Antinociceptive, anti-inflammatory and acute toxicity effects of Zataria multiflora Boiss extracts in mice and rats.

Antinociceptive, anti-inflammatory and acute toxicity of the aqueous infusion and ethanolic maceration extracts of the aerial parts of Zataria multiflora Boiss were studied in mice and rats. Antinociceptive activity was done using hot-plate and writhing tests. The effect of the extracts against acute inflammation was studied by vascular permeability increased by acetic acid and xylene induced ear edema in mice. The activity of the extracts against chronic inflammation was assessed by the cotton pellet test in rats. LD50 of the infusion and maceration extract was 3.85 and 3.47 g/kg, respectively. Intraperitoneal injection of both extracts in mice showed significant and dose-dependent antinociceptive activity. Naloxone, an opioid antagonist, pretreatment inhibited the antinociceptive activity of the extracts. The extracts exhibited antinociceptive activity against acetic acid induced writhing which was partially blocked by naloxone. Both extracts did not show remarkable activity against acute inflammation induced by acetic acid in mice. In the xylene ear edema, Z. multiflora Boiss extracts showed significant activity in mice. In the chronic inflammation the efficacy of the extracts was more than in acute inflammation. It is concluded that aqueous infusion and maceration of the aerial parts of Z. multiflora Boiss have antinociceptive effect and this may be mediated by opioid receptors. The extracts showed also anti-inflammatory effect against acute and chronic inflammation.