题目: α‑Pyrones with Diverse Hydroxy Substitutions from Three MarineDerived Nocardiopsis Strains

作者: Haibo Zhang+, Kumar Saurav+, Ziquan Yu, Attila Mándi, Tibor Kurtán, Jie Li, Xinpeng Tian, Qingbo Zhang, Wenjun Zhang, Changsheng Zhang*

刊物: Journal of Natural Products

年卷期页: 2016, 79(6): 1610-1618

摘要: Eight new α-pyrones 1−8 and three known α-pyrones 9−11 were isolated from three marine-derived Nocardiopsis strains SCSIO 10419, SCSIO 04583, and SCSIO KS107. The structures of compounds 1−8 were elucidated by comprehensive spectral analyses. The absolute configurations of 4-deoxyphomapyrone C (1), 4-deoxy-11-hydroxyphomapyrone C (3), 4-deoxy-7R-hydroxyphomapyrone C (5), and phomapyrone C (11) were determined by TDDFT-ECD calculations for the solution conformers, which revealed that the conformation of the side chain was decisive for the sign of the characteristic high-wavelength ECD transition. (−)-4-Deoxy-8-hydroxyphomapyrone C (4) was isolated from SCSIO 10419 and was deduced as a diastereomeric mixture containing (8S)- and (8R)-4-deoxy-8-hydroxyphomapyrone C in a ratio of 2.6:1 (8R:8S), by chiralphase HPLC analysis and Mosher’s ester analysis. Interestingly, 7-hydroxymucidone (9) was isolated from both SCSIO 04583 and SCSIO KS107, as an enantiomeric mixture containing (7S)-hydroxymucidone (major in 9 from SCSIO 04583) and (7R)-hydroxymucidone (major in 9 from SCSIO KS107). α-Pyrones 3−5 were identified as three isomers of phomapyrone C (11) with diverse hydroxy substitutions. α-Pyrones 10-hydroxymucidone (6), 4-hydroxymucidone (8), and 9, differed in the position of the hydroxy group. Several α-pyrones exhibited moderate growth inhibitory activity against Micrococcus luteus and Bacillus subtilis.