Simultaneous determination of molecular weights and contents of water-soluble polysaccharides and their fractions from Lycium barbarum collected in China

Abstract

Molecular weights and contents of water-soluble polysaccharides and their fractions in fifty batches of fruits of Lycium barbarum (wolfberry) collected from different regions of China, including Qinghai, Ningxia, Inner Mongolia, Xinjiang, and Gansu, were simultaneously determined using high performance size exclusion chromatography (HPSEC) coupled with multi angle laser light scattering (MALLS) and refractive index detector (RID) with the refractive index increment (dn/dc). Results showed that HPSEC chromatograms and molecular weight distributions of polysaccharides in L. barbarum collected from different regions of China were similar. Furthermore, the average contents of each polysaccharide fraction (peaks 1, 2, and 3) in crude polysaccharides of L. barbarum collected from Ningxia were similar with those of Inner Mongolia, Xinjiang, and Gansu, respectively. However, significant difference was found between polysaccharides in L. barbarum collected from Ningxia and Qinghai. Moreover, the average amounts of total polysaccharide fractions (peaks 1, 2, and 3) in the raw material of L. barbarum collected from Ningxia were significantly higher than that of Qinghai. These results may contribute to the rational usage of L. barbarum produced in China, and are beneficial for the improvement of their quality control. Results suggested that HPSEC-MALLS-RID with the dn/dc method could be used as a routine method for the quality evaluation of polysaccharides from natural resources and their products.

Keywords: High performance size exclusion chromatography; Lycium barbarum; Molecular weight; Multi angle laser light scattering; Polysaccharide; Refractive index increment.