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1.
A.Q.H. Habets-Crützen S.J.N. Carlier J.A.M. de Bont D. Wistuba V. Schurig S. Hartmans J. Tramper 《Enzyme and microbial technology》1985,7(1):17-21
Resting cells of ethene grown Mycobacterium 2W produced 1,2-epoxypropane stereospecifically from propene as revealed by optical rotation, 1H n.m.r. using a chiral shift reagent, and also by complexation gas chromatography involving a glass capillary column coated with an optically active metal chelate. The gas-liquid chromatography method allowed the rapid screening of 11 strains with regard to stereospecific formation of 1,2-epoxypropane, 1,2-epoxybutane and 1-chloro-2,3-epoxypropane. Bacteria grown on either ethene, propene or butadiene all predominantly produced the R form of 1,2-epoxypropane from propene and 1,2-epoxybutane from 1-butene while the strains tested for 1-chloro-2,3-epoxypropane production from 3-chloro-1-propene predominantly accumulated the S enantiomer. 相似文献
2.
Enantiomers of diastereomeric benzo[a]pyrene (BP) diol-epoxides, r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydro-BP (BP 7,8-diol-anti-9,10-epoxide), r-7,t-8-dihydroxy-c-9,10-epoxy-7,8,9,10-tetrahydro-BP (BP 7,8-diol-syn-9,10-epoxide), r-9,t-10-dihydroxy-t-7,8-epoxy-7,8,9,10-tetrahydro-BP (BP 9,10-diol-anti-7,8-epoxide), and several 7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrenes (BP tetrols) were resolved by high-performance liquid chromatography (HPLC) using columns packed with either (R)-N-(3,5-dinitrobenzoyl)phenylglycine[(R)-DNBPG] or (S)-N-(3,5-dinitrobenzoyl)leucine [(S)-DNBL], which is either ionically or covalently bonded to gamma-aminopropylsilanized silica. Resolution of enantiomers was confirmed by ultraviolet-visible absorption and circular dichroism spectral analyses. Resolved enantiomers of BP diol-epoxides were each hydrolyzed in acidic solution to a pair of diastereomeric tetrols which were separated by reversed-phase HPLC. Absolute stereochemistries of enantiomeric diol-epoxides were deduced by the absolute configuration of their hydrolysis products. 相似文献
3.
HPLC and 1H-NMR methods for the quantitation of the (R)-enantiomer in (?)-(S)-timolol maleate were developed and validated. The HPLC method requires a 25 cm × 4.6 mm 5 μm Chiracel OD-H (cellulose tris-3,5-dimethylphenylcarbamate) column, a mobile phase of 0.2% (v/v) diethylamine and 4% (v/v) isopropanol in hexane at a flow rate of 1 ml/min and UV detection at 297 nm. A system suitability test was devised to verify the separation of the (R)- and (S)-enantiomers of timolol from other drug-related impurities. The NMR method requires the use of a high-field NMR spectrometer (>360 MHz) and a chiral solvating agent, (?)-(R)-2,2,2-trifluoro-1-(9-anthrylethanol) (R-TFAE). The limits of quantitation were 0.05% and 0.2% (m/m) for HPLC and NMR, respectively. The methods were applied to the determination of the (R)-enantiomer in eight lots of raw material. The results for the two methods were in very good agreement, with results ranging from 0.1 to 4.1% (m/m) by HPLC and none detected to 4.3% (m/m) by NMR. The USP method for specific rotation was found to be unsuitable for detecting the presence of low levels of the (R)-enantiomer in (?)-(S)-timolol maleate. © 1994 Wiley-Liss, Inc. 相似文献
4.
rac-Bupivacaine HCl was infused intravenously to constant arterial blood drug concentrations in sheep using a regimen of 4 mg/min for 15 min followed by 1 mg/min to 24 h. At 24 h, arterial blood was sampled, the animal was killed with a bolus of KCl solution, then rapidly dissected and samples were obtained from heart, brain, lung, kidney, liver, muscle, fat, gut, and rumen. Tissue:blood distribution coefficients for (+)-(R)-bupivacaine exceeded those of (?)-(S)-bupivacaine (P < 0.05) for heart, brain, lung, fat, gut, and rumen by an overall mean of 43%. Blood:plasma distribution coefficients of (?)-(S)-bupivacaine exceeded those of (+)-(R)-bupivacaine by a mean of 29% and this offset the tissue:blood distribution coefficients so that the previously significant enantioselective differences disappeared. It is concluded that although enantioselectivity of bupivacame distribution is shown by the measured tissue:blood distribution coefficients, it is not shown when tissue:plasma water distribution coefficients are calculated, suggesting that there is no intrinsic difference between the bupivacaine enantiomers in tissue affinity. Sheep given fatal intravenous bolus doses of rac-bupivacaine had significantly greater concentrations of (+)-(R)-bupivacaine than (?)-(S)-bupivacaine in brain (P = 0.028) and ventricle (P = 0.036); these could augment the greater myocardial toxicity of this enantiomer found in vitro. © 1993 Wiley-Liss, Inc. 相似文献
5.
Slow response of soil organic matter to the reduction in atmospheric nitrogen deposition in a Norway spruce forest 总被引:1,自引:0,他引:1
NICOLE DÖRR KLAUS KAISER ROBERT MIKUTTA GEORG GUGGENBERGER 《Global Change Biology》2010,16(11):2990-3003
Global nitrogen (N) deposition rates in terrestrial environments have quadrupled since preindustrial times, causing structural and functional changes of ecosystems. Different emission reduction policies were therefore devised. The aim of our study was to investigate if, and over what timescale, processes of soil organic matter (OM) transformation respond to a decline in atmospheric N deposition. A N‐saturated spruce forest (current N deposition: 34 kg ha?1 yr?1; critical N load: 14 kg ha?1 yr?1), where N deposition has been reduced to 11.5 kg ha?1 yr?1 since 1991, was studied. Besides organic C and organic and inorganic N, noncellulosic carbohydrates, amino sugars and amino acids were determined. A decline in organic N in litter indicated initial effects at plant level. However, there were no changes in biomarkers upon the reduction in N deposition. In addition, inorganic N was not affected by reduced N deposition. The results showed that OM cycling and transformation processes have not responded so far. It was concluded that no direct N deposition effects have occurred due to the large amount of stored organic N, which seems to compensate for the reduction in deposited N. Obviously, the time span of atmospheric N reduction (about 14.5 years) is too short compared with the mean turnover time of litter to cause indirect effects on the composition of organic C and N compounds. It is assumed that ecological processes, such as microbial decomposition or recycling of organic N and C, react slowly, but may start within the next decade with the incorporation of the new litter. 相似文献
6.
An enantioselective HPLC bioassay has been developed relying on extraction of (R)- and (S)-atenolol from alkalinized plasma or serum (pH > 12) into dichloromethane containing 5% (v/v) 1-butanol followed by an achiral derivatization of the drug with phosgene leading to (R)- and (S)-oxazolidine-2-one derivatives. Under these conditions there was quantitative conversion of the acetamido group to the corresponding nitrile. These stable derivatives were separated on a (R,R)-diaminocylohexane-dinitrobenzoyl chiral stationary phase [(R,R)-DACH-DNB] using dichloromethane/methanol 98/2 as mobile phase. Determination limits of 0.5 ng for (R)- and 0.6 ng for (S)-atenolol could be achieved using fluorimetric detection. The assay was applied to a human pharmacokinetic study which was performed in a randomized cross-over, double-blind fashion in 12 healthy volunteers, administering single oral doses of 100 mg (R,S)-, 50 mg (R)-, and 50 mg (S)-atenolol AUC0–24 and Cmax values of (R)-atenolol were slightly but significant higher than those of (S)-atenolol. The R/S ratios were 1.09 for AUC(R)/AUC(S) and 1.03 for Cmax (R)/Cmax(S) (P < 0.01) respectively after administration of the racemic drug. However, there were no differences between AUC, Cmax, and t½ values of each enantiomer, whether they were administered as single enantiometers or in the form of its racemic mixture. © 1993 Wiley-Liss, Inc. 相似文献
7.
Xia Wei Chan Feng Xiao‐Hui Li Xing‐Xin Mao Hai‐Bin Luo Dong‐Mei Zhang Li Rong Zhen‐Yu Xie Xin Yu Jie Li Wen‐Cai Ye Xiao‐Jun Huang Cui‐Xian Zhang 《化学与生物多样性》2019,16(6)
One new racemic mixture, penicilliode A ( 1 ) and four pairs of enantiomeric polyketides, penicilliode B and C ( 2 and 3 ) and coniochaetone B and C ( 4 and 5 ), were obtained from the starfish‐derived symbiotic fungus Penicillium sp. GGF16‐1‐2. Interestingly, the strain GGF16‐1‐2 can produce enantiomers. The absolute configuration of 1 was determined by X‐ray diffraction (XRD) analysis, and the absolute configurations of 2 – 4 were determined by the optical rotation (OR) values and electronic circular dichroism (ECD) calculations. Compounds 1 – 5 were firstly isolated from the marine‐derived fungus Penicillium as racemates, and 2 – 5 were separated by HPLC with a chiral stationary phase. All the compounds were evaluated for their antibacterial, cytotoxic and inhibitory activities against PDE4D2. 相似文献
8.
Tolperisone and eperisone used as muscle relaxants possess one chiral center each and exist as two optical isomers for each drug. Therefore, enantioselective assays to measure each enantiomer in biological matrices are of great importance. In the present study a simple and complete reverse‐phase liquid chromatography tandem mass spectrometric method for separation and enantioselective determination of tolperisone and eperisone in rat plasma was developed. The analytes were extracted from rat plasma by a simple protein precipitation method with acetonitrile as the extraction solvent. The enantioselective separation of analytes was achieved on a Cellulose Tris (4‐chloro‐3‐methylphenylcarbamate) chiral column with a mobile phase of acetonitrile: 10 mM ammonium acetate in an isocratic mode of elution and mass spectrometric detection. The calibration curve for each enantiomer was found to be linear over 0.2 to 20 ng/mL for each enantiomer. The proposed method exhibited good intra‐ and interday precision (% CV) ranged between 0.95–6.05% and 1.11–8.21%, respectively. The intra‐ and interday accuracy for the proposed assay method ranged between 94.0–100.5% and 92.7–102.1%, respectively. The proposed method was validated as per regulatory guidelines. Chirality 25:622–627, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
9.
The existence of enantiomer‐enriched mixtures of chiral pesticides in the environment is overwhelmingly positive. However, interactions between enantiomers have not been considered so far in risk assessments. Here, we chose three organophosphorus pesticides as representative chiral pesticides to investigate the possible interaction mode between each pair of enantiomers both in in vivo and in vitro. Data show that the enantiomers of methamidophos and profenofos have a simple additive effect, <zaq;1> whereas fensulfothion acts as an antagonist in AChE‐inhibition model. In contrast, enantiomers of methamidophos and fensulfothion had an additive effect in an acute toxicity test against Daphnia magna. A synergistic effect was observed in the joint toxicity of the profenofos enantiomers. The ability for enantiospecific biodegradation in the in vivo model contributed to the different interaction observed between the in vitro and in vivo models. Moreover, binding affinities were suspected as another reason for the different mode of action of mixture enantiomers. Our study recommends using a joint research model to treat chiral compounds in the real environment. Chirality 25:787–792, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
10.
ZhiLi Fang WenCui Su WeiGuang Zhang Yan Xu YaJin Xiong MiaoLi Luo Jun Fan Xia Yin 《Journal of molecular recognition : JMR》2013,26(4):161-164
The chiral discrimination studies of biological system are theoretically and practically significant for the development of chiral drugs and life science. Our work has embarked upon the interaction between serum albumin (SA) (including human SA and bovine SA), R,S‐1‐(4‐methoxyphenyl)ethylamine, and R,S‐1‐(3‐methoxyphenyl)ethylamine. The formation of intermediate transition state, binding sites, and chiral discrimination ability can be investigated by ultraviolet‐visible spectra and fluorescence spectra. Moreover, both the changes of hydrophobic microenvironment and energy transfer can be detected by synchronous fluorescence spectra and fluorescence lifetime. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献