Studies on the Compounds Related to Colistin. VII. Synthesis and Antibacterial Activity of Acylpentapeptides. (2)

Abstract

In order to investigate the antibacterial activity of acylpentapeptides, the compounds, in which L-lysine in the side chain of acylpentapeptide reported previously was replaced with D-leucine of C-terminal and D-leucine of C-terminal with L-lysine of side chain, were synthesized by the acylation of pentapeptide obtained from N^ε-(formyl-D-leucyl)-L-lysyl-N^ε-formyl-L-lysine methyl ester (V) and N^ε-formyl-N^α-benzyloxycarbonyl-L-lysyl-L-threnine (VII) by dicyclohexylcarbodiimide (DCCD) reaction. The acid chlorides of three suturated fatty acids and two unsuturated fatty acids were employed as an acylating agent. The antibacterial activity of the synthesized acylpentapeptides was generally weak. It is, therefore, suggested that the acylpentapeptides should have the same amino acid sequence as that of the partial structure of lysine-colistin.