Screening of Antioxidant and α-Glucosidase Inhibitory Activities of Indian Medicinal Plants

Background and Objective: Chronic diseases are associated with low-grade inflammation and oxidative damage. Traditional medicines have been used to manage these disorders due to their high polyphenol content and potent antioxidant activity. We evaluated the in-vitro anti-diabetic and antioxidant potential of extracts of several medicinal plants namely, Mangifera indica, Terminalia arjuna, Moringa oleifera, Albizia lebbeck, Terminalia chebula and Hippophae rhamnoides. Methods: Total polyphenol, flavonoid, and saponin contents were estimated by standard methods. Antioxidant activity was measured using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The anti-diabetic potential was evaluated using in-vitro α-glucosidase inhibition assay. Results: Terminalia chebula was found to be the richest in both polyphenols (566.5 ± 21.9 μg Gallic acid equivalents/mg of dry weight) and flavonoids (190.67 ± 10.78 quercetin equivalents/mg of dry weight). Extract of Terminalia arjuna was the richest source of saponins (171.92 ± 12.48 μg saponin equivalents/mg of dry weight). All plant extracts showed potent anti-oxidant activity as reflected by their IC50 values in DPPH assay, with Albizia lebbeck (IC50 = 1.35 μg/ml) being the most potent. All plant extracts also showed potent anti-diabetic activity as inferred from their ability to inhibit α- glucosidase, the principal enzyme involved in the metabolism of dietary carbohydrates in the intestine. It was observed that all tested extracts were more potent (IC50 2.53 to 227 μg/ml) in comparison to the standard α-glucosidase inhibitor Acarbose (IC50=2.7 mg/ml). Conclusion: The plant extracts of Mangifera indica, Terminalia arjuna, Moringa oleifera, Albizia lebbeck, Terminalia chebula, and Hippophae rhamnoides possess potent antioxidant and α- glucosidase inhibitory potential and can aid in the management of postprandial hyperglycemia and oxidative damage.