A novel ansamycin, naphthomycin K from Streptomyces sp
One novel ansamycin, namely naphthomycin K, together with two known naphthomycins A and E, were isolated from the commensal strain Streptomyces sp. CS of the medicinal plant Maytenus hookeri. Their structures were elucidated by the analysis of NMR and MS data. Naphthomycin K showed evident cytotoxicity against P388 and A-549 cell lines, but no inhibitory activities against Staphylococcus aureus and Mycobacterium tuberculosis.