Abstract:
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 anti-
nociceptive 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.
