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Ester Derivatives (ester + derivative)
Selected AbstractsOn the Role of Iron and one of its Chelating Agents in the Production of Protoporphyrin IX Generated by 5-Aminolevulinic Acid and its Hexyl Ester Derivative Tested on an Epidermal Equivalent of Human SkinPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2006Pascal Uehlinger ABSTRACT Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) or its derivatives as precursors of protoporphyrin IX (PPIX) is routinely used in dermatology for the treatment of various pathologies. However, this methodology suffers to some extent from a limited efficacy. Therefore, the main goal of this study was to investigate the modulation and pharma-cokinetics of PPIX buildup after a 5 h incubation with ALA (1.5 mM) and one of its derivatives, the hexyl ester of ALA (h-ALA) (1.5 mM), on the human epidermal equivalent EpidexÔ. PPIX production was modulated with (L+) ascorbic acid iron (II) salt (LAI) or the iron (II)-specific chelating agent deferoxamine (DFO). PPIX fluorescence from the EpidexÔ layers was measured up to 150 h after the precursor administration using a microspectrofluorometer (,ex: 400 ± 20 nm; ,det: 635 nm). The maximum PPIX fluorescence intensity induced by h-ALA was about 1.7x larger than that induced by ALA. The addition of DFO resulted in a more than 50% increase in PPIX fluorescence for both precursors. The decay half life measured for PPIX fluorescence is 30 and 42.5 h, respectively, for ALA and h-ALA. These half lives are doubled when the samples contain DFO. In the samples with the highest fluorescence intensity, a modified fluorescence spectrum was observed after 10 h, with the emergence of a peak at 590 nm, which is attributed to zinc protoporphyrin IX (Zn PPIX). [source] Convenient General Asymmetric Synthesis of Roche Ester Derivatives through Catalytic Asymmetric Hydrogenation: Steric and Electronic Effects of LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2008Cyrielle Pautigny Abstract An efficient and concise asymmetric hydrogenation of acrylate esters promoted by the cationic ruthenium monohydride complex [Ru(H)(,6 -cot)SYNPHOS]+BF4, is reported. A full investigation of the effects of catalyst precursors, solvents, temperature, hydrogen pressure, substrates as well as steric and electronic properties of ligands was carried out. The corresponding valuable Roche ester derivatives were obtained in good to excellent isolated yields and high enantioselectivities under mild conditions. The robustness and practicability of this highly enantioselective hydrogenation was demonstrated by the synthesis of the 3-hydroxy-2-methylpropanoic acid tert -butyl ester on a multigram scale, resulting in excellent yield and ee up to 94%. [source] Skin Permeation of Testosterone and its Ester Derivatives in RatsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000MI-KYEONG KIM To establish the optimum conditions for improving the transdermal delivery of testosterone, we studied the relationship between the lipophilicity of testosterone ester derivatives and the rat skin permeation rate of testosterone. We performed a rat skin permeation study of testosterone and its commercially available ester derivatives, testosterone hemisuccinate, testosterone propionate and testosterone-17,-cypionate, using an ethanol/water co-solvent system. The aqueous solubility and rat skin permeation rate of each drug, saturated in various compositions of an ethanol/water system, was determined at 37°C. The aqueous solubility of testosterone and its ester derivatives increased exponentially as the volume fraction of ethanol increased up to 100% (v/v). The stability of testosterone propionate in both the skin homogenate and the extract was investigated to observe the enzymatic degradation during the skin permeation process. Testosterone propionate was found to be stable in the isotonic buffer solution and in the epidermis-side extract for 10 h at 37°C. However, in the skin homogenate and the dermis-side extract testosterone propionate rapidly degraded producing testosterone, implying that testosterone propionate rapidly degraded to testosterone during the skin permeation process. The steady-state permeation rates of testosterone in the ethanol/water systems increased exponentially as the volume fraction of ethanol increased, reaching the maximum value (2.69 ± 0.69 ,g cm,2 h,1) at 70% (v/v) ethanol in water, and then decreasing with further increases in the ethanol volume fraction. However, in the skin permeation study with testosterone esters saturated in 70% (v/v) ethanol in water system, testosterone esters were hardly detected in the receptor solution, probably due to the rapid degradation to testosterone during the skin permeation process. Moreover, a parabolic relationship was observed between the permeation rate of testosterone and the log P values of ester derivatives. Maximum flux was achieved at a log P value of around 3 which corresponded to that of testosterone (log P = 3.4). The results showed that the skin permeation rate of testosterone and its ester derivatives was maximized when these compounds were saturated in a 70% ethanolic solution. It was also found that a log P value of around 3 is suitable for the skin permeation of testosterone related compounds. [source] Asymmetric Synthesis of Chiral Silacarboxylic Acids and Their Ester Derivatives,ANGEWANDTE CHEMIE, Issue 4 2010Kazunobu Igawa Dr. Sila-Analoga: Die asymmetrische Synthese von Silacarbonsäuren mit einem stereogenen Zentrum am Siliciumatom ausgehend von chiralen nichtracemischen Silanolen gelang ohne Verlust an optischer Reinheit. Die Silacarbonsäuren können durch Mitsunobu-Reaktion in die entsprechenden Ester überführt werden. [source] ChemInform Abstract: BF3·Et2O-Induced Decomposition of Ethyl 2-Diazo-3-hydroxy-3,3-diarylpropanoates in Acetonitrile: A Novel Approach to 2,3-Diaryl ,-Enamino Ester Derivatives.CHEMINFORM, Issue 37 2009Antimo Gioiello Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of Fluorinated Cyclic s-trans Vinylogous Acid and Amide Ester Derivatives.CHEMINFORM, Issue 3 2007Cosmas O. Okoro Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Inhibition of Trypsin and Urokinase by Cbz-Amino(4-guanidinophenyl)methanephosphonate Aromatic Ester Derivatives: The Influence of the Ester Group on Their Biological Activity.CHEMINFORM, Issue 34 2006Marcin Sienczyk Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis and Evaluation of 3-Methyl-4-oxo-6-phenyl-4,5,6,7-tetrahydrobenzofuran-2-carboxylic Acid Ethyl Ester Derivatives as Potent Antitumor Agents.CHEMINFORM, Issue 48 2005Ichiro Hayakawa Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of 3-Nitro-1H-indole-2-carboxylic Acid Ethyl Ester Derivatives from Baylis,Hillman Adducts.CHEMINFORM, Issue 41 2005Clemens R. Horn No abstract is available for this article. [source] Synthesis of ,,,-Branched ,-Amino Ester Derivatives Through Spiroaziridination of (,-Trimethylsilanylmethyl)cyclohexylidene Esters.CHEMINFORM, Issue 9 2004Tecla Gasperi Abstract For Abstract see ChemInform Abstract in Full Text. [source] Base-Mediated Reaction of N-Alkyl-O-acyl Hydroxamic Acids: Synthesis of 3-Oxo-2,3-dihydro-4-isoxazole Carboxylic Ester Derivatives.CHEMINFORM, Issue 4 2004Andrew J. Clark Abstract For Abstract see ChemInform Abstract in Full Text. [source] Methyl 3,3-Difluoro-2-trimethylsilyoxyacrylate: Preparation and Mukaiyama-Type Aldol Condensation as a Novel Route to ,,,-Difluoro-,-keto Ester Derivatives.CHEMINFORM, Issue 48 2002Biao Jiang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Liquid and gas chromatography coupled to isotope ratio mass spectrometry for the determination of 13C,valine isotopic ratios in complex biological samplesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2008Jean-Philippe Godin Abstract On-line gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, high-precision 13C isotopic enrichment can also be measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Indeed, LC-IRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure 13C isotopic enrichment of underivatised amino acids (Asp, Thr,Ser, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(,13C) reported with this method was found to be below 1, . Another key feature of the new LC-IRMS method reported in this paper is the comparison of the LC-IRMS approach with the conventional GC-C-IRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)-ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (,13C = , 12.3 to 150.8,), the calculated root-mean-square (rms) of SD was 0.38 and 0.46, and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GC-C-IRMS and LC-IRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (,13C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GC-C-IRMS and LC-IRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GC-C-IRMS and LC-IRMS instruments were also used to assess isotopic enrichment of protein-bound 13C,Val in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LC-IRMS and GC-C-IRMS were not statistically different (p > 0.05). The results of this work indicate that the LC-IRMS was successful for high-precision 13C isotopic measurements in tracer studies giving 13C isotopic enrichment similar to the GC-C-IRMS but without the step of GC derivatisation. Therefore, for clinical studies requiring high-precision isotopic measurement, the LC-IRMS is the method of choice to measure the isotopic ratio. Copyright © 2008 John Wiley & Sons, Ltd. [source] A novel reactive ester derivative of biotin with reduced membrane permeability for in vivo biotinylation experimentsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 19 2010Verena Strassberger Abstract The in vivo perfusion of rodent models of disease with biotin derivatives and the subsequent comparative proteomic analysis of healthy and diseased tissues represent a promising methodology for the identification of vascular accessible biomarkers. A novel, triply charged biotinylation reagent, NHS-,-Ala-(L -Asp)3 -biotin, was synthesized and validated in terms of its applicability for in vivo protein biotinylation. Compared to sulfo-NHS-LC-biotin, NHS-,-Ala-(L -Asp)3 -biotin exhibited a reduced membrane permeability and a preferential labeling of proteins localized in compartments readily accessible in vivo from the vasculature. [source] A Ru-Hbpp-Based Water-Oxidation Catalyst Anchored on Rutile TiO2,CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 4 2009Laia Francàs Abstract In support of a split: A water oxidation catalyst based on ruthenium bis-(2-pyridyl)pyrazole anchored on rutile TiO2 was prepared. The performance of this new material with regard to its capacity to catalytically oxidize water to molecular oxygen in a heterogeneous phase was evaluated. Two organic ligands based on bis-(2-pyridyl)pyrazole (Hbpp) functionalized with a para -methylenebenzoic acid (Hbpp-Ra) or its ester derivative (Hbpp-Re) were prepared and characterized. The ester-functionalized ligand was then used to prepare a series of related dinuclear ruthenium complexes of general formula [RuII2(L- L)(bpp-Rn)(trpy)2]m+ (L-L=,-Cl, ,-acetato, or (H2O)2; n=e or a; trpy=2,2,:6,,2,,-terpyridine; m=2 or 3). The complexes were characterized in solution by 1D and 2D,NMR spectroscopy, UV/Vis spectroscopy, and electrochemical techniques. The [RuII2(,-Cl)(bpp-Re)(trpy)2](PF6)2 complex was further characterized in the solid state by X-ray diffraction. The complexes containing the free carboxylic acid ligand were anchored onto rutile TiO2 and treated with 0.1,M triflic acid solution to generate the homologous water-oxidation catalysts TiO2 -[RuII2(H2O)2(bpp-Ra)(trpy)2]2+. This new hybrid material catalytically oxidizes water to molecular oxygen in a heterogeneous manner using CeIV as chemical oxidant. The generation of molecular oxygen is accompanied by the formation of carbon dioxide as well as some leaching of the Ru catalyst. [source] Inhibitory effects of gallic acid ester derivatives on Saccharomyces cerevisiae multidrug resistance protein Pdr5pFEMS YEAST RESEARCH, Issue 3 2010Luciana Pereira Rangel Abstract Overexpression of the Saccharomyces cerevisiae ABC transporter Pdr5p confers resistance to a range of structurally unrelated xenobiotics. This property allows Pdr5p to be used as a target for novel multidrug resistance reversal reagents or chemosensitizers. Herein, we report the effects of gallic acid derivatives with substitutions either on the ester moiety or in the benzene ring on the activity of Pdr5p. Compounds with a longer side chain (8,16 carbons) resulted in greater inhibition of Pdr5p ATPase. Derivatives with side chains of 8,12 carbons that retained hydroxyl groups on the benzene ring extensively inhibited Pdr5p ATPase activity. These compounds almost completely inhibited the efflux of the Pdr5p fluorescent substrate Rhodamine 6G and at 25 ,M chemosensitized the Pdr5p-overexpressing strain AD124567 to fluconazole (0.4 mg mL,1). Gallic acid derivatives may be a new class of Pdr5p inhibitors. [source] A New and Efficient Synthesis of the HMG-CoA Reductase Inhibitor PitavastatinHELVETICA CHIMICA ACTA, Issue 6 2007Murat Acemoglu Abstract A new synthetic method for the preparation of pitavastatin is described. The approach circumvents various synthetic problems associated with the buildup of the 3,5-dihydroxy-C7 acid side chain of HMG-CoA reductase inhibitors (statins). The use of the C6 -amide derivative 5 instead of ester derivatives in the coupling reaction with carboxaldehyde 8 (Scheme,3) prevents undesired side reactions, such as eliminations and retro -aldol reactions. The method provides synthetic statins, such as pitavastatin, in >99% ee and exceptionally high overall yield. The enantiomerically pure starting material, (3S)-3-{[(tert -butyl)dimethylsilyl]oxy}-5-oxo-5-{[(1S)-1-phenylethyl]amino}pentanoic acid (3c), is prepared by an improved procedure from 3-{[(tert -butyl)dimethylsilyl]oxy}glutaric anhydride (1) and (1S)-1-phenylethylamine (2c; Scheme,1). [source] Diastereoselective synthesis of chloro- and fluoro-aniline containing phosphonate esters in a three-component condensationHETEROATOM CHEMISTRY, Issue 4 2010Malek Taher Maghsoodlou New phosphonate ester derivatives were obtained by in situ stereo-specific reaction between triphenyl phosphite and dialkyl acetylenedicarboxylates in the presence of a series of halogenated anilines. Spectroscopic data and X-ray crystallography analysis are in agreement with the gauche arrangement for the two vicinal protons in the structures. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:222,227, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20600 [source] Back to Natural Cinchona Alkaloids: Highly Enantioselective Michael Addition of Malononitrile to EnonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Alessio Russo Abstract An efficient and convenient highly enantioselective Michael addition of malononitrile to enones has been developed by using quinine as the organocatalyst. The adducts were isolated in excellent yield and high asymmetric induction (up to 95% ee). An easy route to difficultly accessible ester derivatives has been also disclosed. [source] Use of L -[15N] glutamic acid and homoglutathione to determine both glutathione synthesis and concentration by gas chromatography-mass spectrometry (GCMS)JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2001Bernard Humbert Abstract A method for simultaneous measurement of both glutathione enrichment and concentration in a biological sample using gas chromatography mass spectrometry is described. The method is based on the preparation of N,S -ethoxycarbonylmethyl ester derivatives of glutathione, and the use of homoglutathione (glutamyl,cysteinyl,alanine) as an internal standard. A procedure for determination of glutamate concentration and enrichment is also reported. Both methods have within-day and day-to-day inter-assay coefficients of variation less than 5%, and recoveries of known added amounts of glutathione and glutamate are close to 100%. Taken together, these methods allowed determination of glutathione concentration and fractional synthesis rate in red blood cells using L -[15N] glutamic acid infusion. This approach was applied in vivo to investigate the effects of a 72 h fast, compared with a control overnight fast, on erythrocyte glutathione in a single dog. The 72 h fast was associated with a 39% decline in erythrocyte glutathione level, (2.9 ± 0.4 versus 4.7 ± 0.5 mmol l,1, fasting versus control) with no change in glutathione fractional synthesis (67.4 versus 71.3% d,1, fasting versus control). Copyright © 2001 John Wiley & Sons, Ltd. [source] Skin Permeation of Testosterone and its Ester Derivatives in RatsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000MI-KYEONG KIM To establish the optimum conditions for improving the transdermal delivery of testosterone, we studied the relationship between the lipophilicity of testosterone ester derivatives and the rat skin permeation rate of testosterone. We performed a rat skin permeation study of testosterone and its commercially available ester derivatives, testosterone hemisuccinate, testosterone propionate and testosterone-17,-cypionate, using an ethanol/water co-solvent system. The aqueous solubility and rat skin permeation rate of each drug, saturated in various compositions of an ethanol/water system, was determined at 37°C. The aqueous solubility of testosterone and its ester derivatives increased exponentially as the volume fraction of ethanol increased up to 100% (v/v). The stability of testosterone propionate in both the skin homogenate and the extract was investigated to observe the enzymatic degradation during the skin permeation process. Testosterone propionate was found to be stable in the isotonic buffer solution and in the epidermis-side extract for 10 h at 37°C. However, in the skin homogenate and the dermis-side extract testosterone propionate rapidly degraded producing testosterone, implying that testosterone propionate rapidly degraded to testosterone during the skin permeation process. The steady-state permeation rates of testosterone in the ethanol/water systems increased exponentially as the volume fraction of ethanol increased, reaching the maximum value (2.69 ± 0.69 ,g cm,2 h,1) at 70% (v/v) ethanol in water, and then decreasing with further increases in the ethanol volume fraction. However, in the skin permeation study with testosterone esters saturated in 70% (v/v) ethanol in water system, testosterone esters were hardly detected in the receptor solution, probably due to the rapid degradation to testosterone during the skin permeation process. Moreover, a parabolic relationship was observed between the permeation rate of testosterone and the log P values of ester derivatives. Maximum flux was achieved at a log P value of around 3 which corresponded to that of testosterone (log P = 3.4). The results showed that the skin permeation rate of testosterone and its ester derivatives was maximized when these compounds were saturated in a 70% ethanolic solution. It was also found that a log P value of around 3 is suitable for the skin permeation of testosterone related compounds. [source] Analysis of 3-chlorotyrosine as a specific marker of protein oxidation: the use of N(O,S)-ethoxycarbonyltrifluoroethyl ester derivatives and gas chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2003Jens Pietzsch N(O,S) -Ethoxycarbonyltrifluoroethyl amino acid esters are formed by the reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. The use of these derivatives for a rapid and sensitive determination of 3-chlorotyrosine, a highly specific marker of myeloperoxidase-catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Hantzsch 1,4-dihydropyridine esters and analogs: candidates for generating reproducible one-dimensional packing motifsACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2009R. S. Rathore Examination of the symmetric Hantzsch 1,4-dihydropyridine ester derivatives of the prototypical nifedipine molecule indicates the tendency of this class of molecule to form a common packing motif. Crystal structure analysis of 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic diesters and analogs reveals that they form extended chains, characterized as the C(6) packing motif, via intermolecular (amine) N,H...O=C (C3,C5 carbonyl) hydrogen bonds. In addition, all the prepared derivatives also satisfy the basic structural requirements for their high binding efficiency to the receptor. The reproducible C(6) packing motif observed among these compounds has a use in the design of solid-state materials. [source] Ni(OAc)2: a highly efficient catalyst for the synthesis of enaminone and enamino ester derivatives under solvent-free conditionsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2010Ju-Yan Liu Abstract Ni(OAc)2 was found to be an efficient catalyst for the synthesis of ,-enamino ketones or esters from ,-dicarbonyl compounds and amines under solvent-free conditions. The reusability of the catalyst was successfully examined without noticeable loss of its catalytic activity. Copyright © 2010 John Wiley & Sons, Ltd. [source] The phytochemical analysis and antioxidant activity assessment of orange peel (Citrus sinensis) cultivated in Greece,Crete indicates a new commercial source of hesperidinBIOMEDICAL CHROMATOGRAPHY, Issue 3 2009Firas I. Kanaze Abstract The flavonoid content of several methanolic extract fractions of Navel orange peel (flavedo and albedo of Citrus sinensis) cultivated in Crete (Greece) was first analysed phytochemically and then assessed for its antioxidant activity in vitro. The chemical structures of the constituents fractionated were originally determined by comparing their retention times and the obtained UV spectral data with the available bibliographic data and further verified by detailed LC-DAD-MS (ESI+) analysis. The main flavonoid groups found within the fractions examined were polymethoxylated flavones, O- glycosylated flavones, C- glycosylated flavones, O- glycosylated flavonols, O- glycosylated flavanones and phenolic acids along with their ester derivatives. In addition, the quantitative HPLC analysis confirmed that hesperidin is the major flavonoid glycoside found in the orange peel. Interestingly enough, its quantity at 48 mg/g of dry peel permits the commercial use of orange peel as a source for the production of hesperidin. The antioxidant activity of the orange peel methanolic extract fractions was evaluated by applying two complementary methodologies, DPPH, assay and the Co(II)/EDTA-induced luminol chemiluminescence approach. Overall, the results have shown that orange peel methanolic extracts possess moderate antioxidant activity as compared with the activity seen in tests where the corresponding aglycones, diosmetin and hesperetin were assessed in different ratios. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||