Abstract

The aim of this study was to assess the in vitro α-glucosidase inhibitory activity of Phyllanthus niruri fractions (PNFs) and identify the chemicals involved. The ethanolic P. niruri extract was partitioned using medium-pressure liquid chromatography. The PNFs were examined using ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS), the α-glucosidase inhibitory activity was assessed using yeast α-glucosidase, and molecular docking simulations were performed via Molegro Virtual Docker version 6.0. The extract had a water-soluble content of 37.26%, ethanol-soluble content of 17.16%, total phenol concentration of 167.65 mg GAE/g extract, total flavonoid concentration of 10.07 mg QE/g extract, water content of 2.72%, loss on drying of 33.39%, total ash content of 4.1%, an acid-insoluble ash content of 0.42%, and an in vitro α-glucosidase inhibitory activity with an IC50 of 1.48 μg/ml. Also, at concentrations of 1 and 3 μg/ml, PNF-1 to PNF-6 had a much stronger inhibitory effect on α-glucosidase than PNF-7 and PNF-8. The UPLC-QTOF/MS analysis of the active fraction identified significant chemicals, notably corilagin (7) and gallic acid dimethyl ester (8). The docking analysis revealed advantageous docking scores of −152 and −81. This indicates that these chemicals may serve as effective α-glucosidase inhibitors. The results of this study support the use of P. niruri as a good natural product for treating diabetes through the α-glucosidase inhibitory mechanism.

Key words: α-glucosidase inhibition, fractions, Phyllanthus niruri, molecular docking, compound prediction, UPLC-QTOF/MS