Meroterpenoids with diverse ring systems and dioxolanone-type secondary metabolites from Phyllosticta capitalensis and their phytotoxic activity

Twenty meroterpenoids with diverse ring systems including five new ones (1, 2, 5, 6, and 15), together with two new (23 and 24) and two known dioxolanone-type secondary metabolites were isolated from Phyllosticta capitalensis, an endophytic fungus from Cephalotaxus fortunei Hook. Compound 1 was the first example with a 9,14-seco ring A and a five-membered ring B in guignardone derivatives. Compound 2 represented a novel guignardone derivative possessing a 5/7/6/5 ring system with CH2-7 attached to C-4 rather than C-6 in ring D. The structures of all new compounds were elucidated using spectroscopic data analyses and electronic circular dichroism comparison. The phytotoxic effects of compounds 1-24 on Lactuca sativa and Lolium perenne were evaluated. Compound 22 showed inhibition activity on the shoots growth of L. sativa and L. perenne, as well as the roots growth of L. perenne. (C) 2019 Elsevier Ltd. All rights reserved.