Optimization of polysaccharides extraction from seeds of Pharbitis nil and its anti-oxidant activity

In the present study, polysaccharides were extracted from Pharbitis nil seeds (PNSs) by ultrasonic extraction method for the first time. Response surface methodology with Box-Behnken design was used to optimize the extraction process of PNS polysaccharides (PNSPs). Highest PNSPs yield 6.01 ± 0.15% that agreed closely with the predicted yield 5.99% were obtained under the optimal conditions as follows: ratio of water to raw material 6.5 mL/g, extraction temperature 49.0 °C, ultrasonic power 61.6 W, and extraction time 32.6 min. Preliminary characterization indicated that the sugar, uronic acid and protein contents of the product were 83.6 ± 1.61, 21.8 ± 1.25 and 16.4 ± 0.88% (w/w), respectively. FT-IR analysis revealed the general characteristic absorption peaks of polysaccharides. Besides, PNSPs showed a remarkable antioxidant activity in vitro in a dose-dependent manner. These may provide theoretical basis for further system research and rational development and utilization of PNS resources.