Extraction And Purification Of Flavonoids From Ginkgo Biloba Leaves By Deep Eutectic Solvents

Ginkgo biloba leaves are rich in flavonoids.How to efficiently extract and isolate ginkgo flavonoids is one of the research hotspots.This article aims at the problems of low extraction rate,cumbersome process,and serious volatilization loss of organic solvent in the extraction of flavonoids from ginkgo biloba leaves by using 60%ethanol.Developed a method for extracting flavonoids from ginkgo biloba leaves with ultrasound-assisted deep eutectic solvent,combined with macroporous resin adsorption to purify flavonoids from deep eutectic solvent extracts to prepare gingko leaf extracts.The summaries of this paper are as follows:1.Three deep eutectic solvents:choline chloride/ethylene glycol(1:4),choline chloride/1,4-butanediol(1:4),and choline chloride/triethylene glycol(1:4)were prepared by heating method.The solubility of rutin(the most important flavonoid compound in ginkgo leaves)in these three deep eutectic solvents was measured at 30℃ to 70℃ under atmospheric pressure,and it was found that rutin has good solubility in the above three deep eutectic solvents.The van’t Hoff model,Apelblat model and λh model were used to fit the solubility data,the AARD of the choline chloride/ethylene glycol(1:4)and choline chloride/triethylene glycol(1:4)are from 1%to 3%,and the AARD of choline chloride/1,4-butanediol(1:4)are from 3%to 9%.The fitting results of the Apelblat equation are the best among the three models.2.The extraction conditions of of ultrasound-assisted deep eutectic solvent extraction of flavonoids from Ginkgo biloba leaves were studied.The choline chloride/ethylene glycol molar ratio of 1:4 and water content of 20 vol%was selected as extractant.The ultrasonic extraction temperature,extraction time,and liquid-solid ratio were improved by single-factor tests and response surface optimization methods.The optimal extraction conditions were:extraction time for 39 min,extraction temperature for 65℃,and liquid-solid ratio for 18 mL/g.Under the optimal condition,the extraction field is 17.42 mg/g,and the extraction rate can reach 96.88%,better than the ethanol extraction.The viscosity,density and polarity parameters of deep eutectic solvents were measured at 25℃.the high extraction field was systematically analyzed from the viscosity,polarity and intermolecular hydrogen bonding of deep eutectic solvents.It provides a process route for industrial production with high extraction rate,relatively simple process flow,and effective avoidance of volatilization of extractant.3.The macroporous resin is used to adsorb and separate the flavonoids from the extract,and analysis of the adsorption and desorption effects of AB-8,D140,DM130,D101,NKA-9 and polyamide resins on flavonoids were studied through static adsorption experiments,and screened out that AB-8 macroporous resin has the best adsorption effect on flavonoids.The experimental conditions were further determined through dynamic adsorption experiments:with the 10 g dry weight AB-8 resin,the sample volume is 25 mL,the sample flow rate is 1 mL/min,two gradient elutions were performed using 20%ethanol 30mL and 80%ethanol 50 mL,respectively.After drying,the content of total flavonoids in the product was 28.56%,the yield was 84.87%.The flavonoid yield of this purification method is higher than that of polyamide resin purification and ultrafiltration,which provides technical support and theoretical basis for obtaining higher purity flavonoids from Ginkgo biloba leaves by using ultrasound-assisted deep eutectic solvent method.