Pharmacokinetic comparison with different assays for simultaneous determination of cis-,trans-cefprozil diastereomers in human plasma

The purpose of this study was to compare pharmacokinetic(PK)parameters obtained using two newly developed assays,HPLC-UV and UPLC-ESI-MS/MS.Selection of assay and results obtained therefrom are very important in PK studies and can have a major impact on the PK-based clinical dose and usage settings.For this study,we developed two new methods that are most commonly used in biosample analysis and focused on PK parameters obtained from them.By HPLC-UV equipped with a Luna-C8 column using UV detector,cefprozil diastereomers were separated using water containing 2%(V/V)acetic acid and acetonitrile as a mobile phase.By UPLC-ESI-MS/MS equipped with a HALO-C18 column,cefprozil diastereomers were separated using 0.5%(V/V)aqueous formic acid containing 5 mM ammoniumformate buffer and methanol as a mobile phase.Chromatograms showed high resolution,sensitivity,and selectivity without interference by plasma constituents.Both intra-and inter-day precisions(CV,%)were within 8.88%for HPLC-UV and UPLC-ESI-MS/MS.Accuracy of both methods was 95.67%-107.50%.These two analytical methods satisfied the criteria of international guidance and could be successfully applied to PK study.Comparison of PK parameters between two assays confirmed that there is a difference in the predicted minimum plasma concentrations at steady state,which may affect clinical dose and usage settings.Furthermore,we confirmed possible correlation between PK parameters and various biochemical parameters after oral administration of 1000 mg cefprozil to humans.

Synthesis of New Cyclic Phosphate of Arylglyoxylonitrile Oximeand Their Diastereomers

Keeping in view the biological activities of 1,3,2-dioxaphosphorinane-2-one and oxime esters. some compounds possessing these two moieties have been synthesized. The configurational assignment and the ratio of cis/trans diastereomers of target products were performed on basis of H-1 NMR. P-31 NMR and confirmed by X-ray diffraction analysis.

SYNTHESIS OF NEW CYCLIC PHOSPHATES OF 3-HYDROXYISOXAZOLE AND THEIR DIASTEREOMERS

Keeping in view the biological activities of 3-hydroxyisoxa- zole and cyclic phosphate derivatives,some compounds possessing these two moieties have been synthesized,the structural elucidation of these diastereomers was made depending on spectral analyses.The mechanism could be illustrated by the theories of trigonal bipyramide intermediate and pseudorotation.

Stereospecific Degradation of Diastereomers by Plant Associated Bacteria Influences the Antifungal Performance of Dodemorph

Morpholine fungcides have certain antibacterial side effect, dodemorph being the most active among them. The diequatorial (cis-)?form of dodemorph expressed higher antibacterial activity than the axial-equatorial (trans-)?form, and no synergy in their joint action could be revealed in this respect. Moreover, the partition of diastereomers between cells and medium strictly correlated to their toxicity.?Considerable differences were detected among degradation rates in various bacteria, and the?meso-(RS)-diastereomer was deteriorated more intensively, then the?trans-(SS?and?RR)-forms in?Corynebacterium?betae,?Erwinia uredovora?and?Pseudomonasfluorescens. As a result, the stereospecific degradation of diastereomers changed their ratio in the medium, thus this metabolic step could?influence the antifungal performance of dodemorph based preparations against filamentous fungi. It was demonstrated that due to synergic joint action,?the fungistatic effect of morpholine derivatives noticeably increased against?Botrytis cinerea?by changing the ratio of diastereomers.

Single-run reversed-phase HPLC method for determining sertraline content,enantiomeric purity,and related substances in drug substance and finished product

A direct enantio-,diastereo-,and chemo-selective high-performance liquid chromatographic method was developed for determining the content,enantiomeric purity,and related substances of the chiral antidepressant drug sertraline HCl in a single chromatographic run.The separation was achieved on a chiral stationary phase based on amylose tris(3-chloro-5-methylphenylcarbamate)under reversed-phase conditions.The method was optimized by evaluating the influence of the temperature and mobile phase composition on the retention and selectivity.The application of the single-run approach allowed to baseline resolve all investigated species in less than 15 min,without using buffers or tandem-coupled columns.The chromatographic method was validated according to the guidelines of the Official Medicines Control Laboratory and applied to control the content of sertraline HCl and related chiral substances in a generic antidepressant formulation.

A Novel Approach for the Synthesis of (R) and (S)-Nicotine

Nicotine is an alkaloid mainly found in leaves of tobacco and is used therapeutically for patients seeking relief from tobacco dependence in the form of products such as gums, patches, lozenges etc. In these products, majorly nicotine derived from tobacco is used which is inherently contaminated with undesirable nicotine related substances as impurities at low levels and is difficult to remove. Hence, use of synthetic nicotine is considered as an option which will be devoid of such impurities. In this work, a short and efficient synthesis of (R) and (S) nicotine was achieved by leveraging a key esterification between racemic homoallylic alcohol intermediate (2) and (S)-Ibuprofen (3) to produce diastereomers (5a) and (5b) which were easily separable under standard column chromatography conditions. Use of (S)-Ibuprofen (3) as a chiral resolving agent constitutes a novel approach which was not reported earlier. A subsequent hydrolysis of the diastereomers furnished the homoallylic alcohol intermediates (S)-6a and (R)-6a with high enantiopurity, which was effectively translated to the corresponding (R)-nicotine and (S)-nicotine respectively.

Synthesis of Asymmetric 4H-1, 3, 2-Benzodioxaphosphorin 2-Sulfides from Intramolecular Cyclization Reaction

Asymmetric 6-substituted-2-methoxy-4-(2,4-dichlorophenyl)-4H-1,3,2-benzodioxaphosphorin a-sulfides were prepared from intramolecular cyclization. The diastereomers were separated by column chromatography and fractional crystallization. Their structures were characterized on the basis of H-1 NMR, P-31 NMR and x-ray diffraction analysis.

Synthesis of the Acetate of a New Phenolic Glycoside,Anacardoside,from Semecarpus anacardium and its Diastereomer

the acetate of a novel phenolic glycoside, 1-O-beta-D-glucopyranosyl-( 1-->6)-beta-D-glucopyranosyloxy-3-hydroxy-5-methylbenzene anacardoside, from the fruits of Semecarpus anacardium, and its diastereomer were first synthesized using Koenigs-Knorr method from D-glucose through six steps with total yields 33% and 16% respectively.

Convenient synthesis of nucleoside 5'-(α-P-thio)triphosphates and phosphorothioate nucleic acids(DNA and RNA)

Modified deoxy-and ribo-nucleoside triphosphates are chemically synthesized in multiple steps due to the protection and deprotection of the nucleoside functionalities.To conveniently synthesize the S-modified triphosphates for enzymatically preparing phosphorothioate DNAs and RNAs(PS-DNA and PS-RNA) as potential therapeutics,herein we report a one-pot strategy to synthesize the deoxy-and ribo-nucleoside 5'-(α-P-thio)triphosphates(dNTPαS and NTPαS) without protecting any nucleoside functionalities.This facile synthesis is achieved by treating the nucleosides with a mild phosphitylating reagent,reacting selectively with the 5'-hydroxyl group of each unprotected nucleoside,followed by sulfurization and hydrolysis to afford the crude dNTPαS and NTPαS analogs(mixtures of Sp and Rp diastereomers).We also demonstrated that after just simple precipitation(without HPLC and ion-exchange purification),the quality of the synthesized dNTPαS and NTPαS analogs is excellent for direct DNA polymerization and RNA transcription,respectively.Since Klenow DNA polymerase and T7 RNA polymerase accept the Sp diastereomers of dNTPαS and NTPαS analogs,respectively,while the Rp diastereomers are neither substrates nor inhibitors,the diastereomerically-pure PS-DNAs and PS-RNAs can be conveniently synthesized enzymatically.

ASYMMETRIC SYNTHESIS OF THE DERIVATIVES OF (+)-1R,3R(3S), 5S-2,4,3-DIAZAPHOSPHABICYCLO [3.2.1] OCTANE

<正> A new series of dextrorotatory derivatives of 1R,3RS,5S-1,8,8-trimethyl-2,4,3-diazaphosphabicyclo [3.2.1] octane with a newly formed chiral phosphorus atom has been prepared by an asymmetric reaction of (+)-cis-1R,3S-1,2,2-trimethyl-1,3-cyclopentadiamine with some thiophosphoryl dichlorides. The optically active products consisted of two unequal amounts of diastereomers,(1R, 3R, 5S) isomers and(1R, 3S, 5S) isomers. Two regioselective reactions took place when phenoxy thiophosphoryl dichloride and N,N-dialkylamino thiophosphoryl dichlorides were chosen as the reagents for the reaction. The content of (1R, 3R, 5S) isomers in the product was over 90% for the former and there were only (1R, 3S, 5S) isomers obtained for the latter.

Facile Synthesis of Enantiomerically Pure 1-（5-Bromo-2-chlorophenyl）-1-（4-ethoxyphenyl）ethane

A facile 7-step procedure for the synthesis of enantiomerically pure 1-（5-bromo-2-chlorophenyl）-1-（4-ethoxyphenyl）ethanes[（R）-2 and（S）-2] that started from （5-bromo-2-chlorophenyl）（4-ethoxyphenyl）methanone 3 was developed.The key step was the resolution of 2-（5-bromo-2-chlorophenyl）-2-（4-ethoxyphenyl）acetic acid 6 by crystallizations of its L-and D-menthyl esters 7 and 8 from petroleum ether to give optically pure enantiomers 9 and 10,respectively.The absolute configurations of the products were unambiguously determined by single-crystal X-ray diffractions of four key intermediates,9,10,13 and 14.This procedure is characterized by inexpensiveness,scalability and ability to produce two individual enantiomers of a diarylethane with unambiguously determined absolute configurations and high enantiomeric purities.