New Dihydro-β-agarofuran Sesquiterpenes from Parnassia wightiana Wall: Isolation, Identification and Cytotoxicity against Cancer Cells

Five new (4–8) and three known (1–3) dihydro-β-agarofuran sesquiterpene polyesters were isolated from the whole plants of Parnassia wightiana. The structures of all compounds were elucidated through spectroscopic analysis including 2D-NMR and HR-MS. The absolute configuration of these compounds was established by X-ray diffraction analysis, comparison of NOESY spectra and biogenetic means. The cytotoxities of compounds 2–8 were evaluated in vitro against HL-60, SMMC-7721, A549, MCF-7 and SW480 cell lines. Compounds 5–7 exhibited the highest activities with IC(50) values of 11.8–30.1 μM in most cases. The SAR revealed that the introduction of hydroxyl group was able to significantly improve the activities of the compounds for most of the cell lines.