Extraction and antioxidant activities of polysaccharides from Gynostemma pentaphyllum makino

Crude polysaccharides (GPMPP) and purified polysaccharides (GPMP) were prepared from G. pentaphyllum Makino. An orthogonal design [L₉(3 ⁴)] was applied to optimize the effects of processing parameters of GPMPP on the yield of polysaccharides. Based on the orthogonal test, optimum conditions were determined. The antioxidant activities of GPMPP and GPMP were investigated and evaluated using various in vitro assays. Among these assays, GPMP showed the best ability on the scavenging of hydroxyl radicals, while GPMPP showed the best ability on the inhibition of lipid spontaneous peroxidation, which was higher than that of ascorbic acid. Furthermore, GPMPP showed higher activity of reducing power and scavenging ability on 1,1-diphenyl-2- picryhydrazyl (DPPH) radical but lower activity of inhibitory ability on lipid peroxidation induced by Fe²⁺-H₂O₂ than that of GPMP in the concentration of 0.1-5.0 mg/mL. The polysaccharides from G. pentaphyllum Makino should be explored as a potential antioxidant.