Shearinines U–Y, indole diterpenoids from an entomogenous fungus, Penicillium sp.

Abstract

Five new indole diterpenoids, shearinines U–Y (2–6), and the known compound 22,23-dehydro-shearinine A (1) were isolated from cultures of the entomogenous fungus Penicillium sp. Their structures were elucidated primarily by NMR experiments. The absolute configurations of 2–6 were assigned by electronic circular dichroism calculations, respectively. Compounds 1–3 showed moderate cytotoxicity, with IC₅₀ values of 11.7–26.2 μM.