Ultrasonic-Assisted Biphasic Aqueous Extraction of Polyphenols from Vaccinium Dunalianum Leaves: Optimization, Antioxidant, and Tyrosinase Inhibition Activities.

To optimize the ultrasonic-assisted biphasic aqueous extraction conditions for polyphenolic compounds from Vaccinium dunalianum Wight leaves and investigate their antioxidant and tyrosinase inhibition activities, single-factor experiments were conducted to investigate the effects of ethanol volume fraction (%), ammonium sulfate mass fraction (%), solid-liquid ratio (g/mL), ultrasonic temperature (°C), and ultrasonic time (min) on polyphenolic content during extraction. Based on these experiments, three key factors influencing extraction were selected for response surface methodology (RSM) optimization. The results indicated that under conditions of 26 % ethanol, 20 % ammonium sulfate, a solid-liquid ratio of 1 : 30, and extraction for 35 minutes at 50 °C, the polyphenol content reached 61.62 mg/g. The relative contents of 6'-O-caffeoylarbutin, β-arbutin, and chlorogenic acid were 34.45 %, 4.56 %, and 31.06 %, respectively. The DPPH⋅ and ABTS ⁺ ⋅ scavenging rates were above 95 % and 96 %, respectively, and the ferric reducing ability exhibited a significant dose-effect relationship. The inhibition rates of monophenolase and diphenolase activities of tyrosinase were 43.84 % and 35.73 %, respectively. The optimized process for ultrasonic-assisted biphasic aqueous extraction of polyphenols from Vaccinium dunalianum Wight leaves demonstrated significant antioxidant and tyrosinase inhibition activities.
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