Isolation of Flavonoids from the Potentilla kleiniana and Evaluation of Their α-Glucosidase Inhibitory Activity and Anti-inflammatory Activity

In this study, phytochemical investigation of ethanolic (EtOH 60%, Water 40%) extract from Potentilla kleiniana by reflux extraction was carried out for the isolation and characterization of their chemical structures of seventeen known secondary metabolites. Structure determination of the isolated compounds was carried out using 1D NMR data and mass spectrometry techniques. Compounds 3, 8, 12 and 13 were isolated from P. kleiniana for the first time in this study and were recorded as a new report for the species. Compounds  (2, 6-7, 9, 11 and 14-15)  represent previously unreported constituents within the genus Potentilla. As a result of the α-glucosidase inhibitory activity determination studies performed separately on the isolated compounds, it was determined that compounds 10, 14 and 15 exhibited better inhibition-inhibition percentages of 87.14%, 49.07%, and 86.79%, respectively compared to the positive control acarbose (37.26%). Moreover, compounds 3, 10, 14 and 15 were determined to be secondary metabolites with significant nitric oxide (NO). SAR analyses were performed to understand the relationship between α-glucosidase inhibitory activities and the structures of the molecules, and according to the results of these analyses, it was observed that flavonoid derivatives carrying hydroxyl groups at C-3 and C-7 positions showed higher hypoglycemic activity than their counterparts carrying rhamnose groups at these positions.