Antioxidant, antidiabetic and identification of phenolic constituents from Potentilla discolor Bge

The objective of this study was to investigate the antioxidant and enzyme inhibitory activity, and characterize the bioactive constituents of the phenolic extract of Potentilla discolor Bge. Dry material of Potentilla discolor Bge. was extracted with 80% ethanol solution to obtain the crude phenolic extract (CPE) with the total phenolic content (TPC) of 20.40 ± 0.69 mg of gallic acid equivalents per gram of dry material (mg GAE/g DM). After purified with AB-8 macroporous resin, TPC of the purified phenolic extract (PPE) (353.65 ± 5.50 mg GAE/g DM) was much higher than that of the CPE. PPE exhibited stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity than CPE and 2,6-Di-tert-butyl-4-methylphenol (BHT), with the IC 50 values of 0.030 ± 0.002 mg/mL and 0.059 ± 0.002 mg/mL, respectively. The total antioxidant activities of PPE and BHT were similar, and were higher than CPE. PPE was found to significantly inhibit α -amylase and α-glucosidase with IC 50 values of 0.966 ± 0.072 and 2.431 ± 0.088 mg/mL, respectively. Finally, using UPLC-TOF–MS/MS technology, 35 compounds were tentatively identified, including 12 phenolic acids, 23 flavonoids and their derivatives, 29 of which have been discovered for the first time in Potentilla discolor Bge. These results suggested that PPE had the potential to be used as an antioxidant and anti-diabetic component in functional foods.