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Pharmacokinetics and pharmacodynamics of valproate analogs in rats. III. Pharmacokinetics of valproic acid, cyclohexanecarboxylic acid, and 1-methyl-1-cyclohexanecarboxylic acid in the bile-exteriorized rat.

The pharmacokinetics of valproic acid (VPA) and its structural analogs cyclohexanecarboxylic acid (CCA) and 1-methyl-1-cyclohexanecarboxylic acid (MCCA) were examined in bile-exteriorized rats. A 0.52 mmol/kg dose (equivalent to 75 mg/kg VPA) of test compound (N = 4 rats per compound) was administered as an intravenous bolus. VPA, CCA, and MCCA concentrations in serum, bile, and urine were determined by gas chromatography before and after incubation in sodium hydroxide to hydrolyze base-labile conjugates. Concentration-time profiles of these compounds in serum displayed apparent Michaelis-Menten kinetics. Serum concentrations of base-labile conjugates were similar to parent concentrations for VPA, were an order of magnitude lower than parent concentrations for CCA, and were undetectable for MCCA. Urinary recovery of base-labile (apparently glucuronide) conjugates in the bile-exteriorized rat was 28.8%, 12.0%, and 25.2% of the administered dose for VPA, CCA, and MCCA, respectively. In contrast, more than 50% of the dose for VPA and MCCA was recovered in bile as the base-labile conjugate, with less than 5% of the CCA dose recovered via this excretory route. Bile flow was stimulated significantly by VPA and MCCA, but not by CCA; changes in bile flow correlated with the biliary excretion rate of base-labile conjugates rather than with excretion of the parent compounds themselves.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

The metabolism of cyclohexanecarboxylic acid in the isolated perfused rat liver.

1. Cyclohexanecarboxylic acid in isolated perfused rat livers was eliminated from the perfusion system by a first-order process. 2. After 6 h, 16% was excreted in bile as cyclohexylcarbonyl beta-D-glucuronide. The remainder was present in the perfusate as unchanged cyclohexanecarboxylic acid (10%), hippuric acid (50%), hexahydrohippuric acid (2%), 3,4,5,6-tetrahydrohippuric acid (2%), cyclohexylcarbonyl-beta-D-glucuronide (2-4%) and benzoic acid (1-2%). Six per cent of the dose was associated with the red blood cell present in the perfusion medium. 3. Unlike the whole animal, the isolated rat liver produced no detectable benzoyl glucuronide. 4. The identity and kinetics of production of the metabolites are consistent with a metabolic pathway previously proposed for cyclohexanecarboxylic acid and shikimic acid.

Animals

The aerobic metabolism of cyclohexanecarboxylic acid by Acinetobacter anitratum.

1. The aerobic metabolism of cyclohexanecarboxylic acid by a bacterium isolated from garden soil (Acinetobacter anitratum) was investigated. 2. Evidence for the formation of cyclohex-1-ene-1-carboxylate, 2-hydroxycyclohexanecarboxylate and pimelate when either cell suspensions or cell-free extracts were incubated in the presence of cyclohexanecarboxylic acid is presented. 3. Crude cell-free extracts required ATP, CoA, FAD and Mg2+ as cofactors for the production of pimelate from cyclohexanecarboxylic acid, suggesting the existence of an activating reaction with formation of CoA esters, in this system.

Acinetobacter

The microbial degradation of cyclohexanecarboxylic acid by a beta-oxidation pathway with simultaneous induction to the utilization of benzoate.

The metabolism of cyclohexanecarboxylic acid by a bacterium, designated PRL W19, follows a pathway involving beta-oxidation of coenzyme A intermediates analogous to the classical oxidation of fatty acids. The organism appears to have the property for the constitutive metabolism of caproic acid, and cell extracts contain high levels of the enzymes required for the functioning of the fatty acid cycle. However, the metabolism of cyclohexanecarboxylic acid requires induction by growth or incubation with an appropriate substrate. Extracts of induced cells contain several enzyme activities which are synthesized in response to the induction process. These enzymes include cyclohexanecarboxyl-CoA synthetase, cyclohexanecarboxyl-CoA dehydrogenase, 1-cyclohexenecarboxyl-CoA hydratase, and trans-2-hydroxycyclohexanecarboxyl-CoA dehydrogenase. A characteristics feature of this organism is that it becomes induced for the metabolism of benzoate and catechol during growth on cyclohexanecarboxylic acid, but benzoate does not appear to be an obligatory intermediate in the metabolism of cyclohexanecarboxylic acid.

3-Hydroxyacyl CoA Dehydrogenases

Stereochemistry of cis-2-hydroxy-2-phenyl-cyclohexanecarboxylic acid (cicloxilic acid).

The configuration of cis-2-hydroxy-2-phenyl-cyclohexanecarboxilic acid (cicloxilic acid) was deduced by comparing its NMR and IR spectra with those of its diastereoisomer and of their respective analogs, the 1-hydroxy(bicyclohexyl)-2-carboxylic acids. The diastereoisomer was prepared by converting cicloxilic acid to the corresponding 2-chloro-2-phenyl-cyclohexanecarboxylic acid and subsequent hydrolysis of the latter with aqueous solvents in the presence of wet silver oxide, or by simple solvolysis. The pair of 1-hydroxy(bicyclohexyl)-2-carboxylic acid was prepared from the respective phenylic terms by catalytic hydrogenation. Comparison of the NMR spectra revealed the spatial arrangement of the -H and -COOH groups on the carbon-alpha atom and the study of the interaction between the substitutents -OH and -COOH by IR spectrography revealed the position of the -OH group with respect to the -COOH group, as a result of which the configuration and conformation of the compounds under study were established. Cicloxilic acid is thus represented by the steric formula 4.

Chemical Phenomena

Cellular response to treatment with 4-(3-(2-chloroethyl)-3-nitrosoureido)-cis-cyclohexanecarboxylic acid, a water-soluble nitrosourea derivative.

The lethal effects of 4-(3-(2-chloroethyl)-3-nitrosoureido)-cis-cyclohexanecarboxylic acid (cis-acid), a water-soluble nitrosourea derivative, were investigated on a human lymphoma cell line. The survival of asynchronous cells exposed to increasing concentrations of the drug was characterized by a threshold exponential curve (Do = 20 microgram/ml; Dq = 20 microgram/ml, 1 hour) similar to that of other nitrosourea derivatives. cis-Acid exerted its main killing effect on cells in early S and in late G2 phase. Cells in mid S and early G1 phase were tenfold more resistant. Changes in survival response as a function of cell cycle stage were reflected primarily by changes in the extent of the shoulder region of the survival curve. In contrast to other nitrosoureas, the lethal effectiveness of cis-acid in solution was stable and the drug could sterilize large numbers of cells in short periods of time. Another important major difference observed for cis-acid with respect to classic nitrosourea derivatives was the capacity of treated cells to recover from sublethal and potentially lethal damage. Our studies have shown that cis-acid is as effective in killing cultured human lymphoma cells as other nitrosoureas, but possibly with a mechanism different from that of these compounds. The major shortcoming noted for cis-acid, namely the capacity of treated cells to recover from drug-induced damage, is offset by the relatively long stability of its killing effect. This, and the fact that cis-acid can be administered in an aqueous solution, make this agent an appealing compound for clinical trials.

Antineoplastic Agents

[The determination of chromium in cadaveric material by using cyclohexanecarboxylic acid].

Method of chrome detection in the course of forensic chemical investigation in the cadaveric material on the basis of cyclohexan-carbonic acid use is presented. Results of experimental researches showed efficacy of method tested as compared to the common one. Method suggested can be used in laboratory conditions to extract chrome from visceral organs of human cadaver.

Cadaver

Biosynthesis of ansatrienin by Streptomyces collinus: cell-free transformations of cyclohexene- and cyclohexadienecarboxylic acids.

Cell-free extracts of Streptomyces collinus were tested with various cyclohexene- and cyclohexadienecarboxylic acids in order to determine the latter stages of the conversion of shikimic acid to cyclohexanecarboxylic acid. It was demonstrated that the final three steps of this process involve reduction of the alpha,beta-double bond of 1(6),2-cyclohexadienylcarbonyl CoA, an isomerization of the double bond of the resulting 2-cyclohexenylcarbonyl CoA to afford 1-cyclohexenylcarbonyl CoA, and a subsequent reduction of the newly formed alpha,beta-double bond. Both of the reduction steps were shown to require NADPH as a cofactor.

Anti-Bacterial Agents

Kinetics and mechanism of decomposition of N-chloroamino acids. II: conformationally restricted models.

The kinetics of decomposition of the following conformationally restricted N-chloro-alpha-amino acids were studied: 1-amino-1-cyclopentanecarboxylic acid (2), 1-amino-1-cyclohexanecarboxylic acid (4), 2-amino-2-norbornanecarboxylic acid (6), and 2-amino-2-benzonorbornanecarboxylic acid (8). The first-order rate constants obtained were 0.520, 5.197, 0.198, and 0.078, respectively, which correlated with the ring strain in the structurally related cyclic ketones cyclopentanone, cyclohexanone, norborane-2-one, and benzonorbornane-2-one. The data are supportive of a concerted mechanism for the decomposition reaction involving an imine-like transition state.

Amino Acids

Gas-chromatographic analysis for valproic acid as phenacyl esters.

We describe a novel isothermal gas-chromatographic procedure for measuring valproic acid. Plasma, with cyclohexanecarboxylic acid added as internal standard, is selectively extracted with pentane to minimize the extraction of other acidic drugs. To convert carboxylic acids to their phenacyl esters, alpha-bromoacetophenone is added to the organic extract before evaporating the solvent. These esters are relatively less volatile than the acids themselves and the extracting solvent can be removed without any loss of valproic acid or internal standard. The phenacyl esters, when chromatographed on 3% OV-17, produce sharp, well-shaped peaks and show high response for the flame ionization detector. Valproic acid is well separated from the internal standard, from reagents and plasma constituents, and from some commonly prescribed drugs that we examined. When alpha-bromo-p-nitroacetophenone is sued as the derivatizing agent, the resulting nitrophenacyl esters can be analyzed with use of a nitrogen-specific detector.

Acetophenones

Purification and characterization of a novel enoyl coenzyme A reductase from Streptomyces collinus.

A novel NADPH-dependent enoyl reductase, catalyzing the conversion of 1-cyclohexenylcarbonyl coenzyme A (1-cyclohexenylcarbonyl-CoA) to cyclohexylcarbonyl-CoA, was purified to homogeneity from Streptomyces collinus. This enzyme, a dimer with subunits of identical M(r) (36,000), exhibits a Km of 1.5 +/- 0.3 microM for NADPH and 25 +/- 3 microM for 1-cyclohexenylcarbonyl-CoA. It has a pH optimum of 7.5, is most active at 30 degrees C, and is inhibited by both divalent cations and thiol reagents. Two internal peptide sequences were obtained. Ansatrienin A (an antibiotic produced by S. collinus) contains a cyclohexanecarboxylic acid moiety, and it is suggested that the 1-cyclohexenylcarbonyl-CoA reductase described herein catalyzes the final reductive step in the conversion of shikimic acid into this moiety.

Amino Acid Sequence

Influence of cicloxilic acid on energy production by hepatocyte mitochondria during acute ethanol intoxication.

Liver mitochondria from acute ethanol intoxicated rats show a highly significant uncoupling of oxidative phosphorylation. cis-2-Hydroxy-2-phenyl-cyclohexanecarboxylic acid (cicloxilic acid) early normalizes the P/O ratio and, therefore, the mitochondrial energy producing mechanisms. The significance of these phenomena and the possible role of cicloxilic acid on mitochondrial energy-production are discussed.

Alcoholic Intoxication

Construction, expression, and purification of recombinant kringle 1 of human plasminogen and analysis of its interaction with omega-amino acids.

An Escherichia coli expression vector, containing the alkaline phosphatase promoter and the stII heat-stable enterotoxin signal sequence, along with the cDNA of the kringle 1 (K1) region of human plasminogen (HPg), has been employed to express into the periplasmic space amino acid residues 82-163 (E163----D) of HPg. This region of the molecule contains the entire K1 domain (residues C84-C162) of HPg, as well as two non-kringle amino-terminal amino acids (S82-E83) that are present in their normal locations in HPg and a carboxyl-terminal amino acid, D163, that results from mutation of the E163, normally present at this location in the HPg amino acid sequence. After purification of r-K1 by chromatographic techniques, we have investigated its omega-amino acid binding properties by titration calorimetry, intrinsic fluorescence, and differential scanning microcalorimetry (DSC). The antifibrinolytic agent, epsilon-aminocaproic acid (EACA), possesses a single binding site for r-K1. The thermodynamic properties of this interaction, studied by calorimetric titrations of the heats of binding with this ligand, reveal a Kd of 12 +/- 2 microM at 25 degrees C and pH 7.4, a corresponding delta G of -6.7 +/- 0.1 kcal/mol, a delta H of -3.6 +/- 0.1 kcal/mol, and a delta S of 10.5 +/- 0.8 eu. The intrinsic fluorescence of r-K1 decreases by approximately 44% when its binding site is saturated with EACA, and titrations of this perturbation with EACA lead to calculation of a Kd of approximately 13 microM, a value in good agreement with that obtained from titration calorimetric analysis. EACA represents the strongest binding ligand of a variety of simple aliphatic omega-amino acids examined. A cyclic analogue of EACA, trans-4-(aminomethyl)cyclohexanecarboxylic acid, interacts with r-K1 with an approximate 12-fold tighter Kd (1.0 +/- 0.2 microM). Investigations by DSC, at pH 7.4, demonstrate that a significant stabilization of the r-K1 structure occurs when EACA binds to this domain. The temperature of maximum heat capacity change (Tm) in the thermal denaturation of r-K1 increases from approximately 340.8 to 359.1 K as a consequence of EACA binding. These studies demonstrate that a fully functional EACA-binding kringle from HPg can be expressed and secreted in E. coli, purified by techniques that do not require refolding, and investigated as an independent structural unit.

Amino Acid Sequence

Baclofen (beta-p-chlorophenyl-gamma-aminobutyric acid) enhances [3H]gamma-aminobutyric acid (3H-GABA) release from rat globus pallidus in vitro.

The rat globus pallidus has been investigated as a possible model in which to study pre-synaptic GABA mechanisms in vitro. (+/-)-Baclofen (300 micrometer-1 mM) significantly enhanced the release of radioactivity from superfused slices of rat globus pallidus prelabelled with 3H-GABA in vitro. This releasing action was specific to the (+)-isomer of baclofen: neither the (-)-isomer nor another neuronal depressant dl-alpha-epsilon-diaminopimelic acid had any significant effect. The releasing effect of baclofen appeared unrelated to the phenethylamine moiety of its structure as neither beta-phenethylamine nor dopamine evoked release of 3H-GABA from pallidal slices. Baclofen increased the efflux of radioactivity from pallidal slices prelabelled with either [3H]-beta-alanine or [3H]diaminobutyric acid in vitro. The use of specific glial and neuronal GABA uptake blocking compounds (beta-alanine and (+/-)-cis-1,3-amino-cyclohexanecarboxylic acid) did not permit resolution of the elements from which baclofen was evoking [3H]GABA release. Baclofen also inhibited uptake of [3H]GABA into pallidal slices with an IC50 value of 6 x 10(-4) m. The GABA-like properties of baclofen may be related to the (+)-isomer while non-specific neuronal depressant actions are an effect of the (-)-isomer. The potential of the (+)-isomer as an antipsychotic agent while (-)-baclofen remains the effective antispastic drug free from unwanted side-effects, is discussed.

Alanine

Ligand specificity of human plasminogen kringle 4.

The ligand specificity of the human plasminogen kringle 4 was characterized in terms of ligand size, aromatic/aliphatic character, and ionic charge distribution. The binding of the following ligands was investigated via 1H NMR spectroscopy, and their equilibrium association constants (Ka) were determined: (1) p-aminomethylbenzoic acid (Ka approximately 4.8 mM-1), (2) benzylamine (Ka approximately 0.2 mM-1), (3) l-aminohexane (Ka approximately 0.07 mM-1), (4) 7-aminoheptanoic acid (Ka approximately 6.6 mM-1), (5) 5-aminopentanoic acid (Ka approximately 16 mM-1), (6) N alpha-acetyl-L-arginine (Ka approximately 0.3 mM-1), and (7) N alpha-acetyl-L-arginine methyl ester (Ka approximately 0.08 mM-1). Benzamidine and L-arginine do not bind measurably to kringle 4. We have also established that 1-hexanoic acid and 4-methylbenzoic acid do not interact significantly with kringle 4 (Ka less than 0.05 mM-1). The Trp62 resonances were found to be quite sensitive to aromatic ligands as well as to aliphatic ligand length. Phe64 is similarly sensitive to the ligand aromatic/aliphatic character and chain length and to the identity of the ligand anionic group. His31 and His33 do not respond significantly to variations in ligand structure, although they are perturbed by aromatic and aliphatic effectors. The perturbations induced by the arginine derivatives on these residues show that these compounds interact with the lysine-binding site (LBS) of kringle 4. The LBS was further characterized using 2D NMR studies of a kringle 4/trans-(aminomethyl)cyclohexanecarboxylic acid (AMCHA) complex. A complete assignment of the AMCHA spectrum in the bound state was achieved. This enabled the unambiguous identification of intermolecular contact points between the central AMCHA protons and Trp62 and Trp72. A model based on the X-ray crystallographic structure of kringle 4, incorporating these constraints, has been derived.

4-Aminobenzoic Acid

Aurintricarboxylic acid (ATA) and DNA synthesis. I. Inhibition of DNA synthesis by ATA in Go cells stimulated to proliferate.

Aurintricarboxylic acid (ATA) at a concentration which produces 40% inhibition of protein synthesis, inhibits completely isoproterenol-stimulated DNA synthesis in mouse parotid glands. The drug was found to interfere with some essential changes occurring during the prereplicative phase of IPR-stimulated DNA synthesis. It inhibits the increase in ribosonal protein synthesis that takes place by 2 h after stimulation. The peak of ribosonal RNA that occurs 8 h after isoproterenol was also abolished by ATA. Since the drug completely inhibits isoproterenol-stimulated DNA synthesis, these results suggest that the control of ribosome production may be involved in cell growth activation. In view of the finding that ATA first inerferes with the binding of adenylate-rich RNA to polysomes, it was suggested that the drug may act by preferentially inhibiting that fraction of protein synthesis dependent on the newly transcribed messenger RNA.

Animals