Talaroclauxins A and B: Duclauxin-ergosterol and duclauxin-polyketide hybrid metabolites with complicated skeletons from Talaromyces stipitatus

Talaroclauxins A and B ( 1 and 2 ), two novel duclauxin hybrids, were obtained from Talaromyces stipitatus, along with three new ( 3 -5) and one known analogue ( 6 ). Their structures were determined by NMR spectroscopy, HRESIMS, single-crystal X-ray diffraction, and quantum chemical calculations. Compound 1 is the first example of duclauxin-ergosterol hybrid featuring an unprecedented dodecacyclic ring system formed via a [4 + 2] cycloaddition, while compound 2 , bearing an unusual 6/6/6/5/6/6/6/6 ring system, is a new member of the rare duclauxin-polyketide hybrid class of natural products. Plausible biosynthetic pathways for 1 -6 are proposed. Compound 5 displayed moderate neuroprotective effects in glutamate sodium-induced SH-SY5Y cells.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.