Studies of Peptide Antibiotics. XXIII. Syntheses of Linear Decapeptide Analogs with Gramicidin S Sequence

Six linear decapeptides having the same sequence of amino acids of gramicidin S, wherein the N-terminal amino acid is acylated with formyl or acetyl group, the C-terminal amino acid is in a form of its amide or ethanolamide and the N,C-terminal ones are free, were synthesized to obtain a more reliable picture of the cyclic structure to the antibacterial activity of gramicidin S. All these linear decapeptide analogs were found to be active to some extent against several microorganisms.