Abstract: This study aimed to optimize the ultrasonic-assisted cellulase-based extraction of polyphenols from pomegranate fruitlets. The factors with a significant influence on the yield of polyphenols were selected using a combination of one-factor-at-a-time method and Plackett-Burman (PB) design for the optimization experiments which were carried out using Box-Behnken design combined with response surface methodology. The anti-α-glucosidase activity and kinetics?characteristics of the polyphenols were determined by using α-glucosidase inhibition model in vitro. Results showed that under the following conditions: ultrasonic power, 318 W; enzyme dosage, 23 U/mL; hydrolysis temperature, 46 ℃; and hydrolysis time, 2.7 h, the average yield of polyphenols from pomegranate fruitlets was 11.65%, close to the predicted value. The polyphenols had a strong anti-α-glucosidase activity. The percentage inhibition of α-glucosidase by the polyphenols at a concentration of 1.20 mg/mL reached 70.3% and the half inhibitory concentration (IC50) was 0.747 mg/mL. There was a positive relationship between the anti-α-glucosidase activity and polyphenol concentration in the range of 0.24–1.20 mg/mL. The inhibition was reversible and non-competitive.

Key words: pomegranate fruitlet, polyphenol, ultrasonic-assisted extraction, cellulose, anti-α-glucosidase activity