Methyl Ester Compounds Research Articles

Experimental and chemical kinetic modeling study of small methyl esters oxidation: Methyl (E)-2-butenoate and methyl butanoate

This study examines the effect of unsaturation on the combustion of fatty acid methyl esters (FAME). New experimental results were obtained for the oxidation of methyl (E)-2-butenoate (MC, unsaturated C 4 FAME) and methyl butanoate (MB, saturated C 4 FAME) in a jet-stirred reactor (JSR) at atmospheric pressure under dilute conditions over the temperature range 850–1400 K, and two equivalence ratios ( Φ = 0.375 , 0.75 ) with a residence time of 0.07 s. The results consist of concentration profiles of the reactants, stable intermediates, and final products, measured by probe sampling followed by on-line and off-line gas chromatography analyses. The oxidation of MC and MB in the JSR and under counterflow diffusion flame conditions was modeled using a new detailed chemical kinetic reaction mechanism (301 species and 1516 reactions) derived from previous schemes proposed in the literature. The laminar counterflow flame and JSR (for ϕ = 1.13 ) experimental results used were from a previous study on the comparison of the combustion of both compounds. Sensitivity analyses and reaction path analyses, based on rates of reaction, were used to interpret the results. The data and the model show that MC has reaction pathways analogous to that of MB under the present conditions. The model of MC oxidation provides a better understanding of the effect of the ester function on combustion, and the effect of unsaturation on the combustion of fatty acid methyl ester compounds typically found in biodiesel.

Antinociceptive effect of novel trihalomethyl-substituted pyrazoline methyl esters in formalin and hot-plate tests in mice

The aim of the present study was to evaluate the antinociceptive potential of four novel pyrazoline methyl ester compounds on chemical and thermal models of pain in mice. The following 5-trihalomethylated-4,5-dihydro-1 H-pyrazole methyl ester compounds were tested: 3-methyl-5-trifluoromethyl-(MPF3), 4-methyl-5-trifluoromethyl-(MPF4), 3-methyl-5-trichloromethyl-(MPCl3) and 4-methyl-5-trichloromethyl-(MPCl4). MPF3, MPF4, MPCl3 and MPCl4 (0.03-1.0 mmol/kg) given intraperitoneally decreased neurogenic and inflammatory phases of nociception in the formalin test. Moreover, MPF3, MPF4, MPCl3, MPCl4 (0.1-1.0 mmol/kg) and dipyrone (1.5 mmol/kg) also produced a dose-dependent antinociceptive effect in the hot-plate test. However, MPF3, MPF4, MPCl3 and MPCl4 did not impair motor coordination in the rotarod test or spontaneous locomotion in the open field test. The antinociceptive effect of MPF4 (1.0 mmol/kg, i.p.) was reversed by the opioid receptor antagonist naloxone (2 mg/kg, i.p.), but not by the alpha 2-adrenergic receptor antagonist yohimbine (0.15 mg/kg, i.p.) or by p-chlorophenylalanine ethyl ester (PCPA, 300 mg/kg, i.p.) treatment. In contrast to morphine (5 mg/kg, i.p.), MPF4 given daily for up to 8 days did not generate a tolerance to its antinociceptive effect. However, similar to morphine (11 mg/kg, i.p.), MPF4 reduced gastrointestinal transit in mice. Taken together these results demonstrate that these novel pyrazoline methyl esters tested may be promising prototypes of additional mild analgesics.

Configuration dependence of photon stimulated ion desorption from methyl ester compounds induced by core excitation

Photon stimulated ion desorption (PSID) from methyl ester terminated self-assembled monolayer (MHDA-SAM, HS(CH 2) 15COOCH 3) and methyl mercaptoacetate (MA, HSCH 2COOCH 3) on Ag has been investigated using soft X-ray in the C and O K-edge regions. In MHDA-SAM on Ag, site-selective ion desorption has been clearly observed at resonant core excitations of C 1s, O 1s(OCH 3) → σ ∗(O CH 3) and O 1s(OCH 3) → σ ∗(C OCH 3). Ion intensity in MA on Ag is obviously reduced for CH n + ( n = 1–3) at C 1s, O 1s(OCH 3) → σ ∗(O CH 3) excitations, and no site-selective reaction at O 1s(OCH 3) → σ ∗(C OCH 3) excitations has been observed. These reactions may be influenced by configurational difference of reactive sites. It is suggested that surface effects on the selective reaction due to positioning methyl ester group near the surface plays an important role.

A model study on fatty acid methyl esters as reactive diluents in thermally cured coil coating systems

A model study on the transesterification reaction between fatty acid methyl ester (FAME), e.g. methyl oleate, methyl linoleate, rape seed methyl ester and different alcohols in thin films have been performed. The purpose was to evaluate the possibility to use fatty acid methyl ester (FAME) as reactive diluent in thermally cured coil coating paints. A reactive diluent must be compatible, act as a diluent, react into the film without affecting the end properties. The transesterification between the methyl ester and hydroxyl functional model compounds was monitored by 1H NMR and real time IR. The effects addressed in the present study were compatibility, temperature, catalyst, alcohol structure, and fatty acid methyl ester (FAME) structure. Competing factors with the transesterification reaction were shown to be evaporation and side reactions, i.e. oxidation. The structure of the fatty acid methyl ester (FAME) affects the conversion as a higher amount of unsaturations triggers the competing side reaction oxidation. The reaction time and temperature affects both the degree of transesterification conversion, degree of side reactions and the catalyst choice. The present study has shown that a fatty acid methyl ester (FAME) fulfils the reactivity part for a reactive diluent in a thermally cured coating system.

Ion desorption of surface-oriented methyl-ester compounds using a self-assembled monolayer by core-electron excitations: Polarization-dependence measurements

Polarization dependence of photodesorbing ions by carbon and oxygen core-electron excitations of methyl-ester terminated self-assembled monolayers have been investigated using existing time-of-flight mass spectrometer combined with additional correction electrodes at both sides of the sample holder, which apply an appropriate potential gradient for desorbing ions. Ions which desorb site selectively indicate significant polarization dependence. On the other hand, non-selective ions rarely show the dependence. These findings indicate that site-selective ion desorption takes place only within the functional group where core electron is excited and the initial memory of the core excitation is effectively conserved during desorption. Trends of the polarization dependence differ in desorbing ions as well as resonant excitations. Variation of the dependence can be understood by the different superiority of dissociation/desorption mechanisms: direct dissociation induced by core excitation and indirect dissociation caused by rapid energy relaxation and X-ray-induced electron stimulated desorption.

Tyrosinase inhibitor from black rice bran.

The inhibitor of tyrosinase activity in black rice bran was investigated. The methanol extract from black rice bran was re-extracted with hexane, chloroform, ethyl acetate, or water. The ethyl acetate extract had the most potent inhibition against tyrosinase activity by 80.5% at a concentration of 0.4 mg/mL. Inhibitory compound in the ethyl acetate fraction was isolated by silica gel column chromatography, and identified as protocatechuic acid methyl ester (compound 1) by GC, GC-MS, IR, and 1H and 13C NMR spectroscopy. Compound 1 inhibited 75.4% of tyrosinase activity at a concentration of 0.50 micromol/mL. ID(50) (50% inhibition dose) value of compound 1 was 0.28 micromol/mL. To study the structure-activity relationship, protocatechuic acid (2), vanillic acid (3), vanillic acid methyl ester (4), isovanillic acid (5), isovanillic acid methyl ester (6), veratric acid (7), and veratric acid methyl ester (8) were also assayed.

Development of Sensitive Esterase Assays Based on α-Cyano-Containing Esters

A novel approach is reported for the development of fluorogenic esterase reporters using α-cyano-containing esters as substrates. After ester hydrolysis, the released alcohol, a cyanohydrin, rapidly eliminates HCN to yield the corresponding aldehyde resulting in strong fluorescence. The π conjugation of the resulting aldehyde also greatly enhances UV absorption and red shifts fluorescence emission relative to a corresponding alcohol or phenol. Two substrates, R/S-acetic acid cyano-(6-methoxynaphthalen-2-yl)-methyl ester (compound I) and trans/cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid R/S-cyano-(6-methoxynaphthalen-2-yl)-methyl ester (compound II), were synthesized and evaluated as substrates. Such α-cyano substrates possess very low background fluorescence and are more stable under enzyme assay conditions than phenolic substrates due to the aliphatic cyano group. The higher molar absorbtivity and quantum yield of the aldehyde, along with its larger Stokes' shift combined with the increased stability and lower background signal of the cyanohydrin substrate, increases the utility and sensitivity of the resulting assays over current methods. Moreover, compound II showed high selectivity to pyrethroid-cleaving esterases and may provide a direct tool to monitor pyrethroid resistance in insects.

Preparation of cationic azo dyes derived from 2-amino-6-(2-chloroethoxy)benzothiazole and 2-amino-4-(2-hydroxyethoxy)benzothiazole

Azo dyes derived from 2-amino-6-(2-chloroethoxy)benzothiazole and 2-amino 4-(2-hydroxyethoxy)-benzothiazole were prepared by diazotization and coupling with different N, N-disubstituted anilines. The dyes were then quaternized with various alkylating agents, re. dimethyl sulphate, benzene-sulfonic acid methyl ester, acrylamides and epoxy compounds. Some parameters of the quaternization reaction are critically evaluated. The new benzothiazolic cationic dyes absorb in the region of 606–636 nm and have molar absorptivity of 40 000–80 000 Lmol −1 cm −1.

New chlorin-e6 trimethyl ester compounds as holographic data storage media at liquid helium temperature

The chlorin–polyvinylbutyral (PVB) guest–host system has been the workhorse for most of the previously reported holographic hole burning experiments. In order to extend the spectral range and to improve on some of its properties we synthesized chlorin-e 6 trimethyl ester 1 and brominated chlorin-e 6 trimethyl ester 2, which require a much shorter synthesis pathway than chlorin. We studied the hole burning behaviour of these new dyes with different matrix materials and film preparation methods at liquid helium temperature and measured important properties like hole width and burning kinetics. One result was that we found the methyl ester compounds embedded into a photopolymer to have a five times faster burning rate than the chlorin–photopolymer system.

Lipoconjugates: structure-activity studies for pheromone analogues of Ustilago maydis with varied lipophilicity.

The synthesis, biological activities and conformational behaviour of a variety of analogues of the mating pheromones of the basidomycete Ustilago maydis are reported. The pheromone analogues derived from the two allelic forms H-G-R-D-N-G-S-P-I-G-Y-S-S-Xaa-Z (a1) and H-N-R-G-Q-P-G-Y-Y-Xaa-Z (a2), with Xaa-Z being an unidentified lipophilic cysteine derivative, all differ in the C-terminal residue and include -Cys(farnesyl)-OMe, -Cys(farnesyl)-OH, -Cys(prenyl)-OMe, -Cys-OMe, -Cys(n-dodecyl)-OMe and the unnatural residues -Ahds-OMe (Ahds=alpha-aminohexadecanoic acid), -Ahds-OH, -Ads-OMe (Ads=alpha-aminodecanoic acid) and -N-Hdg-OMe (N-Hdg=N-hexadecylglycine). The synthesis of the unnatural methyl ester analogues was carried out by condensation of the fully protected fragments Fmoc-G-R(Pmc)-D(tBu)-N(Trt)-G-S(tBu)-P-I-G-Y(tBu)-S(tBu)-S(tBu)-OH (a1') and Fmoc-N(Trt)-R(Pmc)-G-Q(Trt)-P-G-Y(tBu)-Y(tBu)-OH (a2') respectively, prepared by Fmoc-SPPS, with the appropriate methylester compounds and subsequent deprotection with TFA/scavenger and piperidine. Synthesis and physicochemical properties of the unnatural lipophilic amino acid methylesters are described. The preparation of the cysteine analogues was performed by condensation of a1' or a2' with H-Cys(Trt)-OMe and subsequent deprotection with TFA/scavenger. Alkylation of the thiol function and Fmoc-deprotection was achieved in a novel one-pot reaction by treatment with alkyl bromide and DIPEA, quenching with EDT and Fmoc removal by addition of 20% piperidine (v/v). Hydrolysis of the methyl esters was carried out by treatment with NaOH in MeOH/H2O. The results of the biological assay reveal an increase in activity with increasing chain length of the lipophilic anchor, with alkyl being better than prenyl and sulfur being not essential, while the position of the anchor is optimal at C7 and the methyl ester moiety is important. NMR studies of two chosen analogues in DMSO and SDS/water demonstrate that the lipophilic C-terminal residue has no influence on the structural behaviour of the peptides. Chemical-shift and NOE patterns indicate a main all-trans conformation of the peptide backbone and a weakly populated cis conformation around the Xaa Pro peptide bond in all eight cases without formation of a defined folded structure. No evidence is seen that the membrane-simulating system SDS/water has a structure-inducing effect on the bound peptide. We therefore conclude that the lipomodification in mating pheromones of U. maydis acts to increase the effective concentration of the drug in the target cell membrane without additional structure-inducing or receptor-binding effects.

High-Performance Liquid Chromatography of Chemical Hybridizing Agent in Wheat

Abstract A simple HPLC method has been developed for the quantification of chemical hybridizing agent (CHA) in grains, leaves, straw and glumes of traited wheat. The procedure included acido-basic extractions of wheat grains and tissues and derivatization of CHA residue as methyl ester compound. The chromatographic separation was achieved with Spherisorb silica using ethyl acetate-methanol (98:2) and UV detection at 285 nm. Good recoveries of CHA for fortified wheat grains and leaves were obtained. Recoveries of CHA in traited wheat demonstrated accumulation of the agent in reproductive organs.

Characteristics and specificity of the inhibition of liver glucose-6-phosphatase by arachidonic acid. Lesser inhibitability of the enzyme of diabetic rats.

The effect of arachidonic acid (delta 4Ach) on liver glucose-6-phosphatase (Glc6Pase) has been studied in vitro using untreated and detergent-treated microsomes prepared from fed and 48-h-fasted normal rats and from streptozotocin-induced diabetic rats. Glc6Pase of both untreated and detergent-treated microsomes (60 micrograms protein/ml) is inhibited by delta 4Ach in a dose-dependent manner between 10-100 microM. The inhibition is very rapid and does not depend on preincubation of microsomes in the presence of delta 4Ach. It does depend on the concentration of microsomal membranes and on the concentration of glucose 6-phosphate: it is more pronounced at low Glc6P concentrations than at high. As a consequence, the enzyme displays sigmoidal kinetics in the presence of delta 4Ach. Hill coefficients (equal to 1 in the control experiments) of about 1.4 were determined in the presence of 50 microM delta 4Ach, indicating a clear positive cooperative dependency of the Glc6Pase upon its substrate in the presence of delta 4Ach. The delta 4Ach inhibition is fully reversible in the presence of bovine serum albumin. The inhibition does not depend on the metabolism of delta 4Ach through the prostaglandin synthase (cyclooxygenase) or arachidonate 12-lipoxygenase pathways since it is not affected by indomethacin and nordihydroguaiaretic acid. Several other unsaturated fatty acids are able to inhibit the enzyme within the same concentration range. In contrast, saturated fatty acids, the arachidonic acid methyl ester and numerous other lipid compounds containing esterified unsaturated fatty acids do not inhibit Glc6Pase within the same concentration range. The enzyme of fed rats was inhibited in the same manner as the enzyme of 48-h-fasted rats. However, Glc6Pase of untreated microsomes from diabetic rats was less inhibitable by delta 4Ach than the Glc6Pase of normal rats. This difference does not persist after solubilization of the membrane lipids by detergent treatment.

Uptake of biotin by native Xenopus laevis oocytes

The present study examined biotin uptake by Xenopus laevis oocytes in vitro. Uptake of low (0.03 microM) and high (10 microM) concentrations of biotin was linear with time for up to 4 h of incubation and occurred with little initial binding to oocytes. Uptake of biotin was dependent on extracellular Na+ concentration [Na+]o and was severely inhibited when Na+ was replaced by other monovalent cations [choline, tetraethylammonia, Li+, and tris(hydroxymethyl)aminomethane]. The initial rate of biotin uptake was saturable as a function of concentration with an apparent Michaelis constant of 3.9 +/- 0.5 microM and maximum velocity of 1,559 +/- 70 fmol.oocyte-1.h-1. Addition to the incubation medium of biotin structural analogues desthiobiotin and thioctic acid caused significant and concentration-dependent inhibition in the uptake of [3H]biotin. This inhibition was found to be competitive in nature with inhibition constant values of 9 and 17.5 microM. In contrast, neither the structural analogue biocytin nor biotin methyl ester (compounds in which the carboxyl group of the valeric acid moiety is blocked) showed any effect on the uptake of [3H]biotin. Biotin uptake was significantly blocked by the metabolic inhibitors dinitrophenol, cyanide, and azide and by incubation at 4 degrees C. Also, the sulfhydryl group blocker p-(chloromercuri)phenylsulfonate caused significant inhibition in biotin uptake. These results demonstrate that Xenopus oocytes possess an uptake system for biotin in its cell membrane that is Na+, energy, and temperature dependent. These characteristics of biotin uptake are similar to those reported in mammalian cells. It is suggested that Xenopus oocytes might be a useful in vitro model system to study the details of the mechanisms and regulation of biotin movement across biological membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and quantitation of trans-9, trans-12-octadecadienoic acid methyl ester and related compounds in hydrogenated soybean oil and margarines by capillary gas chromatography/matrix isolation/Fourier transform infrared spectroscopy

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIdentification and quantitation of trans-9, trans-12-octadecadienoic acid methyl ester and related compounds in hydrogenated soybean oil and margarines by capillary gas chromatography/matrix isolation/Fourier transform infrared spectroscopyMagdi M. Mossoba, Richard E. McDonald, Jo Yun T. Chen, David J. Armstrong, and Samuel W. PageCite this: J. Agric. Food Chem. 1990, 38, 1, 86–92Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://doi.org/10.1021/jf00091a016RIGHTS & PERMISSIONSArticle Views204Altmetric-Citations35LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (798 KB) Get e-Alerts Get e-Alerts

Synthesis and biological activity of 6-O-(3-acyloxytetradecanoyl)-N-acetyl-muramoyl dipeptide methyl ester and related compounds.

A variety of 6–O-(3-acyloxytetradecanoyl)-MDP methyl esters were synthesized using optically-active (3/?)-3-acyloxytetradecanoic acid. Their immunoadjuvant activity was examined.

The preparation and electrochemistry of cysteine-ester oxovanadium(IV) complexes

An improved synthesis of VO(CysOCH 3) 2, (CysOCH 3  the anion of cysteine methyl ester), is reported, as is an analogous preparation of VO(CysOCH 2CH 3) 2, (CysOCH 2CH 3  the anion of cysteine ethyl ester). These are the first two examples of isolated vanadium-cysteine compounds. The oxidation of VO(CysOCH 3) 2 in DMSO is a reversible one electron change at 0.24 V versus SCE followed by a rapid chemical reaction which produces a stable vanadium(V) species. This species is reduced back to the vanadium(IV) complex at −1.30 V. The electrochemistry of VO(Cys-OCH 2CH 3) 2 is nearly identical to that of the methyl ester compound.

Synthesis of L-660,631 methyl ester and related compounds

Summary Triyne carbonate L-660,631 methyl ester ( 2 ) was synthesized in eight steps from cyclooctene. Synthetic methodology to permit systematic variation of the triyne portion of the molecule has been developed.

Chromophoric cinnamic acid substrates as resonance Raman probes of the active site environment in native and unfolded .alpha.-chymotrypsin

Chromophoric [4-(dimethylamino)cinnamoyl]imidazole reacts with the serine protease alpha-chymotrypsin to form an acyl enzyme. At pHs below 4.0, the acyl enzyme turns over very slowly to yield the free acid. During this slow deacylation it is possible to obtain a very good resonance Raman spectrum of the acyl intermediate by using the 350.7-nm line of the krypton laser. The resonance Raman carbonyl frequency of the covalently bonded substrate and its wavelength at maximum intensity in the absorption spectrum of the acyl enzyme have been taken and used to monitor the active site environment. A comparison has been made of the absorption and Raman spectra of the acyl enzyme and those of the corresponding chromophoric methyl ester, aldehyde, and imidazole model compounds. A linear correlation is found between the wavelength of maximum absorption and the Raman frequency of the carbonyl group over a wide range of solvent conditions for each of the model compounds. By combining the Raman carbonyl frequency with the absorption maximum, we can determine that the bond order changes in the carbonyl bond of the bound substrate are not due to changes in the solvent, since the carbonyl frequency and the absorption maximum of the acyl enzyme do not fall on any of the linear correlations for the model compounds. The unusual spectroscopic properties of the bound substrate appear to be due to some specific enzyme-induced change in the substrate when it is bound at the active site. Thermal unfolding of the acyl enzymes changes both the carbonyl frequency of the acyl enzyme and its absorption maximum to completely different values.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of the chymotrypsin substrate, tryptophan methyl ester, by rat α-fetoprotein

We studied how tryptophan methyl ester and related compounds inhibit binding of estrone to rat α-fetoprotein and find that: (a) like chymotrypsin, α-fetoprotein binds tryptophan esters with higher affinity than tryptophan or its amides; (b) the affinity of α-fetoprotein for tryptophan methyl ester is 3.7 · 10 −4 M, which is close to the affinity of chymotrypsin (10 −4 M); (c) α-fetoprotein binding of tryptophan methyl ester is stereoselective and pH dependent. All of these observations suggest that there is a specific interaction between α-fetoprotein and the chymotrypsin substrate, tryptophan methyl ester, and that rat α-fetoprotein contains a site with some structural similarities to the catalytic site in chymotrypsin. Since we also find that tryptophan methyl ester is a competitive inhibitor of estrone binding to α-fetoprotein, it is possible that the protease substrate binding site on α-fetoprotein is spatially close to the estrone binding site.

Addition of thallium triacetate to PFG2αmethyl ester and related compounds in acetic acid. Nuclear magnetic resonance spectral study of novel dioxatricyclic and oxabicyclic products

Addition of Tl(OAc)3 in acetic acid to prostaglandin F2α methyl ester (1) and its congeners (4) and (5) gave, with participation of 9-OH, the bicyclic enol ethers (26) which reacted in situ with a further equivalent of Tl(OAc)3 to yield as the main products the dioxatricyclononane derivatives (2), (6), and (9) and (3), (7), and (10), respectively. Elucidation of the structure of the products by 1H and 13C n.m.r. is presented and a mechanism of the transformations based on model studies is proposed.