The reaction of
N-
tert-butyl-2-benzothiazolesulphenamide with acetic anhydride catalyzed by acetic acid in a nonpolar solvent has been studied by NMR, GC–MS and EPR techniques. In the catalytic ...process homolytic decomposition of
N-
tert-butyl-2-benzothiazolesulphenamide prevails over the heterolytic pathway which is typical for uncatalyzed reaction. Besides the typical products formed during the uncatalyzed reaction, in the acid catalyzed process products formed by recombination of radicals were confirmed by
13
C
NMR and mass spectroscopy. In the formation of TBbisBS by homolytic pathway
N,
N′-dialkylhydrazine radicals and RNH
radicals, produced by decomposition of
N,
N′-dialkylhydrazine, play probably an important role.
1. 31P NMR was used to characterize phosphate pools in perchloric acid extracts of muscles with various composition of muscle fibre types. 2. The white m. pectoralis major (MPM) of chickens 15 min ...post mortem is characterized by 1.6-times higher relative content of phosphocreatine (PCr) in comparison with mixed leg muscle (LM) of this species. The glycerophosphorylcholine (GPC) does not occur in MPM at NMR detectable level in contrast to the leg muscles. Relative amounts of other phosphates are similar in both muscles. 3. The intermediate MPM of pigeons as well as mixed LM of this species contain 15 min post mortem a very small amount of PCr and ATP but a large amount of inorganic phosphate. Relative content of GPC is higher in leg muscles than in intermediate MPM. 4. Muscles with higher occurrence of white fibres contain relatively more PCr than muscles with lower occurrence of white fibres. 5. The occurrence of GPC seems to be connected with metabolism of red muscle fibres.
The effect of the presence of ammonia on (1- super(13)Cglucose metabolism in the rumen fibrolytic bacterium Fibrobacter succinogenes S85 was studied by super(13)C and super(1)H nuclear magnetic ...resonance (NMR). Ammonia halved the level of glycogen storage and increased the rate of glucose conversion into acetate and succinate 2.2-fold and 1.4-fold, respectively, reducing the succinate-to-acetate ratio. The super(13)C enrichment of succinate and acetate was precisely quantified by super(13)C-filtered spin-echo difference super(1)H-NMR spectroscopy. The presence of ammonia did not modify the super(13)C enrichment of succinate C-2 (without ammonia, 20.8%, and with ammonia, 21.6%), indicating that the isotopic dilution of metabolites due to utilization of endogenous glycogen was not affected. In contrast, the presence of ammonia markedly decreased the super(13)C enrichment of acetate C-2 (from 40 to 31%), reflecting enhanced reversal of the succinate synthesis pathway. The reversal of glycolysis was unaffected by the presence of ammonia as shown by super(13)C-NMR analysis. Study of cell extracts showed that the main pathways of ammonia assimilation in F. succinogenes were glutamate dehydrogenase and alanine dehydrogenase. Glutamine synthetase activity was not detected. Glutamate dehydrogenase was active with both NAD and NADP as cofactors and was not repressed under ammonia limitation in the culture. Glutamate-pyruvate and glutamate-oxaloacetate transaminase activities were evidenced by spectrophotometry and super(1)H NMR. When cells were incubated in vivo with 1- super(13)Cglucose, only super(13)C-labeled aspartate, glutamate, alanine, and valine were detected. Their labelings were consistent with the proposed amino acid synthesis pathway and with the reversal of the succinate synthesis pathway.
Introduction of nuclear magnetic resonance has enabled direct measurements of muscle metabolism in vitro and in vivo. In the presented paper some theoretical and practical applications mainly 31P NMR ...spectroscopy in research and diagnostics of muscle skeletal diseases are given. In spite of some limitations, the most important advantage of NMR technique is its non-destructive character, the possibility of simultaneous observation of several phosphorylated metabolites in a muscle tissue and the simple method of sample preparation. 31P NMR is a useful tool for studying and detection of muscle diseases and at the same time for its safety for patients.
1D and 2D nmr spectroscopy was used to assign the structure to the minor product from cyclocondensation of 4‐(2‐hydroxyphenyl)but‐3‐en‐2‐one with cyanamide, which was identified as (6R*, 9R*, 15R*, ...17R*)‐6,9‐dimethyl‐6,17:9,15‐dimemano‐6H,15H,17H‐1,3,5benzoxadiazocino4,5‐d1,3,5benzoxadiazocine‐7(9H)‐carbonitrile, a doubly oxygen‐bridged pyrimido1,2‐apyrimidine derivative. The observed stereose lectivity and reaction mechanisms are discussed with the help of molecular mechanics and semi‐empirical PM3 calculations.
Creatine kinase reaction rates were measured by the magnetisation transfer technique in brains of healthy adult and aged rats and in rats with chronic cerebral ischemia and chronic ethanol ...intoxication. These measurements indicated that the rate constant of the creatine kinase reaction is significantly reduced in the case of severe chronic cerebral ischemia in aged rats. In the adult rats, during chronic ethanol intoxication after 3 weeks of administration of 3 ml of 30% ethanol once a day via a gastric tube, a significant decrease in the pseudo first-order rate constant
k
for of the creatine kinase reaction was also found. In contrast, mild chronic cerebral ischemia in adult rats produced an increase in the reaction rate 4 weeks after occlusion. At the same time, corresponding conventional phosphorus magnetic resonance spectra showed negligible changes in signal intensities.
In vivo super(1)H and super(31)P magnetic resonance spectroscopy techniques were applied to reveal biochemical changes in the rat brain caused by prolonged ethanol consumption. Three models of ...ethanol intoxication were used. super(1)H MRS showed a significant decrease in the concentration of myo-inositol in the brain of rats fed with 20% ethanol for 8 weeks. This change is consistent with perturbances in astrocytes. On the other hand, N-acetyl aspartate and choline content did not differ from controls. super(31)P MRS did not reveal any significant changes in the high-energy phosphates or intracellular free Mg super(2+) content in the brain of rats after 14 weeks of 20% ethanol drinking. The intracellular pH was diminished. By means of a super(31)P saturation transfer technique, a significant decrease was observed for the pseudo first-order rate constant k sub(for) of the creatine kinase reaction in the brain of rats administered 30% ethanol for 3 weeks using a gastric tube. The super(1)H MRS results may indicate that myo-inositol loss, reflecting a disorder in astrocytes, might be one of the first changes associated with alcoholism, which could be detected in the brain by means of in vivo super(1)H MRS. The results from super(31)P MRS experiments suggest that alcoholism is associated with decreased brain energy metabolism. super(31)P saturation transfer, which provides insight into the turnover of high-energy phosphates, could be a more suitable technique for studying the brain energetics in chronic pathological states than conventional super(31)P MRS.
1. In vivo 1H and 31P magnetic resonance spectroscopy techniques were applied to reveal biochemical changes in the rat brain caused by prolonged ethanol consumption. 2. Three models of ethanol ...intoxication were used. 3. 1H MRS showed a significant decrease in the concentration of myo-inositol in the brain of rats fed with 20% ethanol for 8 weeks. This change is consistent with perturbances in astrocytes. On the other hand, N-acetyl aspartate and choline content did not differ from controls. 4. 31P MRS did not reveal any significant changes in the high-energy phosphates or intracellular free Mg2+ content in the brain of rats after 14 weeks of 20% ethanol drinking. The intracellular pH was diminished. 5. By means of a 31P saturation transfer technique, a significant decrease was observed for the pseudo first-order rate constant k(for) of the creatine kinase reaction in the brain of rats administered 30% ethanol for 3 weeks using a gastric tube. 6. The 1H MRS results may indicate that myo-inositol loss, reflecting a disorder in astrocytes, might be one of the first changes associated with alcoholism, which could be detected in the brain by means of in vivo 1H MRS. 7. The results from 31p MRS experiments suggest that alcoholism is associated with decreased brain energy metabolism. 8. 31P saturation transfer, which provides insight into the turnover of high-energy phosphates, could be a more suitable technique for studying the brain energetics in chronic pathological states than conventional 31P MRS.
An isocratic, reversed-phase HPLC procedure was developed for the simultaneous determination of isopropyl-,
tert.-butyl-,
tert.-amyl-, cyclohexylbis(2-benzothiazolylsulfen)amides. Quantitation is ...performed on a C
18 bonded-phase column (Separon SGX C
18 5 μm) using N-dicyclohexyl-2-benzothiazolesulfenamide as internal standard followed by UV photodiode-array detection. The precision (
n = 7) for all derivatives of alkylbis(2-benzothiazolylsulfen)amides is within 1.5%. Identification of the compounds also in the mixtures was done by NMR spectroscopy.
