Preparation and Quality Control of Extract "Ginkgo Zongtongzhi"
|Keywords||Leaves of Ginkgo biloba total flavonol glycosides terpene lactones extract "Ginkgo Zongtongzhi" preparative method quality control|
Objective: The quality control of Ginkgo extract and related preparations has become a major concern for a long time. Considering the different types of disease in clinic require the different preparations which may contain different ratios of active ingredients, the present Ginkgo products which have only one quality control standard (total flavonoid glycosides content≥24%, terpene lactone content≥6%) cann’t meet the different needs of the market, therefore, the development of more Ginkgo extracts for different clinical needs has certain practical significance. The objective of this study is to prepare a Ginkgo extract with the total flavonoid and terpene lactone content in excess of 50% and set up the methods for its quality control.Method:Based on the existing extraction methods, this study developed an orthogonal test to select the appropriate extraction parameters for Ginkgo biloba, and investigated systematically the purification procedure of macroporous resin column chromatography, the isolation procedure of silica gel flash column chromatography to seperate terpene lactone and total flavonol glycosides, and the purification procedure of polyamide column chromatography to purify flavonoids. In addition, above established techniques had been verified and improved according to the industrial requirements. HPLC quantitative method and fingerprint method of active ingredients had been applied to the quality control of the product.Results:This study established a method for the preparation of target extract "Ginkgo Zongtongzhi", i.e, 1kg Ginkgo biloba leaf was crushed and refluxed 3 times with 8 times amount of 50% ethanol (1 hour each time). The extracts were filtered and the filtrate was concentrated to an appropriate concentration. The supernant was subjected on AB-8 macroporous resin column and eluted with 4 column volumes of 10% ethanol, then eluted with 8 column volumes of 70% ethanol. The eluates washed with 70% ethanol were combined and concentrated into a thick extract. The extract was run on flash silica gel column chromatography and eluted with 3 column volumes of ethyl acetate and 4 column volumes of acetone sequentially. The eluate of ethyl acetate was concentrated and dissolved in water then extracted three times with equal amount of cyclohexane. The water fraction was concentrated by vacuum evaporation to yield extract A. The eluate of acetone was dissolved with water and filtered. The filtrate was subjected on polyamide column and eluted with 3 column volumes of water and 4 column volumes of 70% ethanol, sequentially. The eluate of 70% ethanol was concentrated and combined with A then dried by microwave to afford the extract "Ginkgo Zongtongzhi". In addition, this study established an HPLC method for the quality control of extract "Ginkgo Zongtongzhi", i.e, the total content of flavanoids and terpene lactones was in excess of 50%, of which the total content of flavonol glycosides≥38%, terpene lactone content≥12%, ginkgolic acid content≤10ppm. Furthermore, the HPLC fingerprint control method was utilized to ensure the product quality.Conclusion:The method for the preparation of extract "Ginkgo Zongtongzhi" established in this study is stable, reasonable, feasible, energy saving, high efficient and suitable for industrial production. The product has a high content of active ingredients, low level of toxic ingredients, and a reliable quality. The quality control method established in this study is specific and sensitive. Quantitative determination of major active components combined with fingerprint method is an effective tool for the quality control of the product.