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Versiquinazolines A–K, Fumiquinazoline-Type Alkaloids from the Gorgonian-Derived Fungus Aspergillus versicolor LZD-14-1

Cheng, Zhongbin, Lou, Lanlan, Liu, Dong, Li, Xiaodan, Proksch, Peter, Yin, Sheng, Lin, Wenhan
Journal of natural products 2016 v.79 no.11 pp. 2941-2952
Aspergillus versicolor, X-radiation, alkaloids, enantiomers, fungi, inhibitory concentration 50, nuclear magnetic resonance spectroscopy, spectral analysis, thioredoxins
Eleven fumiquinazoline-type alkaloids, namely, versiquinazolines A–K (1–11), along with cottoquinazolines B–D, were isolated from the gorgonian-derived fungus Aspergillus versicolor LZD-14-1. Their structures were determined by extensive analyses of the spectroscopic data (1D and 2D NMR, HRESIMS), in addition to the experimental and calculated ECD data and X-ray single-crystal diffraction analysis for the assignments of the absolute configurations. Versiquinazolines A, B, and F (1, 2, and 6), bearing a methanediamine or an aminomethanol unit and representing a unique subtype of fumiquinazolines, were found from nature for the first time. Possible biogenetic relationships of the versiquinazolines are postulated. In addition, the structures of cottoquinazolines B (12), D (13), and C (14) should be revised to the enantiomers. Compounds 1, 2, 7, and 11 exhibited inhibitory activities against thioredoxin reductase (IC₅₀ values ranging from 12 to 20 μM).