Inhibitory effects of Bridelia retusa on A-amylase and A-glucosidase activities

There has been a massive awareness in the development of alternative medicine for type 2 diabetes, specifically screening for phytochemicals with the ability to delay or prevent glucose metabolism. The antidiabetic therapeutic approach is to reduce gastrointestinal glucose production and absorption through the inhibition in carbohydrate-digesting enzymes such as α -amylase and α -glucosidase. The goal of the present study was to provide in vitro evidence for potential inhibition of α -amylase and α -glucosidase enzymes using methanolic extract of Bridelia retusa (B. retusa) bark (BRB) and fruit (BRF). The bark and fruit of this plant were dried under shade and extracts were prepared using cold maceration. Both of the extracts in different concentrations ranging from 40 – 200 µg/ml were tested in vitro for their enzyme inhibitory effects. The BRB extract showed noticeable α-glucosidase inhibitory effects in a concentration-dependent manner (IC₅₀= 24.6 ± 0.04 µg/ml) and a slight α-amylase inhibitory activity (IC₅₀= 54.1 ± 0.12 µg/ml). BRF extract showed similar α-glucosidase inhibitory effect in a concentration-dependent manner (IC₅₀= 19.3 ± 0.02 µg/ml) and a slight α-amylase inhibitory activity (IC₅₀= 21.7 ± 0.06 µg/ml). Phytochemical study of the said plant part extract indicated that it was rich in total phenolic contents and flavonol, which may be responsible for its pharmacological activity. The positive in vitro enzyme inhibition tests are concreted way for confirmatory in vivo studies. Thus the present in vitro study confirms the hypoglycemic effect of methanolic extract of B. retusa. Hence, our study could justify the use of the plants traditionally to manage diabetes and it may also helpful to develop medicinal preparations or nutraceutical and functional foods for treatment of diabetes.