α -Amylase Inhibitory Activity of Catunaregam spinosa (Thunb.) Tirveng.: In Vitro and In Silico Studies.

α -Amylase is an enzyme involved in the breaking down of large insoluble starch molecules into smaller soluble glucose molecules. Catunaregam spinosa (Thunb.) Tirveng. (syn. Randia dumetorum (Retz.) Lam., Family: Rubiaceace) has been used as traditional medicine for the treatment of gastrointestinal problems, skin diseases, and diabetes. In this context, we studied the in vitro α -amylase inhibiting properties of methanol extracts of leaves and bark of C. spinosa . The methanol extract of bark was further fractionated into hexane, dichloromethane and ethyl acetate, and water-soluble fractions, and their α -amylase inhibitory activity was evaluated. In silico molecular docking and ADMET analysis of several compounds previously reported from the bark of C. spinosa were also performed. The in vitro α -amylase inhibition activity assay of the dichloromethane fraction of extract of bark (IC 50 : 77.17 ± 1.75  μ g/mL) was more potent as compared to hexane and ethyl acetate fractions. The in silico molecular docking study showed that previously reported compounds from the stem bark such as balanophonin, catunaregin, β -sitosterol, and medioresinol were bounded well with the active catalytic residue of porcine pancreatic α -amylase indicating better inhibition. The ADMET analysis showed the possible drug-likeness and structure-activity relationship of selected compounds. These compounds should be studied further for their potential α -amylase inhibition in animal models.