Optimization of extraction process of polysaccharides from mulberry leaves and determination of the antioxidant activity in vitro

ObjectiveThis study aimed to optimize the extraction process of polysaccharides from mulberry leaves using deep eutectic slovents (DES) and assess their antioxidant properties.MethodsAutumn mulberry leaf powder was used as the raw material, and ultrasonic-assisted extraction with complex enzymes facilitated the process. The composition of DES and the extraction conditions were optimized using Box-Behnken response surface methodology, with polysaccharide yield as the primary indicator. Antioxidant activity was evaluated by measuring the scavenging abilities of against DPPH radicals, ABTS+ radicals, and hydroxyl radicals.ResultsThe optimal extraction conditions were as follows: a choline chloride/malic acid molar ratio of 1∶4, water content 44%, liquid-solid ratio of 40∶1 （mL/g）, enzyme dosage of 3%, ultrasonic power of 350 W, and ultrasonic time 40 min. Under these conditions，the yield of mulberry leaf polysaccharides was （10.20±0.05）%. The polysaccharides demonstrated significan antioxidant activity, with a DPPH radical scavenging rate of 67.46% at 0.08 mg/mL and ABTS+ and hydroxyl radical scavenging rates of 87.19% and 93.44%, respectively, at 0.8 mg/mL.ConclusionThe ultrasonic-complex enzyme-assisted DES extraction method proved efficient, yielding high amounts of polysaccharides with strong antioxidant properties. These findings support the potential use of mulberry leaf polysaccharides in food and health-related applications.