Synthetic method of natural product linear pentapeptide AYAPE and cyclic pentapeptide Cyclo-AYAPE thereof

Abstract

The invention discloses a synthetic method of a natural product linear pentapeptide AYAPE and a cyclic pentapeptide Cyclo-AYAPE.The method comprises the steps that known L-alanine methyl ester and L-N-Fmoc-O-tert-butyl ether tyrosine serve as initial raw materials, condensation is conducted, and then methyl ester hydrolysis is conducted to obtain dipeptide; l-N-Boc-proline and glutamic acid tert-butyl ester methyl ester are condensed, methyl ester is hydrolyzed to obtain dipeptide, the dipeptide and the dipeptide are condensed to obtain tetrapeptide, Fmoc protecting groups of the tetrapeptide are removed, the tetrapeptide and L-N-Fmoc alanine are condensed to obtain pentapeptide, all protecting groups of the pentapeptide are removed, and linear pentapeptide AYAPE is obtained; and carrying out self condensation on the obtained pentapeptide to form the cyclic pentapeptide Cyclo-AYAPE. The synthesis method is low in cost, simple and convenient to operate, mild in reaction condition, short in reaction route, high in total yield and suitable for large-scale synthesis of the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE of the linear pentapeptide AYAPE, and an important material basis is provided for biological activity evaluation of the natural product linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE of the linear pentapeptide AYAPE.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis of polypeptide compounds, and specifically relates to a method for synthesizing a natural product linear pentapeptide AYAPE and a cyclic pentapeptide Cyclo-AYAPE. Background Art

[0002] Peptide compounds are a class of compounds formed by condensation of multiple amino acids through amide bonds. They are specifically divided into linear peptides and cyclic peptides. Cyclic peptide compounds are cyclic compounds generated by the closure of chain peptides. The main group in their structure is the amide bond, which is formed by the amino group (-NH 2 The diversity of the structures of linear peptides and cyclic peptides gives them a wide range of biological activities, including anti-aging, antibacterial, anti-tumor, and immunosuppressive activities.

[0003] The linear pentapeptide AYAPE (Ala-Tyr-Ala-Pro-Glu) is a pentapeptide isolated from a microalga (Trichuris glaucosa) in Zhanjiang Bay, southern China. Pharmacological activities have shown that it has antioxidant and anti-inflammatory activities. In addition, it has been shown to inhibit the growth of keratinocytes and promote the proliferation of keratinocytes in the human body. 2 O 2 The induced human skin fibroblast (BJ cell) model found that it has good anti-skin aging activity. The anti-UVB induction mechanism of AYAPE is to reduce DNA damage, reduce the level of intracellular reactive oxygen species (ROS), and enhance the photoaging ability of HaCaT cells, thereby downregulating the phosphorylation of proteins in the MAPK / AP-1 signaling pathway. In addition, AYAPE can attenuate H 2 O 2 Induced expression of senescence-associated effectors in BJ cells. The structure of the linear pentapeptide AYAPE is as follows:

[0004]

[0005] So far, there is no literature reporting the synthesis method of the natural product linear pentapeptide AYAPE and its cyclic pentapeptide Cyclo-AYAPE. Therefore, it is of great significance to develop an economical, simple and efficient synthesis method of the natural product linear pentapeptide AYAPE and its cyclic pentapeptide Cyclo-AYAPE. Summary of the invention

[0006] The purpose of the present invention is to provide a method for synthesizing a natural product linear pentapeptide AYAPE and a cyclic pentapeptide Cyclo-AYAPE, which have the advantages of cheap and readily available raw materials, mild reaction conditions, simple operation and high yield.

[0007] In view of the above purpose, the specific synthesis route and method of the natural product linear pentapeptide AYAPE and its cyclic pentapeptide Cyclo-AYAPE used in the present invention are as follows:

[0008]

[0009] 1. Using dichloromethane as solvent, compound 1 is mixed with compound 2, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and the mixture is stirred at 0°C to room temperature for 6 to 10 hours. After the reaction is completed, the product is separated and purified to obtain compound 3.

[0010]

[0011] 2. Using dichloromethane as solvent, compound 4 was mixed with compound 5, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and the mixture was stirred at 0°C to room temperature for 7 to 12 hours. After the reaction, the product was separated and purified to obtain compound 6.

[0012]

[0013] 3. Using dichloromethane as solvent, mix the dipeptide obtained by alkaline hydrolysis of compound 3, the dipeptide obtained by acid hydrolysis of compound 6, N,N-diisopropylethylamine, 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and stir the mixture at 0°C to room temperature for 6 to 11 hours. After the reaction is complete, separate and purify the product after hydrolysis with methanesulfonic acid to obtain compound 7.

[0014]

[0015] 4. Using dichloromethane as solvent, compound 7 was hydrolyzed with trifluoroacetic acid, and then mixed with compound 8, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole. The mixture was stirred at 0°C to room temperature for 8 to 13 hours. After the reaction, the product was separated and purified to obtain compound 9.

[0016]

[0017] 5. Compound 9 and a base are added to dichloromethane in a molar ratio of 1:(1-3), stirred at room temperature for alkalization for 1-3 hours, and then reacted with an acid in a molar ratio of 1:(4-7), and the product is separated and purified to obtain compound AYAPE.

[0018]

[0019] 6. Using dichloromethane as solvent, compound 9 is alkalized and acidified in sequence, and then mixed with N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole. The mixture is stirred and reacted at 0°C to room temperature for 12 to 48 hours. After the reaction, the product is separated and purified to obtain Cyclo-AYAPE.

[0020]

[0021] In the above step 1, the molar ratio of compound 1 to compound 2, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.2-1.6):(4.0-6.0):(1.5-4.5):(1.1-2.5).

[0022] In the above step 2, the molar ratio of compound 4 to compound 5, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.1-1.7):(4.0-6.5):(1.5-5.0):(1.2-2.5).

[0023] In the above step 3, the base is lithium hydroxide, potassium hydroxide or sodium methoxide, and the acid is hydrochloric acid, trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid.

[0024] In the above step 4, the molar ratio of compound 7 to compound 8, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.1-2.5):(4.2-6.5):(1.5-4.5):(1.1-3.2).

[0025] In the above step 5, the acid is trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid, and the base is sodium ethoxide, lithium hydroxide, potassium hydroxide or sodium methoxide.

[0026] In the above step 6, the acid is trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid, and the base is sodium ethoxide, lithium hydroxide, potassium hydroxide or sodium methoxide; the molar ratio of the compound 9 to N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(4-9):(2-5.5):(1.2-5.5).

[0027] The beneficial effects of the present invention are as follows:

[0028] The synthesis method of the natural product linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE of the present invention is to use known L-alanine methyl ester and LN-Fmoc-O-tert-butyl ether tyrosine as starting materials, and then hydrolyze the methyl ester to obtain a dipeptide after condensation; then condense LN-Boc-proline with glutamic acid tert-butyl ester methyl ester and hydrolyze the methyl ester to obtain a dipeptide, and the dipeptide is condensed with the aforementioned dipeptide to obtain a tetrapeptide, and the obtained tetrapeptide is condensed with LN-Fmoc alanine to obtain a pentapeptide after removing the Fmoc protecting group, and the obtained pentapeptide is condensed with all protecting groups to obtain a linear pentapeptide AYAPE; and the obtained pentapeptide is condensed by itself to form a cyclic pentapeptide Cyclo-AYAPE. The synthesis method of the present invention has low cost, simple operation, mild reaction conditions, short reaction route, and high total yield, and is suitable for the large-scale synthesis of the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE, and provides an important material basis for the biological activity evaluation of the natural product linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE. DETAILED DESCRIPTION

[0029] The invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0030] Example 1

[0031] 1. Add 60 mL of dichloromethane to a round-bottom flask containing 5.00 g (10.9 mmol) of compound 1, stir the reaction system at 0°C, add 50 mL of dichloromethane solution containing 1.35 g (13.1 mmol) of compound 2 dropwise, then add 7.86 mL (43.6 mmol) of N,N-diisopropylethylamine, 5.39 g (16.4 mmol) of 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 1.62 g (12.0 mmol) of 1-hydroxy-7-azobenzotriazole in sequence, return the reaction system to room temperature and continue stirring for 9 hours. After the reaction was completed, 80 mL of saturated aqueous ammonium chloride solution was added to quench the reaction, and then extracted three times with 100 mL of dichloromethane. The dichloromethane phases were combined, washed once with 90 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was evaporated to remove the solvent using a vacuum reduced pressure rotary evaporator. The obtained concentrate was separated using a silica gel column (the eluent was a mixture of ethyl acetate and n-hexane in a volume ratio of 1:4) to obtain 5.63 g of white solid compound 3, with a yield of 94.8%.

[0032]

[0033] The structural characterization data of the obtained compound 3 are as follows: HRMS (m / z): [M+Na]+ [C 32 H 36 N 2 NaO 6 ] + , theoretical value 567.2466; measured value 567.2479.

[0034] 2. Add 30 mL of dichloromethane to a round-bottom flask containing 2.00 g (9.30 mmol) of compound 4, stir the reaction system at 0°C, add 20 mL of dichloromethane solution containing 2.22 g (10.2 mmol) of compound 5 dropwise, then add 6.04 mL (37.2 mmol) of N,N-diisopropylethylamine, 4.58 g (13.9 mmol) of 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 1.52 g (11.2 mmol) of 1-hydroxy-7-azobenzotriazole in sequence, return the reaction system to room temperature and continue stirring for 9 hours. After the reaction was completed, 50 mL of saturated aqueous ammonium chloride solution was added to quench the reaction, and then extracted three times with 60 mL of dichloromethane. The dichloromethane phases were combined, washed once with 75 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was subjected to vacuum reduced pressure rotary evaporation to remove the solvent. The obtained concentrate was separated by silica gel column (the eluent was a mixture of ethyl acetate and n-hexane in a volume ratio of 1:4) to obtain 3.45 g of white solid compound 6 with a yield of 89.6%.

[0035]

[0036] The structural characterization data of the obtained compound 6 are as follows: HRMS (m / z): [M+Na] + [C 20 H 34 N 2 NaO 7 ] + , theoretical value 437.2258; measured value 437.2241.

[0037] 3. Add 100 mL of tetrahydrofuran and water in a volume ratio of 1:1 to a round-bottom flask containing 5.50 g (10.1 mmol) of compound 3, add 847 mg (20.2 mmol) of LiOH at 0°C, and then stir at room temperature for 1 hour. After the reaction, remove the organic solvent with a vacuum decompression rotary evaporator, dilute the concentrate with 80 mL of water, adjust the pH to 1-2 with a 1.0 mol / L hydrochloric acid aqueous solution, extract three times with 10 mL of ethyl acetate, combine the organic phases, wash once with 150 mL of water, wash once with 150 mL of saturated salt water, and then dry with anhydrous sodium sulfate. The filtered filtrate is spun off the organic solvent with a vacuum decompression rotary evaporator to obtain a compound that does not require further purification; dissolve compound 6 (4.18 g, 10.1 mmol) in 100 mL of dichloromethane, stir the reaction system at 0°C, then slowly add 15 mL of trifluoroacetic acid, return the reaction system to room temperature and continue stirring for 2 hours. The reaction solution was then evaporated with a vacuum decompression rotary evaporator to remove low boiling point substances, and the obtained compound did not need further purification. The compound directly alkalized with compound 3 was dissolved in 150 mL of dichloromethane, and the reaction system was stirred at 0°C, followed by the addition of 6.61 mL (40.4 mmol) of N, N-diisopropylethylamine, 4.97 g (0.44815.2 mmol) of 2-(7-oxidized benzotriazole)-N, N, N', N'-tetramethyluronium hexafluorophosphate and 1.65 g (0.22412.1 mmol) of 1-hydroxy-7-azobenzotriazole, and the reaction system was returned to room temperature and continued to stir for 24 hours. After the reaction was completed, the reaction solution was desolventized with a vacuum decompression rotary evaporator, and the obtained concentrate was separated with a silica gel column (the eluent was a mixture of ethyl acetate and n-hexane in a volume ratio of 1:3) to obtain 5.37 g of white solid compound 7, with a yield of 64.3%.

[0038]

[0039] The structural characterization data of the obtained compound 7 are as follows: HRMS (m / z): [M+Na] + [C 46 H 58 N 4 NaO 10 ] + , theoretical value 849.4045; measured value 849.4067.

[0040] 4. Add 25 mL of dichloromethane to a round-bottom flask containing 3.20 g (3.87 mmol) of compound 7, stir the reaction system at 0°C, then slowly add 20 mL of trifluoroacetic acid, return the reaction system to room temperature and continue stirring for 2 hours. The reaction solution was then subjected to vacuum reduced pressure rotary evaporation to remove low boiling point substances. The obtained compound did not need further purification. 25 mL of dichloromethane was directly added to the round-bottom flask, the reaction system was stirred at 0°C, and 25 mL of a dichloromethane solution containing 1.45 g (4.64 mmol) of compound 8 was added dropwise, followed by the addition of 2.53 mL (15.5 mmol) of N,N-diisopropylethylamine, 1.90 g (5.81 mmol) of 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 0.63 g (5.004.64 mmol) of 1-hydroxy-7-azobenzotriazole. The reaction system was returned to room temperature and stirred for 9 hours. After the reaction was completed, 40 mL of saturated aqueous ammonium chloride solution was added to quench the reaction, and then extracted three times with 50 mL of dichloromethane. The dichloromethane phases were combined, washed once with 65 mL of saturated brine, dried over anhydrous sodium sulfate, filtered, and the filtrate was subjected to vacuum reduced pressure rotary evaporation to remove the solvent. The obtained concentrate was separated by silica gel column (the eluent was a mixture of ethyl acetate and n-hexane in a volume ratio of 1:5) to obtain 2.98 g of white solid compound 9 with a yield of 85.9%.

[0041]

[0042] The structural characterization data of the obtained compound 9 are as follows: HRMS (m / z): [M+H] + [C 49 H 64 N 5 O 11 ] + , theoretical value 898.4597; measured value 898.4581.

[0043] 5. Add 30 mL of tetrahydrofuran and water in a volume ratio of 1:1 to a round-bottom flask containing 1.43 g (1.59 mmol) of compound 9, add 133 mg (3.18 mmol) of LiOH at 0°C, and then stir at room temperature for 1 hour. After the reaction, remove the organic solvent with a vacuum decompression rotary evaporator, dilute the concentrate with 50 mL of water, adjust the pH to 1-2 with a 1.0 mol / L hydrochloric acid aqueous solution, extract three times with 50 mL of ethyl acetate, combine the organic phases, wash once with 70 mL of water, wash once with 70 mL of saturated salt water, and then dry with anhydrous sodium sulfate. The filtered filtrate is removed by a vacuum decompression rotary evaporator to remove the organic solvent. The compound does not need further purification. 50 mL of dichloromethane is directly added to the round-bottom flask, and the reaction system is stirred at 0°C. Then 4 mL of trifluoroacetic acid is slowly added, and the reaction system is restored to room temperature and stirred for 2 hours. The reaction solution was then used to remove low boiling point substances using a vacuum reduced pressure rotary evaporator, and the obtained concentrate was separated using a silica gel column (the eluent was a mixture of methanol and dichloromethane in a volume ratio of 1:1) to obtain 0.58 g of a white solid compound AYAPE with a yield of 66.1%.

[0044]

[0045] The structural characterization data of the obtained compound AYAPE are as follows: HRMS (m / z): [M+NH 4 ] + [C 25 H 39 N 6 O 9 ] + , theoretical value 567.2773; measured value 567.2786.

[0046] 6. Add 30 mL of tetrahydrofuran and water in a volume ratio of 1:1 to a round-bottom flask containing 1.43 g (1.59 mmol) of compound 9, add 133 mg (3.18 mmol) of LiOH at 0°C, and then stir at room temperature for 1 hour. After the reaction, remove the organic solvent with a vacuum decompression rotary evaporator, dilute the concentrate with 50 mL of water, adjust the pH to 1-2 with a 1.0 mol / L hydrochloric acid aqueous solution, extract three times with 50 mL of ethyl acetate, combine the organic phases, wash once with 70 mL of water, wash once with 70 mL of saturated salt solution, and then dry with anhydrous sodium sulfate. The filtered filtrate is removed by a vacuum decompression rotary evaporator to remove the organic solvent. The compound does not need further purification. 50 mL of dichloromethane is directly added to the round-bottom flask, and the reaction system is stirred at 0°C. Subsequently, 2 mL of trifluoromethanesulfonic acid is slowly added, and the reaction system is restored to room temperature and stirred for 2 hours. The reaction solution was then spun off low boiling point substances using a vacuum reduced pressure rotary evaporator to obtain a compound without further purification. 50 mL of dichloromethane was directly added to the round-bottom flask, and the reaction system was stirred at 0°C. Subsequently, 1.04 mL (6.36 mmol) of N,N-diisopropylethylamine, 0.78 g (2.39 mmol) of 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 260 mg (1.91 mmol) of 1-hydroxy-7-azobenzotriazole were added in sequence. The reaction system was returned to room temperature and continued to be stirred for 24 hours. Subsequently, 4 mL of trifluoroacetic acid was slowly added, and the reaction system was returned to room temperature and continued to be stirred for 6 hours. After the reaction was completed, the reaction solution was used to remove the solvent using a vacuum rotary evaporator, and the obtained concentrate was separated using a silica gel column (the eluent was a mixture of methanol and dichloromethane in a volume ratio of 1:3) to obtain 450 mg of a white solid compound Cyclo-AYAPE with a yield of 53.2%.

[0047]

[0048] The structural characterization data of the obtained compound Cyclo-AYAPE are: 1 HNMR (400 MHz, DMSO-d 6)δ12.18(s,1H),9.14(s,1H),7.94(d,J=4.8Hz,1H),7.65(d,J=5.6Hz,1H),7.38(s,1H),7. 30(d,J=9.2Hz,1H),6.92(d,J=8.4Hz,2H),6.63(d,J=8.4Hz,2H),4.87(t,J=7.6Hz,1H),4. 21(t,J=7.6Hz,1H),4.02(m,1H),3.94(d,J=8.4Hz,1H),3.84(m,1H),3.37(m,2H),3.11(m, 2H),2.28(t,J=7.6Hz,2H),1.73-2.07(m,5H),1.20(d,J=7.2Hz,3H),1.12(d,J=6.8Hz,3H); 13 CNMR (100MHz, DMSO-d 6 )δ174.46,173.65,172.61,172.07,171.05,170.26,156.03,130.59,130.27,129.30,115.47,61.96,5 6.26,53.72,48.31,47.66,46.56,33.18,30.89,29.21,26.21,25.03,17.34,17.18; HRMS(m / z):[M+H] + [C 25 H 34 N 5 O 8 ] + , theoretical value 532.2402; measured value 532.2597.

Claims

1. A method for synthesizing a natural product linear pentapeptide AYAPE and a cyclic pentapeptide Cyclo-AYAPE, characterized in that It consists of the following steps: (1) Using dichloromethane as solvent, compound 1 is mixed with compound 2, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and the mixture is stirred at 0°C to room temperature for 6 to 10 hours. After the reaction is complete, the product is separated and purified to obtain compound 3; (2) Using dichloromethane as solvent, compound 4 is mixed with compound 5, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and the mixture is stirred at 0°C to room temperature for 7 to 12 hours. After the reaction is complete, the product is separated and purified to obtain compound 6; (3) Using dichloromethane as solvent, the dipeptide obtained by alkaline hydrolysis of compound 3, the dipeptide obtained by acid hydrolysis of compound 6, N,N-diisopropylethylamine, 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole were mixed, and the mixture was stirred at 0° C. to room temperature for 6 to 11 hours. After the reaction was complete, the product was hydrolyzed with methanesulfonic acid and separated and purified to obtain compound 7; (4) Using dichloromethane as solvent, compound 7 is hydrolyzed with trifluoroacetic acid, and then mixed with compound 8, N,N-diisopropylethylamine, 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and stirred at 0°C to room temperature for 8 to 13 hours. After the reaction is completed, the product is separated and purified to obtain compound 9; (5) Compound 9 and a base in a molar ratio of 1:(1-3) are added to dichloromethane, stirred at room temperature for 1-3 hours, and then reacted with an acid in a molar ratio of 1:(4-7) to separate and purify the product to obtain compound AYAPE; (6) Using dichloromethane as solvent, compound 9 is alkalized and acidified in sequence, and then mixed with N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole, and stirred at 0°C to room temperature for 12 to 48 hours. After the reaction is completed, the product is separated and purified to obtain Cyclo-AYAPE; 2. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (1), the molar ratio of compound 1 to compound 2, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.2-1.6):(4.0-6.0):(1.5-4.5):(1.1-2.5).

3. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (2), the molar ratio of compound 4 to compound 5, N,N-diisopropylethylamine, 2-(7-benzotriazole oxide)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.1-1.7):(4.0-6.5):(1.5-5.0):(1.2-2.5).

4. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (3), the base is lithium hydroxide, potassium hydroxide or sodium methoxide, and the acid is hydrochloric acid, trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid.

5. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (4), the molar ratio of compound 7 to compound 8, N,N-diisopropylethylamine, 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(1.1-2.5):(4.2-6.5):(1.5-4.5):(1.1-3.2).

6. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (5), the acid is trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid, and the base is sodium ethoxide, lithium hydroxide, potassium hydroxide or sodium methoxide.

7. The method for synthesizing the linear pentapeptide AYAPE and the cyclic pentapeptide Cyclo-AYAPE according to claim 1, characterized in that: In step (6), the acid is trifluoromethanesulfonic acid, trifluoroacetic acid or glacial acetic acid, and the base is sodium ethoxide, lithium hydroxide, potassium hydroxide or sodium methoxide; the molar ratio of compound 9 to N,N-diisopropylethylamine, 2-(7-oxybenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and 1-hydroxy-7-azobenzotriazole is 1:(4-9):(2-5.5):(1.2-5.5).

Images