Microwave-assisted extraction of flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja leaves, its chemical composition and antioxidant activity were investigated in this study. The influences of parameters including temperature, extraction time, ratio of material to solvent and solvents on the yield of flavonoids were studied. The optimal conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The maximum extraction yield of 15.64 mg/g was achieved at temperature of 76.8 °C, extraction time of 15 min, alcohol concentration of 63.2% and ratio of solvent to material of 21.4:1. Five main constituents in the extract including quercetin-3-O-β-D-glucuronide, quercetin, kaempferol-3-O-β-D-glucuronide, kaempferol-7-O-α-L-rhamnoside and kaempferol were identified by LC-MS. In vitro antioxidant assays showed that the extract exhibited a strong DPPH radical-scavenging ability with IC50 value of 0.146 mg/mL. Results indicated that MAE was a suitable approach for the selective extraction of flavonoids from C. paliurus (Batal.) Iljinskaja leaves.
Keywords: Antioxidant activity; Chemical composition; Cyclocarya paliurus; Flavonoids; Microwave-assisted extraction; Response surface methodology.
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