The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Verapamil (VER) is commercialized as a racemic mixture of the (+)‐(R)‐VER and (−)‐(S)‐VER enantiomers. VER is biotransformed into norverapamil (NOR) and other metabolites through CYP‐dependent pathways. N‐hexane is a solvent that can alter the metabolism of CYP‐dependent drugs. The present study investigated the influence of n‐hexane (nose‐only inhalation exposure chamber at concentrations of 88,...
Triadimefon is a systemic agricultural fungicide of the triazole class whose major metabolite, triadimenol, also a commercial fungicide, provides the majority of the actual fungicidal activity, i.e., inhibition of steroid demethylation. Both chemicals are chiral: triadimefon has one chiral center with two enantiomers while its enzymatic reduction to triadimenol produces a second chiral center and...
The everted rat intestinal‐sac model was utilized to assess the effect of post‐prandial conditions on the stereoselective intestinal metabolism of halofantrine to its active metabolite desbutylhalofantrine. Everted intestinal sacs were incubated with (±)‐halofantrine HCl in the presence of simulated bile solution (containing lecithin, lipase and cholesterol) and lipids to mimic post‐prandial conditions...
The objective of this work was to study the stereoselectivity in excretion of tetrahydropalmatine (THP) enantiomers by rats and identify the metabolites of racemic THP (rac‐THP) in rat urine. Urine and bile samples were collected at various time intervals after a single oral dose of rac‐THP. The concentrations of THP enantiomers in rat urine and bile were determined using a modification of an achiral–chiral...
The transport and uptake of individual propranolol (PPL) enantiomers were studied in human intestinal Caco‐2 cell monolayers, and a reversed‐phase HPLC‐UV assay was used for quantitative analysis. S‐PPL and R‐PPL across Caco‐2 cell monolayers was determined in the concentrations range of 10–500 μM in both apical (AP) to basolateral (BL) and BL to AP directions. S‐PPL exhibited greater permeability...
Using exciton‐coupled circular dichroism (ECCD) spectroscopy, our lab was able to differentiate between the two enantiomers of methamphetamine using a commercially available porphyrin tweezer as an achiral host. The host–guest complex formed with (+)‐(S)‐methamphetamine produced a negative bisignate‐shaped ECCD spectrum, whereas the complex formed with (−)‐(R)‐methamphetamine produced a positive one...
The hyphenation of enantioselective capillary gas chromatography and mass spectrometry is not always sufficient to distinguish between structural isomers, thus requiring peak identification by NMR spectroscopy. Here the first online coupling of enantioselective capillary gas chromatography with proton nuclear resonance spectroscopy is described for the unfunctionalized chiral alkane 2,4‐dimethylhexane...
Dobutamine is a cardiotonic agent, developed as a racemate more than 30 years ago. The compound soon got the label “the β1‐selective adrenoceptor agonist”. However, a closer examination of the enantiomers showed that (+)‐dobutamine is predominantly a β1‐ and β2‐adrenoceptor agonist with modest selectivity whereas (−)‐dobutamine is predominantly an α1‐adrenoceptor agonist. Nevertheless, rac dobutamine...
The resolution of chiral compound‐forming systems using hybrid processes was discussed recently. The concept is of large relevance as these systems form the majority of chiral substances. In this study, a novel hybrid process is presented, which combines pertraction and subsequent preferential crystallization and is applicable for the resolution of such systems. A supported liquid membrane applied...
Tramadol (T) is available as a racemic mixture of (+)‐trans‐T and (−)‐trans‐T. The main metabolic pathways are O‐demethylation and N‐demethylation, producing trans‐O‐desmethyltramadol (M1) and trans‐N‐desmethyltramadol (M2 ) enantiomers, respectively. The analgesic effect of T is related to the opioid activity of (+)‐trans‐T and (+)‐M1 and to the monoaminergic action of (+/−)‐trans‐T. This is the...
Lipocrine has been selected as an effective candidate for in vivo investigation because of its multiple biological properties, namely inhibition of AChE and BChE activities, inhibition of AChE‐induced Aβ aggregation, and ability to protect cells against reactive oxygen species. To evaluate the possibility for lipocrine to become a lead and to be developed as a multipotent drug for the treatment of...
Carvedilol is an antihypertensive drug available as a racemic mixture. (−)‐(S)‐carvedilol is responsible for the nonselective β‐blocker activity but both enantiomers present similar activity on α1‐adrenergic receptor. To our knowledge, this is the first study of carvedilol enantiomers in human plasma using a chiral stationary phase column and liquid chromatography with tandem mass spectrometry. The...
(1R, 3R)‐1‐(1, 3‐Benzodioxol‐5‐yl)‐2‐(chloroacetyl)‐2, 3, 4, 9‐tetrahydro‐1H‐pyrido[3, 4‐b]indole‐3‐carboxylic acid methyl ester ((1R, 3R)‐Cpe) is a key intermediate used in the synthesis of tadalafil, a highly selective phosphodiesterase type‐5 inhibitor. In the present study, a chiral high‐performance liquid chromatography method was developed for the simultaneous determination of diastereoisomeric...
This work reports the result of the enantioselective disposition of pantoprazole, omeprazole, and lansoprazole in a same group of Brazilian health subjects. Ten nongenotyped healthy subjects were used for this study. Each subject received a single oral dose of 80 mg of pantoprazole, 40 mg of omeprazole, and 30 mg of lansoprazole, and the plasma concentrations of the enantiomers were measured for 8...
Local anesthetics are useful probes of ion channel function and structure. Stereoselective interactions are especially interesting because they can reveal three‐dimensional relationships between drugs and channels with otherwise identical biophysical and physicochemical properties. Furthermore, stereoselectivity suggests direct and specific receptor‐mediated action, and identification of such stereospecific...
Metoprolol is available for clinical use as a racemic mixture. The S‐(−)‐metoprolol enantiomer is the one expressing higher activity in the blockade of the β1‐adrenergic receptor. The α‐hydroxymetoprolol metabolite also has activity in the blockade of the β1‐adrenergic receptor. The present study describes the development and validation of a stereoselective method for sequential analysis of metoprolol...
Templated self‐sorting on surfaces has been introduced recently as a new approach to construct multicomponent architectures directly on solid oxide surfaces. In this process, two‐dimensional information placed on the surface is transcribed into three‐dimensional architectures with up to 97% intrinsic templation efficiency. Previously, we have shown that isosteric partners of different color do neither...
Fluoxetine is used clinically as a racemic mixture of (+)‐(S) and (–)‐(R) enantiomers for the treatment of depression. CYP2D6 catalyzes the metabolism of both fluoxetine enantiomers. We aimed to evaluate whether exposure to gasoline results in CYP2D inhibition. Male Wistar rats exposed to filtered air (n = 36; control group) or to 600 ppm of gasoline (n = 36) in a nose‐only inhalation exposure chamber...
Cyclodextrin‐modified micellar electrokinetic chromatography (CD‐MEKC) method was developed for simultaneous enantioseparation of three imidazole drugs namely tioconazole, isoconazole and fenticonazole. Three easily available and inexpensive cyclodextrins namely 2‐hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD), 2‐hydroxypropyl‐γ‐cyclodextrin (HP‐γ‐CD) and heptakis(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DM‐β‐CD)...
The aim of the present study was to elucidate the differences in the plasma concentration of two enantiomers of donepezil in Chinese patients with Alzheimer's disease (AD) and investigate in vitro stereoselective metabolism and transport. Donepezil enantiomers were separated and determined by LC‐MS/MS using D5‐donepezil as an internal standard on a Sepax Chiralomix SB‐5 column. In vitro stereoselective...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.