Evaluation of the antinociceptive and anti-inflammatory effects of essential oil of Nepeta pogonosperma Jamzad et Assadi in rats

Air-dried aerial parts of NP were hydrodistillated and GC-MS analysis of obtained essential oil was conducted. Total 24 male Wister rats weighing 225？±？25 gm were studied. Essential oil of NP was administered intraperitoneally at the doses of 50？mg/kg, 100？mg/kg and 200？mg/kg for the experimental groups. Control rats received equal volume (2？ml/kg) of normal saline. Antinociception was assessed by tail flick test (after 30 minutes) and formalin test (for further 60 minutes). Then the animal was sacrificed and the paw edema was measured using a water plethysmometer.4aα,7α,7aβ-nepetalactone and 1,8-cineole were found as the main concentrated components of NP essential oil. All the doses of NP showed antinociception. NP 200？mg/kg reduced the pain sensation in tail flick (p <0.01) and formalin test (p <0.001 in both phases). In paw edema test, NP 100 and 200？mg/kg significantly reduced the inflammation (p <0.01 and p <0.05).This study reveals that the essential oil of NP may minimize both the acute and chronic forms of nociception and may have potent role against inflammation, but the dose should be maintained precisely to obtain the intended effect.Nepeta L. (from Lamiaceae) contains about 300 species, which are distributed in central and southern Europe and in near East, central and southern Asia also. Within them Iran is one of the centers of origin of this genus with 75 species and approximately 53% endemics [1]. The diversity, species richness and variation as well as chemical properties have led to much research into this genus. The extracts of many Nepeta species are used in domestic medicine. N. cataria L., commonly known as catnip, is the most intensively studied species [2], which is used as a fortifier, a disinfectant and a cure for colds. The extracts of some species are also used because of their diuretic properties and slight bacteriostatic activity, and also in ointments to heal skin disorders of eczema type [3]. Some of the species are widely used in fol