The structures and biological functions of polysaccharides from traditional Chinese herbs

Most of traditional Chinese medicine substances come from herbal plants. The medicinal quality of herbal plants varies with the locations of cultivation, the parts of the herb collected, the season of the herb collected, and the herb processing method. Polysaccharides are major components of the herb plants and their biosynthesis is partly controlled by the genes but mostly influenced by the availability of the nutrition and determined by the various environmental factors. In recent decades, polysaccharides isolated from different kinds of Chinese herbs have received much attention due to their important biological activities, such as anti-tumor, anti-oxidant, anti-diabetic, radiation protecting, antiviral, hypolipidemic, and immunomodulatory activities. Interestingly, different batches of the same herb can obtain different polysaccharide fractions with subtle differences in molecular weight, monosaccharide compositions, glycosidic linkages, and biological functions. Even with these variations, a large number of bioactive polysaccharides from different kinds of traditional Chinese herbs have been purified, characterized, and reported. This review provides a comprehensive summary of the latest polysaccharide extraction methods and the strategies used for monosaccharide compositional analysis plus polysaccharide structural characterization. Most importantly, the reported chemical characteristics and biological activities of the polysaccharides from the famous traditional Chinese herbs including Astragalus membranaceus, Ginseng, Lycium barbarum, Angelica sinensis, Cordyceps sinensis, and Ophiopogon japonicus will be reviewed and discussed. The published studies provide evidence that polysaccharides from traditional Chinese herbs play an important role in their medical applications, which forms the basis for future research, development, and application of these polysaccharides as functional foods and therapeutics in modern medicine.