CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / O praziquantel (PZQ), um fÃrmaco quiral disponÃvel como racemato, e o albendazol (ABZ), um fÃrmaco biotransformado ao metabÃlito ativo quiral sulfÃxido de abendazol (ASOX), tem sido empregados no tratamento da neurocisticercose humana. O estudo abrange a investigaÃÃo da disposiÃÃo cinÃtica, metabolismo e enantiosseletividade na associaÃÃo ABZ - PZQ em voluntÃrios sadios. O estudo cruzado e aleatÃrio foi desenvolvido em trÃs fases (n=9), sendo que alguns voluntÃrios iniciaram pela FASE 1 (400mg de ABZ), outros pela FASE 2 (1500mg de PZQ) e outros pela FASE 3 (400mg de ABZ + 1500mg de PZQ). O perÃodo de washout foi de no mÃnimo 15 dias (FASE 1 seguida da FASE 2 e FASE 1 seguida da FASE 3) ou 7 dias (FASE 2 seguida de uma das outras FASES). As amostras seriadas de sangue foram coletadas no perÃodo de 0-48h. Os metabÃlitos do ABZ foram analisados por HPLC com detecÃÃo por fluorescÃncia e os enantiÃmeros do PZQ e do trans-4-hidroxipraziquantel (4-OHPZQ) foram analisados por LC-MS-MS. Os parÃmetros farmacocinÃticos foram determinados com auxÃlio do programa WinNonlin. O teste de Wilcoxon (p≤0.05) foi empregado para avaliar as razÃes enantiomÃricas de concentraÃÃes plasmÃticas do ASOX, PZQ e 4-OHPZQ. Os dados estÃo expressos como medianas. A disposiÃÃo cinÃtica do PZQ, 4-OHPZQ e do ASOX Ã enantiosseletiva na situaÃÃo de monoterapia; as razÃes de AUC sÃo de 2,97 para (+)-(S)-PZQ /(-)-(R)-PZQ, 0,78 para (+)-(S)-4OHPZQ /(-)-(R)-4-OHPZQ e 7,08 para (+)-ASOX/(-)-ASOX. A administraÃÃo de PZQ resulta em aumento das concentraÃÃes plasmÃticas do (+)-ASOX em 264% (AUC 980,42 vs 2591,80 ng.h/ml), do (-)-ASOX em 358% (139,59 vs 500,28 ng.h./ml) e do sulfona de albendazol em 187% (170,85 vs 319,50ng.h./ml) sugerindo o PZQ como inibidor da Pgp intestinal. A administraÃÃo de ABZ nÃo altera a disposiÃÃo cinÃtica do (+)-(S)-PZQ e dos metabÃlitos (-)-(R)-4-OHPZQ e (+)-(S)-4OHPZQ, mas resulta em aumento das concentraÃÃes plasmÃticas do (-)-(R)-PZQ em 64,77% (AUC 518,02 vs 853,57ng.h/ml) sugerindo inibiÃÃo enantiosseletiva do metabolismo do ASOX. Os dados permitem sugerir a possibilidade de aumento da eficÃcia terapÃutica na interaÃÃo ABZ-PZQ, embora outros estudos sejam necessÃrios para avaliar a seguranÃa da interaÃÃo. / The praziquantel (PZQ), a chiral drug available as racemic, and the albendazole (ABZ), a drug biotransformed into active metabolic chiral suphoxide of abendazol (ASOX), have been used in the treatment of human neurocysticercosis. The study covers the examination / search of the kinetic disposition, the metabolism, and the enantioselectiveness in the ABZ-PZQ association in healthy volunteers. The crossed and random study was developed in three phases (n=9), in which some volunteers started by PHASE 1 (400 mg of ABZ), others by PHASE 2 (1500mg of PZQ), and others by PHASE 3 (400 mg of ABZ + 1500mg of PZQ). The period of washout was of a minimum of 15 days (PHASE 1 followed by PHASE 2 and PHASE 1 followed by PHASE 3) or of 7 days (PHASE 2 followed by one of the other Phases). The serial blood samples were collected in a period of 0-48 hours. The ABZ metabolics were analised by HPLC with detection by fluorescence and the PZQ enantiomers and the trans-4-hydroxypraziquantel (4-OHPZQ) were analised by LC-MS-MS. The pharmacokinetic patterns were determined with the help of the WinNonlin program. The test of Wilcoxon (p≤0.05) was used to evaluate the enantiomer ratios of plasma concentrations of ASOX, PZQ and 4-OHPZQ. The data are shown as medians. The kinetic disposition of the PZQ, 4-OHPZQ and ASOX is enantioselective in the monotherapy situation; the ratios of AUC are of 2.97 to (+)-(S)-PZQ / (-)-(R)-PZQ, 0.78 to (+)-(S)-4-OHPZQ / (-)-(R)-4-OHPZQ, and 7.08 to (+)-ASOX / (-)-PZQ. The administration of the PZQ results in the increase of the plasma concentrations of the (+)-ASOX in 264% (AUC 980.42 vs 2591.80ng.h./ml), of the (-)-ASOX in 358% (139.59 vs 500.28ng.h./ml), and of the sulphona of albendazole in 187% (170.85 vs 319.50ng.h./ml), suggesting the PZQ as an inhibiting factor of the intestinal Pgp. The administration of the ABZ does not change/ alter the kinetic disposition of the (+)-(S)-PZQ, and of the metabolic (-)-(R)-4-OHPZQ and (+)-(S)-4-OHPZQ, but it results in the increase of the plasma concentrations of the (-)-(R)-PZQ in 64.77% (AUC 518.02 vs 853.57ng.h./ml ), suggesting enantioselective inhibition of the metabolism of the ASOX. The data allow us to suggest the possibility of increase of therapeutic efficacy in the ABZ-PZQ interaction; although, other studies are necessary to evaluate the safety of the interaction.

<p>Cetirizine, an H₁-antihistamine, is prescribed for allergic disorders. It exists as a racemic mixture, with levocetirizine being the active enantiomer. The central nervous system side-effects of H₁-antihistamines are caused by their penetration into the brain. In this thesis the plasma pharmacokinetics, transport across the blood-brain barrier (BBB) and H₁ receptor occupancy of cetirizine enantiomers was investigated <i>in vivo</i> in guinea pigs. The transport across the BBB was quantified using the microdialysis technique. Stereoselective brain distribution was investigated by measuring both unbound and total concentrations in plasma and brain. The time aspects of the H₁ receptor occupancy of levocetirizine was studied in the brain and the periphery.</p><p>The plasma pharmacokinetics of cetirizine was stereoselective with clearance and volume of distribution of levocetirizine being approximately half that of dextrocetirizine. This was mainly due to the differences in plasma protein binding of the enantiomers. The stereoselectivity in brain distribution indicated by the partition coefficient K_p (total AUC ratio brain to plasma) was caused by stereoselective plasma protein binding. The transport across the BBB measured in this thesis by the unbound partition coefficient K_p,uu (unbound AUC ratio brain to plasma) was the same for the two enantiomers. Binding within the brain was also not significantly different. The H₁ receptor occupancy of levocetirizine in brain lagged behind the plasma concentrations whereas it was not delayed with respect to the brain concentrations. This indicates that the delayed brain H₁ receptor occupancy of levocetirizine is caused by a slow transport across the BBB.</p><p>In summary, the results of this thesis emphasize the importance of measuring both the unbound and total concentrations in blood and brain to characterize stereoselective brain distribution. The thesis also emphasize the importance of taking local brain pharmacokinetics into consideration in understanding pharmacokinetic-pharmacodynamic relationships of drugs with central activity.</p>

Cetirizine, an H1-antihistamine, is prescribed for allergic disorders. It exists as a racemic mixture, with levocetirizine being the active enantiomer. The central nervous system side-effects of H1-antihistamines are caused by their penetration into the brain. In this thesis the plasma pharmacokinetics, transport across the blood-brain barrier (BBB) and H1 receptor occupancy of cetirizine enantiomers was investigated in vivo in guinea pigs. The transport across the BBB was quantified using the microdialysis technique. Stereoselective brain distribution was investigated by measuring both unbound and total concentrations in plasma and brain. The time aspects of the H1 receptor occupancy of levocetirizine was studied in the brain and the periphery. The plasma pharmacokinetics of cetirizine was stereoselective with clearance and volume of distribution of levocetirizine being approximately half that of dextrocetirizine. This was mainly due to the differences in plasma protein binding of the enantiomers. The stereoselectivity in brain distribution indicated by the partition coefficient Kp (total AUC ratio brain to plasma) was caused by stereoselective plasma protein binding. The transport across the BBB measured in this thesis by the unbound partition coefficient Kp,uu (unbound AUC ratio brain to plasma) was the same for the two enantiomers. Binding within the brain was also not significantly different. The H1 receptor occupancy of levocetirizine in brain lagged behind the plasma concentrations whereas it was not delayed with respect to the brain concentrations. This indicates that the delayed brain H1 receptor occupancy of levocetirizine is caused by a slow transport across the BBB. In summary, the results of this thesis emphasize the importance of measuring both the unbound and total concentrations in blood and brain to characterize stereoselective brain distribution. The thesis also emphasize the importance of taking local brain pharmacokinetics into consideration in understanding pharmacokinetic-pharmacodynamic relationships of drugs with central activity.

The sense of smell in marine mammals is traditionally thought to be poor. However, increasing evidence suggests that pinnipeds may use their sense of smell in a variety of behavioral contexts including communication, foraging, food selection, and reproduction. Using a food-rewarded two-choice instrumental conditioning paradigm, I assessed the ability of South African fur seals, Arctocephalus pusillus, to discriminate between 12 enantiomeric odor pairs, that is, between odorants that are identical in structure except for chirality. The fur seals significantly discriminated between eight out of the twelve odor pairs (according to p &lt; 0.05, with carvone, dihydrocarvone, dihydrocarveol, limonene oxide, menthol, beta-citronellol, fenchone, and alpha-pinene), and failed with only four odor pairs (isopulegol, rose oxide, limonene, and camphor). No significant differences in performance were found between the animals (p &gt; 0.05). Cross-species comparisons between the olfactory performance of the fur seals and that of other species previously tested on the same set of odor pairs lend further support to the notion that the relative size of the olfactory bulbs is not a reliable predictor of olfactory discrimination abilities. The results of the present study suggest that sense of smell may play an important and hitherto underestimated role in regulating the behavior of fur seals.

The distinct response of biological systems to the two enantiomers of a chiral chemical has led to a large market for enantiopure pharmaceuticals and raised fundamental issues about the origin of biological homochirality. It is therefore important to understand the interactions of chiral molecules with chiral environments. Chiral environments associated with solid surfaces could potentially play a useful role in chirally specific chemical processing. There are a variety of routes for creating chiral solid surfaces. Surfaces of materials whose bulk crystal structure is enantiomorphic can be used as one type of chiral solid surfaces. Metal surfaces that are intrinsically chiral due to the presence of kinked surface steps provide another route for creating chiral solid surfaces. Alternatively, we can impart chirality onto surfaces by attaching irreversibly adsorbing chiral organic species on otherwise achiral surfaces. Understanding and ultimately controlling enantiospecific interactions of molecules on this kind of surfaces requires detailed insight into the adsorption geometries and energies of these complex interfaces. To tackle these issues, we performed density functional theory (DFT) calculations that have proved to be a useful tool for quantitative prediction of these effects. Besides our main topic above, we theoretically examine the effects of K atoms as a promoter coadsorbed with small molecules on Mo2C surfaces, a promising catalyst for a range of chemicals applications. Our results in this thesis provide fundamental information about these systems and demonstrate that using DFT for this purpose can be a useful means of identifying the phenomena that control chiral surface chemistry.

This thesis examines the air-soil and air-water gas exchange of persistent organic pollutants (POPs) with emphasis on organochlorine pesticides (OCPs). The current status of net exchange, factors which influence the exchange process, and different approaches used to estimate the surface exchange were explored. The net exchange of chemicals was evaluated using the fugacity approach, with the aid of chemical tracers (congener profiles of complex mixtures and enantiomer proportions of chiral chemicals) to infer current use vs. legacy sources to the atmosphere. DDT in southern Mexico was undergoing net deposition from air to soil. Occurrence of fresher DDT residues in the south was indicated by a higher proportion of p,p’-DDT relative to p,p’-DDE and racemic o,p’-DDT in air and soils. Congener profiles of toxaphene suggested soil emissions as the source to air. The influence of chemical aging on soil-air exchange and bioaccessibility was studied in a high organic soil. The use of nonexhaustive extraction with hydroxypropyl-beta-cyclodextrin (HPCD) to predict bioaccessibility was optimized for OCPs and polychlorinated biphenyls (PCBs). Reduced volatility of spiked chemicals correlated with reduced HPCD extractability for soil that had been aged under indoor and outdoor conditions for 730 d and infers volatility could be used as a surrogate for bioaccessibility. Measured soil-air partition coefficients (Ksa) were lower than those predicted from the Karickhoff relationship, which considers octanol as a surrogate for soil organic matter. The role of soil moisture, organic carbon, temperature, depth of soil surface horizon and dissolved organic carbon in the fate of organic contaminants in soil were assessed using chemical partitioning space maps. These maps allow instant visual prediction of the phase distribution and transport process of a chemical among the three major phases in soil; i.e., air, water and solid. Net volatilization of alpha-hexachlorocyclohexane from water to air was found in the southern Beaufort Sea using fugacity calculations and flux measurements. The influence of ice cover on volatilization was indicated by a winter-summer shift from racemic to nonracemic alpha-HCH in boundary layer air.

This thesis examines the air-soil and air-water gas exchange of persistent organic pollutants (POPs) with emphasis on organochlorine pesticides (OCPs). The current status of net exchange, factors which influence the exchange process, and different approaches used to estimate the surface exchange were explored. The net exchange of chemicals was evaluated using the fugacity approach, with the aid of chemical tracers (congener profiles of complex mixtures and enantiomer proportions of chiral chemicals) to infer current use vs. legacy sources to the atmosphere. DDT in southern Mexico was undergoing net deposition from air to soil. Occurrence of fresher DDT residues in the south was indicated by a higher proportion of p,p’-DDT relative to p,p’-DDE and racemic o,p’-DDT in air and soils. Congener profiles of toxaphene suggested soil emissions as the source to air. The influence of chemical aging on soil-air exchange and bioaccessibility was studied in a high organic soil. The use of nonexhaustive extraction with hydroxypropyl-beta-cyclodextrin (HPCD) to predict bioaccessibility was optimized for OCPs and polychlorinated biphenyls (PCBs). Reduced volatility of spiked chemicals correlated with reduced HPCD extractability for soil that had been aged under indoor and outdoor conditions for 730 d and infers volatility could be used as a surrogate for bioaccessibility. Measured soil-air partition coefficients (Ksa) were lower than those predicted from the Karickhoff relationship, which considers octanol as a surrogate for soil organic matter. The role of soil moisture, organic carbon, temperature, depth of soil surface horizon and dissolved organic carbon in the fate of organic contaminants in soil were assessed using chemical partitioning space maps. These maps allow instant visual prediction of the phase distribution and transport process of a chemical among the three major phases in soil; i.e., air, water and solid. Net volatilization of alpha-hexachlorocyclohexane from water to air was found in the southern Beaufort Sea using fugacity calculations and flux measurements. The influence of ice cover on volatilization was indicated by a winter-summer shift from racemic to nonracemic alpha-HCH in boundary layer air.

Thesis (Ph.D.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

Made available in DSpace on 2015-05-14T12:59:24Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1952542 bytes, checksum: cbb5dfafac619fd1f5d9b4ef4efbccf2 (MD5) Previous issue date: 2011-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Enantiomers are asymmetric compounds that present mirror images of each other, not overlapping and different behaviors in chiral environments, resulting in esterioseletiva discrimination and different biological effects. The carvone is a monoterpene, a constituent of many essential oils found in nature as two enantiomers, (S)-(+)-carvone and (R)-(−)-carvone. The inflammation, a physiological response of the organism, when it occurs exaggerated or inappropriated ways may promote tissue damage and associated pathologies. An example of inflammatory disease is asthma, an immediate hypersensitivity process of the airways and the conventional treatments have significant adverse effects. The aim of this study was to evaluate the carvone enantiomers in experimental models of inflammation and hypersensitivity of the airways. To investigate the effect anti-inflammatory the following parameters were evaluated: NO production by cells J774.A1, paw oedema formation induced by carrageenan, zymosan, compound 48/80 and histamine, cell migration and cytokines production (TNF-α and IL-1β) in the experimental model of peritonitis induced by zymosan in Swiss mice. To evaluate the anti-asthmatic activity of these enantiomers, it was used the experimental model of asthma induced by ovalbumin and the following parameters were analyzed: bronchoalveolar lavage (BAL), mucus production, OVA-specific IgE synthesis, cytokine production (IL-13, IFN-γ and IL-10). The results showed that both enantiomers were able to reduce NO production, inhibit the paw oedema induced by phlogistic agents and inhibit cell migration to the peritoneum, but only the (R)-(−)-carvone was able to reduce levels of TNF-α. In the murine model of asthma, the (R)-(−)-carvone, was able to reduce the cellularity of the BAL, modulate the OVA-specific IgE production, reduce the cell infiltration and mucus in the lungs and further increase the IL-10. However, although the (S)-(+)-carvone has reduced the BAL cellularity and increased IFN-γ levels, it was unable to reduce the cell infiltration in the lung and increase the mucus production. Therefore, both enantiomers of carvone showed anti-inflammatory effect, although only the (R)-(−)-carvone showned potential anti-asthmatic. Additionally, the results presented by (S)-(+)-carvone, revealed a potential adverse effect of this enantiomer in the experimental model of asthma. / Enantiômeros são compostos assimétricos que apresentam a particularidade de serem imagens especulares um do outro, não sobreponíveis e por terem comportamentos diferentes em ambientes quirais, resultando frequentemente na discriminação esterioseletiva e diferentes efeitos biológicos. A carvona é um monoterpeno, constituinte de muitos óleos essenciais e encontrada na natureza na forma de dois enantiômeros: (S)-(+)-carvona e (R)-(-)-carvona. A inflamação uma resposta fisiológica do organismo, quando ocorre de forma exacerbada ou inapropriada pode promover dano tecidual e patologias associadas. Um exemplo de doença inflamatória importante é a asma, um processo hipersensibilidade imediata nas vias aéreas e que tratamentos convencionais apresentam efeitos colaterais importantes. O objetivo desse trabalho foi avaliar os enantiômeros da carvona em modelos de inflamação e de hipersensibilidade das vias aéreas. Para investigar a atividade anti-inflamatória das substâncias os seguintes parâmetros foram avaliados: produção de NO por células J774.A1, formação de edema de pata induzido por carragenina, zimosan, composto 48/80 e histamina, migração de células e produção das citocinas (TNF-α e IL-1β) no modelo de peritonite induzida por zimosan, em camundongos Swiss. Para avaliar a atividade anti-asmática dos enantiômeros, foi utilizado o modelo de asma experimental induzido por ovalbumina e analisado os seguinte parâmetros: celularidade do lavado bronco alveolar (BAL), produção de muco, síntese de IgE OVA-específica, produção de citocinas (IL-13, IFN-γ e IL-10). Os resultados demonstraram que ambos os enantiômeros foram capazes de reduzir a produção de NO, inibir o edema de pata induzido pelos agentes flogísticos utilizados e inibir a migração de células para o peritônio, porém apenas a (R)-( )-carvona foi capaz de reduzir os níveis de TNF-α. No modelo murino de asma alérgica, a (R)-(−)-carvona, foi capaz de reduzir a celularidade do BAL, modular a produção de IgE OVA-específica, reduzir o infiltrado de células e muco no pulmão e ainda, aumentar os níveis de IL-10. Porém, embora a (S)-(+)-carvona, tenha reduzido a celularidade do BAL e aumentado os níveis de IFN-γ, ela não foi capaz de reduzir o infiltrado de células no pulmão e ainda, aumentou a produção de muco. Portanto, ambos enantiômeros da carvona apresentaram efeito anti-inflamatório, embora apenas a (R)-(-)-carvona tenha apresentado potencial anti-asmático e ainda, os resultados apresentados pela (S)-(+)-carvona, revelaram um potencial efeito adverso desse enantiômero em modelo experimental de asma.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O praziquantel (PZQ) à um medicamento anti-helmÃntico de alto espectro utilizado no tratamento de todos os tipos de esquistossomose. No Brasil a mistura racÃmica à utilizada na fabricaÃÃo do medicamento. Sabe-se que a espÃcie enantiomÃrica R-PZQ à a que possui efeito anti-helmÃntico e que esta espÃcie possui sabor menos amargo. Sendo assim formulaÃÃes baseadas no R-PZQ somente teriam metade da dose necessÃria da formulaÃÃo sÃlida da mistura racÃmica e as formulaÃÃes lÃquidas teriam sabor menos amargo. Para obtenÃÃo de enantiÃmeros puros a cromatografia quiral à uma tÃcnica promissora por produzir enantiÃmeros com grau de pureza bastante elevada. Neste trabalho a separaÃÃo dos enantiÃmeros do fÃrmaco praziquantel foi realizada em uma fase estacionÃria quiral (FEQ) celulose tris(3-cloro-4- metilfenilcarbamato), comercialmente conhecida como Lux Celulose-2, por cromatografia lÃquida de alta eficiÃncia (CLAE). Ensaios em soluÃÃo diluÃda (1 g/L) e soluÃÃes concentradas (5, 10, 15 e 20 g/L) foram realizados em laboratÃrio. Em todos estes experimentos foram estudados os efeitos da variaÃÃo da vazÃo da fase fluida (0,5, 1 e 2 mL/min) e do volume de injeÃÃo (20, 60 e 100ÂL). Nestes foram alcanÃadas separaÃÃes por linha de base indicando alta eficiÃncia da coluna para a separaÃÃo requerida. Experimentos com soluÃÃo de PZQ de 40 g/L e com vazÃo de fase fluida de 1 mL/min foram realizados objetivando encontrar as condiÃÃes em que ocorreria sobreposiÃÃo dos picos. Os enantiÃmeros foram separados satisfatoriamente nos volumes de injeÃÃo testados (100, 140 e 180 ÂL), com indicaÃÃo de sobreposiÃÃo no volume injetado de 250 ÂL obtendo-se uma produÃÃo de 533 mg/dia no limite de separaÃÃo por linha de base. Pelos resultados obtidos pode-se prever um comportamento nÃo linear da isoterma de equilÃbrio de adsorÃÃo. Foram estimados parÃmetros da isoterma de Langmuir competitivo a partir dos experimentos nas concentraÃÃes de 5 g/L a 20 g/L por um mÃtodo hÃbrido entre o mÃtodo dos tempos de retenÃÃo e o mÃtodo inverso a partir de uma soluÃÃo analÃtica do modelo ideal. Esses parÃmetros foram utilizados em um programa computacional desenvolvido no Fortran objetivando a simulaÃÃo para prediÃÃo dos perfis cromatogrÃficos pelo modelo do equilÃbrio dispersivo. Os perfis obtidos na simulaÃÃo representaram bem os dados experimentais quando comparados os tempos de retenÃÃo da frente de massa de ambos os enantiÃmeros. Os parÃmetros estimados tambÃm foram utilizados na prediÃÃo dos perfis cromatogrÃficos para as condiÃÃes de 40 g/L e apresentaram resultados satisfatÃrios quando os erros de prediÃÃo foram levados em consideraÃÃo. / Praziquantel is a high spectrum anthelmintic drug used in the treatment of all types of schistosomiasis. In Brazil, the racemic mixture is used on the drug manufacture. It is known that the R-PZQ enantiomeric species is the one which has the anthelmintic effect and a less bitter taste. Thus, the solid formulations based on R-PZQ only, would have half of the dosage and the liquid formulations would have a less bitter taste. To obtain pure enantiomers chiral chromatography is a promising technique which produces high purity enantiomers. In this work the praziquantel enantiomers separation was obtained on a cellulose tris(3-chlorine-4-methyl-phenyl-carbamate) chiral stationary phase (CSP), commercially known as Lux Cellulose-2, by high performance liquid chromatography (HPLC). Experiments with diluted solution (1 g/L) and concentrated solutions (5, 10, 15 and 20 g/L) were carried out. On these experiments the effects of the mobile phase flow rate variation (0,5, 1 e 2 mL/min) and the injection volume (20, 60 e 100ÂL) have been studied. On these baseline separations were achieved indicating high column efficiency for the required separation. Experiments with 40 g/L PZQ solution and a mobile phase flow rate of 1 mL/min were performed aiming to find conditions on which overlapping peaks occur. The enantiomers were well separated on the tested injection volumes (100, 140 and 180 ÂL), indicating an overlapping on the injection volume of 250 ÂL yielding a production of 533 mg per day at the limit of baseline separation. From the results one can predict a nonlinear adsorption equilibrium isotherm behavior. Parameters of the competitive Langmuir isotherm were estimated from experiments in the concentration range 5g/L to 20 g/L by a hybrid method between the retention time method and the inverse method by an analytical solution of the ideal model. These parameters were used on a computer program developed in Fortran aiming at the prediction of the chromatographic profiles by the Equilibrium Dispersive Model. The profiles obtained from the simulation represent well the experimental data when comparing the front mass retention times of both enantiomers. The estimated parameters were also used on the prediction of the chromatographic profiles obtained for 40 g/L conditions and showed satisfactory results when prediction errors were taken into account.