Twenty nine marine strains were isolated from sponge Hymeniacidon perleve at Nanji island, and cytotoxic screening shown two strains show activity to Hela or BGC-823 cancer cell line. The active strains NJ6-3-1 and NJ6-3-2 were identified to be Pseudoalteromonas piscicida and Bacillus megaterium based on their 16s rRNA sequence analysis. The major cytotoxic metabolite of NJ6-3-1, isolated through bioassay-guide fractionation of cytotoxic assay, was identified as norharman (beta-carboline alkaloid) by EI-MS and NMR. TUNEL assay and flow cytometric analysis supposed that norharman exert cytotoxic action through apoptosis mechanism in Hela cells.
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