Structural investigation of the antibiotic ristomycin A. 13C-NMR spectral analysis of the interglycosidic linkages of the heterotetrasaccharide side-chain.

By 13C-NMR studies on Ia, IIa, IIb and IVa obtained by the chemical degradation of ristomycin A and on several synthetic model compounds it has been proved that an O-beta-D-arabinopyranosyl-(1 leads to 2)-O-alpha-D-mannopyranosyl-(1 leads to 2)-O-[alpha-L-rhamnopyranosyl-(1 leads to 6)]-D-glucopyranosyl heterotetrasaccharide moiety is connected to the aglycone of the antibiotic.