Geographic variation in water-soluble polysaccharide content and antioxidant activities of Cyclocarya paliurus leaves

Cyclocarya paliurus is a multiple function woody plant. To reveal the geographic variation pattern of water-soluble polysaccharide content in the leaves and its antioxidant activities, the leaf samples were collected and analyzed from 29 geographic locations of natural C. paliurus populations throughout the distribution areas. Significant differences in the water-soluble polysaccharide content and antioxidant activities were detected among the C. paliurus populations. The water-soluble polysaccharide content in the leaves of different populations ranged from 18.72 to 53.59 mg g−1, and the 29 populations could be classified into four distinct groups. There was a significant correlation between the water-soluble polysaccharide content and scavenging activities for the leaves of C. paliurus (p < 0.01). Multivariable nonlinear regression analysis showed that no clear geographic variation pattern in water-soluble polysaccharide content was detected for the leaves sampled. However, Pearson correlation analysis indicated that the average annual precipitation was significantly correlated to the leaf polysaccharide content (r = 0.428, p < 0.05), and its scavenging activities on DPPH radical (r = 0.386, p < 0.05) and superoxide radical (r = 0.446, p < 0.05). Based on the water-soluble polysaccharide contents of all populations studied, leaves from the Wufeng, Muchuan and Liping were recommended for food and medical use in the future. Results from this study not only demonstrated that the polysaccharide content in C. paliurus leaves could be used either as nutriments, food additives, or antioxidant supplements, but also provided a basis for optimizing cultivation strategies of C. paliurus plantations.