Biosynthesis Of Isoquercitrin With Combination Use Of Ionic Liquid As Reaction Medium And Microwave As Heat Mode

Isoquercitrin has many pharmacological activities, including antioxidant,antidepressant and antihypertensive, which got a lot of attention. The enzymatic hydrolysisof rutin was considered as the most effective method to prepare isoquercitrin. However,there were many restrictive factors in the procedure of transformation of rutin toisoquercitrin, such as substrate concentration, reaction rate and purification. In this paper,the system of selective enzymatic biotransformation of rutin to isoquercitrin using an ionicliquid as a co-solvent and microwave as heat mode was established. In the new catalyticsystem, the conversion of rutin was99.65%, the yield of isoquercitrin was99.27%.Moreover, the reaction rate was increased by120-fold. And the extraction efficiency was68.26%, the concrete results were as following:A new catalytic system containing an ionic liquid as a cosolvent for the production wasestablishsed. And the process conditions of catalytic system of [Bmim][BF4]-buffer and[Emim][BF4]-buffer were optimized. The optimal conditions of [Bmim][BF4]-buffer were asfollowed: pH9.0, ionic liquid content10%(V/V), substrate concentration0.78g/L andenzyme concentration0.05g/mL, respectively. Compared with catalytic system of buffer,the isoquercitrin yield, substrate concentration and apparent kinic parameters were increasedby2.33-fold,8.75-fold and29.39-fold, respectively. Moreover, the reaction time wasreduced by0.67-fold. The optimal conditions of [Emim][BF4]-buffer were as followed:pH5.0, ionic liquid content10%(V/V), substrate concentration0.71g/L and enzymeconcentration0.01g/mL, respectively. Compared with catalytic system of buffer, theisoquercitrin yield, substrate concentration and apparent kinic parameters were increased by1.65-fold,7.86-fold and21.80-fold, respectively, while the reaction time were reduced by0.33-fold. Moreover, the isoquercitrin yield of catalytic system of [Bmim][BF4]-buffer wasincreased by8.60%(99.27±0.55%) through the optimization of response surfacemethodlogy.Based on the establishment of a new catalytic system containing an ionic liquid as acosolvent, effects of microwave on selective enzymatic biostransformation of rutin toisoquercitrin were investigated. With the conditions of temperature30℃, time5min, pH9.0,the isoquercitrin of [Bmim][BF4]-buffer was84.74%. Compared with the traditional heat,the reaction rate was increased by120-fold, and this process had lower cost. Choosing separation factor and extraction efficient as indicators, the glyceryl triacetatewas selected as the suitable extracting agent to separate the isoquercitrin from the reactionmixture. The process conditions of extraction were optimized by one-factor experiment. Theoptimum conditions were as followed: pH6.0, phase ratio1.2, extract temperature30℃, andextract time30min, respectively. With those conditions the extract rate of isoquercitrin was68.26%, while the theoretical extraction stage was four.In this paper, the system of selective enzymatic biotransformation of rutin toisoquercitrin using an ionic liquid as a co-solvent and microwave as heat mode was firstestablished. Furthermore, the conversion, yield and reaction rate were increased. And theextraction system was established. In brief, the establishment of new system provides a newidea and approach for the biotransformation of natural product and purification.