Sesquiterpene lactones from the root tubers of Lindera aggregata.

Phytochemical investigation of the root tubers of Lindera aggregata resulted in the isolation of five new sesquiterpene lactones, linderagalactones A-E (1-5), along with eight known sesquiterpenoids, 3-eudesmene-1beta,11-diol, hydroxylindestenolide, strychnistenolide, hydroxyisogermafurenolide, atractylenolide III, linderane, neolinderalactone, and linderalactone. The structures and relative configurations of 1-5 were determined by spectroscopic methods, especially HRESIMS and 2D NMR techniques. The absolute configurations of 1-4 were defined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Linderagalactone A (1) is a halogenated sesquiterpene lactone possessing a unique rearranged carbon skeleton. Linderagalactone E (5), linderane, hydroxylindestenolide, and linderalactone showed hepatoprotective activity against H2O2-induced oxidative damages on HepG2 cells with EC(50) values of 67.5, 167.0, 42.4, and 98.0 microM, respectively.