Antinociceptive effect of some extracts from Ajuga chamaecistus Ging. ssp. tomentella (Boiss.) Rech. f. aerial parts

Background: The genus Ajuga is used for the treatment of joint pain, gout, and jaundice in traditional Iranian medicine (TIM). Ajuga chamaecistus ssp. tomentella is an exclusive subspecies of Ajuga chamaecistus in the flora of Iran. The aim of this study was to evaluate antinociceptive properties of some extracts from aerial parts of A. chamaecistus ssp. tomentella. Methods: Antinociceptive activities of total water and 80% methanol extracts, hexane, diethyl ether and n-butanolic partition fractions of the methanolic extract were analyzed using the formalin test in mice. Indomethacin (10 mg/kg) and normal saline were employed as positive and negative controls, respectively. Results: Oral administration of all extracts (200, 400 and 600 mg/kg) 30 min before formalin injection had no effect against the acute phase (0–5 min after formalin injection) of the formalin-induced licking time, but hexane fraction (200 mg/kg) caused a significant effect (p 0.001) on the chronic phase (15–60 min after formalin injection). Total water and diethyl ether extracts at a dose of 400 mg/kg showed a very significant analgesic activity on the chronic phase (p 0.001 and p 0.01, respectively). Conclusions: The results of this study suggest that the extracts of A. chamaecistus ssp. tomentella have an analgesic property that supports traditional use of Ajuga genus for joint pain and other inflammatory diseases.