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At least 451 records · Page 25Linked to original sources
PubMed2003

Prediction of in vivo tissue distribution from in vitro data. 3. Correlation between in vitro and in vivo tissue distribution of a homologous series of nine 5-n-alkyl-5-ethyl barbituric acids.

PURPOSE: To evaluate the ability to determine accurate in vivo tissue-to-unbound plasma distribution coefficients (Kpue) from in vitro data. METHODS: Fresh pieces of fifteen rat tissues/organs were incubated at 37 degrees C with a homologous series of nine barbiturates covering a wide range of lipophilicity (Log P 0.02 to 4.13). Steady-state in vivo Kpue values were estimated from the tissue and plasma concentrations following simultaneous dosing by constant rate i.v. infusion of all nine barbiturates. Drug concentrations in the tissues and media were determined by HPLC with UV or mass spectrometric detection. RESULTS: The pharmacokinetics of the barbiturate series following constant rate i.v. infusion indicated a range of clearance (0.49 to 30 ml x min(-1) x kg(-1)) and volume of distribution at steady state (0.51 to 1.9 l x kg(-1)) values. Good agreement was observed between the in vitro and in vivo Kpu values, although for the most lipophilic barbiturates the in vitro data underpredicted the in vivo tissue distribution for all tissues. CONCLUSION: The in vitro system for predicting the extent of in vivo tissue distribution works well for compounds of widely differing lipophilicity, although for the most lipophilic drugs it may result in an underprediction of in vivo values.

Animals↗
PubMed1984

Solution conformations of barbituric acid derivatives: a 3J(13C,1H) NMR study.

The conformations of the 5-alkyl chains of 5,5-dialkylbarbituric acid derivatives in polar and nonpolar media were determined from the magnitudes of the vicinal heteronuclear coupling constants between the alpha-alkyl hydrogens and the carbonyl carbons. The experimental 3J values have been compared to theoretical values, and the conformational populations of the alkyl side chains with respect to the trioxopyrimidine ring have been determined. The results show that all these compounds have a very low barrier to rotation for both butyl and ethyl side chains. The barbiturates that do not have a 1'-methyl group in the butyl side chain, butobarbital and amobarbital, have no preferred conformation for either the butyl or ethyl side chains. However, the compounds with a 1'-methyl group, pentobarbital and alpha-methylamobarbital, exhibit preferred conformation for both alkyl chains. The significance of these results to the relationship between conformations and pharmacological activity is discussed.

Barbiturates↗
PubMed2001

Merocyanine-type dyes from barbituric acid derivatives.

The preparation and the solvatochromic behavior of two dyes, obtained by condensation of N,N'-dimethylbarbituric acid with dimethylaminobenzaldehyde and with 4,4'-bis(N,N-dimethylamino)benzophenone (Michler's ketone) are described. The latter dye is rather sensitive to the polarity of the medium, and in particular, to the hydrogen-bond-donor ability of protic solvents. The solvatochromism of both compounds is discussed in terms of the pi* and E(T)(30) solvent polarity scales and their differences in behavior interpreted with the aid of semiempirical calculations.

Barbiturates↗
PubMed1999

Uridine phosphorylase inhibitors: chemical modification of benzyloxybenzyl-barbituric acid and its effects on urdpase inhibition.

5-(o-Benzyloxy)benzylbarbituric acid (6) and 5-(p-benzyloxy)benzylbarbituric acid (7) were prepared and their inhibitory activities compared to 5-(m-benzyloxy)-benzylbarbituric acid (BBB) a known, potent inhibitor of uridine phosphorylase (UrdPase). Compounds 6 and 7 were 18-fold and 51-fold less active, respectively, than BBB in inhibiting UrdPase. These data provide solid evidence that the 5-benzylbarbituric acids possessing meta substituents are the most active inhibitors. In addition, 2-thioBBB (11) was synthesized and it was shown to be as active an inhibitor as BBB.

Humans↗
PubMed2006

Barbituric acid as a substituent at aryl methylium ions.

Activation of different benzophenone derivatives with triflic anhydride for electrophilic aromatic substitution of 5-phenylbarbituric acids leads to regioselective formation of the ortho-substituted product. The resulting triphenylmethylium salt can be isolated when the Michlers ketone is used. More electrophilic cations form cyclic enol ethers such as 1-n-butyl-9,9-diaryl-1,9-dihydro-10-oxa-1,3-diazaphenanthrene-2,4-diones. Alternatively, supramolecular complex formation with 2,6-diacetamido pyridine as well as carbenium ion generation have been studied. Although in dilute acid only protonation of one of the carbonyl oxygens occurs, ring opening of the cyclic enol ether toward the carbenium ion is observed in 96% sulfuric acid.

Journal Article↗