Anti-inflammatory effect of Ajuga bracteosa Wall Ex Benth. mediated through cyclooxygenase (COX) inhibition

Ethnopharmacological relevance: Ajuga bracteosa Wall Ex Benth. (Labiateae) is described in Ayurveda for the treatment of rheumatism, gout, palsy and amenorrhea. Aim of the study: The aim of present investigation is to study anti-inflammatory activity of Ajuga bracteosa, to understand possible mechanism of action and to identify the constituents responsible for its activity. Materials and methods: The anti-inflammatory activity of 70% ethanolic extract was evaluated in TPA-induced mouse ear edema assay and in vitro cyclooxygenase (COX)-1 and COX-2 inhibitory activity was determined using EIA kits employing appropriate reference standards. Aajugarin I, lupulin A, withaferin A, reptoside and 6-deoxyharpagide were isolated from the 70% ethanolic extract by silica gel column chromatography. Results: The 70% ethanol extract of whole plants of Ajuga bracteosa showed a significant (p < 0.05) and dose-dependent anti-inflammatory activity in an acute inflammation model at the dose of 0.5 and 1.0 mg/ear. The extract also exhibited a strong in vitro COX-1 and COX-2 inhibitory activity at 25 and 50 mu g/mL concentration. Among the isolated compounds 6-deoxyharpagide exhibited highest COX-2 inhibition while rest of the compounds exhibited weak to moderate COX-1 and COX-2 inhibition at 30 mu M concentration. Conclusions: The results suggest that the 70% ethanol extract of Ajuga bracteosa possesses promising anti-inflammatory activity, which is possibly mediated through inhibition of COX-1 and COX-2 enzymes. The isolated constituents could be responsible in part for its anti-inflammatory and COX inhibitory activity. The study supports traditional use of Ajuga bracteosa for inflammatory diseases. (C) 2010 Elsevier Ireland Ltd. All rights reserved.