For the purpose of developing a new chiral crown ether unit as a chiral synthon, three racemic mono azabenzo-15-crown-5-ethers, i.e. (R,S)-1-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-yl)-propan-2-ol, (R,S)-2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-yl)-1-phenyl-ethanol and (R , S)-1-[2-(6,7,9,10,12,13,15,16-octahydro-5,8,14,17-tetraoxa-11-aza-benzocyclopentadecen-11-ylmethyl)-phenyl]-ethanol were esterified with vinyl acetate using a lipase from Candida antarctica. The enzymatic acylation of alcohols produced monoacylated products. Two optically active azacrown ethers, ...

We report a new method developed for the determination of stable carbon isotopic composition of homologous alpha,omega-dicarboxylic acids and phthalic acid isolated from environmental samples such as atmospheric aerosols and snow. Dicarboxylic acids are derivatized with BF3/1-butanol to dibutyl esters, which are analyzed for the stable carbon isotopic composition using ...

From the flowerheads of Arnica lonchophylla Greene ssp. lonchophylla Maguire (Asteraceae), a variety of mono-, di- and trihydroxytriterpenes of the oleanane, ursane, lupane and dammarane types were isolated and their structures elucidated by EI and CI mass spectrometry and extensive NMR spectroscopic analysis. Most of the compounds are esterified at ...

Carboxylic esters were successfully labeled with one of two short-lived positron-emitters, carbon-11 or fluorine-18, within a hydrodynamically-driven micro-reactor. The non-radioactive methyl ester was obtained at room temperature; its yield increased with higher substrate concentration and with reduced infusion rate. Radioactive methyl ester was obtained from the reaction of (10 mM) ...

Research on the structure-activity relationships of molecules with acidic carbon atoms led us to undertake a feasibility study on the determination of their acidity constants by capillary electrophoresis (CE). The studied molecules had diverse structures and were tetronic acid, acetylacetone, diethylmalonate, Meldrum's acid, 3-methylrhodanine, nitroacetic acid ethyl ester, pyrimidine-2,4,6-trione, 3-oxo-3-phenylpropionic ...

The reaction of the anthracycline glycoside antibiotics 1-3 with the squaric acid ester 4 gave the squaric acid amide esters 5-7 under neutral conditions, whereas over pH7 the products are the symmetric diamides (8, 9, 11, and 12). Of the prepared compounds 11 was the most active on MCF-7 human ...

Hepatitis C, Dengue and West Nile virus are some of the most important flaviviruses, that share one important serine protease enzyme. Serine proteases are the most studied class of proteolytic enzyme and, in these cases, a primary target for drug discovery. In this paper, we describe the synthesis and preliminary ...

As a result of a hit-to-lead program using a technique of solution-phase parallel synthesis, a highly potent (2,4-dimethoxyphenyl)-[6-(3-fluorophenyl)-4-hydroxy-3-methylbenzofuran-2-yl]methanone (15b) was synthesized as an optimized derivative of 4-hydroxy-3-methyl-6-phenylbenzofuran-2-carboxylic acid ethyl ester (1), which was discovered as a screening hit from small-molecule libraries and exhibited selective cytotoxicity against a tumorigenic cell line.

Chemoselective hydrolysis of tert-butyl esters in the presence of other acid-labile groups has been explored by employing alpha-amino esters and ZnBr(2) in DCM. Although N-Boc and N-trityl groups were found to be labile, PhF protected amines were compatible with these Lewis acid deprotection conditions such that a variety of N-(PhF)amino ...

Mucohalogen acids have been used for the preparation of a variety of 3,4-dihalogenated 2(5H)-furanones. In one synthetic step the carbamates 2a-c and the pseudoanhydrides 4a-e were prepared using isocyanates and acid anhydrides. A series of 5-alkoxylated 3,4-dichloro-2(5H)-furanones 5a-o have been synthesized with a wide range of lipophilicity, using the hydroxy-form ...

Enzymatic synthesis of l-alanyl, l-leucyl and l-phenylalanyl esters of D-glucose was carried out in a non-polar solvent using lipases from Rhizomucor miehei and porcine pancreas. The unprotected amino acids at millimolar concentrations were used in presence of 10 to 50% (w/w) glucose of the lipases to give ester yields up ...

Photochemical reduction of several 4-picolyl- and N-methyl-4-picolinium esters was examined using product analysis, laser flash photolysis, and fluorescence quenching. It is demonstrated that the radical (anions) formed in these reactions readily fragment to yield a carboxylic acid and a 4-pyridylmethyl radical intermediate. The high chemical and quantum yields observed for ...

Insect repellents such as N,N-diethyl-m-toluamide (DEET) which are used as protection against mosquitoes or ticks were detected in all wastewater and anthropogenically influenced surface waters analyzed. In Germany, the concentrations of DEET have constantly decreased since 1999, when DEET was substituted by Bayrepel (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl), 1-methylpropyl ester; KBR 3023) ...

Carbon deficiencies (CDs) of long-chain fatty acid methyl esters (FAMEs) and dicarboxylic acid dimethyl esters (DDMEs), which lead to decreased response in a flame ionization detection (FID) system, were determined by using full responding hydrocarbons (heptadecane, eicosane and alpha-cholestane) as references. For saturated FAMEs ranging from C12 to C22 and ...

Different toxin profiles of dinophysistoxins and pectenotoxins have been reported before between blue mussel and other bivalve species, such as common cockle, razor clam, clams, etc. Comparison of toxins present in plankton in mussel growing areas and in cockle growing areas, respectively, showed there was no particular incidence of dinophysistoxin-2 ...

N-Arachidonoyl glycine was synthesized in a chemo-enzymatic process where glycine tert -butyl ester was acylated by arachidonic acid and the resulted ester was then de-protected to give the final product. Among various lipases tested and chosen for their ability to cleave fatty amides, that from Candida antarctica B gave the ...

The presence of Campylobacter spp. on broiler carcasses and in scald water taken from a commercial poultry processing facility was monitored on a monthly basis from January through June. Campylobacter agar, Blaser, was used to enumerate Campylobacter in water samples from a multiple-tank scalder; on prescalded, picked, eviscerated, and chilled ...

All fruits, vegetables, and grains contain phytosterols. Numerous clinical studies have documented that phytosterols lower LDL-cholesterol levels and thereby reduce the risk of cardiovascular disease. Most experts believe that the cholesterol-lowering mechanism of phytosterols requires that they be in their "free" form. In addition to their occurrence in the free ...

Glycosylation of hederagenin with the trichloroacetimidate derivatives of six commercial disaccharides (D-cellobiose, D-lactose, D-maltose, D-melibiose, D-gentiobiose, D-isomaltose) was performed giving the protected saponins in high yields. Deprotection then gave the saponins which were transformed into the corresponding methyl esters. The hemolytic activity of these synthetic hederagenin diglycosides was measured in ...

Candida antarctica lipase fraction B (CAL-B) showed substrate specificity in the synthesis of esters in hexane involving reactions of short-chain acids having linear (acetic and butyric acids) and branched chain (isovaleric acid) structures, an unsaturated (tiglic acid) fatty acid, and phenylacetic acid with n-butanol and geraniol. The variation in the ...

A total synthesis of apratoxin A was developed. Apratoxin A, isolated from Lyngbya spp. cyanobacteria, is representative of a growing class of marine cyanobacterial cyclodepsipeptides wherein discrete polypeptide and polyketide domains are merged by ester and amide or amide-derived linkages. In the apratoxins, the N terminus of the peptide domain ...

The ingestion of rapeseed oil batches denatured with aniline and illegally refined and distributed by street vendors was responsible for toxic oil syndrome (TOS), an intoxication episode that took place in Spain in 1981, causing over 400 deaths and affecting more than 20,000 people. Despite the intense research efforts carried ...

PURPOSE: The purpose of this study was to analyze the transport of amino acid esters and the amino-acid-based prodrug valganciclovir by the Na(+)/Cl(-)-coupled amino acid transporter ATB(0,+). METHODS: The interaction of amino acid esters and valganciclovir with the cloned rat ATB(0,+) was evaluated in a mammalian cell expression system and ...

In this article, dedicated to Professor Fred McLafferty, I wish to recollect early observations with regard to the rearrangement named after him for 1-nitropropane and the methyl ester of gamma-nitrobutyric acid. This rearrangement occurs for both cases clearly in a stepwise fashion, although for the ester, it occurs as a ...

Compounds containing the tetrahydroisoquinoline ring system were prepared using solid-supported ester derivatives on a nucleophile-sensitive resin, starting from the corresponding BOC-protected amino acids. The key heterocyclic intermediates were obtained from the Pictet-Spengler reaction between ethyl glyoxylate or methyl 4-formylbenzoate and dopamine or 3-hydroxyphenethylamine. After the resulting amino esters were converted ...

A recently discovered enzyme in the mandelate pathway of Pseudomonas putida, mandelamide hydrolase (MAH), catalyzes the hydrolysis of mandelamide to mandelic acid and ammonia. Sequence analysis suggests that MAH is a member of the amidase signature family, which is widespread in nature and contains a novel Ser-cis-Ser-Lys catalytic triad. Here ...

The total synthesis of the marine cyclodepsipeptide (-)-doliculide is described. An acyclic (2S,4S,6R)-trimethyl alkanoic acid precursor to the "hydrocarbon" portion of doliculide was synthesized starting with l-ascorbic acid based on a stereocontrolled iterative conjugate addition of lithium dimethylcuprate to acyclic delta-Cmethyl alpha,beta-unsaturated ester derivatives. syn/syn selectivity was achieved by relying ...

Lipases from Pseudomonas cepacia (P.c.) and Thermomyces lanuginosa (T.l.) were immobilized in a phyllosilicate sol-gel matrix and studied for their ability to catalyze the alcoholysis of fats and oils to simple alkyl esters. At 50 degrees C and 48 h reaction immobilized T.l. lipase gave higher alkyl ester yields (70 ...

Racemic 2-(5,7-dichloro-3-indolyl)propionic acid (5,7-Cl(2)-2-IPA) was synthesized from 5,7-dichloroindole-3-acetic acid by successive esterification, methoxycarbonylation, methylation, and double hydrolysis. The racemate was converted to diastereomeric esters of l-menthol; these were separated by recycling HPLC into two optically active diastereomers that were then hydrolyzed with p-TsOH to two optically active enantiomers of 5,7-Cl(2)-2-IPA. ...

A series of (3-pyridin-2-yl-thiouriedo)alkanoic acid esters (5a-j) have been synthesized by the reaction of pyridin-2-yl-dithiocarbamic acid methyl ester (2) and amino acid esters (4). Most of the synthesized compounds have been evaluated against glucose-6-phosphatase enzyme but only four compounds (5g-j) displayed significant inhibitory activity of the enzyme.

The structure, reactivity, and acid-base properties of mixed monolayers prepared by photochemical reaction of hydrogen-terminated silicon with mixtures of ethyl undecylenate and n-alkenes were studied by ATR-FTIR spectroscopy and contact-angle measurements. The surface composition of the mixed monolayers and its correlation with the hydrolysis reactivity of terminal ethoxycarbonyl (ester) groups ...

Sequential polydepsipeptides were synthesized by the depsipeptide active ester method using a new approach for the direct synthesis of N-protected depsipeptide free acids from hydroxy acids. The method uses synthesis of Boc-didepsipeptides by reaction of free hydroxy acids with Boc-amino acid N-hydroxysuccinimide esters catalyzed by 4-dimethylaminopyridine and chain elongation of ...

Prodrugs of phosphonoformic acid (PFA), an anti-viral agent used clinically as the trisodium salt (foscarnet), are of interest due to the low bioavailability of the parent drug, which severely limits its utility. Neutral PFA triesters are known to be susceptible to P-C bond cleavage under hydrolytic de-esterification conditions, and it ...

A number of diesters of the topical dermatosis treatment azelaic (nonanedioic) acid were prepared and tested for antibacterial effect. Two esters, bis-[(hexanoyloxy)methyl] nonanedioate and especially bis-[(butanoyloxy)methyl] nonanedioate showed promising activity against acne related bacteria in vitro. No activity of azelaic acid was detected in Mueller Hinton II agar at pH ...

A novel procedure for the deprotection of the carboxyl group of amino acid methyl esters is presented. The process is carried out by the reagent system aluminium trichloride/N,N-dimethylaniline that can successfully be applied to unblock the carboxyl moiety either of N-Fmoc-protected amino acid methyl esters and N-Fmoc-protected short dipeptide methyl ...

Thiazolidinediones improve insulin sensitivity in type 2 diabetes mellitus by acting as peroxisome proliferator-associated receptor gamma (PPARgamma) agonists, and decrease circulating androgen concentrations in polycystic ovary syndrome by unknown mechanisms. Some thiazolidinediones directly inhibit the steroidogenic enzymes P450c17 and 3beta-hydroxysteroid dehydrogenase type II (3betaHSDII) by distinct mechanisms. We synthesized five ...

For the purpose of developing a new synthetic polymer containing an asymmetric molecule branch, three racemic alcohols, i.e. 1-phenylethanol, 1-(4-methylphenyl)ethanol and 1-(2-naphthyl)ethanol, were esterified enzymatically with divinyladipate using a lipase from Pseudomonas cepacia. The enzymatic acylation of alcohols produced monoacylated products. Optically active polymerizable monomers, (R)-vinyl adipic acid (phenyl-1-yl) ethyl ...

Social insects use complex chemical communication systems to govern many aspects of their life. We studied chemical changes in Dufour's gland secretions associated with ovary development in several genotypes of honeybees. We found that C28-C38 esters were associated only with cavity nesting honeybee queens, while the alcohol eicosenol was associated ...

A series of prodrugs of stavudine were synthesized in an effort to enhance spectrum of chemotherapeutic properties for the effective treatment of HIV/AIDS. The 5'-OH function of stavudine was esterified with ciprofloxacin, norfloxacin, isoniazide, pyrazinamide, piperazine and dimethylamine acetic acid. The anti-HIV-1 activity of the esters was determined in CEM ...

Five caffeic acid derivatives; methyl ester of caffeoylglycolic acid (1), dimethyl ester of caffeoyltartaric acid (2), dimethyl ester of caffeoyltartronic acid (3), monomethyl ester of caffeoyltartronic acid (4), methyl ester of caffeic acid (5), and some other secondary metabolites including; quercetin, quercetin 3-O-beta-D-glucuronide methyl ester, kaempferol, 3,5,7,4'-O-tetramethylkaempferol, beta-sitosterol glucoside, 2alpha-hydroxyursolic ...

In biotransformations carried out under similar conditions enzymatic systems from carrot (Daucus carota L.), celeriac (Apium graveolens L. var. rapaceum) and horse-radish (Armoracia lapathifolia Gilib.) hydrolyzed the ester bonds of acetates of phenols or alicyclic alcohols. Nevertheless, methyl esters of aromatic acids did not undergo hydrolysis. Alcohols were oxidized to ...

The labial gland secretions from males of the bumble bee Bombus (Pyrobombus) perplexus Cresson were analysed by gas chromatography/mass spectrometry (GC/MS) in the electron impact and positive ion chemical ionization mode. The major compound of the complex mixture of alkenols, alkenals, fatty acids, hydrocarbons, wax type esters and steroids is ...

Following the recent disclosure of 3-methyl pyrrole-2,4-dicarboxylic acid 2-propyl ester 4-(1,2,2-trimethyl-propyl) ester, a potent and selective mGluR1 non-competitive antagonist, we report here a detailed exploration of the C-2 position of this scaffold with the preparation of differently substituted amides. Great improvement of the pharmacokinetic properties has been achieved through this ...

Enantiomerically pure N-methylated diketopiperazines (DKP) can be obtained by treating a N-methylated resin-bound dipeptide with 20% piperidine in dimethylformamide via a process known as cyclative release. N-methylated resin-bound dipeptides can be formed from N-methylated precursors or N-methylation can be selectively performed on the resin. When on-resin N-methylation was performed on ...

Biphenyl hydrolase-like protein (BPHL, NCBI accession number NP_004323) is a novel human serine hydrolase recently identified as a human valacyclovirase, catalyzing the hydrolytic activation of the antiviral prodrugs valacyclovir and valganciclovir. The substrate specificity of BPHL was investigated with a series of amino acid ester prodrugs of the therapeutic nucleoside ...

A furanose sugar amino acid (SAA) has been utilized as a library scaffold for the first time. Two furanose SAA scaffolds were examined to illustrate their potential for derivatization. The resulting 99-member library contained three orthogonal points of diversification that allowed easy access to ethers and carbamates from a hydroxyl ...

Steam distillation (SD) extraction-solid-phase microextraction coupled to GC-MS was developed for the determination of terpenes and Bligh-Dyer extraction-derivatization coupled with GC for the determination of fatty acids such as ethyl esters were used. It was found that the three different Agave species have the same profile of fatty acids; the ...

We performed the Hershberger assay of 12 chemicals based on the OECD draft protocol. The chemicals tested by the Hershberger assay were phthalic acid di-n-hexyl ester, phthalic acid di-n-amyl ester, phthalic acid di-n-propyl ester, diethylstilbestrol, 17beta-estradiol, tamoxifen, 5alpha-dihydrotestosterone, dichlorodiphenyldichloroethane, cyproterone acetate, 6alpha-methyl-17alpha-hydroxy-progesterone, atrazine, and spironolactone. Phthalic acid di-n-hexyl ester, phthalic ...

Many currently known antagonists for P2 purinergic receptors are anionic molecules bearing one or several phenylsulfonate groups. Among the P1 (adenosine) receptor antagonists, the xanthine phenylsulfonates are a potent class of compounds. Due to their high acidity, phenylsulfonates are negatively charged at physiologic pH values and do not easily penetrate ...

Cholic and deoxycholic acid amides 10-17 have been synthesised from (1R,2R)-1-phenyl-2-amino-1,3-propanediol 2, (1S,2S)-1-phenyl-2-amino-1,3-propanediol 4, (1R,2R)-1-para-nitrophenyl-2-amino-1,3-propanediol 3, (1S,2S)-1-para-nitrophenyl-2-amino-1,3-propanediol 5. Amide 12 derived from N-succinimidyl ester 9 of deoxycholic acid and (1R,2R)-1-phenyl-2-amino-1,3-propanediol 2, found to be active against Cryptococcus neoformans and the amide 17 obtained from N-succinimidyl ester 9 of deoxycholic acid ...