Mass spectra of acetylenic fatty acid methyl esters and derivatives

A series of isomeric methyl octadecynoates was analyzed by mass spectrometry; each isomer gave a unique spectrum. The characteristic ions were those resulting from a McLafferty rearrangement of the allenic sites or of the already-rearranged allenic sites. The acetylenic esters were also subjected to oxymercuration whereupon a carbonyl group was formed at either of the original actylenic carbon atoms providing two oxostearates. Further reaction with NaBH4 formed hydroxy esters which, after silylation, gave diagnostic mass spectra indicative of the triple bond location. Applied to esters with both double and triple bonds, this procedure permitted differentiation between the two types of unsaturation. Methoxyl groups marked the original double bond locations and hydroxyls did so for triple bonds.     

Antiviral activity of cholesteryl esters of cinnamic acid derivatives

Cholesteryl 3",4"-dimethoxycinnamate (7) and a new synthesized o-coumaroyl ester of 3 beta-(2'-hydroxyethoxy)-cholest-5-en (13) exhibited a marked activity against poliovirus type 1 (Mahoney). Compound 7 showed an approximately 20-fold greater selectivity in its antiviral activity than compound 13. These compounds were selected from thirteen steryl esters of cinnamic acid derivatives through an in vitro antiviral screening against viruses belonging to taxonomic groups with causative agents of important human infectious diseases to which chemotherapy is indicated, i.e. Picornaviridae, Orthomyxoviridae, Paramyxoviridae and Herpesviridae.     

Kinetic resolution of amino acid esters catalyzed by lipases

Racemic amino acids were resolved by lipase via hydrolysis of their esters. Lipases (Pseudomonas lipase from Amano PS, Rhizopus lipase from Serva, and porcine pancrease lipase from Sigma) could selectively hydrolyze the L-amino acid esters in aqueous solution with high reactivities and selectivities. The effect of the structural changes in the ester moiety on the stereoselectivity of the lipases was also investigated using D,L-homophenylalanine as a model. Procedures were developed for the resolution of natural and unnatural amino acids.     

Biodegradation of phthalic acid esters in river water and activated sludge

Infants born in New England with congenital heart defects were examined for association with time of year or population density. Moderate seasonal peaks in births were noted for complex ventricular septal defect, malposition defects, and transposition of the great arteries. Positive associations with population density were found for pulmonary atresia with ventricular septal defect, ventricular septal defect with secondary anomalies, and tricuspid atresia.     

Depolymerization reactions of hyaluronic acid in solution

Samples of microbial sodium hyaluronate were degraded by heating, ultrasonication ultraviolet (UV) and gamma-ray irradiation and enzymatic treatment. The weight-average molecular weight, Mw, of hyaluronate in 0.15 M NaCl and 0.06 M Na2HPO4 was determined by gel filtration with UV detection. The Mw of the degraded samples varied from 8 x 10(4) to 1.38 x 10(6). Depolymerization processes can be described by linear relationship (1/Mw)2 = f(t) in the case of ultrasonic treatment and by non-linear relationships in the cases of heating and UV irradiation at 257 nm. Gamma-ray irradiation and enzymatic treatment caused chemical degradation and depolymerization to oligosaccharides, respectively.     

Effects of dietary supplementation with n-3 fatty acid ethyl esters on coccidiosis in chickens

The ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were added to a broiler starter diet singly or in combination [as bulk purified ethyl ester concentrate from menhaden oil (n3FAC)] in quantities similar to those found in a diet supplemented with 5% menhaden oil (MO). Diets were fed to chickens from 1 d of age through 3 wk of age. At 2 wk of age, the chickens were infected with Eimeria tenella, Eimeria acervulina, or Eimeria maxima. At 6 d postinfection (PI), the effects of the diets were assessed on weight gains, plasma carotenoids, gross lesion scores, and histological parasite scores in gut cross sections, or oocyst output. Significant ameliorating effects of diet on lesion scores and parasite scores were only seen in E. tenella infections and were only produced by the n3FAC and MO supplements. These two supplements, which contained higher molar concentrations of double bonds than the other supplements, also significantly reduced plasma carotenoids in uninfected chickens, indicating that they promoted a state of oxidative stress. These results are consistent with previous reports on the interaction of coccidiosis with dietary n-3 fatty acids and strengthen the hypotheses that dietary-induced oxidative stress is an effective deterrent against cecal coccidiosis in chickens.     

Lichen planus-like contact dermatitis due to methacrylic acid esters

We report a patient who had lichen planus-like lesions on sites repeatedly exposed to methacrylic acid esters used in the car industry. Histologically, the lesions showed all the features of classical lichen planus. Patch testing revealed positive reactions to methacrylic acid esters in concentrations as low as 5 x 10(-3)%. As dental devices contain methacrylic acid esters, it is possible to speculate that methacrylic acid esters may be one of the causative agents for oral lichen planus.     

Insulinotropic action of the D-glucosyl and 3-O-methyl-D-glucosyl monomethyl esters of succinic acid

Succinic acid methyl esters are currently under investigation as potential insulinotropic tools in animal models of non-insulin-dependent diabetes mellitus. The in vivo administration of these esters may result in the undesirable generation of methanol through their intracellular hydrolysis. As a first attempt to circumvert this drawback, we have now investigated whether the esterification of the carboxylic group of succinic acid monomethyl ester by D-glucose or 3-O-methyl-D-glucose affects its insulin-otropic action. Both the 6-O-D-glucosyl and 6-O-(3-O-methyl)-D-glucosyl esters were found to stimulate insulin release in pancreatic islets and the isolated perfused pancreas. The 6-O-D-glucosyl ester also stimulated insulin release after intravenous administration to anaesthetized rats. These findings suggest that the undersirable generation of methanol from the methyl esters of succinic acid could eventually be avoided by using other esters of this dicarboxylic acid, whilst keeping the benefit of their insulinotropic action.     

Gas chromatography of dimethylalkylsilyl ether derivatives of bile acid methyl esters

The gas chromatographic separation of the DMAS ether derivatives of ten bile acid methyl esters, namely DMES, DMnPS and DMiPS ethers, have been studied by use of an open tubular glass capillary column, coated with SE-30. The DMAS ether derivatives were eluted in sequence according to the number of hydroxyl groups except of 12-KCDCA, and separated. This contrasts with the poorly resolved gas chromatographic peaks produced by the TMS ether derivatives. The DMES ether derivatives were resolved and baseline separation in 30 min, but those of HCA and 12-KCDCA had similar methylene unit values.     

High pressure reverse phase liquid chromatography of fatty acid p-bromophenacyl esters

High pressure reverse phase liquid chromatography has been employed to rapidly separate saturated and unsaturated fatty acids as the corresponding p-bromophenacyl esters. Through the use of a highly efficient C18 reverse phase column packing, it has also been possible to distinguish among geometrical and positional isomers of the unsaturated acids. The use of ultroviolet-sensitive esters has permitted the detection of low (nanogram range) concentrations of fatty acids. The time required for analysis has been further reduced by employing a novel and rapid method for the preparation of the esters.     

Urinary organic acid screening by solid-phase microextraction of the methyl esters

According to ICSD criteria, sleep paralysis (SP) occurs at least once in a lifetime in 40-50% of normal subjects. Variation in the reported incidence could be attributed to the difference in the expression in survey or an influence of cultural background. Some factors assumed to affect the appearance of SP include psychological, biological, developmental, and genetic influences. Sleep onset REM period (SOREMP) is one of the factors which is 'assumed to be related to SP in normal subjects' as well as narcoleptic patients. We conducted an experiment for eliciting SOREMP and SP. Our result indicated a relationship between SOREMP and SP. Polysomnograms during SP were characterized by REM/W stage dissociated states. Other factors which may influence the occurrence of SP are also discussed.     

Transformations of glycyrrhizic acid. VIII. Synthesis of immunomodulating glycopeptides using tert-butyl amino acid esters

Triterpene glycopeptides, derivatives of glycyrrhizic acid, were synthesized with the use of tert-butyl esters of L-amino acids. The condensation of glycoside with esters was carried out with N-hydroxysuccinimide--N,N-dicyclohexylcarbodiimide or N-hydroxybenzotriazol--N,N'-dicyclohexylcarbodiimide in the presence of a base (triethylamine, N-methyl- or N-ethylmorpholine). The protection groups were removed with the use of trifluoroacetic acid.     

Intravenous feeding of the rat with short chain fatty acid esters. I. Glycerol monobutyrate

Intravenous nutrition was investigated using butyric acid because it is oxidized independent of carnitine transport into the cell mitochondria. This carnitine independent fatty acid, in the form of water soluble monobutyrin, was continuously infused into rats for seven days at 27 g monobutyrin per kilogram of body weight per day and provided half the daily energy requirement. All experimental animals survived the alimentation in good health and were free of detectable physiological and behavioral abnormalities. The intravenous infusion depressed the test animals spontaneous food intake to half their preinfusion level. These experimental rats still demonstrated continuous weight pain in contrast to weight loss by pair-fed controls. At decapitation, the monobutyrin infused rats had hepatic glycogen levels three times that of the controls, along with lower soluble hepatic protein, and normal lipid and water content. The plasma acetoacetate was also elevated in experimental rats. It was inferred from these results that monobutyrin was hydrolyzed, and the metabolites were oxidized by the rat. It is concluded from these observations that monobutyrin produces no obvious toxic affects during short infusion periods and provides calories for the rat when given intravenously.     

Electrochemical reactions of pyrite in acid perchlorate solutions

Abstract

Pyrite has been subjected to electrochemical measurements in 1M HClO₄ to determine anodic and cathodic electrode reactions. Under anodic conditions only ferric and sulphate ions are formed, while under cathodic conditions ferrous ions and H2S are discharged, with hydrogen. If oxygen is present, its reduction will cause an additional increment of cathodic current.

Ordinary pyrite, exposed to air, exhibits a rest potential of about +0.62 volt (vs. SHE) which is more noble than for any other sulphide mineral. Cathodic excursions that generate H₂S and leave a clean pyrite surface when the soIi[~on is bub bled with helium lead to rest potentials of between 0.2 and 0.3 volt, much more consistent with the thermodynamically estimated reversible potential of pyrite. The 0.62-volt value is therefore regarded as evidence of a ‘passive’ condition. Thus, between 0.3 and 0.6 volt, passive pyrite is cathodic, while ‘active’ pyrite is anodic

Résumé

On a fait des mesures électrochimiques sur la pyrite dans HClO₄ 1M afin de determiner les réactions d'électrodes anodiques et cathodiques. A l'anode on ne forme que des ions ferriques et des ions sulfate alors qu'à la cathode des ions ferreux et H₂S sont déchargés en mê;me temps que de l'hydrogéne. S'il y a de l'oxygène il y a augmentation du courant cathodique provenant de sa réduction.

La pyrite ordinaire ayant été exposée a l'air présente une tension de coupure d'environ '0.62 volt (par rapport à ESH) ce qui est plus élevé que pour tout autre sulfure minéral. Quand il y a un barbotage d'helium dans la solution les réactions cathodiques qui liberent H₂S et laissent une surface de pyrite propre conduisent à des potentials de coupure compris entre 0.2 et 0.3 volt. Cette mesure est plus en accord avec la valeur estimée du potentiel réversible de la pyrite. La valeur 0.62 volt met done en évidence un état ‘passif’. Done entre 0.3 et 0.6 volt, la pyrite passive est cathodique alors que la pyrite ‘active’ est anodique.     

Assay of aldehydes from lipid peroxidation: gas chromatography-mass spectrometry compared to thiobarbituric acid

Measurements of neurotransmitters in conscious animals have been restrictive in real-time. The use of specific enzymes within an amperometric probe, based upon a microdialysis membrane, may overcome some of these problems. I report the use of such a probe, with different perfusions of enzymes, to allow real-time measurement of glutamate, catecholamines and indoleamines, in conscious animals. At an adjacent site microdialysis sample collections were made concurrently and neurotransmitters measured in the dialysate. Both probes were positioned within the somatosensory cortex. Values obtained by amperometric probes were similar to those in dialysate samples for glutamate, catecholamines and indoleamines during basal and stimuli related collections. Amperometric measurements showed higher peak concentrations and better time resolution than dialysate sampling. This reflects sampling differences. Application of external stimuli increased extracellular concentrations of glutamate, catecholamines and indoleamines, in both forms of sampling. Dopamine measurements did not correlate well between the two forms of sampling. This may reflect the non-specificity of the enzyme (dopamine-beta-hydroxylase) used in the amperometric probe. This combination, of microdialysis and amperometry, offers a useful tool for real-time neurotransmitter studies in vivo.