An unprecedented ergostane with a 6/6/5 tricyclic 13(14 → 8)abeo-8,14-seco skeleton from Talaromyces adpressus
Mi Zhang1, Qin Li2, Shuangjun Li3
1Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Department of In Vitro Diagnostic Reagent, National Institutes for Food and Drug Control (NIFDC), Beijing 100050, China.
Abstract:
Talasterone A (1), an unprecedented 6/6/5 tricyclic 13(14 → 8)abeo-8,14-seco-ergostane steroid, together with two known congeners dankasterone B (2) and (14β,22E)-9,14-dihydroxyergosta-4,7,22-triene-3,6-dione (3), were characterized from Talaromyces adpressus. The structure of 1 with absolute configuration was elucidated based on NMR spectroscopic data and ECD calculation. Compound 2 belongs to a class of unconventional 13(14 → 8)abeo-ergostanes, which have been renewed via the 1,2-migration of C-13-C-14 bond to C-8. In addition, compound 1 represents the first example of ergostane with a tricyclic 13(14 → 8)abeo-8,14-seco-ergostane skeleton. The proposed biosynthetic pathway was established with the support of the coisolation of the known congeners from the producing organism. It is especially noteworthy that compound 1 exhibited potent anti-inflammatory activity with an IC50 value of 8.73 ± 0.66 μM, inhibiting the NF-κB pathway and thus reducing the production of proinflammatory cytokines.
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