Cyclopiazonic Acid and Okaramine Analogues, Including Chlorinated Compounds, from <i>Chrysosporium undulatum</i> YT-1
Lingyan Liu, Xueqing Qian, Tao Yang, Dongmei Fang, Zhangyi Qin, Bo Ren, Guo‐You Li
Abstract
Eight new cyclopiazonic acid (1–8) and five new okaramine (9–13) alkaloids together with 13 known compounds were isolated from the fungus Chrysosporium undulatum YT-1. Compounds 2, 4, 5, 7, 10, 11, and 13 were chlorinated indole alkaloids. The structures of compounds 1–13 were elucidated by HRESIMS and NMR spectroscopic data. Their relative and absolute configurations were established by J-based configuration analysis, NOESY, NOEDIFF experiments, ECD spectroscopic data, and biogenetic considerations. Compound 4 inhibited the growth of Bacillus subtilis with an MIC value of 6.3 μg/mL. Compounds 9–11 exhibited strong insecticidal capacity against the third instar larvae of silkworm and cotton bollworm (LD50: ≤7.56 μg/g). At 40 μM, compound 1 showed obvious neuroprotection to the PC12 cells with 6-OHDA treatment.