Metabolites of microorganisms. 143. Echinocandin B, a novel polypeptide-antibiotic from Aspergillus nidulans var. echinulatus: isolation and structural components

From a strain of Aspergillus nidulans var. echinulatus, A 32204, echinocandin, a novel polypeptide antibiotic complex with high and specific anti-yeast activity was isolated. The main component, echinocandin B, was separated by counter-current distribution. A tentative molecular formula C₅₂H₈₁N₇O₁₈ is discussed. The antibiotic is characterized by its IR. and NMR. spectra and by its characteristic hydrolytic degradation products: linoilic acid, L -4-hydroxyproline, L -4-oxoproline, (2S, 3S, 4S)-4-methyl-3-hydroxy-proline, L -threonine (2 mols), and 1-(p-hydroxyphenyl)-3-amino-propan-2-one.