Study On Resolution Of ?-aromatic Acid Enantiomers By Enzymatic Hydrolysis

?-aromatic acid chiral drugs are an important class of non-steroidal anti-inflammatory drugs(NSAIDs).Pharmacological studies have shown that only(S)-enantiomers have pharmacological activity,while(R)-enantiomers has almost no pharmacological activity or different activity.Taking single enantiomer can improve the efficacy and reduce the side effects.At present,most of these drugs are sold in a racemic form.Therefore,chiral resolution of?-aromatic acid has important scientific significance and practical application value.In this paper,the resolution of three enantiomers of 2-phenylbutyric acid,2-(3-chlorophenyl)propionic acid and2-phenylpropionic acid by enzymatic hydrolysis were studied.The main work and results of this paper as follows:1.An efficient reactive system was established to resolution of 2-phenylbutyric acid by enzymatic hydrolysis.Lipase CALA from Canadian antarctica was screened as the optimal lipase and hexyl 2-phenylbutyrate was the best substrate.The addition of hydroxyethyl-?-cyclodextrin(HE-?-CD)to the system increased the conversion by 1.5 times.The effects of important factors were investigated,including temperature,pH,concentrations of enzyme,substrate and HE-?-CD as well as reaction time.The optimal conditions were obtained through response surface methodology,which including 30 mmol/L substrate,50 mg/mL lipase,60 mmol/L HE-?-CD,pH of 6.5,temperature of 83 ~oC and 18 hours of reaction time.The enantiomeric excess and overall conversion rate were 96.05%and 27.28%,respectively.The mean relative errors between the experimental data and model predictions are 0.7704%and 6.156%,respectively.2.A reactive system was established to resolution of 2-(3-chlorophenyl)propionic acid by enzymatic hydrolysis.Lipase PS from Pseudomonas cepacia was screened as the optimal lipase and heptyl 2-(3-chlorophenyl)propionate was the best substrate.With polyethylene glycol(PEG 400)as co-solvent,the conversion is increased by88%.The effects of temperature,pH,concentrations of enzyme,PEG 400 and substrate as well as reaction time were investigated,and the optimal conditions were obtained as follows:15 mg/mL lipase,20 mmol/L substrate,30%(m/m)PEG 400,pH of 6.5,temperature of 70 ~oC and 36 hours of reaction time,where the enantiomeric excess and overall conversion rate could reach up to 99.02%and42.09%,respectively.The kinetics of enzymatic hydrolysis was studied,and the results showed that the heptanol had inhibitory effect on the enzyme with the mechanism of uncompetitive inhibition.A mathematical model has developed based on the reaction mechanism and the inverse reaction of hydrolysis was considered.The reaction rate equation of both(S)-and(R)-enantiomers were derived.The parameters of model were estimated by fitting time-concentration curves with the Matlab program.The results of model validation showed that the predicted values are in good agreement with the experimental data.3.A reactive system was constructed to resolution of 2-phenylpropionic acid by enzymatic hydrolysis.Lipase PS from Pseudomonas cepacia was screened as the optimal lipase and isobutyl 2-phenylpropionate was the best substrate.The effect of temperature,pH,concentrations of enzyme and substrate as well as reaction time on the catalytic resolution of enzyme were investigated.Based on the interface reaction mechanism,a mathematical model has developed and the reaction rate equation of both(S)-and(R)-enantiomers were derived.The parameters of model were estimated by applying Matlab program to fit time-concentration curves.By simulation and optimization,the optimum conditions were obtained as follows:20 mg/mL lipase,30mmol/L substrate,temperature of 55 ~oC,pH of 6.0 and 26 hours of reaction time,under which the enantiomeric excess and conversion rate of(S)-enantiomer could reach up to 99.59%and 91.12%,and the mean relative errors with the predicted values are 0.0100%and 1.166%,respectively.