Chemical compositions, antioxidant, and anti-hyperglycemic activities of the extract fractions of Terminalia bellirica trunk-bark in streptozotocin-induced diabetic rats

Abstract

The research aimed to evaluate the antioxidant and anti-hyperglycemic activities of different fractions of extract from the trunk bark of Terminalia bellirica (T. bellirica), a plant commonly used in traditional Asian remedies. The antioxidant activity was determined using DPPH radical-scavenging activity. The in vitro anti-hyperglycemic activity was evaluated via the inhibitory activities against α-glucosidase and α-amylase, while the measurement of fasting blood glucose reduction capacity in treated diabetic rats was used for the in vivo anti-hyperglycemic test. The results indicated that the increase in polarity of the extraction solvent led to higher polyphenol content and DPPH radical scavenging of the extracts. The ethyl acetate fraction (EAF) and water fraction (WF) of T. bellirica exhibited significantly higher α-amylase inhibitory activity (IC₅₀ values of 0.118 ± 0.001 and 0.404 ± 0.001 mg/mL, respectively) than acarbose (IC₅₀ = 0.492 mg/mL), but the α-glucosidase inhibitory activity of all fractions was lower than that of acarbose. In the in vivo test, all fractions significantly lowered fasting blood glucose levels in streptozotocin-induced diabetic rats at a dose of 200 mg/kg body weight without body weight loss, while no effect was observed with acarbose treatment. In addition, the UPLC-QTOF-MS analysis showed that the EAF contains phenolic acids, flavonoids, triterpenes, and their derivative compounds. Thus, the trunk-bark of T. bellirica is recommended as a potent source of natural compounds having antioxidant and anti-hypoglycemic activities.