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PubMed1975

Electron-capture gas chromatography of barbituric acids and diphenylhydantoin after pentafluorobenzylation.

Alkylation of barbituric acids and diphenylhydantoin with pentafluorobenzyl bromide is described; the reaction is quantitative in the presence of excess of triethylamine. The electron-capture detector response of the derivatives is high, ranging from 2 to 8 x 10(-17) moles/sec. The derivatives demonstrate excellent peak symmetry and are well suited to quantitative analysis. The structures of the derivatives have been confirmed by mass spectrometry.

Alkylation↗
PubMedDate not supplied

Temperature-dependent ESR studies of radical pairs in single crystals of barbituric acid.

After irradiation of single crystals of barbituric acid with X-rays at 77 K different types of radical pairs are found, which are composed of only one type of monoradical. The properties of radical pairs of the unpaired electrons are studied using frequency-variable ESR methods at various temperatures. In addition to the radical pairs AD and BC two further pairs A'D' and XY were identified. Measurements of the fine structure parameter D showed a linear temperature dependence in some regions between 77 K and 290 K. At 240 K the radical pairs AD and A'D' changed reversibly into A*D* and this pair remained stable up to 290 K. A level anticrossing effect was observed with the pair AD. The exchange energy J between the singlet state and the triplet state was determined as -(15.1 +/- 0.6) GHz at 77 K and its temperature coefficient as -(3.8 +/- 0.8) x 10(-3)K-1.

Barbiturates↗
PubMed1977

Relative electron capture response of the 2-chloroethyl derivatives of some barbituric acids and anticonvulsant drugs.

Data are given for the relative electron capture response of the 2-chloroethyl derivatives of ten barbituric acids and five common anticonvulsant drugs. Results indicate that these new derivatives significantly improve the detection limits of the barbituric acids but lead to no advantages for the anticonvulsant compounds. Structural features in the two classes of compounds are believed to explain the differences in the sensitivity of detection. Linear calibration plots exist for the concentration ranges 0.1-1.0 and 1.0-10.0 microgram/ml of amobarbital.

Anticonvulsants↗
PubMed1995

Membrane permeability and lipophilicity in the isolated perfused rat liver: 5-ethyl barbituric acid and other compounds.

The distribution kinetics of 5-ethyl barbituric acid (EBA) has been examined in the rat liver. The isolated in situ liver (n = 4) was perfused at a constant rate (15.1 +/- 0.2 ml/min, mean +/- S.D.) with protein-free Krebs bicarbonate medium in a single-pass mode. [14C]Sucrose (extracellular reference) and [14C]EBA were injected separately as bolus doses into the portal vein. The outflow data were analyzed using the axial dispersion model. The one-compartment dispersion model adequately described the data for sucrose, with a dispersion number (DN) of 0.25 +/- 0.04 and a volume of distribution (VH) of 0.14 +/- 0.01 ml/g liver. The two-compartment dispersion model, which incorporates a cellular permeability barrier, provided a better description of the EBA outflow data. The estimated VH, influx and efflux rate constants and permeability-surface area product (PS) for EBA were 0.37 +/- 0.04 ml/g liver, 0.028 +/- 0.004 sec-1, 0.019 +/- 0.001 sec-1 and 3.4 +/- 0.5 ml/min, respectively. Despite low hepatocyte membrane permeability, the DN value for EBA (0.28 +/- 0.03) was not significantly different from that of sucrose, which supports the concept that dispersion of compounds in the liver is primarily determined by the heterogeneity of the hepatic microvasculature. The relationship between PS values in the perfused rat liver (either abstracted or taken from the literature data) and physicochemical properties for 17 compounds has been explored. There appears to be a continuous relationship between PS and logD, a measure of lipophilicity that takes into account the degree of ionization in the perfusate. The PS value for EBA is close to that expected based on its physicochemical properties.

Animals↗
PubMed1987

Inhibitory effects of pyrimidine, barbituric acid and pyridine derivatives on 5-fluorouracil degradation in rat liver extracts.

The inhibitory effects of about 30 compounds, mainly pyrimidine and pyridine derivatives, on 5-fluorouracil degradation catalyzed by dihydrouracil dehydrogenase (DHU dehydrogenase) were investigated. The inhibitory activities of 5-substituted uracil derivatives decreased time-dependently during preincubation with liver extracts, indicating that these compounds are substrates of DHU dehydrogenase. During preincubation, 4,6-dihydroxypyrimidine derivatives were found to be converted to barbituric acid derivatives, which have stronger activities. The inhibitory activity of 2,4-dihydroxypyridine (3-deazauracil), which was stronger than that of uracil, did not change during preincubation, indicating that this compound is not a substrate but is an inhibitor of DHU dehydrogenase, and suggesting that 2,6-dihydroxypyridine (1-deazauracil) could be a potent inhibitor. In the light of these findings, we examined various derivatives of barbituric acid, 2,4-dihydroxypyridine and 2,6-dihydroxypyridine. Among these compounds, 3-cyano-2,6-dihydroxypyridine and 5-chloro-2,4-dihydroxypyridine were the strongest inhibitors with Ki values for DHU dehydrogenase of 2.3 X 10(-7) M and 3.6 X 10(-7) M, respectively.

Animals↗
PubMed2000

Uptake of barbituric acid derivatives in small intestinal brush border membrane vesicles from retinyl palmitate-treated rats.

Brush border membrane was prepared from the small intestinal (jejunum) cells along the crypt-villus axis. The fluorescence spectra of 1,8-anilinonaphthalene sulfonic acid and the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene were measured in the brush border membrane vesicle suspension. The hydrophobicity of brush border membrane was found to be in the order villus tip >mid villus >lower villus. The fluidity of brush border membrane was in the order villus tip <mid villus <lower villus. The uptake of barbituric acid derivatives by brush border membrane vesicles was well correlated with their partition coefficients (isopentyl acetate/water). No significant difference was observed between the uptake of hexobarbital by brush border membrane vesicles from the villus tip and lower villus. When retinyl palmitate was administered to rats, the fluidity of brush border membrane was found to be higher in the retinyl palmitate-treated rats than in the control rats. However, no significant difference in the uptake of hexobarbital by brush border membrane vesicles was observed between the retinyl palmitate-administered rats and the control rats. Thus, the retinyl palmitate treatment seems unlikely to affect the passively transported ligands like barbituric acid derivatives in brush border membrane vesicles.

Alkaline Phosphatase↗
PubMedDate not supplied

[Action of barbituric acid derivatives on the physiocochemical properties of DNA].

The action of barbituric acid derivatives--phenobarbital, sodium ethaminal and sodium amytal--on the physico-chemical properties of mucleic acids was studied. It is shown that as compared to sodium ethaminal and sodium amytal phenobarbital exerts a more potent action on the secondary and tertiary structure of native DNA molecules.

Amobarbital↗
PubMed2004

An NMR study of merocyanine-type dyes derived from barbituric acid.

The 13C NMR of two solvatochromic dyes derived from a barbituric acid acceptor and dimethylaminophenyl donor fragments, compound 1 and the related merocyanine 2, were recorded in various solvents. The observed chemical-shift variations were used to interpret their structural differences and solvatochromic behavior in solution.

Barbiturates↗
PubMedDate not supplied

Application of pyridinium salts derived of barbituric acid in Kröhnke's reaction.

A series of pyridinium salts derived of barbituric acid (BAC) was obtained, as starting substances in Kröhnke's reaction. On the example of 3-(1',3'-dimethyl-5'-isopropylbarbituryl-5')-1-acetonylene-N-pyrifinium bromide it was stated that the corresponding nitron can be formed only when in positions 1 and 3 of barbituric ring are no hydrogen atoms able to enolization. 3-(1',3'-Dimethyl-5'-isopropylbarbituryl-5')-pyruvic aldehyde (XIII) was obtained by decomposition of nitron XII.

Barbiturates↗
PubMed2002

Synthesis and properties of spiro nucleosides containing the barbituric acid moiety.

The two chiral spiro nucleosides 4 and 5 containing the barbituric acid moiety were efficiently synthesized from optically pure precursors, and their properties were studied. The carbocyclic nucleoside 5 is considerably more stable against ring opening than the deoxyribosyl derivative 4. Both compounds present enhanced hydrogen bonding capacity with diacetyladenosine.

Barbiturates↗
PubMed1995

[Study on metabolite of 5-ethyl-5-(para-fluorobenzoylpropyl) barbituric acid in rabbits].

The metabolite of 5-ethyl-5-(p-fluorobenzoylpropyl) barbituric acid (coded as F-B-1) in rabbit has been separated with HPLC. UV-spectra of F-B-1 and its metabolite obtained with DAD, in combination with EI-MS and CI-MS of F-B-1, its metabolite and their derivatives were examined. Possible structure of the metabolite was obtained. Possible metabolic way of F-B-1 is the reduction of carbonyl on the benzene ring with formation of hydroxyl group. This was further confirmed by identity of HPLC and MS behavior of the metabolite and NaBH4 reductive product. In the structure of the latter, the carbonyl on the benzene ring was reduced, as proved by NMR (1H-NMR and 13C-NMR) spectra.

Animals↗