CYCLOPEPTIDE ANTIBIOTICS FROM ASPERGILLUS SPECIES - STRUCTURE OF ECHINOCANDIN-C AND ECHINOCANDIN-D

Cyclopeptide antibiotics from Aspergillus species. Structure of echinocandins C and D The echinocandins B, C and D are antifungal antibiotics produced by a strain of Aspergillus rugulosus. All three metabolites are closely related representing cyclic oligopeptides composed of six amino acids and a linolic acid residue in an amide linkage. The complete structure of echinocandin B (1) has recently been established by X‐ray analysis. Structural assignments to the new minor metabolites C and D have now been made by hydrolytic and oxidative cleavage reactions, formation of N‐acyl‐α‐aminoethers as well as by chemical correlations and extensive NMR. examinations. Echinocandin C (2), C52H81N7O15, contains 3‐hydroxyhomotyrosine in the place of 3, 4‐dihydroxyhomotyrosine present in 1. Echinocandin D (3), C52H81N7O13, differs in two amino acids: 3, 4‐dihyroxyhomotyrosine and 4, 5‐dihydroxyornithine, unusual units of 1 being replaced by 3‐hydroxyhomotyrosine and ornithine. Copyright © 1979 Verlag GmbH & Co. KGaA, Weinheim