Identification of carbohydrate isomers in flavonoid glycosides after hydrolysis by hydrophilic interaction chromatography

A method for carbohydrate isomers (saccharide units) identification in flavonoid glycosides after hydrolysis by an HPLC system with two detectors (diode array UV-VIS detector and evaporative light scattering detector) was set up in this work. Experimental procedure was optimized with two types of model glycosides, namely rutin and hesperidin. The model glycosides were hydrolyzed to saccharide units and aglycone parts; the aglycone was characterized by its UV-VIS spectrum and the saccharide unit was identified by its retention time and elution profile (anomeric signals). Acidic and enzymatic hydrolyses were compared in the first step of the method; in acidic hydrolysis, trifluoracetic acid was used, while glucosidase, galactosidase, and hesperidinase were used in enzymatic hydrolysis. A complete enzymatic hydrolysis was achieved with hesperidin and neohesperidin, but not with 3-O-glycosides. The method was applied for the identification of a glycone from a glycoside isolated from Polygonum lapathifolium (Polygonaceae sp.).