Salinisporamycin, a novel metabolite from Salinispora arenicola. [corrected]

A new rifamycin antibiotic, salinisporamycin (1), has been isolated from a culture of a marine actinomycete. The producing organism was identified as Salinispora arenicola [corrected] on the basis of the 16S rRNA sequence. High-resolution FAB-MS established the molecular formula of 1 as C(33)H(43)NO(9). The planar structure of 1 was elucidated by NMR spectral analysis including COSY, heteronuclear single quantum coherence and heteronuclear multiple bond correlation. The relative stereochemistry of 1 was determined on the basis of rotating frame nuclear Overhauser effect spectroscopy. In addition, the solvatochromic behavior of 1 was investigated by measuring the UV spectra. This compound inhibited the growth of A549 cells, the human lung adenocarcinoma cell line, with an IC(50) value of 3 microg ml(-1), and also showed antimicrobial activity.