Optimization of ultrasonic-assisted extraction of polysaccharide from fig leaves and its antioxidant activity

Using fig leaves as raw materials, extraction time, extraction temperature, solid to liquid ratio, and ultrasonic power were selected as influencing factors to analyze their effects on the yield of fig leaf polysaccharides (FLPS). The response surface methodology was carried out to optimize the extraction parameters. Furthermore, the antioxidant activity of FLPS was studied. The experimental results show that the optimum extraction conditions are: extraction time of 121 min, extraction temperature of 72 °C, solid to liquid ratio of 1: 48 g/mL, and ultrasonic power of 250 W. In this case, the measured extraction rate of FLPS was 11.78%, which was in agreement with the theoretical extraction rate. Response surface analysis was used to accurately and reliably optimize the extraction of FLPS. The results of the antioxidant activity showed that FLPS had antioxidant activity. It has the best scavenging effect on ABTS radical cation (ABTS+·), and it also has ability to scavenge DPPH radical (DPPH·), hydroxyl radical (·OH), superoxide anion radical (·O2-), and ferric reducing activity. This study laid a theoretical foundation for the further development and application of FLPS.