SF 2446B2

Structures of new antibiotics SF2446A1, A2, A3, B1, B2 and B3 have been deduced by means of spectral analyses and chemical studies. The structure of SF2446A1 which is a main product of fermentation and has the strongest antimicrobial activity, has been proposed to be 11-(2,4-di-O-methyl-beta-L-rhamnopyranosyl)amino-5,6,6a,14a-tetrah ydro- 1,6,8,14a-tetrahydroxy-6a-methoxy-2-methoxycarbonyl-3-methyl- benzo[a]naphthacene-7,9,12,14-tetra-one. All of antibiotics have a novel benzo[a]naphthacene quinone skeleton and SF2446A1, A2, B1 and B2 have an N-glycosidic linkage with 2,4-di-O-methyl-L-rhamnose.

New antibiotics SF2446A1, A2, A3, B1 and B2 have been isolated from the culture of Streptomyces sp. SF2446 and antibiotic SF2446B3 has been obtained by methanolysis of SF2446B1 or B2. SF2446A1, A2 and B1 showed strong inhibitory activities against mycoplasmas and Gram-positive bacteria. Empirical molecular formulae of antibiotics SF2446-A1, A2, A3, B1, B2 and B3 were determined to be C34H35NO15, C26H21NO11, C34H35NO14, C34H35NO14 and C26H21NO10, respectively.