摘要Penicine A(1),a meroterpenoid featuring a novel 3/5/6/6/11/6/6 polycyclic backbone,to-gether with two new metabolites,penicines B(2)and C(4),and six known compounds,were isolated from the mangrove rhizosphere soil-derived fungus Penicillium brefeldianum SMU03.The structures of these metabolites were elucidated through extensive spectroscopic analysis combined with quantum chemical calculations.Notably,1 exhibits a highly unusual molecu-lar architecture,incorporating a dioxaspiro[4.5]decane motif and a rare bridgehead double bond(anti-Bredt system).A plausible biosynthetic pathway,involving sequential inter-molecular[4+2]cycloaddition reactions,is proposed.Additionally,meroterpenoids 1 and 3 demonstrate significant antifibrotic activity in transforming growth factor β1(TGF-β1)-in-duced human renal proximal tubular epithelial cells.