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  • 31
    Electronic Resource
    Electronic Resource
    Distribution of the enantiomers of hydroxychloroquine and its metabolites in ocular tissues of the rabbit after oral administration of racemic-hydroxychloroquine (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 347-354 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective tissue sequestration ; hydroxychloroquine stereoisomers ; cornea ; iris ; retina ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The disposition of the enantiomers of hydroxychloroquine (HCQ) and its major metabolites in ocular tissues of rabbits has been studied. Both albino, New Zealand White (NZW), and pigmented animals were administered daily oral doses of rac-HCQ, (S)-HCQ or (R)-HCQ (20 mg/kg) over 1, 6, or 8 day periods or for 8 days followed by a 7-day washout period. At the end of the study periods, plasma and whole blood samples were collected and the rabbits were sacrificed. The eyes were collected, the aqueous humor removed with a syringe, and the eyes separated into the cornea, lens, vitreous body, iris, choroid-retina, sclera, and conjunctiva. The concentrations of (R)-HCQ, (S)-HCQ, and their respective metabolites were determined using a validated enantioselective liquid chromatographic assay. The data from these studies indicate that HCQ accumulated in both pigmented and nonpigmented ocular tissues. In the pigmented tissues, HCQ and its metabolites were bound to melanin and the binding was not enantiospecific. In the nonpigmented tissues and in the iris and retina-choroid of the NZW rabbits, the accumulation appeared to be the result of a reversible and enantioselective binding of HCQ and its metabolites to an unidentified biopolymer present in these ocular tissues. © 1994 Wiley-liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530060419
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  • 32
    Electronic Resource
    Electronic Resource
    Determination of the enantiomeric composition of mexiletine and its four hydroxylated metabolites in urine by enantioselective capillary gas chromatography (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 30-34 
    Details
    ISSN: 0899-0042
    Keywords: gas chromatography ; modified β-cyclodextrin column ; chiral separation ; assay ; mexiletine ; hydroxylated metabolites ; urine ; conjugation/deconjugation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of mexiletine and four of its hydroxylated metabolites were directly separated by capillary gas chromatography using a heptakis(6-O-tert-butyl-dimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin column. The method was applied to the analysis of urine samples from cancer patients who were treated with racemic mexiletine as part of a study of the use of mexiletine in the relief of neuropathic pain. Samples analyzed before and after deconjugation of the urine with β-glucuronidase/arylsulfatase showed a high stereoselectivity in the formation and conjugation of these compounds. © 1996 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 33
    Electronic Resource
    Electronic Resource
    Chiral resolution of some antimalarial agents by sub- and supercritical fluid chromatography on an (S)-naphthylurea stationary phase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 173-180 
    Details
    ISSN: 0899-0042
    Keywords: (S)-naphthylurea chiral stationary phase ; subcritical fluid chromatography ; supercritical fluid chromatography ; antimalarial agents ; enantiomeric separations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of mefloquine, halofantrine, enpiroline, quinine, quinidine, chloroquine and primaquine is studied by subcritical fluid chromatography on a (S)-naphthylurea column (250 mm × 4.6 mm ID) with a subcritical mobile phase composed of carbon dioxide, methanol and triethylamine (flow rate of 3 ml/min). Except for primaquine and chloroquine, each enantiomer was separated at a temperature between 40 and 60°C, and at a pressure below 15 MPa. A 98/2, v/v CO2/methanol 0.1% triethylamine mixture allowed the separation of halofantrine enantiomers while the enantiomers of the more polar metabolite (N-desbutylhalofantrine) were separated with a 80-20 v/v mixture as used for mefloquine, enpiroline, quinine and quinidine. The influence of temperature, pressure and of the nature of the mobile phase is discussed. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050313
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  • 34
    Electronic Resource
    Electronic Resource
    Influence of specific albumin ligand markers used as modifiers on the separation of benzodiazepine enantiomers by chiral liquid chromatography on a human serum albumin column (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 71-77 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; mobile phase modifier ; digoxin ; warfarin ; medium chain fatty acid ; bilirubin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Specific ligand markers for the various binding sites of human serum albumin (HSA) have been described in the literature. Some of these markers (medium chain fatty acids, warfarin, digoxin, and bilirubin) were used as mobile phase modifiers. Using a high performance liquid chromatographic (HPLC) column containing HSA as stationary phase, their influence was investigated on the separation in this phase of the enantiomers of three benzodiazepines (temazepam, oxazepam, and lorazepam). Displacement effects were observed with medium chain fatty acids. This influence was proportional to the chain length and to the concentration of acid. Allosteric cooperative effects were noted with digoxin for the three benzodiazepines. Both displacement and cooperative effects were observed with warfarin. Stereoselectivity was decreased for temazepam and oxazepam and increased for lorazepam. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050206
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  • 35
    Electronic Resource
    Electronic Resource
    Enantioselective separation of enantiomeric amides on three amylose-based chiral stationary phases: Effects of backbone and carbamate side chain chiralities (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 173-177 
    Details
    ISSN: 0899-0042
    Keywords: chiral high-performance liquid chromatography ; polysaccharides ; structure-retention relationships ; amides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of enantiomeric amides have been chromatographed on three amylose-based chiral stationary phases (CSPs): amylose tris(3,5-dimethylphenylcarbamate) (AD-CSP), amylose tris (S-phenylethylcarbamate) (AS-CSP), and amylose tris(R-phenylethyl-carbamate) (AR-CSP). The relative retentions and enantioselectives of the solutes on the three CSPs were compared and basic structure-retention relationships developed to describe the chromatographic results. The data indicate that for these solutes the observed elution order was a function of the chirality of the amylose backbone, while the magnitude of the enantioselective separations was affected by the chirality of the carbamate side chain. Chirality 9:173-177, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 36
    Electronic Resource
    Electronic Resource
    Immobilized serum albumin: Rapid HPLC probe of stereoselective protein-binding interactions (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 263-268 
    Details
    ISSN: 0899-0042
    Keywords: protein binding ; stereoselectivity ; immobilized human serum albumin ; HPLC chiral stationary phase ; chiral drugs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A human serum albumin-based HPLC chiral stationary phase (HSA-CSP) has been examined as a tool to investigate binding of chiral drugs to HSA and drug-drug protein-binding interactions. Rac-oxazepam hemisuccinate (OXH) was used as a model compound and the chromatographic retention (k′) of its enantiomers was determined after addition of displacers to the mobile phase. Compounds known to bind at the same site as OXH and at different sites were tested for their displacing capacities. Competitive binding interactions between the OXH enantiomers and displacers in the mobile phase were reflected by decreases in the k′s of (R)- and (S)-OXH. The results indicate that retention on the HSA-CSP accurately reflects binding to native HSA and the technique can determine enantioselective and competitive binding interactions at specific sites on HSA. The HSA-CSP was also able to recognize separate binding areas for (S)- and (R)-OXH.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020412
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  • 37
    Electronic Resource
    Electronic Resource
    Editorial: Chirality receives award from the association of american publishers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 341-341 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040602
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  • 38
    Electronic Resource
    Electronic Resource
    Enantioselective separation of cyclic chiral ketones and their corresponding diastereomeric alcohols by HPLC on chiral and chiral/chiral coupled stationary phases (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 551-555 
    Details
    ISSN: 0899-0042
    Keywords: amylose tris-3,5-dimethylphenyl carbamate CSP {AD-CSP} ; cellulose tris-3,5-dimethylphenyl carbamate CSP {ODH-CSP} ; enantioselective HPLC ; coupled column chromatography ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective HPLC methods have been developed for the resolution of (RS)-2-phenylcyclohexanone (compound 1) and (RS)-2-phenyltetrahydropyran-4-one (compound 4) and the diastereoselective and enantioselective separations of their respective cis- and trans-alcohols; reduction of compound 1 yields trans- and cis-2-phenyl-1-cyclohexanol (compounds 2 and 3, respectively) and reduction of compound 4 yields trans- and cis-2-phenyl-tetrahydropyran-4-ol (compounds 5 and 6, respectively). Compounds 1, 2, and 3 were stereochemically resolved using a chiral stationary phase (CSP) based upon amylose tris(3,5-dimethylphenyl carbamate) coated on 10 μm silica-gel (Chiralpak AD-CSP). Compounds 4, 5, and 6 were stereochemically resolved on a coupled column system where a column containing a CSP based upon cellulose tris(3,5-dimethylphenyl carbamate) coated on 5 μm silica (Chiralcel OD-H-CSP) was coupled in series to the AD-CSP. The strategy employed in the identification of the peaks in the respective chromatograms is also discussed in this presentation. Chirality 8:551-555, 1996. © 1997 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 39
    Electronic Resource
    Electronic Resource
    Determination of the enantiomers of albuterol in human and canine plasma by enantioselective high-performance liquid chromatography on a teicoplanin-based chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 484-491 
    Details
    ISSN: 0899-0042
    Keywords: salbutamol ; chiral separation ; validated assay ; fluorescence detection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive enantioselective high-performance chromatographic (HPLC) method was developed and validated to determine low levels of (-)-R and (+)-S-albuterol in plasma. Baseline resolution was achieved by using a teicoplanin-based chiral stationary phase with a polar organic mobile phase consisting of methanol/acetonitrile/glacial acetic acid/diethylamine, 40:60:0.3:0.2, (v/v/v/v) and a flow-rate of 1.0 ml/min. Enantioselectivity (α) equaled 1.18 and resolution (Rs) equaled 1.8. By using fluorescence detection maximized at 230 and 310 nm for excitation and emission, respectively, concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Initially, the method was applied to plasma samples from a small single-dose inhalation study of racemic albuterol in a human volunteer and, later, to in vivo samples from a canine inhalation study of the single enantiomer, (-)-R-albuterol. Results from the canine study showed that no chiral inversion of (-)-R-albuterol occurs in the dog. Chirality 10:484-491, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 40
    Electronic Resource
    Electronic Resource
    The stereochemical resolution of the enantiomers of aspartame on an immobilized α-chymotrypsin hplc chiral stationary phase: The effect of mobile-phase composition and enzyme activity (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 32-37 
    Details
    ISSN: 0899-0042
    Keywords: aspartame stereoisomers ; chiral separations ; column liquid chromatography ; chymotrypsin on silica ; binding sites ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective and diastereoselective resolutions of the stereoisomers of Nα-aspartyl-phenylalanine 1-methyl ester (APME) have been accomplished on an HPLC chiral stationary phase based upon α-chymotrypsin (the ACHT-CSP) with observed enantioselectivities (α1) for the DL-/LD-enantiomers of as high as 29.17 and for the DD-/LL-enantiomers of as high as 28.97. In addition, the effect on the chromatographic retention of the APME stereoisomers of the activity of the ACHT and the composition of the mobile phase - structure of the anionic component, molarity, and pH - have been studied. The results of this study suggest that the aspartyl moiety and/or the aspartyl-phenylalanine amide linkage play key roles in the observed enantioselectivity; the APME stereoisomers containing L-phenylalanine, i.e., DL- and LL-APME, bind at a different site in the ACHT molecule (the L-Phe site) than the APME stereoisomers containing D-phenylalanine (the D-Phe site); and the observed enantioselectivity is a measure of the difference in the binding affinities at the two sites rather than the consequence of differential affinities at a single site.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020105
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