potent anti-nociceptive and anti-inflammatory effects of methanol fraction of otostegia persica extract and its components

background and objectives: otostegia persica (labiatae) is an endemic plant of iran and is used for its anti-inflammatory properties in folk medicine of sistan and baluchestan province. the aim of the present study was to investigate the anti-nociceptive and anti-inflammatory effects of o. persica different fractions and identification of the natural compounds from the most active fraction. methods: total extract of o. persica was fractionated with petroleum ether (pe), chloroform (cl), ethyl acetate (ea), n-butanol (bu) and methanol (me). the analgesic activities of different fractions were determined by formalin test. then, activity of effective fractions was investigated on carrageenan-induced paw edema assay. finally, the compounds of effective fraction were isolated and their structures were elucidated. results: anti-nociceptive activity of ea and bu fractions (100 mg/kg) and me fraction (100 and 200 mg/kg) demonstrated significant difference with normal saline during the second phase of the formalin test. me fraction showed higher analgesic effects in comparison to indomethacin (p0.05). vicenin-2 and isorhamnetin-3-o-glucoside were elucidated from me as the effective anti-inflammatory fraction. conclusion: it was concluded that the existence of flavonoids in o. persica extract could play an important role for its anti-nociceptive and anti-inflammatory effects similar to various non-steroidal anti-inflammatory drugs (nsaids) and inhibitors of nitric oxide synthase (nos).