Extraction, characterization and antioxidant activities of polysaccharides of Chuanminshen violaceum.

A single factor experiment and Box-Behnken design were applied to optimize the microwave-assisted extraction (MAE) of Chuanminshen violaceum polysaccharides (CVPs). The CVPs yield was 34.59 ± 0.51%, which was in accordance with the predicted value of 35.54%, under the following optimum conditions: microwave power of 466 W, extraction temperature of 64.5 °C, extraction time of 15 min, and water-raw material ratio of 40 mL/g. Two CVPs fractions (CVPs-I and CVPs-II) were obtained via stepwise ethanol precipitation. CVPs-II was further purified using DEAE cellulose-52 chromatography to obtain the major fraction of CVPs-IIa. Fourier transform infrared spectroscopy (FTIR) and GC-MS analysis revealed that crude CVPs, CVPs-I, and CVPs-II were neutral polysaccharides and were mainly composed of glucose and galactose. The molecular weights of CVPs-I and CVPs-IIa were 233.69 and 11.02 kDa, respectively. Furthermore, all samples exhibited certain antioxidant activity or reducing power to scavenge the DPPH and ABTS radicals, among which CVPs-II was the strongest. In conclusion, MAE is an efficient method for extracting CVPs of C. violaceum, and this plant root has the potential to be explored as a source of natural antioxidants.