Ultrasonic extraction optimization of L. macranthoides polysaccharides and its physicochemical properties

The dried flower buds of L. macranthoides, belong to the item Shan Yin Hua, are widely used as raw materials for pharmaceutical, food additive, healthy food and cosmetic industry in China. To optimize the effects of the ultrasonic-assisted extraction (UAE) processing parameters on the yield of L. macranthoides polysaccharides (LMPs), a response surface methodology with a central composite rotatable design was employed. Four independent variables were investigated: ultrasonic power (X1), temperature (X2), time (X3), and the ratio of water volume to raw material weight (W/M ratio, X4). The experimental data were fitted to a quadratic polynomial equation using multiple regression analysis and also examined using appropriate statistical methods. The optimum conditions were: X1, 113.6 W; X2, 71.5°C; X3, 54.7 min; and X4, 30.7 mL/g. Under the optimal conditions, the extraction yield of LMPs was (4.81±0.12)%, which is in close agreement with the value predicted by the statistical model. Further, LMPs were characterized by FT-IR, XRD, TGA/DSC and NMR. In vitro experiments indicated that LMPs had strong scavenging capacities towards the DPPH, hydroxyl and superoxide radicals. Overall, LMPs may have potential applications in the medical and food industries.