study on antinociceptive activity of different extracts of peganum harmala and possible mechanism of action

the seeds of peganum harmala l. ( pgh ) (zygophyllaceae) have been used in moroccan traditional medicine for treatment of a various diseases and to relieve dolorous process. the major objective of this paper was to investigate the analgesic effect of ethyl acetate (eae), butanolic (be) and aqueous (aqe) extracts of seeds of peganum harmala and elucided the possible underlying action mechanism of each extract. in the present work, the antinociceptive action was assayed in several experimental models in mice: writhing, formalin, tail flick and hot plate tests. the eae, be and aqe given by i.p or p.o. routes showed significant reduction in acetic acid induced writhings in mice with a maximum effect of  35.12 % reduction of be at dose 25 mg/kg, i.p. (p<0.001). in the formalin test, the pre-traetment with eae and be (12.5 and 25mg/kg, i.p.) caused marked and dose-related inhibition of formalin-induced licking in mice in the both phase, whereas, the aqe (25mg/kg, i.p.) reduced the nociception response only in the second phase of formalin test. the results on hot plate and tail flick tests, showed a significant central acting analgesic properties of eae and be. these result showed that the eae and be, which were the most effectives, contains active analgesic principles acting both centrally and peripherally. preliminary phytochemical screening of the extracts showed the presence of alkaloids, flavonoids, quinons and saponin. furthermore, this antinociceptive effect has been avoided by naloxone at a dose 1 mg/kg in the first phase of formalin and hot plate tests indicating that these extracts acts partly through an opioid-mediated mechanism. in conclusion, our results demonstrated that the different extracts of peganum harmala had both central and peripheral antinociceptive activities that may be mediated by opioid receptors.