Quality evaluation of Lycium barbarum (wolfberry) from different regions in China based on polysaccharide structure, yield and bioactivities

BACKGROUND: Lycium barbarum (wolfberry) has been widely cultivated in China, particularly in northwest regions. However, the fruit size and taste of L. barbarum from different habitats are quite different. Traditionally, only the fruit of L. barbarum produced in Ningxia province is recorded as an authentic herb, although the detailed mechanism responsible for this remains obscure. Polysaccharides are considered major active ingredients in L. barbarum which is crucial for its quality evaluation. METHODS: In this study, we assessed the yield, monosaccharide composition, molecular weight, and conformation of L. barbarum polysaccharides (LBPs) collected from different regions of China. The antioxidant and immune activities of LBPs were also determined as its quality indicator. RESULTS: Our results showed that the similarity values of monosaccharide composition were larger than 0.926, and the Mw of the two fractions (peaks 1–2) in LBPs were ranging from 1.36 × 10(6) to 2.01 × 10(6) (peak 1), and 6.85 × 10(4) to 10.30 × 10(4) (peak 2) which indicated that the structure of LBPs were similar. In addition, results showed that there was no significant difference in antioxidant and immune activities of nine LBPs from different regions. However, the yield of LBPs from Qinghai Province (low atmospheric temperature, high altitude) was significantly lower (p < 0.05) than those collected from Xinjiang and Ningxia province. CONCLUSIONS: These data suggested that the L. barbarum produced in Ningxia and Xinjiang maybe more suitable as materials for medicines and functional foods. This study also provides a reference for improving the quality control standard of LBPs.