ANALGESIC EFFECT OF IRVINGIA-GABONENSIS STEM BARK EXTRACT

Irvingia gabonensis is used medicinally in most parts of tropical Afri ca for the treatment of a number of ailments. In West Africa the Mende tribe of Sierra Leone uses the stem bark to relieve pain. In order to establish a pharmacological rationale for the traditional use of this plant as a remedy for pain, the water and ethanol extracts of the pow dered stem bark were screened for analgesic activity and compared with standard analgesic drugs. The water extract and morphine protected th e mice from heat-induced pain. In contrast, the ethanol extract and me tamizole sodium showed very low level of analgesic activity in this te st. However, using tail pressure as a source of pain, the water and et hanol extracts, metamizole sodium and morphine offered protection to t he mice against pain stimuli. Morphine and the water extract were more potent as analgesic agents in heat than non-heat pain test. The analg esic effects of the water extract and morphine were blocked by a non-s elective opioid receptor antagonist, naloxone in both tests, whereas t he analgesic effects of the ethanol extract and metamizole sodium were not antagonized by the same dose of the opioid antagonist. The data p resented in this study suggest that the active principle(s) in the wat er extract has analgesic profile similar to that of the narcotic analg esic and the ethanol extract might contain compound(s) that behave lik e nonnarcotic analgesic agent. These findings provide for the first ti me the pharmacological basis for the folkloric use of Irvingia gabonen sis in the relief of pain.