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Biomedical subjects

E Boyland

Publications and source records attributed to E Boyland.

At least 37 records · Page 2Linked to original sources
PubMed1970

Enzyme-catalysed reactions between some 2-substituted 5-nitrofuran derivatives and glutathione.

1. A glutathione transferase present in rat and human liver supernatant catalyses the reaction of some 2-substituted 5-nitrofuran derivatives with GSH, with formation of a conjugate and release of the nitro group as inorganic nitrite. Some of the substrates undergo the same reaction at a slower rate in the absence of enzyme. Nitrofuran derivatives commonly used as drugs, and five other drugs containing nitro groups, did not react. 2. Substrate activity in the nitrofuran derivatives showed an approximate correlation with the lability of the nitro group to alkali. 3. Optimum pH values ranging from 6.6 to 9.0 were found for the enzymic reaction with various derivatives, the values being influenced by alkali-lability and pK values of the compounds. 4. Tenfold purification of rat liver glutathione S-aryl-transferase resulted in an equal purification of the activities that catalyse the reaction of two of the nitrofuran derivatives with GSH.

Aged↗
PubMed1969

Reaction of urethane with nucleic acids in vivo.

1. [1-(14)C]Ethyl carbamate, ethyl [carboxy-(14)C]carbamate, [1-(14)C]ethanol and sodium hydrogen [(14)C]carbonate were injected intraperitoneally into C57 mice, and nucleic acids and proteins were separated from the liver and lungs with phenol as described by Kirby (1956). 2. Chromatographic analysis of the hydrolytic products of the urethane-labelled RNA showed the presence of a single radioactive compound differing in behaviour from the major pyrimidine nucleotides and purines. 3. The products from RNA labelled by [1-(14)C]ethyl carbamate or ethyl [carboxy-(14)C]carbamate appeared chromatographically identical but could not be detected in the RNA of mice given [1-(14)C]ethanol or sodium hydrogen [(14)C]-carbonate. 4. The labelled product appeared to be the ethyl ester of cytosine-5-carboxylic acid formed by the reaction of urethane with RNA in vivo. 5. A direct reaction between labelled urethane or the labelled metabolite of urethane, [1-(3)H]-ethyl N-hydroxycarbamate, and RNA was not detected.

Animals↗
PubMed1969

Mercapturic acid formation during the metabolism of arecoline and arecaidine in the rat.

1. In the rat, arecoline is converted into arecaidine and both compounds are converted into N-acetyl-S-(3-carboxy-1-methylpiperid-4-yl) -l-cysteine. 2. The structure of the metabolite was established by (a) synthesis, (b) conversion into N-acetyl-S-(3-methoxycarbonyl-1-methylpiperid-4-yl) -l-cysteine methyl ester, which was chromatographically identical with the synthetic material, and (c) n.m.r.-and i.r.-spectral analysis of the 3-methoxycarbonyl derivative. 3. In ethanolic solution, or in phosphate buffer at pH7.0, arecoline reacted with N-acetyl-l-cysteine to give N-acetyl-S-(3-methoxycarbonyl-1-methylpiperid-4-yl) -l-cysteine; under similar conditions, arecaidine reacted more slowly to give N-acetyl-S-(3-carboxy-1-methylpiperid-4-yl) -l-cysteine. 4. The reaction between arecoline and glutathione or N-acetyl-l-cysteine occurred maximally at neutral pH and decreased rapidly with increasing acidity. At neutral pH, the reactions were bimolecular and second-order when the reactants were in approximately equimolar concentrations and pseudo-unimolecular first-order when arecoline was in large excess. 5. Consideration of the pK(a) values and degrees of ionization of the reactants and the effect of pH on the stoicheiometry of reaction between arecoline and glutathione or N-acetyl-l-cysteine indicated that reaction between un-ionized species occurred more readily than nucleophilic addition (Ad(N)) reactions involving charged intermediates.

Animals↗