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  • 1
    Digitale Medien
    Digitale Medien
    Calmodulin discriminates between the two enantiomers of the receptor-operated calcium channel blocker sk&f 96365: A study using 1H-NMR and chiral HPLC (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 229-232 
    Details
    ISSN: 0899-0042
    Schlagwort(e): receptor-operated calcium channel antagonist ; 1H NMR ; chiral HPLC ; calmodulin ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-{β-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl}-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530020407
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Species differences in the stereoselectivity of N-oxygenation of N-ethyl-N-methylaniline in vitro (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 430-440 
    Details
    ISSN: 0899-0042
    Schlagwort(e): N-ethyl-N-methylaniline N-oxide ; chiral nitrogen centre ; flavin-containing monooxygenase ; stereoselective metabolic N-oxidation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The prochiral tertiary amine N-ethyl-N-methylaniline (EMA) is known to be stereoselectively N-oxygenated in the presence of hepatic microsomal preparations. This biotransformation is thought to be mediated predominantly by the flavin-containing monooxygenase (FMO) enzyme system. In order to characterise this reaction further, the in vitro metabolism of EMA in the presence of hepatic microsomal preparations derived from a number of laboratory species has been examined. EMA N-oxide formation was stereoselective with respect to the (-)-S-enantiomer in the presence of microsomal preparations from all species examined, with the degree of selectivity decreasing in the order of rabbit 〉 rat ∼ LACA mouse ∼ DBA/2Ha mouse 〉 guinea-pig 〉 dog. The enantiomeric composition of the metabolically derived EMA N-oxide appeared to be determined solely by the differential rate of formation of the two enantiomers as opposed to any differences in affinities for the substrate in its pro-R and pro-S conformations. The use of enzyme inhibitors, activators and inducers indicated that EMA N-oxide formation was predominantly mediated by FMO in the presence of rabbit hepatic microsomes and that these agents did not generally affect the stereochemical outcome of the biotransformation. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Species variability in the stereoselective N-oxidation of pargyline (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 91-97 
    Details
    ISSN: 0899-0042
    Schlagwort(e): pargyline N-oxide ; chiral nitrogen centre ; flavin-containing monooxygenase ; chiral stationary phase ; high-performance liquid chromatography ; Chiralcel OD ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The monoamine oxidase inhibitor pargyline (N-benzyl-N-methyl-2-propynylamine) is known to undergo extensive in vitro microsomal N-oxidation, thought to be mediated predominantly by the flavin-containing monooxygenase (FMO) enzyme system. Formation of the pargyline N-oxide (PNO) metabolite creates a chiral nitrogen centre and thus asymmetric oxidation is possible. This study describes a reverse-phase high-performance liquid chromatographic (HPLC) method for the quantitation of PNO and a chiral-phase HPLC method for the determination of the enantiomeric ratio of PNO. In vitro microsomal N-oxidation of pargyline was found to be highly steroselective in a number of species, with the (+)-enantiomer being formed preferentially. This metabolic transformation was stereospecific when purified porcine hepatic FMO was used as the enzyme source. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530060209
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  • 4
    Digitale Medien
    Digitale Medien
    Investigations into the chirality of the metabolic sulfoxidation of cimetidinePresented at the Fourth International Symposium on Chiral Discrimination 1993, Montreal, Canada. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 6 (1994), S. 607-614 
    Details
    ISSN: 0899-0042
    Schlagwort(e): cimetidine ; sulfoxidation ; urinary metabolite ; enantiomeric composition of cimetidine sulfoxide ; sequential achiral - chiral high-performance liquid chromatography ; preparative chromatographic resolution ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The individual enantiomers of cimetidine sulfoxide were resolved by preparative chromatography using a Chiralcel OC stationary phase and were characterized by the determination of optical rotation and circular dichroism spectra. Cimetidine sulfoxide was isolated from the urine of two healthy male volunteers following oral administration of cimetidine (400 mg). Urine was collected every 2 h for 12 h postdosing, after which time HPLC analysis indicated negligible recovery of the drug as the sulfoxide. Some 7% of the dose was recovered as cimetidine sulfoxide over this period. The enantiomeric composition of cimetidine sulfoxide was determined by sequential achiral - chiral chromatography using the OC phase. Over the collection period the enantiomeric ratio was found to be constant in all samples at (+/-) of 71 ± 2.5:29 ± 2.5. The enantiomeric composition of cimetidine sulfoxide was also determined in rat urine (24 h) following the administration of cimetidine (30 mg/kg po) to male Wistar rats (n = 7). The enantiomeric ratio in this case was found to be (+/-) 57 ± 2.3:43 ± 2.3. These preliminary data indicate that sulfoxidation of cimetidine is stereoselective with respect to the (+)-enantiomer and that species variation in enantiomeric composition occurs. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.530060802
    Standort Signatur Einschränkungen Verfügbarkeit
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