Isolation, structure elucidation, and induction of hepatoma cell apoptosis of abietane diterpenoids from Abies faxoniana
Two new abietane diterpenoids (1–2) and 13 known compounds (3–15) were characterized from the branches and leaves of Abies faxoniana. The chemical structures of the new diterpenoids (1–2) were determined through the analysis of various 1D/2D NMR techniques. Compound 3 is 151,617-trinor-abietane diterpenoid conjugated with a three-membered epoxide ring. The isolated diterpenoids were tested for their cytotoxicities. Among them, compound 3 exhibited the strongest antiproliferative effect against human hepatoma cell SMMC7721 with an IC50 value of 12.5 μM. To elucidate the preliminary mechanism responsible for compound 3-induced inhibition of cell proliferation, we investigated the effects of compound 3 on apoptosis, cell cycle progression, and reactive oxygen species generation in SMMC7721 cells. The results showed that compound 3 induced cell apoptosis and excessive ROS production, but did not change the cell cycle distribution in SMMC7721 cells.