| Deep eutectic solventsare considered to be a novel class of green solvent,formed by simply mixing two or more componets with some advandages such as negligible volatility,non-flammability,non-toxicity,biodegradability,and thermal stability.Furthermore,Deep eutectic solvents possess high solubilization power strength for a wide range of compounds,especially poorly water-soluble compounds.All these properties make them of interest for application in health-related areas such as pharmaceuticals,foods,and cosmetics.A series of deep eutectic solvents were prepared and applied for the extraction of different types of alkaloids in this paper.The main research contents are as follows:(1)Preparation and physicochemical properties of deep eutectic solventsFour types of binary deep eutectic solvents,and three types of ternary deep eutectic solvents were prepared for further exploration of the relationship between physicochemical properties and extraction ability in this part.Binary eutectic solvents include choline chloride,betaines,glycerides and organic acids;ternary eutectic solvents include betaines,citric acids and levulinic acids.The binary and ternary deep eutectic solvents were diluted as 75%aqueous solution,for the test of viscosity,pH and polarity.The results showed that the viscosity and pH of the deep eutectic solvent are mainly affected by chemical properties and molar ratio of the constituent components,and the composition varies greatly depending on the composition.The viscosity of binary deep eutectic solvent ranged from 9.6 to 196 mPa?s;The pH of binary deep eutectic solvent ranged from 0.46 to 9.93;the polarity of binary deep eutectic solvent ranged from 47.65to 50.78 kcal/mol.The pH of the ternary eutectic solvents based on betaine fluctuated around 3,the viscosity fluctuated around 20 mPa?s,and the polarity fluctuated around49kcal/mol.CaMaGly(citric acid-malic acid-glycerol),ternary deep eutectic solvents based on citric acid,with pH of 0.61 was considered as the most acidic reagent among all ternary deep eutectic solvent.The viscosity was slightly larger than that of the betaine,and the polarity fluctuated around 47.8 kcal/mol.The pH of levulinic acid ternary deep eutectic solvent is less than 1,and the viscosity changes greatly due to the difference of the constituent groups,and the polarity fluctuated around 48 kcal/mol.(2)Study on the extraction of different types of alkaloids by deep binary eutectic solventsIn order to clarify the rule of extracting different types of alkaloids by binary deep eutectic solvents,HPLC-UV analysis was adoptedforthe detectionof dictamine,rutaecarpine,piperine,sophoridine and oxymatrine.Condition:microwave-assisted extraction method,water content of 25%,ratio of material to liquid 1:20,temperature of90°C and microwave power of 600 W.Result:the extraction yield of dictamine extracted by ChCl-Ox(Choline chloride-Oxalic acid)was 0.262±0.002 mg/g,with an increase of13%compared to 0.231±0.002 mg/g of methanol.Condition:ultrasound-assisted extraction method,water content of 25%,ratio of material to liquid of 1:50,extraction time of 40 min.Result:the extraction yield of rutaecarpine extracted by La-Buta(levulinic acid-1,4-butanediol)was 0.910±0.011 mg/g with an increase of 4.76%compared with 0.8693±0.0027 mg/g of 80%ethanol aqueous solution.The extraction yieldof piperine extracted by ChCl-La(Choline chloride-levulinic)was 33.302±1.925mg/g,with an increase of 3.35%compared to 32.221±1.449 mg/g of absolute ethanol.The extraction yield of sophoridine extracted by Bet-La(betaine-levulinic acid)was1.919±0.047 mg/g with an increase of 44.3%compared with 1.329±0.089 mg/g of methanol.The extraction yield of oxymatrine extracted by La-Buta(levulinic acid-1,4-butanediol)was 14.998±0.048 mg/g with an increase of 20.57%compared with12.341±0.957 mg/g of methanol.(3)Study on ternary eutectic solvent for external preparationIn order to explore the feasibility of the ternary eutectic solvent in the application of cosmetic additives,ternary eutectic solvents were prepared on the basis of the screening of binary eutectic solvent by using dermatological active ingredient dicitamine as an example.The optimal extraction solvent was CaMaGly(citricacid-DL-malic acid-glycerol).Optimal solvent system:molar ratio of 1:2:2,water content of 25%.Optimization of microwave extraction process parameters:The optimal extraction conditions were optimized by single factor test and Box-Behken response surface experiment:extraction time:10.5 min,liquid-to-solid ratio:25,microwave power:590 W,temperature 90°C.The extraction yield is 0.3087mg/g,with an increase of33.30%compared with methanol.(4)Characterization and application of deep eutectic solvent of La-ButaHydrogen-hydrogen correlation between levulinic acid and 1,4-butanediol was confirmed by~1H-NMR and NOESY.The results showed that there was a correlation between the carboxyl group of levulinic acid and the hydroxyl group of 1,4-butanediol.To further improve the extraction capacity of La-Buta,the solvent system was optimized.Optimal solvent system:molar ratio 1:0.5,water content 25%.Optimization of ultrasonic extraction process parameters:The optimal extraction conditions were optimized by single factor test:extraction time 40 min,temperature 55°C,and ratio of material to liquid1:30.Under this condition,the extraction yield of rutaecarpine extracted by La-Buta was1.105±0.009 mg/g,which was increased by 10%compared with 0.911±0.011 mg/g of La-Buta before optimization.To expand the application of La-Buta,ZuojinPills and Wuji Pills containing Tetradium ruticarpum.were selected as sample.The extraction process was carried out under the optimal extraction conditions.The results showed that the extraction yields of rutaecarpine extracted by La-Buta(1:0.5,25%)from ZuojinPills and Wuji Pills were 0.346±0.006 mg/g and 0.140±0.006 mg/g with an increase of 35%and118%compared with traditional organic solvent extraction method.The extraction yield of rutaecarpine extracted from ZuojinPills bymethanol with ultrasound-assisted method was0.256±0.002 mg/g,and the extraction yield of rutaecarpineextracted from Wuji Pills by ethanol with reflux method was 0.064±0.001 mg/g.Therefore,La-Buta is also suitable for the extraction of target components in Chinese patent medicines.Compared with traditional organic solvents,deep eutectic solventsarestable in nature,safe,non-toxic,degradable,andlow cost,can be regareded as promising green solvents. |
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