Chemical synthesis and characterisation of the complement C5 inhibitory peptide zilucoplan.

The complement component C5 inhibitory peptide zilucoplan is currently in phase III clinical trials for myasthenia gravis (MG). Despite being at an advanced stage of clinical development, there have been no published reports in the literature detailing its chemical synthesis. In this work, we describe an approach for the chemical synthesis of zilucoplan and validate that the synthesised compound blocks LPS-induced C5a production from human blood.

Synthesis of porcine C5a anaphylatoxin by the solution procedure and confirmation of the reported structure.

Porcine C5a anaphylatoxin, the primary structure of which was first determined by Gerard and Hugli in 1980 as a 74-amino acid peptide having three intramolecular disulfide bonds, was synthesized by the solution procedure applying our maximum protection strategy. The fully deprotected peptide was subjected to air oxidation in an acetate buffer at pH 7.5, and the product was isolated as a single entity by HPLC. Amino acid analysis and biological activities of the synthetic peptide agreed well with the reported values. However, the retention time of the synthetic C5a was different from that of the natural product, supplied by Dr. Hugli, on both reversed phase (RP) and ion-exchange (IEX) HPLC systems. The tryptic peptide mapping on HPLC revealed that Gln which was incorporated into the peptide at position 65 was replaced by Glu in the natural product. The elution pattern of tryptic peptides containing three disulfide bonds was identical with natural and synthetic C5a. It was also identical with that of a peptide which was synthesized following the estimated secondary structure proposed by Zimmermann and Vogt in 1984.