Determination Of Free Monosaccharides In Ginkgo Biloba Leaves

Ginkgo biloba extract is one of the world’s most valuable natural botanical extracts,with functions such as promoting blood circulation,eliminating congestion,lowering turbidity and lipids,sedation,analgesia and antioxidant.At present,domestic and foreign research on Ginkgo biloba extract and other preparations mainly focuses on the content of flavonoids,flavonols,lactones and ginkgolic acid in Ginkgo biloba,but there is less research on other components in Ginkgo biloba such as sugar compounds,and their quality control lacks comprehensiveness and accuracy.Some studies have shown that the pharmacological activity of herbal medicines is closely related to their sugar content.As sugars have a variety of biological activities（anti-cancer,anti-inflammatory,etc.）have become a hot research topic in recent years.Therefore,the analysis of sugars in Ginkgo biloba is of great significance for exploring the structural identification,conformational relationships and comprehensive utilization of this valuable plant resource.In this paper,the free xylose,glucose,mannose,fucose,rhamnose and galactose in Ginkgo biloba were determined by liquid chromatography,ion chromatography and high performance capillary electrophoresis,respectively,to provide data and methodological support for the determination of glycans in Ginkgo biloba.In this paper,the flow rate and mobile phase ratio were firstly optimized on an NH2P-50 column using a high performance liquid chromatography with an oscillometric refractive index detector.The best separation was achieved with the mobile phase of acetonitrile-water（70:30）,column temperature of 30℃and flow rate of 1.0mL·min^-1,but the baseline separation of the above six monosaccharides was still not achieved.New assays are therefore needed for the purpose of separating monosaccharides.Then,the ion chromatography electrochemical amperometric detector was applied to the Carbo Pac PA20 anion-exchange column without derivatization,and the separation conditions were optimized for the concentration of the Na OH eluent,and the final determination of the monosaccharides was achieved under the gradient elution of12.5 mmol·L^-1Na OH eluent.The recoveries of monosaccharides in Ginkgo biloba were in the range of 83.40%to 116.30%.Secondly,the effects of the number of extractions,buffer concentration and pH of the derivatives on the separation of the six monosaccharides were investigated by single-factor experiments using high performance capillary zone electrophoresis and UV detector,and the optimal process conditions were obtained as follows:the number of extractions was 3,the concentration of borate buffer was 30 mmol·L^-1,pH=9.5 and the RSD of the six monosaccharides was less than 5%.The recoveries ranged from 80.64%to 114.67%for the determination of the six monosaccharides in Ginkgo biloba.In addition,a new amine derivatizer,p-anisidine,was used for the simultaneous separation of uridine diphosphate galactose and uridine diphosphate glucose using capillary zone electrophoresis with UV detection,and the heating time and temperature,buffer concentration and separation voltage of the derivatization were investigated by single-factor experiments for optimal separation results.The best separation was achieved at a buffer concentration of 50 mmol·L^-1,pH 9.0 and a separation voltage of 20 kV.The separation of the two monosaccharide isomers was achieved within 15 min with an RSD of less than 5%.