Linaclotide synthesis method

Abstract

The invention relates to the field of pharmaceutical synthesis and discloses a linaclotide synthesis method. The linaclotide synthesis method includes: performing solid-phase synthesis to obtain linaclotide resin with an N terminal, a Thr side chain, a Cys side chain, an Asn side chain, a Tyr side chain and a Glu side chain of an amino acid sequence shown in SEQ ID NO:1 coupled with protecting groups and with a C terminal coupled with a resin solid-phase carrier, cracking to remove the protecting groups and the resin solid-phase carrier prior to carrying out oxidizing reaction by the aid of a GSH (glutathione) / GSSH (oxidized glutathione) oxidization system to obtain a crude linaclotide product, and purifying the crude linaclotide product so that linaclotide is obtained. By the method, an Mmt protecting group is used for protecting a cysteine side chain, crude linear linaclotide peptide is synthesized by a one-by-one coupling mode, and the linaclotide is obtained by oxidization by the aid of the GSH / GSSH oxidization system. Compared with existing methods, the linaclotide synthesis method has the advantages that purity of the crude linear peptide is improved, the oxidization step can be performed without purification, and purity and yield of the crude linaclotide product are remarkably improved.

Description

technical field [0001] The invention relates to the field of pharmaceutical synthesis, in particular to a method for synthesizing linaclotide. Background technique [0002] Linaclotide is a new type of GC-C (intestinal cell uridylate cyclase C) receptor agonist. The compound is a polypeptide composed of 14 amino acids, which is obtained by solid-phase synthesis technology. Linaclotide activates GC-C receptors on the apical surface of intestinal epithelial cells, resulting in increased intracellular and extracellular cyclic guanylate. Its net effect is increased secretion of chlorine and bicarbonate into the intestinal lumen, which in turn leads to increased fluid secretion and accelerated stool passage, for the treatment of adults with slow transit constipation and irritable bowel syndrome with constipation (IBS-C), structural sequence for: [0003] NH 2 -Cys-Cys-Glu-Tyr-Cys-Cys-Asn-Pro-Ala-Cys-Thr-Gly-Cys-Tyr-COOH (3 pairs of disulfide bonds are 1-6, 2-10, 5-13). [000...

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Problems solved by technology

However, methods 2 and 3 use a variety of side chain removal and oxidation reagents, and each step will inevitably bring about an increase in impurities, so it is not conducive to obtaining high-purity, high-yield products, and is also not conducive to the enlargement of the process.

[0005] Although method 1 has simple steps, only one protecting group is used to protect the cysteine ​​side chain sulfhydryl group, but the choice of cysteine ​​side chain protecting group is one of the key factors affecting the synthesis of linaclotide. Method 1 uses The Trt protecting group is not conducive to the improvement of the purity of the linear crude peptide of linaclotide, resulting in low purity of the linear crude peptide, and often requires purification to carry out the cyclization of the 3-pair disulfide bond of linaclotide, which is not conducive to large-scale production

[0006] In addition, method 1 uses GSH (reduced glutathione) oxidation system for cyclization of 3 pairs of disulfide bonds in the final step of oxidation to form crude linaclotide, but this oxidation system cannot accurately locate 3 pairs of disulfide bonds. The position of the sulfur bond can easily lead to the production of a large amount of impurities, resulting in low purity of the crude linaclotide, which is not conducive to subsequent purification and overall yield

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