Melithiazols, new beta-methoxyacrylate inhibitors of the respiratory chainisolated from myxobacteria - Production, isolation, physico-chemical and biological properties

New antibiotic compounds, melithiazols, were isolated from the culture brot h of strains of the myxobacteria Melittangium lichenicola, Archangium gephy ra, and Myxococcus stipitatus. The compounds belong to the group of beta-me thoxyacrylate (MOA) inhibitors and are related to the myxothiazols. The mel ithiazols show high antifungal activity, but are less toxic than myxothiazo l A and its methyl ester in a growth inhibition assay with mouse cell cultu res. The melithiazols inhibit NADH oxidation by submitochondrial particles from beef heart. Melithiazol A blocks the electron transport within the bc( 1)-segment (complex III) and causes a red shift in the reduced spectrum of cytochrome b.