Constituents from the Roots of Actinidia chinensis and Their Cytochrome P450 Enzyme Inhibitory Activities.

A newly discovered triterpenoid, (2α,3β)-2,3,23-trihydroxyurs-13(18)-en-28-oic acid (1), along with twelve known compounds (2 - 13), were isolated from the roots of Actinidia chinensis Planch (Actinidiaceae). Their chemical structures were determined by 1D- and 2D-NMR spectra and mass spectrometry (MS). The crude extracts and six main constituents (8 - 13) were tested for cytochrome P450 (CYPs) enzyme inhibitory activity. The results showed that, except for compound 8, compounds 9 - 13 had different inhibitory effects on the cytochrome P450 (CYPs) enzyme, and compound 9 significantly inhibited the catalytic activities of CYP3A4 to < 10% of its control activities.