Effect of Aloe vera on nitric oxide production by macrophages during inflammation

Abstract

Objective : To demonstrate the mechanism of action mediating the acute and chronic antiinflammatory activity of leafy exudate of Aloe vera (AVL) in animal models of inflammation. Materials and Methods: The acute antiinflammatory activity of AVL was evaluated using carrageenan and dextran as phlogistic agents while its chronic antiinflammatory effect was investigated in a complete Freund's adjuvant-induced model of arthritis. The degree of inflammation in all models was measured plethysmographically. The effect of AVL on nitric oxide production in mouse peritoneal macrophages was measured by the Griess reagent. Results : AVL (25 mg/kg) significantly reduced carrageenan and dextran-induced pedal edema in rats by 61.9% and 61.7%, respectively. In the Freund's adjuvant-induced model of chronic inflammation, AVL showed chronic antiinflammatory activity but failed to decrease the arthritic index indicating the absence of antiarthritic activity. AVL (10 µg/ml) caused a decrease in NO production in macrophages without causing toxicity. Conclusion : AVL possesses acute and chronic antiinflammatory activity, which is partly mediated by reduced production of NO, which in turn prevents the release of inflammatory mediators.