Three undescribed diterpenoids from Pini Lignum Nodi with hepatoprotective activities

Three new abietane-type diterpenes, named pinusins A-C (<b>1</b>-<b>3</b>) were isolated from Pini Lignum Nodi (the dried tuberculate or branched nodes of <i>Pinus massoniana</i> Lamb.), together with five known diterpenoids (<b>4</b>-<b>8</b>), a flavonoid (<b>9</b>) and a monoterpene (<b>10</b>). 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 <i>in vitro</i> for their protective activities against acetaminophen (APAP)-induced hepatotoxicity at 10 <i>μ</i>M. Compounds <b>1</b>-<b>4</b>, <b>9</b>, and <b>10</b> experimentally exerted protective effects against APAP-induced HepG2 cell damage.