Two new seco-abietane type diterpenoids from the leaves of Isodon serra

Two new seco-abietane type diterpenoids, named as isodonserra acid A and B (1-2), along with six known compounds, angustanoic acid A (3), epipalustric acid (4), raserrane (5), 7-methoxy coumarin (6), umbelliferone (7), and (-)-loliolide (8), were obtained from the leaves of Isodon serra. The new structures of compounds 1 and 2 were elucidated by analysing their 1D NMR, 2D NMR and HR-ESI-MS spectra. Compounds 1-8 showed moderate hepatoprotective activity against APAP-induced HepG2 cell injury with a cell survival rate from 50.4% to 78.7% at a concentration of 10 μM (p < .001, bicyclol as the positive drug, 71.7%).