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Antinociceptive action of aqueous extract of the leaves of <i>Ixora coccinea</i>

Ratnasooriya, W. D., Deraniyagala, S. A., Bathige, S. D. N. K., Goonasekara, C. L., Jayakody, J. R. A. C.
Acta biologica Hungarica 2005 v.56 no.1-2 pp. 21-34
Ixora coccinea, adverse effects, alkaloids, analgesic effect, antioxidant activity, dose response, flavonoids, formalin, leaf extracts, leaves, males, models, nociception, oral administration, rats, tail, toxicity
The aim of this study was to examine the antinociceptive potential of leaves of <i>Ixora</i><i>coccinea</i> (family: Rubeaceae). One of four doses (500, 750, 1000 or 1500 mg/kg, n=8/dose) of aqueous leaf extract (ALE) or 1 ml of distilled water was orally administered to male rats and antinociceptive activity was ascertained using three models of nociception (tail flick, hot plate and formalin tests). The results showed that ALE possesses considerable antinociceptive activity (when evaluated in hot plate and formalin test but not in tail flick test). The antinociceptive activity of the ALE had a rapid onset (within 1 h) and a fairly long duration of action (up to 5 h) with a peak effect at 3 h. Further, the antinociceptive activity was dose-dependent and was not associated with harmful side-effects or toxicity even following subchronic administration. The antinociceptive action was mediated centrally at the supraspinal level mainly via dopaminergic mechanism. In addition, it is likely that antioxidant activity of the ALE could have played an auxiliary role in inducing antinociception. Dopaminergic and antioxidative activities of ALE could arise, respectively, from its quaternary base alkaloid and flavonoid constituents.