Saccharomicins, Novel Heptadecaglycoside Antibiotics Effective against Multidrug-Resistant Bacteria

Abstract

Two novel heptadecaglycoside antibiotics, saccharomicins A (1) and B (2), were isolated from a new species of Saccharothrix. Their structures were determined by a combination of chemical degradation and spectroscopic methods. Saccharomicin B (2) was identified as N-(m,p-dihydroxycinnamoyl) taurine p-O-[α-4-epi-vancosaminopyranosyl(1→4)-α-4-epi-vancosaminopyranosyl(1→4)-α-digitoxopyranosyl(1→4)-α- 4-epi-vancosaminopyranosyl(1→4)-α-digitoxopyranosyl(1→3)-β-fucopyranosyl(1→4)-β-saccharosaminopyranosyl(1→4)-α-digitoxopyranosyl(1→3)]-[α-4-epi-vancosaminopyranosyl(1→4)]-β-fucopyranosyl(1→4)-β- saccharosaminopyranosyl(1→4)-α-rhamnopyranosyl(1→3)-β-fucopyranosyl(1→4)-β-saccharosaminopyranosyl(1→4)-β-fucopyranosyl(1→4)-β-saccharosaminopyranosyl(1→4)-β-2-sulfate-fucopyranoside. Saccharomicin A (1) differs from saccharomicin B (2) only in the 10th sugar residue, where α-digitoxopyranosyl(1→3) is replaced with α-rhamnopyranosyl(1→3). The novel amino sugar residue, designated saccharosamine, was identified by NMR spectroscopy and X-ray crystallography. Both saccharomicins A (1) and B (2) showed antimicrobial activity against Gram-positive bacteria.