Optimization of Ultrasonic-Assisted Total Flavonoids Extraction from Flower of Albizia Julibrissin Durazz. by Response Surface Methodology for Characterization of Chemical Profile and Evaluation of Antioxidant and Tyrosinase Inhibitory Activities

To investigate the flavonoids in flower of Albizia julibrissin (‘He Huan Hua’ in Chinese), the ultrasonic-assisted extraction of total flavonoids from ‘He Huan Hua’ was optimized by response surface methodology and the chemical profile was characterized by HPLC- QTOF-MS/MS. What’s more, the antioxidant and tyrosinase inhibitory activities of ‘He Huan Hua’ were also evaluated in this study. The extraction time, extraction temperature and ethanol concentration were optimized by single factor experiments and response surface methodology. The three factors were optimized to be 43 min, 40℃ and 49% (v/v) respectively. Under the optimized extraction condition, the yield of total flavonoids from ‘He Huan Hua’ was 3.31% (W/W). There were 32 different flavonoids identified from the extracts of ‘He Huan Hua’, which mainly were flavonol glycosides and the principal component was quercitrin. The antioxidant activity of the extracts of ‘He Huan Hua’ was evaluated by Diphenyl Picryl Hydrazinyl Radical (DPPH), 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and reducing power assays. The extracts of ‘He Huan Hua’ exhibited good antioxidative activity with IC50/EC50 of 90.91±3.36 (DPPH assay), 15.09±0.17 (ABTS assay) and 67.69±2.97 (reducing power assay) μg/mL, respectively. Most importantly, the extracts of ‘He Huan Hua’ also showed good tyrosinase inhibitory activity (IC50:1.32±0.01 mg/mL). The higher antioxidant and tyrosinase inhibitory activities of ‘He Huan Hua’ might be related to the presence of rich flavonol compounds. In summary, flavonoids in ‘He Huan Hua’ have great value for developing antioxidants and tyrosinase inhibitors and are deserved to be applied for prevention of premature skin aging.