Aspersteroids A-C, Three Rearranged Ergostane-type Steroids from Aspergillus ustus NRRL 275
Lin Liu1, Fang-Fang Duan1, Ying Gao1
1School of Pharmacy, Tongji Medical College, Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, Huazhong University of Science and Technology, Wuhan 430030, P. R. China.
Abstract:
Aspersteroid A (1), a highly rearranged 1(10 → 6)-abeo-18,22-cyclosterol, together with two new 18,22-cyclosterols (2 and 3), was isolated from the culture extract of Aspergillus ustus NRRL 275. Their structures were determined by spectroscopic analysis, X-ray diffraction, modified Mosher's method, and Rh2(OCOCF3)4-induced electronic circular dichroism experiments. Compound 1 represents a new carbon skeleton with an uncommon 6/6/6/5/5 ring system, which is presumably biosynthesized from A-ring scission, double 1,2-shifts, and C-18/C-22 cyclization. Compound 1 exhibited potent immunosuppressive and antimicrobial activities.
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