Rhapontigenin is a natural analog of resveratrol with antioxidant and anti-cancer activity. It is a mechanism-based, selective inactivator of cytochrome P450 1A1 (IC50 = 400 nM), an aryl hydrocarbon hydroxylase which activates polycyclic aromatic hydrocarbons that act as procarcinogens. At higher concentrations, rhapontigenin inhibits the proliferation of HepG2 and HL-60R cancer cell lines (IC50 = 48 μM).