Evaluation of in vitro α-amylase inhibitory activity and antidiabetic effect of Myrica salicifolia in streptozotocin-induced diabetic mice

Abstract

The study was aimed to evaluate in vitro antioxidant, α-amylase inhibitory and in vivo antidiabetic activities of Myrica salicifolia root extracts. The powdered roots of M. salicifolia were extracted with 80% methanol and then dried. The dried extract was further fractionated into chloroform, ethyl acetate, butanol and aqueous fractions. The phytochemical screening of the crude extract was performed using standard chemical identification tests. The antioxidant activity of the extracts was determined by in vitro method using 2,2-diphenyl-1-picrylhydrazyl (DPPH) as radical scavenging reagent. The in vitro α-amylase inhibitory activity was performed using the chromogenic3,5-dinitrosalicylic (DNSA) method. The antidiabetic activity of M. salicifolia root crude extract (200, 400 and 600 mg/kg) and fractions (400 mg/kg) were evaluated in normal, glucose loaded hyperglycemic and streptozotocin (STZ)-induced diabetic mice. The crude root extract of M. salicifolia showed strong DPPH radical scavenging activity (IC50 = 4.54µg/ml) which was comparable with the standard antioxidant, ascorbic acid. In α-amylase inhibitory activity, the crude extract and butanol fraction showed highest enzyme inhibition. In the antidiabetic activity, daily administration of the crude extract, aqueous and butanol fractions for fifteen days showed highest significant reduction in fasting blood glucose level (BGL) compared to diabetic control in STZ-induced diabetic mice model. The root extract and fractions of M. salicifolia exhibited significant antihyperglycemic, α-amylase inhibitory and antioxidant activity with no sign of toxicity. The antidiabetic effect of the plant could be due to the synergistic effect of various classes of constituents present in the root part of the plant.