Potent anti-inflammatory activities of hydroalcoholic extract from aerial parts of Stachys inflata on rats

Extracts obtained from aerial parts of Stachys inflata have been used in Iranian folk medicine in infective, rheumatic and other inflammatory disorders. In the present study, the anti-inflammatory properties of total methanol extract isolated from aerial parts of Stachys inflata were investigated in two well-characterised inflammatory models in rats, carrageenan-induced paw oedema and formalin-induced paw licking. Intraperitoneal injection of the extract, 60 min before induction of inflammation, revealed a dose-related inhibition of carrageenan-induced rat paw oedema over the dose range 50-200 mg/kg. In the formalin test, the extract (50, 100 and 200 mg/kg) had no effect against the first phase (0-5 min) of the formalin-induced pain, but all three doses produced a significant blockade of the second phase (P < 0.001). Myeloperoxidase (MPO) activity was determined, and a histopathological study was carried out in paw tissue 4 h after induction of inflammation. The hydroalcoholic extract (200 mg/kg) substantially reduced MPO activity (P < 0.05), which was increased in the control group. Histological examination showed a marked reduction in tissue injury and inhibition in neutrophil infiltration in rats treated with the extract (200 mg/kg).