The Approaches To Chiral Separation Of Enantiomers For Sulpiride And Flurbiprofen

Benzamides antipsychotics and aryl propionic acid class of non-steroidalanti-inflammatory analgesics are two kinds of the most useful clinic drugs. Theyalways include different enantiomers, which influence clinical therapeutic effect andsafety of medication, because that they have obviously unequal pharmacologicalactivity and toxicity. As far as we known, most of these drugs are sale as racemicdrugs on the market and clinical application. Chemical synthesis and separation ofenantiomer from racemic are the main methods to obtain a single enantiomer, whichhas great significance for in-depth study of the pharmacological, physiological andtoxicological effects of enantiomers. Recently, more attention is focus on chiralseparation of enantiomers of drugs.Sulpiride and flurbiprofen are the most typical drugs in those two kinds of drugs.In this paper, molecular imprinting technique, aqueous two-phase extraction techniqueand chromatographic separation technique were applied to studying the chiralseparation of enantiomers for sulpiride and flurbiprofen. The influence factors ofenantiomeric separation investigated systematically to these two kinds of drugs.Furthermore, the mechanisms of separation of the chiral drugs by the techniquesmentioned above were explored respectively. Based on experimental results, the newmethods of chiral separation of enantiomers for sulpiride and flurbiprofen wereestablished, and applied to separation and analysis of enantiomers for these two kindsof drugs. The main contents are as follows:1. Molecularly imprinted polymer (MIP) was synthesized by bulk polymerization under the optimized experimental conditions. The optimum conditions were asfollowing:0.15mmol S-sulpiride,0.60mmol allyl tryptophan,7.5mL acetonitrile,12mmol acrylic esters of ethylene glycol dimethacrylate,60mg azobisisobutyronitrile,then polymerization of MIP at60℃. The property and structure of MIP wereinvestigated. The results showed that MIP offered strong adsorption of S-Sulpiridewith87.12μmol/g of maximum adsorption capacity and2.34of imprinted factor. TheScatchard analysis suggests that MIP have two sorts of recognition sites includingspecific adsorption recognition sites and non-specific recognition. Infraredspectroscopy indicated that the MIP reserved the hole of S-sulpiride molecularlyimprinted; Scanning electron microscopy and particle size analysis revealed thatsurface on MIP has a porous structure and large surface area, the mean of particle sizeis4.856m.2. Based on the structure of sulpiride is composed of the structural unitsincluding1-methyl-pyrrolidin, N-methyl-benzamide, benzenesulfonamide, anisole,they were used as substrate to study the recognition mechanism of MIP. Theadsorption performance of MIP was carried out to analogues of sulpiride and otherdrugs. The results showed that amine group and methoxy group of N-methyl pyrrolealkane are the main recognition sites of MIP, the other groups are only provide spatialstructure. The MIP exhibited better specific adsorption and selectivity to analogues ofsulpiride, and has little adsorption to others such as sulfamethoxazole, toluenesulfonamide, sulfanilamide because of different structures from sulpiride.3. For further application of MIP, the MIP has been utilized in uses ofsolid-phase extraction and drug delivery material. The results showed that MIPexhibited the ability of chiral separation. The recovery of sulpiride was8.15%in thesolid-phase extraction; Drug-loaded MIP had lower release rate(70%) than ordinarysulpiride tablets(90%), and the release rate between S-sulpiride and R-sulpiride wasalso difference to a certain extent. MIP could act as a good material to control therelease rate of sulpiride and S-sulpiride.4. Using amylose-3(5-chloro-2-methyl phenyl carbamate)(ACMPC) as chiral stationary phase in normal phase chromatography as chiral separation method, theseparation behaviors of sulpiride and its analogues drug such as amsulpiride andmosapride were systematically studied. The mechanism of chromatographicseparation was structurally considered by thermodynamics. The results proved thatthe mobile phase composition, additives, and column temperature had greater impactto enantiomeric separation. When0.1%diethylamine n-hexane and0.1%diethylamine ethanol used as mobile phase, sulpiride, amisulpride and mosapridewere separated at15℃on ACMPC. The order of chromatographic retention wassulpiride> amisulpride> mosapride. The enantiomers of those drugs displayed goodpeak shape, Rs greater than1.5. Thermodynamic analysis indicated that the process ofchiral separation for sulpiride and mosapride was enthalpy-driven, while amisulpridenot only control by enthalpy driven, but also driven by entropy. The method ofdetermination of the enantiomers for three drugs was established, and successfullyapplied to analysis of their contents in tablets and serum sample, the recoveries isfrom87.7%to104.3%, RSDs was in the range from1.8%to2.6%.5. Using ethanol/ammonium sulfate aqueous two-phase system (ATPS) asextraction medium with aqueous two-phase extraction technology, the method ofchiral extraction of flurbiprofen enantiomers was developed. The influence of chiralrecognition extractant such asβ-cyclodextrin derivatives, L-tartaric acid esters andamino acids substances, were investigated to the separation of flurbiprofenenantiomers. Experiments result showed that L-tartaric acid octyl ester andL-tryptophan were extracted the enantiomers of flurbiprofen in top phase or bottomphase respectively. L-tartaric acid octyl ester and L-tryptophan can be selected aschiral recognition extractant for co-extraction of the enantiomers of flurbiprofen inATPS. The influence factors of chiral extraction of the enantiomer in ATPS wereinvestigated, the optimal conditions were as following: L-tryptophan: L-tartaric acidoctyl ester (1:2), pH=4.0, phase ratio2:1, extraction temperature25℃. The resultsshowed that the factorαof enantiomeric separation of flurbiprofen reached2.34,Enantiomeric excess up to43.9%in the extract conditions. L-tartaric acid octyl esterand L-tryptophan as chiral recognition extractants can form complexes with R-enantiomer and S-enantiomer, extracted into top phase and bottom phase in ATPS,respectively. The cooperative action of two extractants allocated can significantlyimproved the chiral extraction of the flurbiprofen enantiomers. Adding L-tryptophanand L-tartaric acid octyl ester in ATPS, the method of chiral extraction of flurbiprofenenantiomers is simple, feasible, easy to operate and industrialization amplificationwithout organic solvent.