Structural investigation of the antibiotic ristomycin A. The amino acid constituents.

Abstract

Hydrolysis of the O-methylated aglycone of ristomycin A by a mixture of KOH and NaBH4 yielded a mixture of aromatic amino acids which, after N-acetylation and O-methylation, were separated by chromatography on silica gel. Compounds III-VII were isolated and identified by PMR and mass spectroscopy. Compounds V-VII were also oxidatively degraded to the corresponding benzoate esters. Compounds III and IV are derived from ristomycinic acid (I) and V from actinoidinic acid (II), both of which were obtained in earlier acid hydrolyses of the antibiotic. Compounds VI and VII were not detected previously nor was glycine, which was also a product of base hydrolysis. It is postulated that the new products arise from bisdechlorovancomycinic acid (X). Aglycoristomycin A comprises I, II and X, which also constitute the aglycone of ristocetin A.