Scabrosteroids A–D, Four Pyrrolidinone–Ergosterol Heterodimers from <i>Penicillium scabrosum</i> FXI744
Zheng Li, Chunlun Qin, Ting Zhou, Wanpeng Li, Jia-Yun Hu, Yin-Hui Zhou, Hanli Ruan
Abstract
Scabrosteroids A–D ( 1 – 4 ), four novel steroidal heterodimers, were isolated from Penicillium scabrosum FXI744. These compounds represent the first naturally occurring pyrrolidinone–ergosterol hybrids, linked by a C-3/C-3′ bond between pyrrolidinone and ergosterol moieties. Their structural elucidation, including the determination of absolute configurations, was accomplished using HRESIMS, NMR, X-ray crystallography, and ECD calculation. A plausible biosynthetic pathway for these metabolites was proposed. Biological evaluation revealed that compounds 1 – 4 inhibited NO production with IC 50 values ranging from 9.5 to 14.4 μM, and compounds 1 and 4 also showed moderate in vitro immunosuppressive effects.