Ultrasonic Microwave Assisted Extraction, Chemical Characterization and Antioxidant Activity of Polysaccharides from Fig Leaves

Abstract

This study employed ultrasonic-microwave-assisted extraction (UMAE) to isolate water-soluble polysaccharides from fig (Ficus carica L.) leaves (FLPs). Polysaccharide yield was used as the primary index to evaluate extraction efficiency. The effects of material-liquid ratio, microwave power, extraction temperature, and extraction time on polysaccharide yield were systematically investigated through single-factor experiments, followed by response surface methodology optimization. Structural characterization and antioxidant activity of FLPs were subsequently evaluated. The optimal UMAE conditions were determined as: material-liquid ratio 1:51 (g/mL), microwave power 714 W combined with ultrasonic power 50 W, extraction temperature 63°C, and extraction time 18 min. Under these conditions, FLPs exhibited a molecular weight of 2.56×10⁵ Da and consisted of rhamnose, arabinose, xylose, glucose, and galactose in a molar ratio of 9.97:7.86:0.78:25.61:5.05, respectively. FLPs demonstrated potent antioxidant activity: at 0.6 mg/mL concentration, the scavenging rates for superoxide anion, DPPH, and hydroxyl radicals were 73.21±1.34%, 76.77±1.31%, and 61.90±1.22%, respectively. These findings indicate that FLPs possess significant potential as a natural antioxidant and functional food ingredient. The optimized UMAE method provides an efficient approach for extracting bioactive polysaccharides from fig leaves, supporting their application in the food industry.