Pleosmaranes A-R, Isopimarane and 20-nor Isopimarane Diterpenoids with Anti-inflammatory Activities from the Mangrove Endophytic Fungus sp. HNQQJ-1.

Pleosmaranes A-R (-), 18 new isopimarane-type diterpenoids, together with four known analogs (-), were isolated from the mangrove endophytic fungus sp. HNQQJ-1. Their structures and absolute configurations were established by analysis of their spectroscopic data and electronic circular dichroism (ECD) calculations. Compounds - possess an unusual aromatic B ring and a 20-nor-isopimarane skeleton. Compounds - contain a unique 2-oxabicyclo[2.2.2]octane moiety. Compound features an unexpected 2-oxabicyclo[3.2.1]octane moiety. Compounds and exhibited a moderate inhibitory effect against LPS-induced NO production, with IC values of 19 and 25 μM, respectively.