| Flavonol glycosides and terpene trilactones from Ginkgo biloba leaves have a unique effect on cardiovascular diseases.In recent years,with the expansion of Ginkgo cultivation,the Ginkgo fruit resources have not been utilized effectively.According to incomplete statistics,nearly 40 thousand tons of Ginkgo biloba exocarp and 5 thousand tons of Ginkgo biloba seeds were discarded every year,which caused a great pollution at the same time.In this paper,a series of chemical basic researches of bioactive compositions in Ginkgo biloba seeds and exocarp were conducted,in order to make the Ginkgo resources a comprehensive utilization.The main research contents are as follows:(1)Twenty kinds of chemical compositions of Ginkgo biloba seeds and exocarp were analyzed,including nutrients,active and toxic compositions.Among them,the nutrients consist of free amino acid,water-soluble protein,crude fat,polysaccharide,starch and trace elements.The contents of them in Ginkgo biloba seeds were 1.80%,1.52%,4.80%,2.80%,68.09%and 0.84%respectively,while in Ginkgo biloba exocarp were 0.79%,1.20%,15.97%,3.16%,14.09%and 0.44%respectively.The active compositions consist of flavonol glycosides,terpene trilactones and bioflavonoids.The contents of them in Ginkgo biloba seeds were 0.17 mg/g,0.07mg/g and 0.01 mg/g respectively,while in Ginkgo biloba exocarp were 0.67 mg/g,0.19 mg/g and 2.31 mg/g respectively.As for toxic compositions,cyanogenic glycosides,ginkgolic acids and 4'-O-methylpyridoxine(MPN)were analysed,and the contents of them in Ginkgo biloba seeds were 0.21?g/g,0.54 mg/g and 60.38?g/g respectively.In Ginkgo biloba exocarp,only cyanogenic glycosides and ginkgolic acids were detected with the contents of 0.33?g/g and 71.80 mg/g,while MPN content was below the detection limit of 4.95?g/g.(2)In the analysis of polysaccharide in Ginkgo biloba seeds and exocarp,the molecular weight and distribution,molecular morphology,monosaccharide composition and content were studied by methods of gel permeation chromatography(GPC),dynamic light scattering(DLS)and high performance liquid chromatography with evaporative light scattering detector(HPLC-ELSD).The molecular weight of polysaccharide in Ginkgo biloba seeds(GBSP)was 1.416×10~6,with a polydispersity coefficient of 5.60,and the hydrodynamic radius was 13.93 nm.After hydrolyzed under the optimal conditions,GBSP was made up of fructose and glucose with the molar ratio of 1:23.82.The polysaccharide content was redetermined by a modified phenol-sulfuric acid method based on the the monosaccharide composition of polysaccharide with the result of 2.81%.Polysaccharide in Ginkgo biloba exocarp(GBEP)with molecular weight 9.154×10~5was composed of rhamnose,xylose,arabinose,fructose,mannose,glucose and galactose with a molar ratio of1.99:1.86:19.98:1:2.19:2.57:2.22,the hydrodynamic radius was 14.95 nm and the content was 3.55%redetermined by modified phenol-sulfuric acid method.(3)A HPLC method for the determination of MPN was optimized,and the effects of different heat treatment conditions including methodes,temperature and time on the contents of ginkgolic aicd,MPN and cyanogenic compounds were studied as well.The results showed that heat treatment with microwave has the best effect,the content of cyanogenic glycosides was below the detection limit,the contents of ginkgolic acid and MPN decreased to 0.05 mg/g and 7.05?g/g respectively.An optimal heat treatment conditions were established,which was heated at 100?for 15min,and the ginkgolic acids content was degraded to 0.23 mg/g,MPN reduced to the lowest content of 13.17?g/g,with a degradation rate of 78.19%. |
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