Streptokordin, a new cytotoxic compound of the methylpyridine class from a marine-derived Streptomyces sp KORDI-3238

A new cytotoxic compound, streptokordin, and four known compounds, nonactic acid, dilactone, trilactone, and nonactin, were isolated from the fermentation broth of a marine actinomycete strain collected in deep-sea sediments. Biochemical tests and 16S rDNA analysis indicated that the strain belongs to the genus Streptomyces. This actinomycete produces various bioactive secondary metabolites. Fractionations by solvent partitioning, silica vacuum flash chromatography, and reversed-phase HPLC gave a pure cytotoxic compound, designated streptokordin. Its structure was elucidated by FAB-MS, H-1, C-13, and 2D NMR spectroscopy. Streptokordin exhibited significant cytotoxicity against seven human cancer cell lines but showed no growth inhibition against various microorganisms including bacteria and fungi.