Immunomodulatory Activity of n-Butanol Extract of Oroxylum indicum

Abstract

The present study evaluated the immunomodulatory activity and mechanism of action of the n-butanol extract [100 mg/kg body weight (b.w.), per oral (p.o.)] of Oroxylum indicum Vent. (Bignoniaceae) root bark against different experimental animal models, i.e., immune response to sheep red blood cells in stress-induced immunosuppression, carbon clearance assay and neutrophil adhesion test. In the immune response to sheep red blood cell model, the n-butanol extract of Oroxylum indicum treatment group showed a significant rise (P < 0.05) in circulating antibody-titer as compared to the stress-induced control group. This observation suggests that the drug treatment caused potentiation of humoral antibody immune response to antigen. Also, it significantly decreases the rise in malondialdehyde content along with an increase (p < 0.05) in superoxide dismutase, catalase and reduced glutathione levels as compared to the stress-induced control group and, thus, exhibits significant antioxidant potential. Pretreatment with the n-butanol extract of Oroxylum indicum showed a significant rise (P < 0.05) in phagocytic index indicating phagocytic activity. In the neutrophil adhesion model, a significant increase (P < 0.05) in percentage neutrophil adhesion was observed in the n-butanol extract treatment group as compared to the control group. From these findings, the n-butanol extract of Oroxylum indicum possesses immunomodulatory activity by enhancing specific immune response (humoral immunity) and non-specific immune response (phagocytosis) of the body as well as exhibiting antioxidant potential. Our results suggest that the n-butanol extract of Oroxylum indicum root bark possesses a significant immunostimulant activity.