Maduraflavacins A-E, Unusual Phenyl Polyene Metabolites Produced by a Rare Marine-Derived sp.

Phenyl polyenes comprise a small family of bacterial natural products with broad and potent bioactivities, primarily found in actinobacteria. Here we report the discovery of five new phenyl polyene metabolites, maduraflavacins A-E (-), from a rare, marine-derived actinobacteria strain NA03286. The structures of these natural products were determined by NMR spectroscopy, HRESIMS, LC-MS/MS, and chemical derivatization. All of these new maduraflavacins feature methyl substitutions at the polyene side chain, and maduraflavacins A-C (-) possessed a 1--β-d-glucosamine-(3 → 1)--β-d-glucopyranosyl-(3 → 1)--β-d-glucopyranosyl-(6 → 1)--β-d-glucopyranoside tetrasaccharide moiety via an amido linkage with a phenyl polyene skeleton. Compounds and showed weak antibacterial activities against the Gram-positive bacteria Sau 16339 and , respectively.