CN111808169A

CN111808169A - Solid-phase synthesis method of melanotan I

Info

Publication number: CN111808169A
Application number: CN202010353399.7A
Authority: CN
Inventors: 沈永刚; 肖攀; 谢振亮; 付坤; 沈永良; 程益明; 胡桂香
Original assignee: Hangzhou Gotop Biotechnology Co ltd
Current assignee: Hangzhou Gotop Biotechnology Co ltd
Priority date: 2020-04-29
Filing date: 2020-04-29
Publication date: 2020-10-23
Anticipated expiration: 2040-04-29
Also published as: CN111808169B

Abstract

The invention discloses a solid-phase synthesis method of melanotan I, which comprises the following steps: selecting Ramage Amide AM resin with the substitution degree of 0.40-0.80mmol/g, and coupling Fmoc-Val-OH to obtain Fmoc-Val-amino resin; sequentially coupling on Fmoc-Val-amino resin according to a sequence, and using Ac-Ser (tbu) -OH in the last step; cracking the synthesized resin polypeptide to obtain crude peptide of the melanotan I; and finally, after a sample is dissolved, separating and purifying by using high performance liquid chromatography to collect qualified peptide liquid, and freeze-drying to obtain a refined melanotan I product. The synthesis method used by the invention can effectively improve the product yield and reduce the discharge of three wastes, and is suitable for large-scale production.

Description

Solid-phase synthesis method of melanotan I

Technical Field

The invention relates to the technical field of chemical industry, in particular to a solid-phase synthesis method of melanotan I.

Background

With the marketing of melanotan I, the linear polypeptide consisting of 13 amino acids will have a greater role in drug research. The main English names of the Melanotan I are melantotan-1 and Afamelanotide, which belong to alpha-MSH analogues, and the Melanotan I can be used for treating photosensitive diseases caused by erythropoiesis protoporphyrinemia. The molecular formula of the melanotan I is C78H111N21O19, the molecular weight is 1646.85, and the specific sequence is as follows: Ac-SYS { Nle } EH { D-Phe } RWGKPV-NH2, the sequence structural formula is:

in conventional solid phase synthesis, the choice of resin has a great influence on the coupling rate and the final purity of the product.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid-phase synthesis method of melanotan I, which has high synthesis efficiency, low cost, and high yield.

In order to achieve the purpose, the invention adopts the following technical scheme: a solid-phase synthesis method of melanotan I comprises the following steps: selecting Ramageamide AM resin with the substitution degree of 0.40-0.80mmol/g (preferably 0.40-0.60mmol/g), and coupling Fmoc-Val-OH to obtain Fmoc-Val-amino resin; sequentially coupling amino acids to carrier resin according to a sequence of the melanotan I by adopting an Fmoc solid-phase synthesis method, wherein the amino acids are protected by Fmoc groups, and the last amino acid is Ac-Ser (tBu) -OH, and finally synthesizing to obtain the melanotan I-amino resin with fully protected side chains; the condensing agent adopted by sequential coupling is condensing agent and organic base, and the condensing agent comprises condensing agent consisting of DIEA and one of PyBop, TBTU, HBTU, HATU or PyAop; or a condensing agent consisting of DIC and one or more of HOBT, HOAT and Cl-HOBT; separating the melanotan I-amino resin with the protected side chain from the solid phase carrier through a lysate, and removing a side chain protecting group; precipitating with glacial ethyl ether and washing to obtain crude melanotan I peptide; purifying and separating the crude peptide by high performance liquid chromatography, and freeze-drying to obtain melanotan I; the cracking liquid for separating and removing the side chain protecting group from the solid phase carrier is a mixed liquid consisting of trifluoroacetic acid, triisopropylsilane, ethanedithiol, phenol and water.

Further, the protected amino acids used in the solid phase synthesis are protected with Fmoc group and acetyl group, and each amino acid is used in the form of Fmoc-Val-OH, Fmoc-Pro-OH, Fmoc-Lys (Boc) -OH, Fmoc-Gly-OH, Fmoc-Trp (Boc) -OH, Fmoc-Arg (Pbf) -OH, Fmoc-D-Phe-OH, Fmoc-His (Trt) -OH, Fmoc-Glu (otBu) -OH, Fmoc-Nle-OH, Fmoc-Ser (tBu) -OH, Fmoc-Tyr (tBu) -OH, Ac-Ser (tBu) -OH.

Further, the volume ratio of a reagent formula adopted by the lysate is TFA: thioanisole: phenol: triisopropylsilane: water (81-83): (7-8): (4-6): (2-4): (1-3).

Further, the Ramage Amide AM resin is one of the following resins:

ramage Amide AM resin

Ramage Amide MBHA Resin

Ramage AM Resin

Rink Amide MBHA resin

Further: the condensing agent adopted by the sequential coupling is condensing agent and organic base, and the condensing agent comprises condensing agent consisting of one of PyBop, TBTU, HBTU, HATU or PyAop and DIEA; or a condensing agent consisting of DIC and one or more of HOBT, HOAT and Cl-HOBT; wherein, the seventh amino acid Fmoc-D-Phe-OH in the N end in the sequence is optimally selected by using a condensing agent system consisting of HOBT and DIC.

Compared with the prior art, the invention has the following beneficial effects: the invention can effectively improve the product yield, reduce the discharge of three wastes and is suitable for large-scale production.

Drawings

FIG. 1 is a mass spectrum of melanotan I (melantotan I) in the solid phase synthesis of melanotan I.

FIG. 2 is a high performance liquid chromatogram of melanotan I (melantotan I) in a solid phase synthesis of melanotan I.

Detailed Description

The solid phase synthesis of melanotan I is described in further detail below with reference to the examples.

Example 1: preparation of Fmoc-Val-amino resin

Step 1, weighing 11.11g (5mmol) of Ramage Amide AM resin with the substitution degree of 0.45mmol/g, adding the Ramage Amide AM resin into a solid phase reactor, adding DCM to swell the resin for 30min, draining, washing with DMF for three times, adding 20% of piperidine DMF solution in volume ratio, reacting for 5min, adding 20% of piperidine DMF solution again, reacting for 10 min, washing once with intermediate DMF, draining after the reaction is finished, and washing with DMF for 3 times.

And 2, dissolving 5.09g of Fmoc-Val-OH, 2.02g of HOBT (1-hydroxybenzotriazole) and 2.32ml of DIC (N, N' -diisopropylcarbodiimide) in DMF at 0 ℃, adding the mixture into a reaction column after complete dissolution, reacting for 1 hour at room temperature, judging the reaction process by detecting the reaction is negative by adopting a ninhydrin detection method, and washing the DMF for three times after the reaction is finished to obtain the Fmoc-Val-amino resin.

Example 2: preparation of melanotan I fully-protected resin peptide

Step 1, adding 20% by volume of piperidine DMF solution into the Fmoc-Val-amino resin, reacting for 5min, adding 20% by volume of piperidine DMF solution again, reacting for 10 min, washing with intermediate DMF once, draining after the reaction is finished, and washing with DMF for 3 times.

And 2, dissolving 5.06g of Fmoc-Pro-OH, 2.02g of HOBT (1-hydroxybenzotriazole) and 2.32ml of DIC (N, N' -diisopropylcarbodiimide) in DMF at 0 ℃, adding the mixture into a reaction column after complete dissolution, reacting for 1 hour at room temperature, judging the reaction process by detecting the reaction is negative by adopting a ninhydrin detection method, and washing the DMF for three times after the reaction is finished to obtain the Fmoc-Pro-Val-amino resin.

And 3, sequentially coupling each amino acid according to the sequence of the melanotan I according to the method in the step 2, reacting until Ac-Ser (tBu) -OH is completed, washing with DMF for three times, washing with DCM for three times, washing with methanol for three times, and drying to obtain 23.89g of the melanotan I full-protection resin peptide.

Example 3: preparation of crude melanotan I peptide

Putting 23.89g of melanotan I fully-protected resin peptide into a round-bottom flask, slowly adding 250ml of prepared lysate (the volume ratio of a reagent formula adopted by the lysate is TFA: benzylthioether: phenol: triisopropylsilane: water is 82.5: 7.5: 5: 3: 2) at 0 ℃, slowly stirring, reacting at low temperature for 0.5 hour, reacting at room temperature for 2 hours, performing suction filtration to obtain the lysate, slowly adding the lysate into 2L of anhydrous ethyl glacial ether, stirring, filtering and separating crude polypeptide, and washing with the ethyl glacial ether for 3 times to obtain 8.55g of crude melanotan I peptide.

Example 4: preparation of refined melanostan I peptide

Step 1, dissolving the crude melanotan I peptide in 100ml of purified water, and filtering with a 0.45-micrometer filter membrane to obtain a crude peptide solution.

Step 2, purifying the crude peptide of the melanotan I by using a high performance liquid chromatography instrument: and (2) performing gradient elution, separation and purification by passing through a DAC-HB50 dynamic axial compression column, wherein a mobile phase A is a trifluoroacetic acid aqueous solution with the mass percentage concentration of 0.05%, and a mobile phase B is a trifluoroacetic acid acetonitrile solution with the mass percentage concentration of 0.05%, detecting a sample by adopting an ultraviolet detector, and collecting a peptide solution of a target peak in a segmented manner.

And 3, purifying by using a high performance liquid phase to obtain 180ml of melanotan I trifluoroacetic acid liquid with the purity of more than 99%, and performing rotary evaporation and concentration to obtain 50ml of liquid.

Step 4, sample loading 50ml of chromatographic column after being balanced by deionized water

Eluting the melanotan I trifluoroacetic acid liquid with the purity of more than 99% in a 2% acetic acid aqueous solution system for 50min, carrying out rotary concentration on the collected target product to 80ml, and carrying out pre-freeze-drying and freeze-drying treatment to finally obtain 5.33g (MS and HPLC are shown in figures 1 and 2) of the melanotan I refined peptide, wherein the yield is 32.33%.

The above-mentioned comparison table of the abbreviations for the respective raw material names and the full names of the raw materials is shown in Table 1.

TABLE 1 comparison table of raw material name abbreviations and raw material names

Claims

1. The solid-phase synthesis method of the melanotan I is characterized by comprising the following steps:

s101: selecting Ramage Amide AM resin with the substitution degree of 0.40-0.80mmol/g, and coupling Fmoc-Val-OH to obtain Fmoc-Val-amino resin;

s102: sequentially coupling amino acids to carrier resin according to a sequence of the melanotan I by adopting an Fmoc solid-phase synthesis method, wherein the amino acids are protected by Fmoc groups, and the last amino acid is Ac-Ser (tBu) -OH, and finally synthesizing to obtain the melanotan I-amino resin with fully protected side chains; the condensing agent adopted by sequential coupling is condensing agent and organic base, and the condensing agent comprises condensing agent consisting of DIEA and one of PyBop, TBTU, HBTU, HATU or PyAop; or a condensing agent consisting of DIC and one or more of HOBT, HOAT and Cl-HOBT;

s103: separating the melanotan I-amino resin with the protected side chain from the solid phase carrier through a lysate, and removing a side chain protecting group; precipitating with glacial ethyl ether and washing to obtain crude melanotan I peptide; purifying and separating the crude peptide by high performance liquid chromatography, and freeze-drying to obtain melanotan I; the cracking liquid for separating and removing the side chain protecting group from the solid phase carrier is a mixed liquid consisting of trifluoroacetic acid, triisopropylsilane, ethanedithiol, phenol and water.

2. The solid phase synthesis method of melanotan I as claimed in claim 1, characterized in that: the protected amino acids used in the solid phase synthesis are protected with Fmoc group and acetyl group, and each amino acid is used in the form of Fmoc-Val-OH, Fmoc-Pro-OH, Fmoc-Lys (Boc) -OH, Fmoc-Gly-OH, Fmoc-Trp (Boc) -OH, Fmoc-Arg (Pbf) -OH, Fmoc-D-Phe-OH, Fmoc-His (Trt) -OH, Fmoc-Glu (otBu) -OH, Fmoc-Nle-OH, Fmoc-Ser (tBu) -OH, Fmoc-Tyr (tBu) -OH, Ac-Ser (tBu) -OH.

3. The solid phase synthesis method of melanotan I as claimed in claim 1, characterized in that: the volume ratio of a reagent formula adopted by the lysate is TFA: thioanisole: phenol: triisopropylsilane: water (81-83): (7-8): (4-6): (2-4): (1-3).

4. The solid phase synthesis method of melanotan I as claimed in claim 1, characterized in that: the Ramage Amide AM resin is one of the following resins:

ramage Amide AM resin

Ramage Amide MBHA Resin

Ramage AM Resin

Rink Amide MBHA resin