JBIR-129 and -139, Cytotoxic 34-Membered Polyol Macrolides of Microbial Origin
New 34-membered polyol macrolides JBIR-129 (1) and JBIR-139 (2) were isolated from the culture of the terrestrial Streptomyces RK74. The planar structures of 1 and 2 were established on the basis of 1D and 2D NMR, ESI-TOF-MS, IR, and UV spectra. The relative configurations of the sugar units were determined by analyzing vicinal 1H?1H coupling constants and steric information. Both 1 and 2 showed cytotoxic activity against human ovarian adenocarcinoma SKOV-3 cells with IC50 values of 0.3 and 0.4 ?M, respectively.