Saccharomicins, novel heptadecaglycoside antibiotics effective against multidrug-resistant bacteria

Two novel heptadecaglycoside antibiotics, saccharomicins A (1) and B (2), w ere isolated from a new species of Saccharothrix. Their structures were det ermined by a combination of chemical degradation and spectroscopic methods. Saccharomicin B (2) was identified as N-(m,p-dihydroxycinnamoyl) taurine p -O-[alpha-4-epi-vancosaminopyranosyl( 1-4)-alpha-4-epi-vancosaminopyranosyl (1-->4)-alpha-digitoxopyranosyl(1-->4)-alpha-4-epi-vancosaminopyranosyl(1-- >4)-alpha-digitoxopyranosyl(1-->3)-beta-fucopyranosyl(1-->4)-beta-saccharos aminopyranosyl(1-4)-alpha-digitoxopyranosyl( 1-->3)]-[-4-epi-vancosaminopyr anosyl(1-->4)]-beta-fucopyranosyl(1-->4)-beta-saccharosaminopyranosyl(1-4)- alpha-rhamnopysyl(1-4)-beta-fucopyranosyl(1-4)-beta-saccharosaminopyranosyl (1-4)-beta-2-sulfate-fucopyranoside. Saccharomicin A (1) differs from sacch aromicin B (2) only in the 10th sugar residue, where alpha-digitoxopyranosy l(1-3) is replaced with alpha-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 antimicr obial activity against Gram-positive bacteria.