Anti-nociceptive and antioxidant activities of an aqueous leaf extract of Corchorus olitorius L. (Tiliaceae)

A preliminary study had shown that C. olitorius has analgesic activity possibly mediated through opioidergic pathway. The study was a follow up work to evaluate the anti-nociceptive effects and other possible mechanisms of action of an aqueous leaf extract of C. olitorius (COE) using formalin-induced nociception test. COE was screened for its analgesic, and antioxidant activities. The anti-nociceptive effect of COE (3x10-2, 1x10-1 and 3x10-1 g kg-1, p.o), and morphine (1x10-3, 3x10-3 and 1x10-2 gkg-1, i.p.) were evaluated using the formalin-induced nociception test. The study showed that C. olitorius has analgesic activity possibly mediated through opioidergic pathway. COE produced significant (P ˂ 0.05) dose-dependent antinociceptive effects similar to morphine in both phases of formalin-induced nociception. The extract showed free radical scavenging properties and different phyto-constituents such as alkaloids, flavonoids, saponins, cardiac glycosides, tannins, anthraquinones and terpenoids were identified. COE has both central and peripheral anti-nociceptive effects mediated through opioidergic receptor activation and also partly through ATP-sensitive K+ channel activation systems. The findings confirms earlier reports, and further shows that C. olitorius produces anti-nociception by interrupting many pain processing pathways. Results further suggest that the extract (COE) might possess some chemical constituents that are responsible for the analgesic and the antioxidant activities.Keywords: Naloxone, glibenclamide, morphine, nociception, DPPH, formalin test.