Iridoids with anti-inflammatory activity from Vitex peduncularis.

A new iridoid, pedunculariside, together with the known iridoid agnuside were isolated from the butanol extract of Vitex peduncularis stem bark. Both pedunculariside and agnuside showed preferential inhibition of COX-2, with IC50 values of 0.15 +/- 0.21 mg/ml and 0.026 +/- 0.015 mg/ml respectively, while having only small inhibitory effects on COX-1. Both compounds did not exhibit cytotoxicity against vero cells.