Antioxidant activity of Gmelina arborea Roxb. (Verbenaceae) bark extract: In vivo and in vitro study

Abstract

Context: Gmelina arborea Roxb (Family: Verbenaceae) is widely used in Sri Lankan traditional Ayurvedic medicine for long -term treatment of diabetes mellitus. Aims: To investigate the in vitro and in vivo antioxidant activities of the aqueous bark extract of G. arborea. Materials and Methods: The in vitro total antioxidant activities of the hot water bark extract of G. arborea were evaluated by 2,2'-diphenyl-2-picrylhydrazyl hydrate (DPPH), ferric reducing antioxidant potential (FRAP), and NO inhibition assays. The in vivo antioxidant activity was evaluated by the activities of liver enzymes, antioxidant enzymes, and extent of lipid peroxidation (LPO) in the liver of streptozotocin (STZ)-diabetic rats. Results: In vitro antioxidant assays (DPPH, FRAP, and NO) clearly demonstrated the antioxidant potential of G. arborea extract. The G. arborea extract decreased LPO by 27%; activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase decreased by 29%, 23% and 29%, respectively (P < 0.05). The liver reduced glutathione, activities of glutathione reductase, glutathione peroxidase, and glutathione S-transferase of plant extract treated diabetic rats increased to 606.47 ± 8.04 μg/g liver tissue, 7.92 ± 0.75, 8.56 ± 1.00, and 7.44 ± 1.42 nmol/min/mg protein, respectively (P < 0.05). The extract was more effective than glibenclamide in restoring the hepatic antioxidant enzymes in STZ diabetic rats. Conclusions: The present investigation revealed that the bark extract of G. arborea exerts significant in vivo and in vitro antioxidant activities.