Chromatographic determination of polysaccharides in Lycium barbarum Linnaeus

Polysaccharides in Lycium barbarum Linnaeus have been shown to be effective in preventing cancer. The objectives of this study were to develop an appropriate method for molecular weight determination of polysaccharides in L. barbarum. The most suitable analytical condition was: a volume-ratio of L. barbarum sample to deionized water at 1:10, followed by shaking in a 100 °C water bath for 30 min, concentrating to 50 mL and adding 250 mL of 95% ethanol for precipitation at −20 °C for 8 h, hydrolysing protein with 2.5 U/mL of proteinase at pH 8 and 60 °C for 4 h and separating polysaccharide into five fractions by high-performance size exclusion chromatography (HPSEC) with the molecular weight of two major fractions being 79,250 and 24,468 Da. Analysis of monosaccharides by gas chromatography (GC) indicated the presence of rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio at 0.3:2.7:0.3:0.2:2.7:0.9, respectively.