Lipase-catalyzed Synthesis Of Flurbiprofen L-ascorbic Acid Ester

Flurbiprofen belongs to non-steroidal anti-inflammatory drugs(NSAIDs)and is widely used for the treatment of inflammatory disease.The S-Flurbiprofen can be used as a drug for human connective tissue diseases,the R-Flurbiprofen may help to prevent Alzheimer's disease.However,poor brain delivery of flurbiprofen due to the blood-brain barrier(BBB)has hampered the application of flurbiprofen as neuroprotective agents.Recently,It has been reported that L-ascorbic acid could be used as a carrier to improve its BBB permeation properties and then to promote brain drugs delivery.Therefore,in this thesis,the synthesis of flurbiprofen L-ascorbic acid ester was achieved in nonaqueous organic medium with Novozym 435 lipase as biocatalyst.The main research contents are as follows:The lipase-catalyzed synthesis of flurbiprofen L-ascorbic acid ester in organic solvent system was investigated.It has been found that Novozym435 lipase has the highest catalytic activity in tert-butanol.The structure of the product was characterized by TLC,HPLC,IR and MS.The reaction conditions were optimized by single factor test,and the influence of each factor on the catalytic reaction was discussed.Beneficial effects of esterification reaction and transesterification reaction were compared by reaction conversion.A maximum conversion of 85.36%for esterification reaction was obtained at 60?,200r/min for 144h catalyzed by 55mg N435 lipase in lOmL t-butanol solution with 0.56mmol L-ascorbic acid,2.8mmol flurbiprofen and 0.8g molecular sieve.A maximum conversion of 73.63%for transesterification reaction was obtained at 60?,200r/min for 28h catalyzed by 55mg N435 lipase i n10mL t-butanol solution with 0.56mmol L-ascorbic acid,2.8mmol flurbiprofen methyl ester and 0.8g molecular sieve.The kinetic and thermodynamics of the esterification reaction and transesterification reaction was investigate.The initial rate was greatly influenced by the internal and external diffusion limitations,substrate and product inhibition.Based on the Arrhenius law,the relationship between the initial reaction rate constant and the temperature was determined.In the case where the enzymatic reaction is controlled by the reaction kinetics,the kinetic parameters are as follows:In the esterification reaction,the apparent maximum reaction rate is 0.112mmol/(g·h),the apparent Michaelis-Menten constant is 0.282mol/L,and the activation energy is 2.395kJ/mol.In the transesterification reaction,the apparent Michaelis-Menten constant was 0.143mol/L,the apparent maximum reaction rate was 0.133 mmol/(g·h),and the activation energy Ea was 2.566kJ/mol.The kinetic and thermodynamic parameters of the esterification and transesterification were compared.The results indicated that Novozym435 lipase has higher affinity for flurbiprofen methyl ester and lower affinity with flurbiprofen.Although the rate of esterification is slower than that of transesterification,if a choice is at all available,from the standpoint of productivity and the amount of steps required,lipase-catalyzed esterification has been judged to be superior for the synthesis of flurbiprofen L-ascorbic acid ester.