Alpha-Glucosidase Inhibitory Effects of Flavonoids, Phenolic Acids and Iridoids Isolated From Vinca Soneri: In Vitro and In Silico Perspectives

Various Vinca species have been traditionally used for their antihypertensive, sedative, and hemostatic properties, as well as for treating diabetes. In this study, some flavonoids, phenolic acids and iridoids were isolated from an endemic Vinca species, Vinca soneri for the first time. alpha-Glucosidase inhibitory effects of the isolates were tested and kaempferol-3-O-alpha-rhamnopyranosyl (1 -> 6) beta-galactopyranoside (1) was found to be the most active one with an IC50 value of 285.73 +/- 7.35 mu M. Enzyme kinetic assay revealed that it inhibited alpha-glucosidase in competitive manner. Molecular geometry of 1 was predicted and Frontier molecular orbital analysis was performed using Density Functional Theory (DFT) calculations. Molecular docking and MM-GBSA calculations predicted good fit for 1 in the enzyme active site and key interactions with the catalytic residues. As a result, current study identifies 1 as a promising competitive alpha-glucosidase inhibitor to be developed as a potential antidiabetic drug candidate.