Anti-inflammatory activity of four solvent fractions of ethanol extract of Mentha spicata L. investigated on acute and chronic inflammation induced rats

Anti-inflammatory effects of four solvent fractions of ethanol extract of Mentha spicata were evaluated in acute and chronic inflammation induced in Wistar albino rats. Lipid peroxidation (LPO) and some antioxidants produced during chronic inflammation were quantitated. Hexane (320 mg/kg of body weight in 25% DMSO), chloroform (320 mg/kg body weight in 25% DMSO), ethyl acetate (160 mg/kg body weight in 25% DMSO), aqueous (320 mg/kg of body weight in ddH2O) fractions, two negative control groups (25% DMSO and ddH2O) and two anti-inflammatory drugs (Diclofenac: 25 mg/kg of body weight; Indomethacin: 10 mg/kg of body weight both in ddH2O) were administered by oral intubations to the eight groups of rats consisting six animals, each. In acute study, 1% carrageenan was injected subcutaneously in the sub-plantar region of the right hind paw after 1 h of administration of test doses. The increased paw edema was measured at 0.5, 1, 2, 4, 8, 16 and 24 h intervals. In the chronic study, the oral administration was carried out for seven consecutive days. On eighth day, four sterile cotton pellets (50 mg each) were implanted subcutaneously in the dorsal region of the rats. On the sixteenth day, the rats were sacrificed and the cotton pellets with granulomatous tissue were dissected out and weighed (fresh and dry). Both in chronic and acute inflammation, ethyl acetate (EAF) and aqueous fraction (AF) were effective. EAF is comparable with the positive standards in chronic inflammation. The results indicate that EAF's anti-inflammatory activity is largely due to its ability to modulate in vivo antioxidants.