Two new naphthoquinones with antiviral activity from Rhinacanthus nasutus

Two new naphthoquinones, rhinacanthin-C (1) and rhinacanthin-D (2), exhibit inhibitory activity against cytomegalovirus (CMV), with EC50 values of 0.02 and 0.22 microgram/mL, respectively, against human CMV. They were isolated from the medicinal plant Rhinacanthus nasutus (Acanthaceae). The structures of the compounds were determined by analysis of their spectroscopic data, in particular, 2D NMR.