Studies on Antibacterial Peptide. XIX. Synthesis and Antibacterial Activity of α-Acylpentapeptides, containing Basic Amino Acids. VIII

Three derivatives of α-acyl-DL-A2pr-DL-A2pr-Thr-DL-A2pr-D-Leu-OH including 2, 3-diaminopropionic acid (A2pr) (a component of tuberactinomycin (Tum)) were synthesized to investigate the relationship between the chemical structure and antibacterial activity. These compounds were synthesized as pentapeptide by stepwise elongation method and by liquid phase method with dicyclohexylcarbodiimide and 1-hydroxybenzotriazole, and acylated by (+)-6-methyloctanoyl chloride or two kinds of aliphatic acyl chloride. It was proved that these compounds show very strong antibacterial activity against gram-negative bacteria. Each compound has about one fourth as strong activity as colistin sulfate has.