Viscosine: A new microbial flavonoid from marine-derived, Streptomyces sp. RMS518F: Viscosine: A new microbial flavonoid from marine-derived, Streptomyces sp. RMS518F

During the search for bioactive metabolites from marine sediment derived-actinomycetes, a new microbial flavonoid 6-hydroxykaempferol-3,6-dimethyl ether, viscosine (1) was isolated from the marine sediment derived-actinobacteria RMS518F strain. Structure of the compound (1) was determined by 1D- and 2D-NMR (1 and 2-Dimensional Nuclear Magnetic Resonance), mass spectrometry and comparison of these data with literature. Taxonomically, the strain was characterized as Streptomyces carpaticus on the bases of 16S rRNA gene sequence. Biologically, compound (1) exhibited moderate antimicrobial activity against the Gram-positive bacteria, Staphylococcus aureus ATCC6538-P; Bacillus cereus ATCC11778 and Saccharomyces cerevisiae ATCC9080 yeast. Compound (1)was also significantly active against the human colon carcinoma cell line (HCT-116) and the hepatocellular carcinoma cell line (Hep G2) with IC50 values of 73.4 and 62.8 mu g/mL, respectively compared with the antineoplastic drug (Doxorubicin) (37.6 and 21.6 mu g/mL), while no activity has been noticed against the human breast cancer cell line (MCF-7).