摘要:

AbstractEnantiomeric (S,S)‐ and (R,R)‐bis(1‐phenylethyl)diamidomethylphosphonates, the phosphorus atom being prochiral, have been synthesized, starting from the methanephosphonic acid dichloride and corresponding chiral amines. The splitting observed in the31P‐NMR spectra of their nonracemic mixtures may be accounted for the self‐discrimination of chiral species. This effect can be very useful for enantiomeric analysis of amines based on coupling reactions with methanephosphonic acid dichloride. © 1994 Wiley

ISSN:0899-0042    

DOI:10.1002/chir.530060103

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe influence of a single oral dose of 30 mg nicardipine on the pharmacokinetics of (R)‐ and (S)‐propranolol, given orally asrac‐propranolol 80 mg, was studied in 12 healthy volunteers. The plasma concentrations were higher for the (S)‐enantiomer than for the (R)‐enantiomer. The Cloand the Cl′introf (S)‐propranolol were significantly lower than the Cloand Cl′introf (R)‐propranolol. The unbound fraction of (R)‐propranolol was significantly higher than that of (S)‐propranolol. Coadministration of nicardipine significantly increased the AUC andCmaxand significantly decreased the Cloand Cl′intrfor unbound drug of (R)‐ and (S)‐propranolol. These changes were more important for (R)‐ than for (S)‐propranolol. The protein binding was not altered by nicardipine. The enantioselective effect of nicardipine on the metabolic clearance of propranolol appears to be due to an interaction at the level of the metabolizing enzymes. The effect on blood pressure ofrac‐propranolol was little affected when nicardipine was coadministered withrac‐propranolol, and its bradycardic effect

ISSN:0899-0042    

DOI:10.1002/chir.530060104

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe steady‐state kinetic parameters for pig liver carboxylesterase (PLE)‐catalyzed hydrolysis of the prochiral substrate dimethyl phenylmalonate (DMPM) (product enantioselectivity) and the separate enantiomers of three chiral 2‐phenylpropionic acid esters (substrate enantioselectivity) were measured at seven temperatures between 288 K and 312 K. Arrhenius plots of turnover numbers against the reciprocal of experimental temperatures yielded enthalpies and entropies of activation at enzyme saturation. (+)‐(S)‐methyl‐2‐phenylpropionate, (+)‐(S)‐4‐nitrophenyl 2‐phenylpropionate, and both enantiomers of phenyl 2‐phenylpropionate showed very similar activation enthalpies and entropies (approximately 50 kJ mol−1and −50 J mol−1K−1, respectively), but differences were observed for (−)‐(R)‐methyl 2‐phenylpropionate and (−)‐(R)‐4‐nitrophenyl 2‐phenylpropionate. Whereas the entropies of activation of all 2‐phenylpropionates were negative, positive entropies of activation were measured in the formation of monomethyl phenylmalonate enantiomers from DMPM. Enthalpy–entropy compensation analysis of the data indicates a common mechanism of PLE substrate and product enantiospecificity

ISSN:0899-0042    

DOI:10.1002/chir.530060105

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractMale C57BL/6 mice were exposed to 1% (w/w) (+)‐ or (−)‐2‐ethylhexanoic acid or an equimolar mixture of these enantiomers in their diet for 4 or 10 days. A significant increase in liver weight and a 2‐ to 3‐fold increase in the protein content of the mitochondrial fraction were seen in all cases. Peroxisomal palmitoyl‐CoA oxidation was increased 2‐ to 3.5‐fold after 4 days of treatment and 4‐ to 5‐fold after 10 days, while the corresponding increases in peroxisomal lauroyl‐CoA oxidase activity were 2‐ to 3‐fold and 9‐ to 12‐fold, respectively. Peroxisomal catalase activity was unchanged, whereas the microsomal and cytosolic activities were increased 2‐ to 3‐fold and 6‐ to 16‐fold, respectively. These treatments also induced microsomal ω‐hydroxylation of lauric acid 7‐fold and soluble epoxide hydrolase activity in the mitochondrial and cytosolic fractions, as well as microsomal epoxide hydrolase activity about 50–100%. The only significant differences observed between the effects of (+)‐2‐ethylhexanoic acid and its (−)‐enantiomer were on peroxisomal palmitoyl‐CoA oxidation and lauroyl‐CoA oxidase activity after 4 days of treatment. In both these cases the (+)‐enantiomer resulted in increases which were 50–75% gre

ISSN:0899-0042    

DOI:10.1002/chir.530060106

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe preconditions are outlined for enantioselective separations in capillary electrophoresis (CE) with chiral selectors as additives to the background electrolyte. Free solution capillary electrophoresis conditions are characterised by a single solution phase. Chiral separations are reviewed by selector type (chiral ligand exchange, cyclodextrins, crown ethers, glycoproteins) with the extensive studies on cyclodextrins grouped into sections on amino acids, pharmaceuticals, and speciality chemicals, optimisation, biological fluids, and quantitative aspects. In micellar electrokinetic capillary chromatography, enantioselective discrimination occurs by partition in a two‐phase system, with a chiral micellar phase as selector. Optimum separation conditions can be readily predicted for a given selector–selectand combination, and absolute values of binding constants determined by CE. Advantages of CE in comparison with HPLC using a chiral stationary phase include robust, rapid assays and the use of small volumes of aqueous solutions; disadvantages include less favourable detection limits. © 1994 Wiley‐Lis

ISSN:0899-0042    

DOI:10.1002/chir.530060107

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

摘要:

Abstract(Z)‐1,1‐Dichloro‐2‐(4‐benzyloxyphenyl)‐2,3‐bis(4‐methoxyphenyl)cyclopropane (5), a potential antitumor agent designed to treat breast cancer, was prepared in three steps. A stereospecific palladium‐catalyzed cross coupling reaction which provided the intermediate (Z)‐triaryl alkene4was a crucial step in the synthesis. Makosza phase transfer reaction on4gave the enantiomeric (Z)‐dichlorocyclopropane derivatives5which were resolved by semipreparative HPLC on a chiral stationary phase consisting of amylose tris‐3,5‐dimethylphenyl carbamate coated on silica ge

ISSN:0899-0042    

DOI:10.1002/chir.530060108

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530060109

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY

ISSN:0899-0042    

DOI:10.1002/chir.530060102

出版商:Alan R. Liss, Inc.    

年代:1994

数据来源: WILEY