Evaluation of antinociceptive activity of Ritchiea longipedicellata (Capparaceae) leaf extract in mice.
The antinociceptive effect of ethanolic extracts of Ritchiea long-ipedicellata (Capparaceae) leaves was evaluated in acetic acid, formalin, tail immersion, and hot plate models. Motor effect was assessed with rota-rod and open field tests. The effect of recep-tor antagonists was examined in the formalin test. The extract (50, 100, or 200 mg.kg−1, p.o.) showed dose dependent inhibi-tion of writhing with percent inhibition of 36.88%, 46.29%, and 52.48%, respectively. There was a reduction in the time spent in paw-licking in both the early and late phases of formalin test. The extract increased the withdrawal latency of the mice in tail immersion test, but failed to show an effect beyond 60 min of hotplate test. The extract impaired the mice motor performance function in the rota-rod and open field tests. The effect of the extract in formalin test was only reversed by yohimbine in the late phase. The results suggested that R. longipedicellata leaf extracts exerted antinociceptive effects which may partly involve α2 adrenergic receptor mechanism.