved in 200 ml of tetrahydrofuran, Lawson's reagent (37 g, 91.64 mmol) was added, and after the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. The mixture was extracted three times with ethyl acetate, and the organic phases were combined and washed successively with water and saturated brine. The organic layer was dried with anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography with petroleum ether and ethyl acetate mixed in a volume ratio of 8:1 as the eluent to obtain 12 g of compound 2 as a yellow solid. ③ Thiazole cyclization reaction: Compound 2 was dissolved in 100 mL DME. Potassium bicarbonate solid (52.93 g, 528.67 mmol) was added to the reaction solution, and the reaction system was transferred to a cryogenic reactor. After stirring for 15 min, ethyl bromopyruvate (27.7 mL, 176.22 mmol) was added, and stirring continued for 1 h. Then, 2,6-dimethylpyridine (34.2 mL, 293.7 mmol) was slowly added, and stirring continued for 1 h. Trifluoroacetic anhydride (24.5 mL, 176.2 mmol) was then slowly added, and the reaction continued for 2 h. The reaction was then quenched with water. The reaction solution was extracted three times with ethyl acetate. The combined organic phases were washed successively with 1 M hydrochloric acid and saturated brine. The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography using a 5:1 mixture of petroleum ether and ethyl acetate as the eluent to obtain compound 3 as a white solid (10 g).

[0023] ④ Ammoniation reaction: Compound 3 was dissolved in 90 mL of ethanol, 60 mL of ammonia was added, the reaction was concentrated under reduced pressure and dried to obtain compound 4, which was 9 g of gray solid.

[0024] ⑤ Sulfation reaction: Compound 4 was dissolved in 100 mL of tetrahydrofuran, and Lawson's reagent (10.06 g, 24.88 mmol) was added. After the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. The mixture was extracted three times with ethyl acetate, and the organic phases were combined and washed successively with water and saturated brine. The organic layer was dried with anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography with a 3:1 volume ratio of petroleum ether to ethyl acetate as the eluent to obtain compound 5, which was 6 g of yellow solid.

[0025] ⑥ Thiazole cyclization reaction: Compound 5 was dissolved in 100 mL DME. Potassium bicarbonate solid (18.81 g, 187.89 mmol) was added to the reaction solution, and the reaction system was transferred to a cryogenic reactor. After stirring for 15 min, ethyl bromopyruvate was added, and stirring continued for 1 h. Then, 2,6-dimethylpyridine was slowly added, and stirring continued for 1 h. Trifluoroacetic anhydride was then slowly added, and the reaction continued for 2 h. The reaction was then quenched with water. The reaction solution was extracted three times with ethyl acetate. The combined organic phases were washed successively with 1 M hydrochloric acid and saturated brine. The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography using a 5:1 mixture of petroleum ether and ethyl acetate as the eluent to give compound 6 as 5 g of a white solid.

[0026] ⑦ Ammoniation reaction: Compound 6 was dissolved in 90 mL of ethanol, 60 mL of ammonia was added, the reaction was concentrated under reduced pressure and dried to obtain compound 7, which was 4 g of gray solid.

[0027] ⑧ Sulfidation reaction: Compound 7 was dissolved in 100 mL of tetrahydrofuran, and Lawson's reagent (3.42 g, 8.46 mmol) was added. After the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. The mixture was extracted three times with ethyl acetate, and the organic phases were combined and washed successively with water and saturated brine. The organic layer was dried with anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography with a 3:1 volume ratio of petroleum ether to ethyl acetate as the eluent to obtain compound 8, which was 3 g of yellow solid.

[0028] ⑨ Thiazole cyclization reaction: Compound 8 was dissolved in 100 mL of DME. Potassium bicarbonate solid (7.3 g, 72.87 mmol) was added to the reaction solution, and the reaction system was transferred to a cryogenic reactor. After stirring for 15 min, ethyl bromopyruvate (3.82 mL, 24.29 mmol) was added, and stirring continued for 1 h. Then, 2,6-dimethylpyridine (4.72 mL, 40.49 mmol) was slowly added, and stirring continued for 1 h. Trifluoroacetic anhydride (3.38 mL, 24.29 mmol) was then slowly added, and the reaction continued for 2 h. The reaction was then quenched with water. The reaction solution was extracted three times with ethyl acetate. The combined organic phases were washed successively with 1 M hydrochloric acid and saturated brine. The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by column chromatography using a 3:1 mixture of petroleum ether and ethyl acetate as the eluent to give compound 9 as a white solid (1.8 g).

[0029] (2) Construction of the polypeptide backbone ① Deprotection of Boc: Dichloromethane was added to compound 9 and stirred to dissolve it. Trifluoroacetic acid was then added, with a volume ratio of trifluoroacetic acid to dichloromethane of 1:1. After the reaction was complete, the mixture was concentrated under reduced pressure, the residual solvent was purged with nitrogen, and the mixture was freeze-dried to obtain compound 11, which was 2.2 g of an oil.

[0030] ② Condensation of the first amino acid: Compound 11 was dissolved in dichloromethane, and Boc-Ile-COOH (2.27 g, 9.8 mmol), HATU (2.57 g, 6.69 mmol), and DIPEA (3.17 g, 24.50 mmol) were added. The mixture was reacted at room temperature for 10 h. After the reaction was complete, the mixture was filtered and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography using a 2:1 mixture of petroleum ether and ethyl acetate as the eluent to obtain compound 12, which was 2.8 g of a white solid.

[0031] ③ Deprotection of Boc: Compound 12 was added to dichloromethane and stirred until dissolved. Trifluoroacetic acid was then added, with a volume ratio of trifluoroacetic acid to dichloromethane of 1:1. After the reaction was complete, the mixture was concentrated under reduced pressure, the residual solvent was removed by nitrogen purging, and the mixture was freeze-dried to obtain compound 13, which was an oily substance.

[0032] ④ Condensation of the second amino acid: 150.0 mg of compound 13 was dissolved in 20 mL of dichloromethane, and Boc-Phe-COOH (57.86 mg, 0.32 mmol), HATU (124.05 mg, 0.32 mmol), and DIPEA (125.18 mg, 0.97 mmol) were added. The reaction was carried out at room temperature for 10 h. After the reaction was completed, the reaction was quenched with 0.1 M hydrochloric acid aqueous solution (15 mL) and extracted with dichloromethane (2 × 75 mL). The organic layer was washed successively with saturated sodium bicarbonate solution and saturated brine, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and the crude product was purified by column chromatography with a 5:1 volume ratio of petroleum ether and ethyl acetate as the eluent to obtain the protected polypeptide intermediate 14.

[0033] (3) Deprotection and purification of peptides A mixed solvent of tetrahydrofuran and water (volume ratio 3:1) was added to the obtained protected polypeptide intermediate 14. After stirring and dissolving, 1 M lithium hydroxide solution was added for ester hydrolysis. After the reaction was complete, the tetrahydrofuran was removed by concentration under reduced pressure. A saturated potassium hydrogen sulfate solution was added to the reaction solution, and the precipitated solid was collected, filtered, and freeze-dried to obtain a solid reactant. A mixed solution of trifluoroacetic acid and dichloromethane (volume ratio 1:1) was added to the solid reactant, and the mixture was stirred for 6 h to obtain a crude product. The crude product was purged with nitrogen to remove residual solvent, freeze-dried, and then recrystallized with water and methanol to obtain the pure target product polypeptide 1, with an overall yield of 0.3%.

[0034] The structure of polypeptide 1 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6) δ(ppm): 8.98 (d , J=8.0 Hz, 1H), 8.59 (d , J=8.0 Hz, 1H), 8.52 (s, 1H), 8.38 (s, 1H), 8.32 (s, 1H), 8.17 (s, 2H), 7.33(m,2H), 7.28(m, 2H), 7.27(m, 1H), 5.28 (m, 1H), 4.22 (t, J=8.0 Hz, 1H), 4.18 (t, J=8.0 Hz, 1H), 3.05 (d, J=8.0, 16.0 Hz, 1H), 2.97 (dd, J=16.0, 8.0 Hz,1H), 1.64(m, 1H), 1.55 (d, J=4.0 Hz, 3H), 1.24 (m, 1H), 0.90 (m, 1H), 0.77(m, 3H), 0.75 (m, 3H). 13C NMR (100 MHz, DMSO-d6) δ(ppm): 175.5, 170.3, 168.0, 163.0, 162.1,162.0, 148.7, 148.3, 147.1, 134.9, 129.5, 129.3, 128.6, 127.2, 118.8, 118.4,57.1, 53.3, 46.8, 37.4, 37.0, 24.5, 24.2, 15.2, 11.0. Example 2: Preparation of polypeptide 2 Peptide 2 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for further peptide backbone construction; in step (2), during peptide backbone construction, the amino protecting group was not removed after the condensation of the first amino acid, but instead, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to tert-butyl-L-tyrosine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 2 was obtained with an overall yield of 1.8%.

[0035] The structure of polypeptide 2 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.28 (s, 1H), 9.28 (d, J=7.9 Hz,1H), 8.31 (s, 1H), 8.29 (s, 1H), 8.24 (d, J=8.1 Hz, 1H), 8.16 (s, 2H), 7.05(d, J=8.0 Hz, 2H), 6.66 (d, J=8.0 Hz, 2H), 5.37-5.30 (m, 1H), 4.65-4.60 (m,1H), 3.67 (d, J=5.5 Hz, 1H), 3.14-3.03 (m, 2H), 1.91-1.82 (m, 1H), 1.59 (d, J=7.0 Hz, 3H), 1.56-1.49 (m, 1H), 1.18 (s, 1H), 0.96 (d, J=6.8 Hz, 3H), 0.90(t, J=7.3 Hz, 3H). 13C NMR (100 MHz, DMSO-d6) δ 174.48, 173.19, 168.02, 162.34, 160.48,156.50, 150.51, 147.64, 130.55, 127.74, 125.26, 118.81, 115.60, 60.23, 57.02,54.03, 47.26, 36.75, 24.52, 20.86, 15.08, 11.67. Example 3: Preparation of polypeptide 3 Peptide 3 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the amino protecting group was not removed after the condensation of the first amino acid, but instead, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to glycine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 3 was obtained with a total yield of 2.7%.

[0036] The structure of polypeptide 3 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.25 (d, J=7.8 Hz, 1H), 8.66 (t,J=6.1 Hz, 1H), 8.34 (s, 1H), 8.27 (s, 1H), 8.14 (s, 2H), 5.37-5.30 (m, 1H),3.98 (d, J=6.1 Hz, 1H), 2.70 (s, 2H), 1.94-1.84 (m, 1H), 1.60 (d, J=6.9 Hz,3H), 1.53-1.49 (m, 1H), 1.18-1.12 (m, 1H), 0.96 (d, J=6.8 Hz, 3H), 0.90 (t, J=7.3 Hz, 3H). 13C NMR (100 MHz, DMSO-d6) δ 174.63, 171.55, 168.02, 162.36, 161.12,150.68, 147.71, 125.18, 118.71, 57.06, 47.35, 41.35, 40.46, 40.25, 40.05,39.84, 39.63, 39.42, 39.21, 36.72, 24.53, 20.86, 15.00, 11.71. Example 4: Preparation of polypeptide 4 Peptide 4 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the amino protecting group was not removed after the condensation of the first amino acid, but instead, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to valine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 4 was obtained with a total yield of 1.3%.

[0037] The structure of polypeptide 4 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.26 (d, J=7.8 Hz, 1H), 8.37 (s,1H), 8.34 (s, 1H), 8.32 (s, 1H), 5.37-5.30 (m, 1H), 4.45 (q, J=7.5, 14.5 Hz,1H), 3.71-3.64 (m, 1H), 1.92-1.80 (m, 3H), 1.59 (d, J=6.9 Hz, 3H), 1.56-1.48(m, 1H), 1.40-1.32 (m, 2H), 1.23-1.11 (m, 2H), 0.97-0.88 (m, 8H). 13C NMR (100 MHz, DMSO-d6) δ 174.08, 173.50, 167.79, 161.92, 160.27,150.21, 147.28, 124.83, 118.47, 56.70, 51.79, 46.85, 36.38, 33.08, 24.08,20.46, 18.76, 14.69, 13.55, 11.25. Example 5: Preparation of peptide 5 Peptide 5 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for further peptide backbone construction; in step (2), during peptide backbone construction, the amino protecting group was not removed after the condensation of the first amino acid, but instead, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to cyclopropylglycine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 5 was obtained with a total yield of 2.8%.

[0038] The structure of polypeptide 5 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.23 (d, J=7.9 Hz, 1H), 8.41 (s,1H), 8.36 (s, 1H), 8.04 (d, J=8.7 Hz, 1H), 5.36-5.29 (m, 1H), 4.39-4.35 (m,1H), 3.62 (d, J=5.6 Hz, 1H), 1.89-1.83 (m, 2H), 1.72-1.69 (m, 3H), 1.59 (d, J=6.9 Hz, 3H), 1.55-1.50 (m, 1H), 1.25-1.02 (m, 8H), 0.95 (d, J=6.8 Hz, 3H), 0.90 (d, J=7.3 Hz, 3H). 13C NMR (100 MHz, DMSO-d6) δ 174.65, 173.04, 168.08, 162.54, 160.59,150.38, 147.60, 125.35, 119.07, 57.19, 57.01, 55.32, 47.36, 38.67, 36.76,29.82, 28.64, 26.06, 25.96, 24.52, 20.87, 15.02, 11.62. Example 6: Preparation of polypeptide 6 Peptide 6 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the amino protecting group was not removed after the condensation of the first amino acid, but instead, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to tert-leucine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 6 was obtained with a total yield of 3.3%.

[0039] The structure of polypeptide 6 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.29 (d, J=7.8 Hz, 1H), 8.44 (s,1H), 8.39 (s, 1H), 7.88 (d, J=9.4 Hz, 1H), 5.36-5.29 (m, 1H), 4.35 (d, , 0.96 (d, J=6.8 Hz, 3H), 0.89 (t, J=7.3 Hz, 3H). 13C NMR (100 MHz, DMSO-d6) δ 174.65, 173.04, 168.08, 162.54, 160.59,150.38, 147.60, 125.35, 119.07, 57.01, 55.32, 47.36, 38.67, 36.76, 29.82,28.64, 25.96, 24.52, 20.87, 15.02, 11.62. Example 7: Preparation of polypeptide 7 Peptide 7 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the first amino acid raw material was changed from Boc-Ile-COOH to Boc-Val-COOH during the condensation of the first amino acid, and instead of removing the amino protecting group after the condensation of the first amino acid, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to tert-butyl-L-tyrosine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 7 was obtained with a total yield of 2.7%.

[0040] The structure of polypeptide 7 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.35 (d, J=7.6 Hz, 1H), 8.31 (s,1H), 8.28 (s, 1H), 8.23 ​​(d, J=8.0 Hz, 1H), 7.05 (d, J=8.0 Hz, 2H), 6.67 (d, J=8.0 Hz, 2H), 5.37-5.30 (m, 1H), 4.65-4.60 (m, 1H), 3.67 (d, J=6.0 Hz, 1H), 3.14-3.03 (m, 2H), 2.19-2.11 (m, 1H), 1.60 (d, J=7.0 Hz, 3H), 1.24-1.15 (m,1H), 0.98 (t, J=6.4 Hz, 6H). 13C NMR (100 MHz, DMSO-d6) δ 174.67, 173.21, 168.12, 162.36, 160.45,156.52, 150.55, 147.66, 130.56, 127.76, 125.19, 118.75, 115.59, 57.88, 54.12,47.29, 36.12, 30.36, 20.89, 18.75, 18.14. Example 8: Preparation of polypeptide 8 Peptide 8 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the first amino acid raw material was changed from Boc-Ile-COOH to Boc-Val-COOH during the condensation of the first amino acid, and instead of removing the amino protecting group after the condensation of the first amino acid, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to glycine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 8 was obtained with a total yield of 1.3%.

[0041] The structure of polypeptide 8 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.27 (d, J=7.8 Hz, 1H), 8.64 (t,J=6.0 Hz, 1H), 8.34 (s, 1H), 8.26 (s, 1H), 5.37-5.30 (m, 1H), 3.97 (d, J=6.0Hz, 2H), 3.62 (d, J=5.5 Hz, 1H), 2.18-2.09 (m, 1H), 1.60 (d, J=7.0 Hz, 3H), 0.98 (t, J=8.8 Hz, 6H). 13C NMR (100 MHz, DMSO-d6) δ 174.68, 171.57, 168.31, 162.33, 161.00,150.78, 147.75, 125.18, 118.60, 57.99, 47.27, 41.44, 30.42, 20.96, 18.83,18.09. Example 9: Preparation of polypeptide 9 Peptide 9 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for further peptide backbone construction; in step (2), during peptide backbone construction, the first amino acid raw material was changed from Boc-Ile-COOH to Boc-Val-COOH during the condensation of the first amino acid, and instead of removing the amino protecting group after the condensation of the first amino acid, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to valine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 9 was obtained with a total yield of 2.6%.

[0042] The structure of polypeptide 9 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.32-9.28 (m, 1H), 8.37 (s, 1H), 8.35 (s, 1H), 8.32 (s, 1H), 8.19 (s, 2H), 5.38-5.30 (m, 1H), 4.46 (q, J=7.4,14.5 Hz, 1H), 3.64 (d, J=5.4 Hz, 1H), 2.19-2.10 (m, 1H), 1.86-1.80 (m, 2H),1.60 (d, J=6.9 Hz, 3H), 1.44-1.32 (m, 2H), 0.99 (t, J=7.4 Hz, 6H), 0.92 (t, J=7.3 Hz, 3H). 13C NMR (100 MHz, DMSO-d6) δ 174.51, 173.92, 168.03, 162.34, 160.72,150.63, 147.73, 125.28, 118.91, 57.87, 52.13, 47.29, 33.45, 30.34, 20.94,19.21, 18.77, 18.10, 13.97. Example 10: Preparation of polypeptide 10 Peptide 10 was prepared using a method essentially the same as in Example 1, with the following differences: the thiazole monomer was synthesized to compound 6 and then used for subsequent peptide synthesis; during peptide synthesis, after the condensation of the first amino acid, the amino protecting group was not removed, but instead, methyl ester hydrolysis was performed; the first amino acid starting material was replaced with Boc-Val-COOH, and the second amino acid starting material was replaced with cyclopropylglycine methyl ester hydrochloride. After ester hydrolysis, amino protecting group removal, and purification, the target product peptide 10 was obtained, with an overall yield of 1.9%.

[0043] The structure of polypeptide 10 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.42-9.40 (m, 1H), 8.31 (d, J=6.0Hz, 2H), 8.03 (d, J=8.6 Hz, 1H), 5.34-5.27 (m, 1H), 4.31-4.27 (m, 1H), 3.67(d, J=5.6 Hz, 1H), 2.18-2.09 (m, 1H), 1.90-1.84 (m, 1H), 1.73-1.64 (m, 5H), 1.58 (d, J=7.1 Hz, 3H), 1.21-1.04 (m,5H), 0.97 (t, J=5.9 Hz, 6H). 13C NMR (100 MHz, DMSO-d6) δ 174.60, 168.16, 162.21, 159.92, 150.56,147.29, 124.71, 118.73, 118.52, 115.76, 59.91, 57.78, 57.65, 47.05, 30.11,29.77, 28.25, 25.89, 25.84, 20.56, 18.44, 17.82. Example 11: Preparation of polypeptide 11 Peptide 11 was prepared using a method essentially the same as in Example 1, with the following differences: In step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for further peptide backbone construction; in step (2), during peptide backbone construction, the first amino acid raw material was changed from Boc-Ile-COOH to Boc-Val-COOH during the condensation of the first amino acid, and instead of removing the amino protecting group after the condensation of the first amino acid, methyl ester hydrolysis was performed; the second amino acid raw material was changed from Boc-Phe-COOH to tert-leucine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 11 was obtained with a total yield of 2.7%.

[0044] The structure of polypeptide 11 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.44 (d, J=7.9 Hz, 1H), 8.38 (s,1H), 8.33 (s, 1H), 7.90 (d, J=9.2 Hz, 1H), 5.33-5.25 (m, 1H), 4.29 (d, J=9.5Hz, 1H), 3.68-3.66 (m, 1H), 2.17-2.09 (m, 1H), 1.57 (d, J=6.9 Hz, 3H), 1.00-0.95 (m,15H). 13C NMR (100 MHz, DMSO-d6) δ 174.66, 168.01, 162.50, 160.05, 150.19,147.27, 125.15, 118.84, 115.79, 60.59, 57.64, 47.17, 34.44, 30.14, 26.88,20.61, 18.46, 17.93. Example 12: Preparation of polypeptide 12 Peptide 12 was prepared using a method essentially the same as in Example 1, except that: in step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the first and third steps did not involve the removal of amino protecting groups, but instead involved methyl ester hydrolysis; the first amino acid raw material was replaced by isoleucine methyl ester hydrochloride instead of Boc-Ile-COOH, and the second amino acid raw material was replaced by tert-butyl-L-tyrosine methyl ester hydrochloride instead of Boc-Phe-COOH. After ester hydrolysis, removal of amino protecting groups, and purification, the target product peptide 12 was obtained with a total yield of 2.7%.

[0045] The structure of polypeptide 12 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 9.16 (s, 1H), 8.50 (d, J=7.7 Hz,1H), 8.42 (s, 1H), 8.36 (s, 1H), 7.90 (d, J=9.4 Hz, 1H), 7.01 (d, J=8.4 Hz,2H), 6.59 (d, J=8.3 Hz, 2H), 4.78-4.73 (m, 1H), 4.50-4.46 (m, 1H), 4.37-4.31(m, 1H), 2.96-2.91 (m, 1H), 2.82-2.76 (m, 1H), 1.88-1.82 (m, 1H), 1.58 (d, J=6.8 Hz, 3H), 1.50-1.43 (m,1H), 1.11-1.04 (m,1H), 0.89-0.81 (m,6H). 13C NMR (100 MHz, DMSO-d6) δ 172.94, 170.80, 169.06, 161.72, 159.79,156.03, 150.24, 147.14, 130.10, 127.59, 125.42, 120.24, 115.09, 56.52, 54.08,47.52, 37.56, 35.91, 24.24, 19.78, 15.41, 11.08. Example 13: Preparation of polypeptide 13 Peptide 13 was prepared using a method essentially the same as in Example 1, except that: in step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the first and third steps did not involve the removal of amino protecting groups, but instead involved methyl ester hydrolysis; the first amino acid raw material was replaced by isoleucine methyl ester hydrochloride instead of Boc-Ile-COOH, and the second amino acid raw material was replaced by glycine methyl ester hydrochloride instead of Boc-Phe-COOH. After ester hydrolysis, removal of amino protecting groups, and purification, the target product peptide 13 was obtained with a total yield of 2.7%.

[0046] The structure of polypeptide 13 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 8.84 (s, 2H), 8.67 (t, J=5.8 Hz,1H), 8.52 (s, 1H), 8.40 (s, 1H), 8.03 (d, J=9.3 Hz, 1H), 4.97 (q, , 1.22-1.10 (m,1H), 0.95-0.86 (m,6H). 13C NMR (100 MHz, DMSO-d6) δ 171.27, 171.19, 169.19, 161.84, 159.92,150.33, 147.23, 125.47, 120.29, 56.77, 47.58, 40.85, 37.63, 24.58, 19.83,15.48, 11.21. Example 14: Preparation of polypeptide 14 Peptide 14 was prepared using a method essentially the same as in Example 1, except that: in step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, neither the first nor the third step involved the removal of amino protecting groups, but rather methyl ester hydrolysis; the first amino acid raw material was replaced by isoleucine methyl ester hydrochloride instead of Boc-Ile-COOH, and the second amino acid raw material was replaced by valine methyl ester hydrochloride instead of Boc-Phe-COOH. After ester hydrolysis, removal of amino protecting groups, and purification, the target product peptide 14 was obtained with a total yield of 2.7%.

[0047] The structure of polypeptide 14 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 8.52-8.50 (m, 2H), 8.40 (s, 1H), 7.99 (d, J=9.2 Hz, 1H), 4.98-4.93 (m, 1H), 4.55-4.51 (m, 1H), 4.21-4.16 (m,1H), 1.92-1.86 (m, 1H), 1.67 (d, J=6.8 Hz, 3H), 1.64-1.51 (m,2H), 1.39-1.29(m,2H), 1.20-1.10 (m,2H), 0.96-0.85 (m,9H). 13C NMR (100 MHz, DMSO-d6) δ 173.77, 171.23, 169.29, 162.02, 160.09,150.49, 147.42, 125.55, 120.31, 56.77, 52.20, 47.75, 37.90, 33.18, 24.61,19.91, 19.06, 15.58, 13.76, 11.23. Example 15: Preparation of polypeptide 15 Peptide 15 was prepared using a method essentially the same as in Example 1, except that: in step (1), after the synthesis of the thiazole monomer reached compound 6, compound 6 was used as a bithiazole monomer for peptide backbone construction; in step (2), during peptide backbone construction, the first and third steps did not involve the removal of amino protecting groups, but instead involved methyl ester hydrolysis; the first amino acid raw material was replaced by isoleucine methyl ester hydrochloride instead of Boc-Ile-COOH, and the second amino acid raw material was replaced by cyclopropylglycine methyl ester hydrochloride instead of Boc-Phe-COOH. After ester hydrolysis, removal of amino protecting groups, and purification, the target product peptide 15 was obtained with a total yield of 2.7%.

[0048] The structure of polypeptide 15 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) δ 8.75 (s, 2H), 8.52 (d, J=5.8 Hz,1H), 8.51 (s, 1H), 8.40 (s, 1H), 7.95 (d, J=9.5 Hz, 1H), 4.98-4.93 (m, 1H),4.69-4.65 (m, 1H), 4.17-4.11 (m, 1H), 3.64-3.61 (m, 1H), 1.88-1.82 (m, 1H),1.71-1.68 (m, 2H), 1.66 (d, J=6.7 Hz, 3H), 1.58 (d, J=11.9 Hz, 3H), 1.52-1.46(m,1H), 1.26-1.02(m,5H), 0.96-0.84(m,7H). 13C NMR (100 MHz, DMSO-d6) δ 172.89, 171.03, 169.12, 161.77, 159.75,150.28, 147.12, 125.41, 120.26, 57.02, 56.36, 47.48, 40.53, 38.10, 29.43,28.07, 25.79, 25.70, 25.64, 24.27, 19.79, 15.66, 11.19. Example 16: Preparation of polypeptide 16 Peptide 16 was prepared using a method essentially the same as in Example 1, except that in step (2), during the construction of the peptide backbone, the amino protecting group was not removed before the condensation of the second amino acid; instead, methyl ester hydrolysis was performed. The second amino acid raw material was changed from Boc-Phe-COOH to tert-butyl-L-tyrosine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 16 was obtained with a total yield of 0.5%.

[0049] The structure of polypeptide 16 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) 9.20 (s, 1H), 8.96 (s, 1H), 8.34-8.32 (m, 3H), 8.25 (d, J=7.8 Hz, 1H), 7.04 (d, J=11.1 Hz, 2H), 6.59 (d, J=8.4Hz, 2H), 5.33-5.27 (m, 1H), 4.57-4.52 (m, 1H), 3.10-3.04 (m, 1H), 1.80-1.73(m, 1H), 1.59 (d, J=7.0 Hz, 3H), 1.54-1.47 (m, 1H), 1.18-1.10 (m, 1H), 0.93–0.83 (m, 6H). 13C NMR (100 MHz, DMSO-d6) 174.89, 172.99, 163.12, 161.86, 159.87,156.00, 150.57, 148.66, 147.05, 130.33, 129.79, 127.88, 124.83, 118.79,118.50, 115.13, 57.54, 54.34, 46.93, 37.02, 31.42, 24.22, 20.59, 15.09,11.43. Example 17: Preparation of polypeptide 17 Peptide 17 was prepared using a method essentially the same as in Example 1, except that in step (2), during the construction of the peptide backbone, the amino protecting group was not removed before the condensation of the second amino acid; instead, methyl ester hydrolysis was performed. The second amino acid raw material was changed from Boc-Phe-COOH to glycine methyl ester hydrochloride. After ester hydrolysis, removal of the amino protecting group, and purification, the target product peptide 17 was obtained with a total yield of 0.7%.

[0050] The structure of polypeptide 17 was confirmed by proton and carbon NMR spectroscopy, and the data are as follows: 1H NMR (400MHz, DMSO-d6, J in Hz) 9.21 (d, J=7.8 Hz, 1H), 8.65 (s,1H), 8.37-8.34 (m, 3H), 5.37-5.32 (m, 1H), 4.57-4.52 (m, 1H), 3.97 (d, J=6.0Hz, 2H), 1.89-1.82 (m, 1H), 1.60 (d, J=6.9 Hz, 3H), 1.56-1.50 (m, 1H), 1.20-1.11 (m, 1H), 0.97-0.88 (m, 6H). 13C NMR (100 MHz, DMSO-d6) 174.33, 167.91, 163.21, 161.89, 160.72,150.50, 148.79, 147.10, 125.06, 118.82, 118.75, 56.77, 48.74, 47.02, 41.16,36.48, 24.19, 20.57, 14.79, 11.35. Experimental Example I. Anticancer activity test 1. Experimental materials The test cells were human liver cancer cells Huh7, breast cancer cells MDA-MB-231, and melanoma cells A375.

[0051] The test compounds were polypeptide 1 prepared in Example 1 and polypeptide 2 prepared in Example 2, with cisplatin as a positive control drug.

[0052] 2. Experimental Methods The inhibitory activity of the test compounds against cancer cells was detected using the MTT assay. Huh7, MDA-MB-231, and A375 cells were seeded at 6000 cells per well in 96-well plates and cultured for 24 h. Then, peptide 1, peptide 2, and cisplatin were added at a concentration of 50 μM for 24 h, respectively.

[0053] After treatment, 20 μL of MTT solution (concentration 2.5 mg / mL) was added to each well, and the mixture was incubated at 37 °C for 4 h. After incubation, the culture medium was discarded, and 100 μL of DMSO was added to each well to fully dissolve the generated formazan crystals. The OD values ​​of each well were then measured at 570 nm using a microplate reader.

[0054] Using the OD value of untreated cancer cells as a blank control, the inhibition rate of the test compound against cancer cells was calculated according to the following formula: Inhibition rate (%) = 100 - (OD value of the treated group / OD value of the blank group) × 100% The experimental results are shown in Table 1-3 below.

[0055] 3. Experimental Results Table 1. Activity of Huh7 liver cancer cells

[0056] Table 2. MDA-MB-231 activity in breast cancer cells

[0057] Table 3 Melanoma cells A375

[0058] As shown in Tables 1-3, at a drug concentration of 50 μM, peptide 1 prepared in Example 1 and peptide 2 prepared in Example 2 of this invention all exhibited significant inhibitory effects on Huh7 liver cancer cells, MDA-MB-231 breast cancer cells, and A375 melanoma cells. Specifically, peptide 1 showed inhibition rates of 85.52±5.44%, 83.74±4.68%, and 86.26±5.17% against Huh7, MDA-MB-231, and A375 cells, respectively; while peptide 2 showed inhibition rates of 83.51±5.59%, 85.63±6.53%, and 89.08±5.93% against the same three cancer cell types, respectively. Under the same experimental conditions, the inhibition rates of peptide 1 and peptide 2 against the three cancer cell types were higher than those of the positive control drug cisplatin, indicating that the peptides described in this invention possess good anticancer activity and can be used to prepare anticancer drugs.

[0059] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A polypeptide with anticancer activity, characterized in that, The polypeptide is a compound having the structure shown in formula (I), or a pharmaceutically acceptable salt thereof: ； Ⅰ; In formula (I), R1 and R2 are each independently selected from amino acid residues, combined amino acid residues linked by amide bonds, hydroxyl groups or hydrogen, R is a thiazole ring, or R is absent and its two sides are directly connected.

2. The polypeptide with anticancer activity according to claim 1, characterized in that, The amino acid residues are selected from one of glycine residues, alanine residues, valine residues, isoleucine residues, leucine residues, normal valine residues, phenylalanine residues, tyrosine residues, cyclopropylglycine residues, and tertiary leucine residues; the combined amino acid residues linked by amide bonds are dipeptide residues or tripeptide residues formed by linking two or three amino acids selected from glycine, alanine, valine, isoleucine, leucine, normal valine, phenylalanine, tyrosine, cyclopropylglycine, and tertiary leucine through amide bonds.

3. The polypeptide with anticancer activity according to claim 1, characterized in that, The polypeptide is selected from one of polypeptide 1, polypeptide 2, polypeptide 3, polypeptide 4, polypeptide 5, polypeptide 6, polypeptide 7, polypeptide 8, polypeptide 9, polypeptide 10, polypeptide 11, polypeptide 12, polypeptide 13, polypeptide 14, polypeptide 15, polypeptide 16 and polypeptide 17, or a pharmaceutically acceptable salt thereof.

4. The polypeptide with anticancer activity according to claim 3, characterized in that, The polypeptide is selected from one of polypeptide 1 and polypeptide 2, or a pharmaceutically acceptable salt thereof.

5. A method for preparing a polypeptide with anticancer activity as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Amino acid ester starting materials are subjected to an ammoniation reaction to obtain amide intermediates; (2) The amide intermediate is subjected to a sulfidation reaction to obtain a thioamide intermediate; (3) The thioamide intermediate is subjected to a thiazole cyclization reaction, and the ammoniation, sulfidation and thiazole cyclization reactions are repeated according to the target polypeptide structure to obtain a thiazole monomer or a bithiazole monomer. (4) The thiazole monomer or bithiazole monomer is subjected to amino protecting group removal or ester hydrolysis to obtain a condensable intermediate; (5) The condensable intermediate is subjected to an amide condensation reaction with a protected amino acid or an amino acid ester salt to obtain a polypeptide intermediate; (6) The polypeptide intermediate is subjected to ester hydrolysis, removal of amino protecting groups or a combination thereof, and purified to obtain the polypeptide with anticancer activity.

6. The preparation method according to claim 5, characterized in that, In step (1), the amination reaction uses methanol or ethanol as solvent and ammonia water as amination reagent, and the volume ratio of methanol or ethanol to ammonia water is (2~5):(1~3).

7. The preparation method according to claim 5, characterized in that, In step (2), the sulfidation reaction uses Lawson's reagent as the sulfidation reagent, and the molar ratio of Lawson's reagent to the amide intermediate is (0.5~1.2):

1.

8. The preparation method according to claim 5, characterized in that, In step (3), the thiazole cyclization reaction uses DME as solvent and adds potassium bicarbonate, ethyl bromopyruvate, 2,6-dimethylpyridine and trifluoroacetic anhydride. The molar ratio of the thioamide intermediate, potassium bicarbonate, ethyl bromopyruvate, 2,6-dimethylpyridine and trifluoroacetic anhydride is 1:(6~12):(2~5):(4~8):(2~5).

9. The preparation method according to claim 5, characterized in that, In step (5), the amide condensation reaction uses HATU as the condensing agent and DIPEA as the organic base. The molar ratio of the protected amino acid or amino acid ester salt, HATU and DIPEA is 1:(1.0~1.5):(2~5). In step (6), the ester hydrolysis is carried out using tetrahydrofuran, water and lithium hydroxide solution. The volume ratio of tetrahydrofuran to water is (2~5):

1. The removal of the amino protecting group is carried out using dichloromethane and trifluoroacetic acid. The volume ratio of dichloromethane to trifluoroacetic acid is (0.5~2):

1.

10. The use of the polypeptide with anticancer activity according to any one of claims 1-4 in the preparation of an anticancer drug, characterized in that, The anticancer drug is used to inhibit the proliferation of Huh7 liver cancer cells, MDA-MB-231 breast cancer cells, or A375 melanoma cells.

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