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Academic literature on the topic 'Enantiomeric effect'

Author: Grafiati

Published: 19 February 2023

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Journal articles on the topic "Enantiomeric effect"

1

Tok, Kenan Can, Mehmet Gumustas, Giorgi Jibuti, Halit Sinan Suzen, Sibel A. Ozkan, and Bezhan Chankvetadze. "The Effect of Enantiomer Elution Order on the Determination of Minor Enantiomeric Impurity in Ketoprofen and Enantiomeric Purity Evaluation of Commercially Available Dexketoprofen Formulations." Molecules 25, no. 24 (December 11, 2020): 5865. http://dx.doi.org/10.3390/molecules25245865.

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In a recent study, opposite enantiomer elution order was observed for ketoprofen enantiomers on two amylose-phenylcarbamate-based chiral columns with the same chemical composition of the chiral selector but in one case with coated while in the other with an immobilized chiral selector. In the present study, the influence of this uncommon effect on method validation parameters for the determination of minor enantiomeric impurity in dexketoprofen was studied. The validated methods with two alternative elution orders for enantiomers were applied for the evaluation of enantiomeric impurity in six marketed dexketoprofen formulations from various vendors. In most of these formulations except one the content of enantiomeric impurity exceeded 0.1% (w/w).

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2

Zhou, Juan, Qiao Chen, Li-lan Wang, Yong-hua Wang, and Ying-zi Fu. "Chiral Discrimination of Tryptophan Enantiomers via (1R, 2R)-2-Amino-1, 2-Diphenyl Ethanol Modified Interface." International Journal of Electrochemistry 2011 (2011): 1–6. http://dx.doi.org/10.4061/2011/502364.

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The paper reported that a simple chiral selective interface constructed by (1R, 2R)-2-amino-1, 2-diphenyl ethanol had been developed to discriminate tryptophan enantiomers. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characteristic analysis of the electrode. The results indicated that the interface showed stable and sensitive property to determine the tryptophan enantiomers. Moreover, it exhibited the better stereoselectivity for L-tryptophan than that for D-tryptophan. The discrimination characteristics of the chiral selective interface for discriminating tryptophan enantiomers, including the response time, the effect of tryptophan enantiomers concentration, and the stability, were investigated in detail. In addition, the chiral selective interface was used to determine the enantiomeric composition of L- and D-tryptophan enantiomer mixtures by measuring the relative change of the peak current as well as in pure enantiomeric solutions. These results suggested that the chiral selective interface has the potential for enantiomeric discrimination of tryptophan enantiomers.

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Gładkowski, Witold, Aleksandra Włoch, Aleksandra Pawlak, Angelika Sysak, Agata Białońska, Marcelina Mazur, Paweł Mituła, Gabriela Maciejewska, Bożena Obmińska-Mrukowicz, and Halina Kleszczyńska. "Preparation of Enantiomeric β-(2′,5′-Dimethylphenyl)Bromolactones, Their Antiproliferative Activity and Effect on Biological Membranes." Molecules 23, no. 11 (November 20, 2018): 3035. http://dx.doi.org/10.3390/molecules23113035.

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Three novel enantiomeric pairs of bromolactones possesing a 2,5-dimethylphenyl substituent at the β-position of the lactone ring have been synthesized from corresponding enantiomeric (E)-3-(2′,5′-dimethylphenyl)hex-4-enoic acids (4) by kinetically controlled bromolactonization with N-bromosuccinimide (NBS). γ-Bromo-δ-lactones (5) were isolated as the major products. Absolute configurations of stereogenic centers of γ-bromo-δ-lactones (5) were assigned based on X-ray analysis; configurations of cis δ-bromo-γ-lactones (6) and trans δ-bromo-γ-lactones (7) were determined based on mechanism of bromolactonization. Synthesized compounds exhibited significant antiproliferative activity towards the four canine cancer cell lines (D17, CLBL-1, CLB70, and GL-1) and one human cancer line (Jurkat). Classifying the compounds in terms of activity, the most active were enantiomers of trans δ-bromo-γ-lactones (7) followed by enantiomers of cis isomer (6) and enantiomeric γ-bromo-δ-lactones (5). Higher activity was observed for all stereoisomers with S configuration at C-4 in comparison with their enantiomers with 4R configuration. Synthesized compounds did not induce hemolysis of erythrocytes. The results of the interaction of bromolactones with red blood cell membranes suggest that these compounds incorporate into biological membranes, concentrating mainly in the hydrophilic part of the bilayer but have practically no influence on fluidity in the hydrophobic region. The differences in interactions with the membrane between particular enantiomers were observed only for γ-lactones: stronger interactions were found for enantiomer 4R,5R,6S of cis γ-lactone (6) and for enantiomer 4S,5R,6S of trans γ-lactone (7).

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4

Nathan, I., G. Agam, R. Mechoulam, A. Dvilansky, and A. A. Livne. "Effect of synthetic enantiomeric cannabinoids on platelet aggregation." Canadian Journal of Physiology and Pharmacology 70, no. 10 (October 1, 1992): 1305–8. http://dx.doi.org/10.1139/y92-182.

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The effect of a synthetic pair of enantiomeric cannabinoids on platelet function was evaluated. The nonpsychotropic enantiomer, the 1,1-dimethylheptyl homolog of (+)-(3S,4S)-7-hydroxy-Δ-6-tetrahydrocannabinol (HU-211), was found to be more active in inhibiting ADP-induced platelet aggregation than the highly psychotropic (−)-enantiomer (HU-210). The related (+)-(3R,4R) cannabinoid, HU-213, which lacks the 7-hydroxy moiety, exerted its inhibitory effect within a wider range of concentrations. The results indicate a differentiation between psychotropic activity and inhibition of platelet aggregation in the cannabinoid group of compounds.Key words: enantiomeric cannabinoids, platelet aggregation.

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5

Cook, J. I., S. Majeed, R. Ignell, J. A. Pickett, M. A. Birkett, and J. G. Logan. "Enantiomeric selectivity in behavioural and electrophysiological responses of Aedes aegypti and Culex quinquefasciatus mosquitoes." Bulletin of Entomological Research 101, no. 5 (May 18, 2011): 541–50. http://dx.doi.org/10.1017/s0007485311000162.

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Abstract1-Octen-3-ol is a kairomone for many haematophagous insects including mosquitoes. Numerous studies have examined the effects of racemic 1-octen-3-ol; however, few studies have investigated the role of individual enantiomers in relation to mosquito attraction. In the present study, we investigated the behavioural and electrophysiological responses of two mosquito species, Aedes aegypti and Culex quinquefasciatus, to individual enantiomers and mixtures of 1-octen-3-ol, employing a laboratory Y-tube olfactometer and single sensillum recordings. The olfactory receptor neurons of both Ae. aegypti and Cx. quinquefasciatus had a significantly higher response to the (R)-1-octen-3-ol enantiomer compared to the (S)-1-octen-3-ol enantiomer at 10−9 g μl−1 to 10−6 g μl−1. Behaviourally, Ae. aegypti was more responsive to the (R)-1-octen-3-ol enantiomer, showing an increase in flight activity and relative attraction compared to Cx. quinquefasciatus. The (R)-1-octen-3-ol enantiomer caused an increase in activation for Cx. quinquefasciatus. However, the most notable effect was from an (R:S)-1-octen-3-ol mixture (84:16) that caused significantly more mosquitoes to sustain their flight and reach the capture chambers (demonstrated by a reduced non-sustained flight activity), suggesting that it may have a behaviourally excitatory effect. For Cx. quinquefasciatus, a reduced relative attraction response was also observed for all treatments containing the (R)-1-octen-3-ol enantiomer, either on its own or as part of a mixture, but not with the (S)-1-octen-3-ol enantiomer. This is the first time enantiomeric selectivity has been shown for Ae. aegypti using electrophysiology in vivo. The implications of these results for exploitation in mosquito traps are discussed.

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6

Pálovics, Emese, Dorottya Fruzsina Bánhegyi, and Elemér Fogassy. "Effect of the Enantiomeric Ratio of Eutectics on the Results and Products of the Reactions Proceeding with the Participation of Enantiomers and Enantiomeric Mixtures." Chemistry 2, no. 3 (September 21, 2020): 787–95. http://dx.doi.org/10.3390/chemistry2030051.

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This perspective is focused on the main parameters determining the results of crystallization of enantiomers or enantiomeric mixtures. It was shown that the ratio of supramolecular and helical associations depends on the eutectic composition of the corresponding enantiomeric mixture. The M and P ratios together with the self-disproportionation (SDE) of enantiomers define the reaction of the racemic compound with the resolving agent. Eventually, each chiral molecule reacts with at least two conformers with different degrees of M and P helicity. The combined effect of the configuration, charge distribution, constituent atoms, bonds, flexibility, and asymmetry of the molecules influencing their behavior was also summarized.

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7

Salom, S. M., R. F. Billings, W. W. Upton, M. J. Dalusky, D. M. Grosman, T. L. Payne, C. W. Berisford, and T. N. Shaver. "Effect of verbenone enantiomers and racemic endo-brevicomin on response of Dendroctonusfrontalis (Coleoptera: Scolytidae) to attractant-baited traps." Canadian Journal of Forest Research 22, no. 7 (July 1, 1992): 925–31. http://dx.doi.org/10.1139/x92-123.

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Different enantiomeric ratios and elution rates of the inhibitor pheromones verbenone and racemic endo-brevicomin were evaluated for their effects on the numerical response of the southern pine beetle, Dendroctonusfrontalis Zimm., to attractant-baited traps. Enantiomeric ratios and elution rates of verbenone were important factors in inhibiting response of male D. frontalis. Deterrence was most effective for enantiomeric ratios of verbenone containing 34 and 50% of the (+) enantiomer. Using a 34% (+): 66% (−) mixture of verbenone, the number of male D. frontalis captured in attractant-baited traps declined as elution rates increased from 4.2 to 12.5 mg/h. None of the enantiomeric ratios or elution rates of verbenone tested consistently influenced female response. endo-Brevicomin added to attractant-baited traps reduced catches of male D. frontalis, but did not significantly reduce catches further when added to traps also emitting verbenone. Female catches were not reduced significantly by the presence of endo-brevicomin. Numerical responses of the predatory beetle Thanasimusdubius Fab. are generally unaffected by the presence of verbenone alone or in combination with endo-brevicomin.

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Bai, Hui. "Research progress of chiral ligand exchange stationary phases in the enantiomer resolution." E3S Web of Conferences 271 (2021): 04020. http://dx.doi.org/10.1051/e3sconf/202127104020.

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The structure of chiral drugs contains at least one asymmetric center. When the enantiomers act on the human body, they are recognized by chiral receptors and enzymes in vivo, which will show different physiological effects and even adverse reactions. Therefore, it is very important for the development of chiral pharmacy to obtain chiral enantiomers with a single configuration by racemic resolution. Some general impurities will be introduced in the production of chiral drugs, thus the detection of impurities is also a crucial step in the quality control of chiral medicines. The chiral ligand exchange stationary phase has a strong recognition effect on enantiomer analytes with multiple chelating sites, and is very suitable for the separation and control of biological samples such as amino acids. In this work, the development of chiral ligand exchange stationary phases in enantiomeric resolution is reviewed, which is expected to provide a basis for the quality control of complex chiral drug components.

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9

Rajin, Mariani, Asiah Binti Zulkifli, Sariah Abang, S. M. Anissuzzaman, and Azlina Harun Kamaruddin. "Effect of Reaction Parameters on the Lipase-Catalyzed Kinetic Resolution of (RS )-Metoprolol." ASEAN Journal of Chemical Engineering 20, no. 1 (June 29, 2020): 20. http://dx.doi.org/10.22146/ajche.51857.

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Racemic metoprolol is a selective ß1-blocker, which is used in cardiovascular disease treatment. It has been found that (S)-metoprolol has a higher affinity to bind the ß-adrenergic receptor compared to (R)-metoprolol. Moreover, the regulatory authorities’ high market demand and guidelines have increased the preference for single enantiomer drugs. In this work, the lipase-catalyzed kinetic resolution of racemic metoprolol was performed to obtain the desired enantiomer. The type of lipase, acyl donor, and solvent were screened out. This was achieved by Candida antarctica B lipase-catalyzed transesterification of racemic metoprolol in hexane and vinyl acetate as the solvent and an acyl donor, which gave maximum conversion of (S)-metoprolol (XS) of 52%, enantiomeric excess of substrate, (ees) of 92% and product (eeP) of 90% with enantiomeric ratio (E) of 62. This method can be considered as green chemistry, which can be applied to produce other enantiopure beta-blockers.

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10

Gambassi, G., M. C. Capogrossi, M. Klockow, and E. G. Lakatta. "Enantiomeric dissection of the effects of the inotropic agent, EMD 53998, in single cardiac myocytes." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 3 (March 1, 1993): H728—H738. http://dx.doi.org/10.1152/ajpheart.1993.264.3.h728.

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The effects of the thiadiazinone derivative, 5-[1-(3,4-dimethoxybenzoyl)-1,2,3,4-tetrahydrochinolin-6-yl]-6-met hyl-3,6- dihydro-2H-1,3,4-thiadiazin-2-on (EMD 53998), and of its (+)EMD 57033 and (-)EMD 57439 enantiomers, were tested on the contractile properties and cytosolic [Ca2+] ([Ca2+]i) transients of single intact guinea pig cardiac myocytes. Cells were loaded with the ester form of the fluorescent probe, indo-1, and bathed in a N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid-buffered solution at 25 degrees C (1 mM of CaCl2, 1 Hz stimulation rate). All three substances exerted a pronounced increase in twitch amplitude: the maximal effect of the racemate (380% of control value) was approximately the sum of the effects of its two enantiomers (186 and 236% of control value for the (+)- and (-)-enantiomer, respectively). The [Ca2+]i transient, measured as the 410-to-490 nm indo-1 fluorescence ratio transient after excitation, was increased by the racemate and its (-)-enantiomer (172 and 152% of control value, respectively), but was not increased by the (+)-enantiomer. The racemate and the (-)-enantiomer, but not the (+)-enantiomer, markedly reduced the contraction duration and [Ca2+]i transient duration. In unstimulated cells resting length was significantly reduced by the (+)-enantiomer, and this was accompanied by a decrease in indo-1 fluorescence; the (-)-enantiomer had no effect on either parameter. In the presence of 2,3 butanedione monoxime (BDM), which markedly reduces twitch amplitude by inhibiting cross-bridge mechanics, addition of the (+)-enantiomer restored the twitch contraction to above the pre-BDM level without augmenting the [Ca2+]i transient. In contrast, the (-)-enantiomer failed to reverse the BDM-induced contractile depression, even though it caused a significant increase of the [Ca2+]i transient. Thus, in intact cells the positive inotropic effect of EMD 53998 is due to specific properties of its enantiomers: the (-)-enantiomer has adenosine 3',5'-cyclic monophosphate-like effects (increase in amplitude and reduction of [Ca2+]i transient and contraction durations), whereas the (+)-enantiomer enhances the myofilament-Ca2+ interaction.

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Dissertations / Theses on the topic "Enantiomeric effect"

1

Piva, Olivier. "Photodeconjugaison enantioselective de systemes conjugues." Reims, 1988. http://www.theses.fr/1988REIMS001.

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2

James, Bryce. "(+/-)-Z-bisdehydrodoisynolic acid and specific enantiomers : effects on traumatic brain injury /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1459903541&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Pratt, Sarah Kathryn. "A study of the disposition of vitamin Kâ†1 and the enantiomers of warfarin in relation to pharmacodynamic response." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291736.

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Liang, Hongxi. "An investigation into the use of #beta#-cyclodextrins as additives to effect enantiometric separation by reversed phase HPLC." Thesis, Robert Gordon University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260042.

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Stanley, Jacob K. Brooks Bryan William. "Effects of chiral contaminants to aquatic organisms pharmaceuticals as model compounds for enantiomer specific ecological hazard assessment /." Waco, Tex. : Baylor University, 2006. http://hdl.handle.net/2104/5104.

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6

Smith, Doug. "Antidepressant-like Effects of Amisulpride, Ketamine, and Their Enantiomers on Differential-Reinforcement-of-Low-Rate (DRL) Operant Responding in Male C57/BL/6 Mice." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/5041.

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Major depressive disorder (MDD) is a widespread psychiatric disorder that affects millions of people worldwide and is hypothesized to occur due to impairments in several neurotransmitter systems, including the monoaminergic and glutamatergic neurotransmitter systems. Antidepressant medications targeting multiple monoamine neurotransmitters have been shown to be effective for the treatment of depression. Racemic amisulpride is an atypical antipsychotic that has been used at low doses to treat dysthymia, a mild form of depression, and functions as an antagonist at DA2/3, 5-HT2B, and 5-HT7 receptors. Recent preclinical studies have suggested that the S(+) isomer may be more critical for amisulpride’s antidepressant-like effects; however, this interpretation has not been fully characterized in comparison to the R(-) isomer. The glutamatergic system also has been shown to play a critical role in alleviating depression. Several studies have demonstrated that the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine produces rapid and sustained antidepressant-like effects in clinical trials; however, few studies have examined the degree to which ketamine’s isomers contribute to antidepressant-like effects. Fully characterizing these differences in a preclinical model of depression may offer important insight into the role of these neurotransmitter systems on depression. The present study used a 72-sec differential-reinforcement-of-low-rate (DRL) task to assess the antidepressant-like effects of amisulpride, ketamine, and their isomers in mice. The DRL 72-sec task has shown to be a reliable and sensitive screen for drugs that possess antidepressant-like activity as reflected by an increase in the number of reinforcers, a decrease in the number of responses, and a right-ward shift in the interresponse time distributions (IRTs; i.e. the elapsed time between two successive responses). For comparison, the effects of the tricyclic antidepressant imipramine and the N-methyl-D-aspartate antagonist MK-801 as positive and negative controls, respectively, were determined. Consistent with previous findings, we hypothesized that amisulpride and S(-)-amisulpride, but not R(+)-amisulpride, would produce antidepressant-like effects, and all formulations of ketamine would produce antidepressant effects. Racemic amisulpride and S(-)-amisulpride, but not R(+)-amisulpride, produced an antidepressant-like effect, evidenced by a significant increase in the number of reinforcers and a significant decrease in the number of responses. Racemic ketamine and R(-)-ketamine significantly increased the number of reinforcers and decreased the number of responses, while S(+)-ketamine significantly increased the number of reinforcers, but did not decrease the number of responses (at the doses tested). Overall, these results indicate that the racemic formulations of amisulpride and ketamine, S(-)-amisulpride, and both ketamine isomers demonstrate antidepressant-like effects as assessed in the DRL task and may be useful in a clinical context. If either of the ketamine isomers can be shown to produce fewer psychotomimetic effects in humans, then the isomers may offer a significant clinical advantage over the parent compound ketamine. Regarding amisulpride, the present results demonstrate that the S(-) isomer, but not the R(+) isomer, possess antidepressant-like activity similar to racemic amisulpride.

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7

Pham, Yen-Thu. "Passage stereoselectif des medicaments chiraux au niveau des barrieres hemato-encephalique et intestinale : application aux enantiomeres de la mefloquine (doctorat : pharmacotechnie et biopharmacie)." Paris 11, 2000. http://www.theses.fr/2000PA114821.

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8

Jamal, Eddine Jamal. "Utilisation des nucléofuges chiraux dans la réaction de méthylation énantiosélective des énolates dérivés de la glycine." Rouen, 1986. http://www.theses.fr/1986ROUES028.

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On montre, qu'il est possible d'alkyler avec une bonne énantiosélectivité des énolates prochiraux au moyen d'agents électrophiles à nucléofuges chiraux dérivés du d(+)-glucose. La glycine est ainsi transformée en alanine avec excès énantiomère atteignant 75%. Mise en évidence du rôle des substituants R2 et R3 de l'imine dérivée de l'aminoacide. C'est ainsi qu'en encombrant la région syn de la base de Schiff, les excès énantiomères passent de 0 à 70%. De même des modifications de la structure de l'agent d'alkylation ont permis d'attribuer des centres d'asymétrie importants dans le phénomène de l'induction

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9

Patel, Ankita Anil. "Examination Of A Post-Stroke Drug Treatment For Its Effect On Blood Brain Barrier Permeability, And Gene Expression Changes In The Peri-Infarct Region." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1472131819.

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Putnam, Joel Garrett. "The Elucidation of Stationary Phase Treatment Effects in Enantiomeric Separations." 2011. http://trace.tennessee.edu/utk_graddiss/1014.

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Acid/base modifiers are sometimes used as additives in the elution on columns packed with amylose tris(3,5-dimethylphenylcarbamate) stationary phase to separate enantiomers. When modifiers are removed from the mobile phase, the stationary phase is affected in ways that are not understood because of the lack of systematic studies, making the scale-up of preparative separations difficult to predict. Once a column has been exposed to these modifiers, the selectivity of certain pairs of enantiomers may change, for the better or the worse. Numerous pairs of molecules affected by this phenomenon are listed in the literature. Five pairs of these molecules were chosen, the selectivity of which changes after an acidic or basic solutions has been percolated through the column. The selectivity of the ketoprofen, 4-chlorophenylalanine methyl and ethyl esters improves after a solution of ethanesulfonic acid is percolated through the column. The selectivity of the propranolol HCl and Troger’s base increases after a solution of diiospropylethylamine is percolated through the column. The selectivity of these the 4-chlorophenylalanine ethyl ester, propranolol and Troger's base enantiomers are inversely affected by percolation of the opposite acid/base solution. This residual change in certain enantiomeric separations has been named the Memory Effect. In contrast, trans-stilbene oxide (TSO) was used as a standard to determine the column's stability because no Memory Effect is observed for this separation (the retention, enantioselectivity, and resolution remain constant). Karl Fischer titrations showed that only slight changes in the mobile phase's water content occurred, and that the water to polymer repeat unit ratio is important. Analytical studies of the stationary phase suggest that slow protonation/deprotonation of water bounded to the carbamate moiety may be responsible for the Memory Effect. It has been shown that the Memory Effect can be minimized by percolating through the column a sufficiently concentrated solution of the appropriate acid or base. Thus, columns that were unreliable for method development, due to the Memory Effect, can now be used. As a result, the scale-up of separations can be predicted and successfully performed. Finally, a test was devised to determine if a column was under the influence of the Memory Effect.

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Books on the topic "Enantiomeric effect"

1

Paradiso, Frances Lori. The central nervous system effects and pharmacokinetics of propranolol enantiomers. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1993.

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Jr, Wilson Ronald George. The effects of cannabinoid enantiomers on the cystoskeleton of pheochromocytoma cells (PC-12 cells). Ottawa: National Library of Canada, 1993.

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Kwan, Debora. The effects of acute and chronic acetaminophen dosing on the pharmacodynamics and pharmacokinetics of the (R)- and (S)- enantiomers of warfarin. Ottawa: National Library of Canada, 1993.

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Kwan, Debora. The effects of acute and chronic acetaminophen dosing on the pharmacodynamics and pharmacokinetics of the (R)- and (S)- enantiomers of warfarin. 1994.

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Book chapters on the topic "Enantiomeric effect"

1

Obermayer-Pietsch, B., C. Stiegler, H. Warnkroß, G. Obermayer, S. Sager, W. Lindner, and G. Leb. "Effects of Propranolol enantiomers in hyperthyroidism (Poster)." In New Aspects in Thyroid Diseases, edited by H. F. Deckart and E. Strehlau, 354. Berlin, Boston: De Gruyter, 1992. http://dx.doi.org/10.1515/9783110874051-047.

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Pinkus, L. M., and J. C. Gordon. "Utilization of Zacopride and its R- and S-Enantiomers in Studies of 5-HT3 Receptor “Subtypes”." In Serotonin: Molecular Biology, Receptors and Functional Effects, 439–48. Basel: Birkhäuser Basel, 1991. http://dx.doi.org/10.1007/978-3-0348-7259-1_44.

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Auth, F., I. Laszlovszky, B. Kiss, E. Kárpáti, S. Berényi, Cs Csutorás, S. Makleit, and M. Lõw. "Differential Effects of 2-(Ethylthio)Apomorphine Enantiomers on Striatal Dopamine Overflow in Vivo." In Neurochemistry, 215–19. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-5405-9_36.

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4

Ide, Soichiro, and Kazutaka Ikeda. "Distinct Roles of NMDA Receptor GluN2 Subunits in the Effects of Ketamine and Its Enantiomers." In Ketamine, 157–73. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2902-3_10.

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Gasparrini, F., D. Misiti, and C. Villani. "A Note on Temperature Effects on High-Performance Liquid Chromatographic Enantiomeric Resolution Using Chiral Stationary Phases Containing Trans-1,2-Diaminocyclohexane Derivatives." In Recent Advances in Chiral Separations, 109–16. New York, NY: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-8282-9_16.

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Taber, Douglass F. "C–H Functionalization: The Shaw Synthesis of E-δ-Viniferin." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0022.

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Thomas Lectka of Johns Hopkins University reported (J. Org. Chem. 2014, 79, 8895) a simple protocol for free radical monofluorination, exemplified by the conversion of 1 to 2. Michael K. Hilinski of the University of Virginia used (Org. Lett. 2014, 16, 6504) a catalytic amount of the ketone 4 to mediate the oxidation of 3 to 5. Oxidation of 3 with DMDO gave the regioisomeric tertiary alcohol (not illustrated). Jeung Gon Kim and Sukbok Chang of KAIST used (Chem. Commun. 2014, 50, 12073) an Ir catalyst to convert 6 selectively to the primary sulfonamide 7. Paul J. Chirik of Princeton University employed (J. Am. Chem. Soc. 2014, 136, 12108) a Co catalyst to effect the migration of the internal alkene of 8 to the terminal alkene, that then underwent dehydrogenative silylation with 9 to deliver the allyl silane 10. Jiang Cheng of Changzhou University developed (J. Org. Chem. 2014, 79, 9847) conditions for the aminoalkylation of cyclohexane 11 with 12 to give 13. Ilhyong Ryu of Osaka Prefecture University and Maurizio Fagnoni of the University of Pavia observed (Chem. Sci. 2014, 5, 2893) high selectivity in the addition of 14 to 15. Of the five possible regioisomers, 16 dominated. In another light-mediated transformation, Shin Kamijo of Yamaguchi University and Masayuki Inoue of the University of Tokyo added (Chem. Sci. 2014, 5, 4339) 17 to 18 to give 19. Huw M. L. Davies of Emory University established (J. Am. Chem. Soc. 2014, 136, 17718) conditions for the enantioselective alkylation of a methyl ether 21 with 20 to give the ester 22. Selective methyl insertion was observed even with much more complex substrates. The trichloroethyl ester was critical for this transformation. James A. Bull of Imperial College London effected (Org. Lett. 2014, 16, 4956) selective cis-arylation of the proline-derived amide 23 with 24 to give 25. E. Peter Kündig of the University of Geneva coupled (Chem. Eur. J. 2014, 20, 15021) the amine 27 with 26, then cyclized that product to the indoline 28. The enantiomeric Pd catalyst delivered the regioisomeric C–H insertion product.

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7

Taber, Douglass. "Enantioselective Construction of Alkylated Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0040.

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Carsten Bolm of RWTH Aachen developed (Angew. Chem. Int. Ed. 2008, 47, 8920) an Ir catalyst that effected hydrogenation of trisubstituted enones such as 1 with high ee. Benjamin List of the Max-Planck-Institut Mülheim devised (J. Am. Chem. Soc. 2008, 130, 13862) an organocatalyst for the enantioselective reduction of nitro acrylates such as 3 with the Hantzsch ester 4. Gregory C. Fu of MIT optimized (J. Am. Chem. Soc. 2008, 130, 12645) a Ni catalyst for the enantioselective arylation of propargylic halides such as 6. Both enantiomers of 6 were converted to the single enantiomer of 8. Michael C. Willis of the University of Oxford established (J. Am. Chem. Soc. 2008, 130, 17232) that hydroacylation with a Rh catalyst was selective for one enantiomer of the allene 9, delivering 11 in high ee. Similarly, José Luis García Ruano of the Universidad Autónoma de Madrid found (Angew. Chem. Int. Ed. 2008, 47, 6836) that one enantiomer of racemic 13 reacted selectively with the enantiomerically- pure anion 12, to give 14 in high diastereomeric excess. Ei-chi Negishi of Purdue University described (Organic Lett. 2008, 10, 4311) the Zr-catalyzed asymmetric carboalumination (ZACA reaction) of the alkene 15 to give the useful chiron 16. David W. C. MacMillan of Princeton University developed (Science 2008, 322, 77) an intriguing visible light-powered oxidation-reduction approach to enantioselective aldehyde alkylation. The catalytic chiral secondary amine adds to the aldehyde to form an enamine, that then couples with the radical produced by reduction of the haloester. Two other alkylations were based on readily-available chiral auxiliaries. Philippe Karoyan of the Université Pierre et Marie Curie observed (Tetrahedron Lett . 2008, 49, 4704) that the acylated Oppolzer camphor sultam 20 condensed with the Mannich reagent 21 to give 22 as a single diastereomer. Andrew G. Myers of Harvard University developed the pseudoephedrine chiral auxiliary of 23 to direct the construction of ternary alkylated centers. He has now established (J. Am. Chem. Soc. 2008, 130, 13231) that further alkylation gave 24, having a quaternary alkylated center, in high diastereomeric excess.

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8

Taber, Douglass. "Enantioselective Preparation of Secondary Alcohols and Amines." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0034.

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Secondary alcohols can be prepared in high enantiomeric excess by catalytic hydrogenation of ketones. Zhaoguo Zhang of Shanghai Jiaotong University has established (Organic Lett. 2007, 9, 5613) that β-keto sulfones such as 1 are suitable substrates for this hydrogenation. Reinhard Brückner of the Universität Freiburg has demonstrated (Angew. Chem. Int. Ed. 2007, 46, 6537) that the rate of hydrogenation of β-keto esters such as 3 and 5 depends on the alcohol from which the ester is derived, so 3 can be reduced to 4 in the presence of 5. Enantiomerically-pure secondary alcohols and amines can also be prepared by adding an oxygen or a nitrogen to an existing carbon skeleton. Both Srivari Chandrasekhar of the Indian Institute of Chemical Technology, Hyderabad (Tetrahedron Lett. 2007, 48, 7339) and Arumugam Sudalai of the National Chemical Laboratory, Pune (Tetrahedron Lett. 2007, 48, 8544) have taken advantage of the previously-described enantioselective α-aminoxylation of aldehydes to establish what appears to be a robust preparative route to the enantiomerically-pure epoxides such as 9 of terminal alkenes. Karl Anker Jørgensen of Aarhus University has developed (Chem. Commun. 2007, 3646) a catalyst for the enantioselective addition of 11 to nitroalkenes such as 10. Armando Córdova of Stockholm University has shown (Tetrahedron Lett. 2007, 48, 5976) that epoxy aldehydes such as 14, easily prepared by the protocol he developed, are converted by the Bode catalyst to β-hydroxy esters such as 15. Hyunsoo Han of the University of Texas, San Antonio has described (Tetrahedron Lett. 2007, 48, 7094) an improved protocol for the enantioselective conversion of primary allylic carbonates 16 to secondary amines 17. René Peters of ETH Zurich has used (Angew. Chem. Int. Ed. 2007, 46, 7704) a related procedure for the construction of aminated quaternary centers. Mukund P. Sibi of North Dakota State University has devised (J. Am. Chem. Soc. 2007, 129, 8064) a catalyst for the conjugate addition of the benzyloxyamine 20 to acyl pyrazoles, and Claudio Palomo of the Universidad de País Vasco has found (Angew. Chem. Int. Ed. 2007, 46, 8054) that a simple diphenyl prolinol catalyst will effect enantioselective α-amination of aldehydes.

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9

Taber, Douglass. "Enantioselective Preparation of Alcohols and Amines." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0035.

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Enzymatic reduction of a ketone can proceed in high enantiomeric excess, but this would require a stoichiometric amount of a reducing agent. Wolfgang Kroutil of the Karl-Franzens-Universität Graz devised (Angew. Chem. Int. Ed. 2008, 47, 741) a protocol for preparing the alcohol 2 in high ee starting from the racemic alcohol. The alcohol dehydrogenase chosen was selective for the R-alcohol, and the microorganism reduced the ketone so produced selectively to the S alcohol. James M. Takacs of the University of Nebraska established (J. Am. Chem. Soc. 2008, 130, 3734) that chiral Rh catalyzed addition of pinacolborane to a β,γ-unsaturated N-phenyl amide 3 proceeded with high enantiocontrol. The product organoborane was oxidized to the alcohol 4 . J. R. Falck of the UT Southwestern Medical Center used (J. Am. Chem. Soc. 2008, 130, 46) an organocatalyst to effect addition of phenylboronic acid to the γ-hydroxy enone 5, to give, after hydrolysis, the diol 6. John F. Hartwig of the University of Illinois effectively telescoped (Angew. Chem. Int. Ed. 2008, 47, 1928) alcohol formation and protection into a single step, by developing a procedure for the direct conversion of a primary allylic acetate 7 to the enantiomerically-enriched secondary benzyl ether 8. Tsutomu Katsuki of Kyushu University designed (Chemistry Lett. 2008, 37, 502) a catalyst for the enantioselective hydrocyanation of an aldehyde 9, by HCN transfer from the inexpensive 10. Mei-Xiang Wang of the Chinese Academy of Sciences, Beijing and Jieping Zhu of CNRS, Gif-sur-Yvette devised (Angew. Chem. Int. Ed. 2008, 47, 388) a catalyst for a complementary one-carbon homologation, the enantioselective Passerini three-component coupling of an aldehyde 12, an isonitrile 13, and an acid 14. Joseph M. Ready, also of UT Southwestern, developed (J. Am. Chem. Soc. 2008, 130, 7828) the preparation of enol benzoates such as 17 from the corresponding alkynes. Sharpless asymmetric dihydroxylation of 17 proceeded with high ee to give, after reduction, the diol 18. Toshiro Harada of the Kyoto Institute of Technology described (Angew. Chem. Int. Ed. 2008, 47, 1088) a potentially very practical enantioselective homologation, the catalyzed addition of an alkyl titanium, prepared in situ from the corresponding Grignard reagent, to the aldehyde 19, to give 21 in high ee.

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Bernardo-Bermejo, Samuel, Elena Sánchez-López, María Castro-Puyana, and María Luisa Marina. "Chiral Capillary Electrophoresis in Food Analysis." In Current and Future Developments in Food Science, 291–320. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815036152122020012.

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Chiral analysis is a powerful tool in Food Science for quality and safety assessment since the enantiomeric composition of food samples can reveal adulterations, the effects of processing and storage or give valuable information on the bioactivity, traceability or even toxicity of foods. This chapter describes the potential of Capillary Electrophoresis in the chiral analysis of food and beverages. The separation modes used in CE for the chiral analysis of food samples are described, including different strategies for sample preparation and sensitivity enhancement. The most relevant applications developed in the period from 2010 to the present are depicted and the main conclusions and future prospects are outlined.

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Conference papers on the topic "Enantiomeric effect"

1

Rincón, D. A., M. C. Daza, and M. Doerr. "Application of the quantum theory of atoms in molecules (QTAIM) to the study of the enzymatic kinetic resolution of propranolol, an amino alcohol with pharmaceutical applications." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020135.

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Propranolol, ((R,S)-1-iso-propylamino-3-(1-naphthoxy)-2-propanol), is a β-adrenergic antagonist and is commercially available as a racemic mixture. Only the S-enantiomer has the desired therapeutic effect. Therefore, many researchers have been working on strategies to obtain S-propranolol with high enantiomeric purity. One approach to carry out the acetylation of (R,S)-Propranolol using Candida antarctica lipase B, CalB. This reaction leads to an enantiomeric purity of 96% at a relatively low conversion rate of 30 %. In our research group, we have been studying this reaction. The CalB active site is composed by the triad catalytic (ASP 187, HIS 224 and SER 105) and oxyanion hole (GLN 106 and THR 40). In a previous work, a QM/MM (Quantum Mechanics / Molecular Mechanics) study was carried out, using a QM region consisting only of the catalytic triad of CalB and (R,S)-propranolol [1]. In the present study, we investigate the effect of expanding the quantum region to include the oxyanion hole and to comprehend the effect of intermolecular hydrogen bonds present between the (R,S)-propranolol and the CalB active site. The electronic structure was analyzed using the Quantum Theory of Atoms In Molecules, QTAIM. Our results show that: 1. the studied reactions are more exothermic with the inclusion of the oxyanion hole than with only the catalytic triad. 2. the intermolecular interactions between (R,S)-propranolol and the CalB active site are dominated by hydrogen bonds (HB). Among those HBs, only one between propranolol and HIS 224, and another one between THR 40 and the carbonyl oxygen of acetylated SER 105 play an important role.

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2

Gardner, A., N. Purohit, and F. Torres. "β2-Adrenergic Receptor-to-Effector Signaling: Differential Effects of Enantiomers of Albuterol in Human Airway Smooth Muscle Cells." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a1940.

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3

Gruber, Ryan B., Francis J. Golder, Scott L. Dax, Sean Peng, D. Euan MacIntyre, and James C. Mannion. "The Effects Of Doxapram Enantiomers On The Hypoxic Ventilatory Response In Adult Rats." In American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a3618.

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4

Sasaki, Tetsuo, Tomoaki Sakamoto, and Makoto Otsuka. "Effects of Low Content Enantiomer Impurity in L-histidine Crystal Observed by Terahertz Spectroscopy." In 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz). IEEE, 2019. http://dx.doi.org/10.1109/irmmw-thz.2019.8874142.

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5

Agrawal, DK, G. Cheng, and PW Kelbe. "Comparative Effects of the Enantiomers of Formoterol on Importins in Human Bronchial Smooth Muscle Cells." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a5719.

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6

Shindo, Mami, Nisha Purohit, and Alice Gardner. "Differential Effects Of Enantiomers Of Albuterol On Phosphodiesterase Signaling In Human Airway Smooth Muscle Cells." In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a6371.

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7

Jensen, Ask S., Cristian P. Pennisi, Cristian Sevcencu, Jorn B. Christensen, Jette E. Kristiansen, and Johannes J. Struijk. "Model-based analysis of the effects of thioridazine enantiomers on the rabbit papillary action potential." In 2015 Computing in Cardiology Conference (CinC). IEEE, 2015. http://dx.doi.org/10.1109/cic.2015.7411104.

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Johnson, G. J., P. C. Dunlop, M. J. Rabiet, L. A. Leis, and AH L. From. "THE DIHYDROPYRIDINE CALCIUM CHANNEL AGONIST, BAY K 8644, AND THE ANTAGONIST, NIFEDIPINE, INHIBIT U46619-INDUCED HUMAN PLATELET ACTIVATION BY COMPETITIVE BINDING TO THE THROMBOXANE A22/PGH2 RECEPTOR." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643756.

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The dihydropyridine (DP) Ca2+ channel antagonist, nifedipine (NF), inhibits platelet aggregation .in vitro and ex vivo by an undefined mechanism. Inhibition of Ca2+ influx via Ca2+ channels is a postulated mechanism, but voltage-dependent Ca2+ channels have not been demonstrated in platelets. We previously observed that NF blocked thromboxane A2 (TXA2)-induced platelet aggregation and secretion. In order to further evaluate the mechanism of DP inhibition of platelet activation, we studied the effects of NF and BAY K 8644, (BAY), a DP with opposite (agonist) effects on muscle cells, on human platelet aggregation and secretion induced by the TXA2 mimic, U46619. We also observed the effects of DP on biochemical consequences of platelet activation: cytoplasmic ionized Ca2+ ([Ca2+]i) by fura-2 fluorescence; phosphorylation of 40,000 Dalton protein (40KP) substrate of protein kinase C by SDS-PAGE and [32p] counting; TXA2 formation by RIA of TXB2. 1μM BAY and 10μM NF inhibited the 2nd wave of platelet aggregation and secretion induced by ADP or epinephrine and blocked aggregation and secretion induced by U46619. A Schild plot gave a slope of -1 indicating competitive inhibition of U46619 by BAY (K1[=0.7μM).BAY and NF also blocked U46619-induced phosphorylation of 40KP, rise in [Ca2+]i and TXB2 formation. The (+)-(R) enantiomer of BAY (BAY+) was responsible for BAY inhibition. BAY, BAY(+), and the R enantiomer of another DP, 202-791, all functioned as competitive antagonists of [3H]-U4661 9 binding (K1[ for BAY=2.8 μM-comparable to known receptor antagonists, 13-azaprostanoic acid and BM 13.177; K1 for BAY(+)=0.69μM). Neither BAY nor NF inhibited[3H]-yohimbine binding to α adrenergic receptors.NF, BAY, BAY(+) and BAY(-) in nM concentrations slightly stimulated platelet aggregation,secretion and biochemical events induced by U46619 similar to their effects on muscle. Therefore, DP's do not inhibit platelet activation by blocking voltage-dependent Ca2+ channels. The mechanism of DP inhibition of TXA2-induced platelet activation is stereoselective, competitive binding to the TXA2/PGH2 receptor. DP's may exert similar effects on TXA2-induced vascular smooth muscle contraction.

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Zhao, X., J. Yi, and S. N. Burokur. "Direct dark mode excitation of electromagnetically induced reflection effect in enantiomer-based metasurface and its application in terahertz detection." In 2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting. IEEE, 2020. http://dx.doi.org/10.1109/ieeeconf35879.2020.9330491.

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10

Zapata-Romero, Gilberto A., Markus Doerr, and Martha C. Daza. "Enantioselective lipase-catalyzed O-acylation of (RS)-propranolol: analysis of the hydrogen bonds essential for catalysis." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020131.

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We investigated the effect of the acyl group size in the enantioselectivity of the acylation of propranolol, an amino alcohol used as β-adrenergic blocking agent. We applied a methodology frequently used to model enantioselectivity that is based on the hydrogen bonds present in the tetrahedral intermediate, which occurs in lipase-catalyzed reactions. We sampled the conformations of the tetrahedral intermediate corresponding to the esterification of both enantiomers of propranolol with ethanoyl and butanoyl, employing molecular dynamics simulation together with a quantum mechanics/molecular mechanics approach. We found that the population of these hydrogen bonds provides insight into the mechanism of the reaction. However, they are not conclusive about the role of the acyl group in the enantioselectivity. For both acyl groups, we found that the reaction from the Michaelis complex to the tetrahedral intermediate is more favorable for (R)-propranolol and the reaction from the tetrahedral intermediate to the enzyme/product complex is more favorable for (S)-propranolol.

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