Three undescribed diterpenoids from Pini Lignum Nodi with hepatoprotective activities

Three new abietane-type diterpenes, named pinusins A-C (1-3) were isolated from Pini Lignum Nodi (the dried tuberculate or branched nodes of Pinus massoniana Lamb.), together with five known diterpenoids (4-8), a flavonoid (9) and a monoterpene (10). The structures of these compounds were elucidated based on detailed spectroscopic analyses (1D, 2D NMR, HRESIMS, IR, and UV), while ECD calculations determined their absolute configurations. All compounds were assayed in vitro for their protective activities against acetaminophen (APAP)-induced hepatotoxicity at 10 μM. Compounds 1-4, 9, and 10 experimentally exerted protective effects against APAP-induced HepG2 cell damage.