Sphenalactones A-D, a new class of highly oxygenated trinortriterpenoids from Schisandra sphenanthera

Four novel highly oxygenated trinortriterpenoids, sphenalactones A-D (1-4), were isolated from the leaves and stems of Schisandra sphenanthera and their structures were elucidated by extensive analysis of 1D and 2D NMR data. Compounds 1-4 featured a C27 backbone and showed anti-HIV-1 activity with EC50 values in the range of 35.5-89.1 μg/mL with a low cytotoxicity against C8166 cells (CC50 > 200 μg/mL).