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-methylated, 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 had been obtained in earlier acid hydrolyses of the antibiotic. Compounds VI and VII had not been detected previously nor glycine which was also found to be a product of base hydrolysis. It is postulated that the new products arise from bisdechlorovancomycinic acid (X). It is concluded that aglycoristomycin A comprises I, II and X which also corstitute the aglycone of ristocetin A.
ASJC Scopus subject areas
- Drug Discovery