Identification of carbohydrate in Polygonatum sibiricum: fructo-oligosaccharide was a major component

Polygonatum sibiricum, famous for its physiological activities, is a popular Chinese food and a traditional Chinese herb containing many carbohydrates as the main component. However, except for most reported polysaccharides, other detailed compositions of carbohydrates are still not clear. To verify the controversial existence of starch and investigate other components, especially oligosaccharides, we used iodine-potassium iodide colorimetric detection and enzymatic hydrolysis to determine starch. Then, oligosaccharides were analyzed by thin-layer chromatography, gel permeation chromatography, high-performance anion exchange chromatography with pulsed amperometric detection, and hydrophilic interaction chromatography-electrospray tandem mass spectrometry. The results showed that the rhizome of P. sibiricum lacked starch, and fructo-oligosaccharides were the main component, accounting for approximately 28.95%. Oligosaccharides with degrees of polymerization above 10 were the most abundant components. This study clearly illustrated the unknown carbohydrate components of the Polygonatum rhizome, promoting its functional value with new evidence.