Optimization for the Extraction of Polysaccharide from Walnut (Juglans regia L.) Leaves: Antioxidant Activities in Vitro

Cellulase-assisted extraction of Walnut Leaf Polysaccharide (WLP) was studied. Single factor test and response surface design were employed to optimize the technological conditions. The consequences indicated that the highest WLP yield of 5.21% was achieved with raw material ratio of 50 mL/g, cellulase dose of 41488.52 U/g, enzymolysis pH of 5.88, enzymolysis time of 29.74 min and enzymolysis temperature of 52.07°C. Moreover, in vitro antioxidant assays revealed that WLP has significant eliminating capability against 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl free radicals in a dose-dependent manner and exhibited a strong reducing power. These results suggest that WLP could be developed as a promising natural antioxidant agent in the pharmaceutical and functional food industries.