Investigations into the antinociceptive activity of Sapindus trifoliatus in various pain models.

The effect of the aqueous extract of Sapindus trifoliatus (ST) on chemical, thermal-induced pain, nitroglycerin-induced hyperalgesia and pain on inflamed tissue was investigated. The extract (20 and 100 mg x kg(-1), i.p.) significantly inhibited acetic-acid-induced abdominal constrictions, formalin-induced pain licking and hotplate-induced pain in mice. Furthermore, the extract significantly increased the response latencies of nitroglycerin-induced hyperalgesia by the tail-flick method and mechanical pain on carrageenan-induced inflamed paw in rats. The data suggest that ST has an inhibitory activity on both peripheral and central pain mechanisms and has a modulatory role in NO-mediated nociceptive transmission.