Monoterpenes from the leaves of Hydrangea paniculata and their hepatoprotective activities

Three new monoterpenes, hydrangines A-C (1-3), together with four known compounds, were isolated from the ethanol extract of the leaves of Hydrangea paniculata. The structures of new isolates were elucidated on the basis of extensive 1D and 2D NMR analyses, and their absolute configurations were determined by comparison of experimental and calculated electronic circular dichroism spectra. In in vitro bioassays at 10 μM, compounds 1-6 showed hepatoprotective activities against dl-galactosamine-induced toxicity in HL-7702 cells.