[Application of 13CNMR to structural identification of the flavonoid glycosides]

13CNMR has become an important method for the structural determination of organic natural products. It is especially useful for identifying the structure of glycosides. This paper deals with the application of 13CNMR to the identification of the flavonoid glycosides isolated from the roots of Glycyrrhiza eurycarpa P.C. Li. The discrimination of chemical shifts of C-2, C-3 and C-4 (carbonyl) signals for different types of flavonoids, such as isoflavones, flavanones, chalcones, flavones and pterocarpans is discussed. The application of 13CNMR in the determination of structure and configuration of sugar moieties, for determination of glycosidic linkage, and for confirmation of the position of glycosidation and linkage between two sugar moieties are also discussed briefly.