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C Danzin

Publications and source records attributed to C Danzin.

At least 37 records · Page 2Linked to original sources
PubMed1984

High-performance liquid chromatographic analysis of S-adenosylmethionine and its metabolites in rat tissues: interrelationship with changes in biogenic catechol levels following treatment with L-dopa.

A method is described for the simultaneous analysis of S-adenosylmethionine (SAM) and its metabolites, S-adenosylhomocysteine (SAH) and decarboxylated S-adenosylmethionine along with the natural polyamines, putrescine, spermidine and spermine. The separation is obtained by a reversed-phase ion-pair liquid chromatographic procedure with gradient elution followed by dual detection. The UV absorbance at 254 nm is used for the analysis of SAM and of the SAM metabolites, whereas the polyamines and some major amino acids, e.g., methionine, tyrosine and tryptophan, are analyzed by fluorescence detection after UV-cell derivatization with o-phthalaldehyde. A separate ion-pair reversed-phase high-performance liquid chromatographic (HPLC) procedure using isocratic elution and electrochemical detection is employed to analyse in the same tissue extracts the catechols and 5-hydroxyindoles, 3,4-dihydroxyphenylalanine (DOPA), dopamine, norepinephrine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 4-hydroxy-3- methoxyphenylalanine , tryptophan, 5-hydroxytryptophan, serotonin and 5- hydroxyindolacetic acid. The sample preparation for the two HPLC procedures requires only homogenization of the tissues in perchloric acid and centrifugation before injection onto the column. The two chromatographic procedures have been applied to study the interrelationship, in various tissues of rats, between the SAM and SAH levels and the biogenic catechols after different treatments with L-DOPA alone or in combination with alpha- monofluoromethyl -DOPA, a potent enzyme-activated irreversible inhibitor of aromatic L-amino acid decarboxylase.

Adrenal Glands↗
PubMed1984

A rapid high-performance liquid chromatographic procedure for the simultaneous determination of methionine, ethionine, S-adenosylmethionine, S-adenosylethionine, and the natural polyamines in rat tissues.

A method for the analysis of S-adenosyl-L-methionine (SAM) and S-adenosyl-L-ethionine (SAE) and their major metabolites by high-performance liquid chromatography is described. The procedure allows the simultaneous analysis of the natural polyamines, putrescine, spermidine, and spermine, and some of the major amino acids, methionine, tyrosine, and tryptophan. The uv absorbance at 254 nm is used for the determination of the SAM and SAE analogs, whereas the polyamines and amino acids are analyzed by fluorescence detection after postcolumn derivatization with o-phthalaldehyde. The method allows SAM and polyamine determinations by direct injection of the tissue extracts without prepurification. The procedure is applied to study the effects of DL-ethionine treatment on the SAM, SAE, methionine, and polyamine levels in various tissues of rats.

Adenosine↗
PubMed1983

Comparison of 3-isobutyl-1-methylxanthine-induced accumulation of putrescine in rat pancreas and liver.

3-Isobutylmethylxanthine (IBMX), a potent phosphodiesterase inhibitor, causes accumulation of putrescine of same magnitude in rat pancreas and liver. IBMX produces increases of acetyl CoA: polyamine N'-acetyltransferase (PAT) and of ornithine decarboxylase (ODC) activities in both organs. However ODC activity is 300 times higher in liver than in pancreas. In the latter organ, there is a transient increase of N1-acetylspermidine, followed by a decrease of spermidine, alpha-Difluoromethylornithine (DFMO), a potent ODC inhibitor, impairs the accumulation of putrescine in liver but not in pancreas. These results suggest that in pancreas the accumulated putrescine is essentially formed from spermidine, via N1-acetylation and oxidation, while in liver it is formed from decarboxylation of ornithine. A possible involvement of cAMP in the stimulation of the polyamine interconversion pathway is discussed.

1-Methyl-3-isobutylxanthine↗
PubMed1983

(2R,5R)-6-heptyne-2,5-diamine, an extremely potent inhibitor of mammalian ornithine decarboxylase.

It was previously shown that 5-hexyne-1,4-diamine is a potent enzyme-activated irreversible inhibitor of mammalian ornithine decarboxylase. However this compound has secondary pharmacological effects owing to its in vivo oxidation to 4-aminohex-5-ynoic acid, an irreversible inhibitor of 4-aminobutyrate aminotransferase. The first step of this oxidation is catalysed by mitochondrial monamine oxidase. The monomethyl and dimethyl analogues of 5-hexyne-1,4-diamine, i.e. 6-heptyne-2,5-diamine and 2-methyl-6-heptyne-2,5-diamine, which cannot be substrate of monoamine oxidase, were tested as selective irreversible inhibitors of ornithine decarboxylase. Our results demonstrate that (2R,5R)-6-heptyne-2,5-diamine is greater than 10 times more potent, both in vitro and in vivo, than alpha-difluoromethylornithine, the most widely used irreversible inhibitor of this enzyme.

Alkynes↗
PubMed1983

alpha-(Fluoromethyl)dehydroornithine and alpha-(fluoromethyl)dehydroputrescine analogues as irreversible inhibitors of ornithine decarboxylase.

(E)-Dehydro analogues of alpha-(fluoromethyl)putrescine and -ornithine derivatives were synthesized and evaluated in vitro as irreversible inhibitors of a preparation of ornithine decarboxylase (ODC, EC 4.1.1.17) obtained from rat liver. The key step in the synthesis of (E)-alpha-(fluoromethyl)dehydroornithine (17) and -putrescine (14) was the addition of propenylmagnesium bromide to fluoroacetonitrile. The resulting unstable conjugated imine salt was reduced regioselectively in situ with NaBH4 or was quenched with a solution of NaCN to give the corresponding unsaturated alpha-(fluoromethyl) amine and alpha-amino nitrile, respectively. These were transformed into 17 and 14 via a four-step sequence involving (a) phthaloyation of the amine function; (b) allylic bromination of the methyl group; (c) Gabriel reaction; and (d) hydrolytic cleavage of the protective groups. (E)-alpha-(Difluoromethyl)dehydroornithine (10) and -putrescine (7) were prepared from ethyl tert-butyl 2-(difluoromethyl)-2-(2-propenyl)malonate and di-tert-butyl 2-(difluoromethyl)-2-(2-propenyl)malonate, respectively, via a sequence similar to that reported previously for the synthesis of the saturated analogues. Compounds 17, 14, 10, and 7 proved to be much more potent enzyme-activated irreversible inhibitors of ODC than the corresponding saturated analogues. The increase in potency is particularly marked in the alpha-fluoromethyl series. The apparent dissociation constants (KI) and the times of half-inactivation of enzyme (tau 50) at infinite concentration of inhibitors are 2.7 microM and 2.6 min for 17 and 42 microM and 0.2 min for 14. The KI and tau 50 of the corresponding saturated analogues are 75 microM and 1.6 min for the ornithine derivative and 56 microM and 4.4 min for the putrescine derivative.

Animals↗
PubMed1982

alpha-Monofluoromethyl and alpha-difluoromethyl putrescine as ornithine decarboxylase inhibitors: in vitro and in vivo biochemical properties.

In vitro, 5-fluoropentane-1,4-diamine and 5,5-difluoropentane-1,4-diamine are potent enzyme-activated inhibitors of rat liver ornithine decarboxylase (EC 4.1.1.17). The two alpha-fluoromethyl derivatives of putrescine activate to different degrees S-adenosyl-L-methionine decarboxylase (EC 4.1.1.50). The difluoromethyl derivative differs from the monofluoromethyl derivative in that it is not a substrate of diamine oxidase (EC 1.4.3.6), but is a better substrate of mitochondrial monoamine oxidase (EC 1.4.3.4) than the monofluoromethyl derivative. In vivo, a single i.p. injection of 200 mg/kg of 5-fluoropentane-1,4-diamine to rats causes a marked decrease of the ornithine decarboxylase activity in the ventral prostate and to a lesser extent in the thymus, whereas 5,5-difluoropentane-1,4-diamine causes only a slight decrease of this enzyme activity in the prostate and does not affect it in the thymus. Both compounds produce a decrease of 4-aminobutyrate: 2-oxoglutarate aminotransferase (EC 2.6.1.19) activity in the brain. The differences observed between the biochemical properties of the two alpha-fluoromethyl derivatives of putrescine are discussed in relation to the pKa value of the alpha-amino group which decreases from 7.75 for 5-fluoropentane-1,4-diamine to 6.4 for 5,5-difluoropentane-1,4-diamine.

Animals↗
PubMed1982

Reversed-phase ion-pair liquid chromatographic procedure for the simultaneous analysis of S-adenosylmethionine, its metabolites and the natural polyamines.

A method using reversed-phase ion-pair liquid chromatography with dual detection was developed for the simultaneous determination of the S-adenosylmethionine (SAM) analogues and the natural polyamines. The separation is obtained with a gradient elution and by adjusting the concentration of octanesulfonic acid used as ion-pairing agent, the ionic strength of the eluent, the pH and the acetonitrile content of the eluents. The SAM analogues are analyzed by UV detection at 254 nm and the polyamines by fluorescence detection after post-column derivatization with o-phthalaldehyde. The method allows the determination of the SAM analogues and the polyamines in one single run by direct injection of tissue extracts. The procedure is applied to the study in rats and in hepatoma tissue culture cells of the biochemical effects of alpha difluoromethylornithine, a potent enzyme-activated irreversible inhibitor of ornithine decarboxylase.

Animals↗
PubMed1982

Effect on prostatic growth of 2-difluoromethylornithine, an effective inhibitor of ornithine decarboxylase.

2-Difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ornithine decarboxylase, causes marked changes in the polyamine metabolism of ventral prostate when given to adult rats in drinking water (20 g/l) for 3 consecutive days. A 90% inhibition of ornithine decarboxylase activity is accompanied by approx. 80% decreases of the concentrations of putrescine and spermidine and by a 36% decrease in spermine. Concomitantly, S-adenosylmethionine decarboxylase activity increases 7-fold and the concentration of decarboxylated S-adenosylmethionine 450-fold. When DFMO is given to immature rats for 12 consecutive days the above described changes are accompanied by a marked reduction in the age-dependent increases of the wet weight and RNA and DNA contents of the ventral prostate. In adult rats DFMO decreases the weight and RNA content of the ventral prostate within 4 days by 32% and 24% respectively and maintains them constant for the next 19 days. After 23 days of treatment, the prostatic weight is 46% of that of control animals of the same age, whereas the weights of other organs are only slightly decreased. Cytological studies carried out at this time show that DFMO reduces the size of both prostatic acini and the epithelial cells lining the acini.

Animals↗
PubMed1982

Synthesis and biochemical properties of chemically stable product analogues of the reaction catalyzed by S-adenosyl-L-methionine decarboxylase.

Structural analogues of decarboxylated S-adenosyl-L-methionine (dc-SAM), product of the reaction catalyzed by S-adenosyl-L-methionine decarboxylase (SAM-DC), with modifications in the side-chain portion of the molecule have been synthesized, and their ability to inhibit SAM-DC has been investigated. Mainly, compounds with a nitrogen atom in place of the sulfur were investigated. The data from these inhibition studies have resulted in a delineation of the structural features required for binding on SAM-DC. It was concluded that a terminal primary amino group, a terminal carboxyl group, and the sulfonium functionality are not required for binding on SAM-DC. It was also found that analogues of dc-SAM in which replacement of the sulfur by nitrogen was the only modification were still able to form an azomethine with the enzyme. As found for SAM and dc-SAM, these compounds also caused a time-dependent inactivation of SAM-DC.

Adenosylmethionine Decarboxylase↗
PubMed1982

Accumulation of decarboxylated S-adenosyl-L-methionine in mammalian cells as a consequence of the inhibition of putrescine biosynthesis.

Biological transmethylation reactions and polyamine biosynthesis share the substrate S-adenosyl-L-methionine. Under normal conditions, decarboxylated S-adenosyl-L-methionine, the aminopropyl donor for polyamine biosynthesis, does not accumulate because of its rapid utilization in spermidine and spermine synthesis. Alteration of polyamine synthesis by DL-alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor of L-ornithine decarboxylase, leads to a striking accumulation of decarboxylated S-adenosyl-L-methionine in rat hepatoma cells cultured in vitro and in rat ventral prostate. This increase is due both to lack of putrescine and spermidine for the aminopropyltransferase reactions and to the elevation of S-adenosyl-L-methionine decarboxylase activity. The biological implications of accumulation of decarboxylated S-adenosyl-L-methionine are discussed with regard to the regulation of S-adenosyl-L-methionine decarboxylase activity and to the antiproliferative effects of DL-alpha-difluoromethylornithine.

Adenosylmethionine Decarboxylase↗
PubMed1981

alpha-Ethynyl and alpha-vinyl analogues of ornithine as enzyme-activated inhibitors of mammalian ornithine decarboxylase.

alpha-Ethynyl- and alpha-vinylornithine were designed and synthesized as potential enzyme-activated inhibitors of mammalian ornithine decarboxylase. These two new inhibitors produce both immediate and time-dependent inhibition of rat liver ornithine decarboxylase in vitro. The inhibitions exhibition saturation kinetics. The apparent dissociation constants (KI) are 10 and 810 microM, and the times of half-inactivation at infinite concentration of inhibitor (t1/2) are 8.5 and 27 min, respectively, for alpha-ethynyl- and alpha-vinylornithine. In rats, alpha-ethynylornithine causes a rapid dose-dependent decrease of ornithine decarboxylase activity in prostate and, to a lesser extent, in thymus and testis.

Animals↗
PubMed1979

Effects of alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor or ornithine decarboxylase, on testosterone-induced regeneration of prostate and seminal vesicle in castrated rats.

1. Castration of adult rats markedly decreases the amounts of polyamines (putrescine, spermidine and spermine) and of RNA and DNA in the ventral prostate and the seminal vesicle. 2. Daily injections of testosterone propionate to rats castrated 7 days previously increase polyamine and nucleic acid contents more rapidly in the seminal vesicle than in the ventral prostate. 3. After 7 days of androgen treatment, polyamine and nucleic acid contents of the seminal vesicle are significantly higher than those of intact animals. Nucleic acid, but not polyamine, contents return to normal values during the next 4 days of continued treatment. In the prostate, androgen treatment increases polyamine and nucleic acid contents to, but not above, normal values. 4. Repeated doses of alpha-difluoromethylornithine, a potent enzyme-activated irreversible inhibitor of ornithine decarboxylase, totally blocked the testosterone-induced increase of putrescine and spermidine in the ventral prostate and of putrescine in the seminal vesicle. They slowed significantly the accumulation of spermine in the ventral prostate and of spermidine in the seminal vesicle. alpha-Difluoromethylornithine also retarded the testosterone-induced accumulation of RNA in the ventral prostate. However, no clear correlation was apparent between accumulation of polyamines and of nucleic acids in the two organs. 5. alpha-Difluoromethylornithine markedly slows the testosterone-induced weight gain of the prostate, but not of the seminal vesicle. Cytological studies suggest that this effect on the prostate is due to inhibition of the androgen-induced restoration of the secretion content of prostatic acini.

Animals↗