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Experimental and quantum-chemical studies on the thermochemical stabilities of mercury carbodiimide and mercury cyanamide.

Calorimetric dissolution measurements of the solid compounds mercury carbodiimide HgNCN(I) and mercury cyanamide HgNCN(II) in aqueous HCl that targeted at their thermochemical stabilities show the cyanamide species HgNCN(II) to be the more stable phase in terms of both enthalpy and Gibbs energy with an enthalpy difference of 2-3 kJ mol-1. While the stability ranking of HgNCN(I) and HgNCN(II) thus perfectly matches Pearson's HSAB concept, quantum-chemical stability predictions using common parametrizations of density functional theory appear to be fundamentally flawed. An analysis of the error is attempted on the basis of correlated wave functions for related molecules.

Journal Article↗

Cyanamide mediated syntheses under plausible primitive earth conditions. IV. The synthesis of acylglycerols.

The synthesis of palmitoylglycerols in good yields occurs when a solution of glycerol, ammonium palmitate, cyanamide and imidazole is dried and heated at ambient humidity at temperatures ranging from 60 degrees--100 degrees C for 16 h. Much less product is formed in the absence of either or both cyanamide or imidazole. This work suggests that acylglycerols could have been synthesized on the primitive Earth under plausible prebiotic conditions which were similar but not identical to those which have been shown to condense deoxynucleotides into oligodeoxynucleotides and amino acids into peptides.

Chemical Phenomena↗

Effect of Hydrogen Cyanamide on Amino Acid Profiles in Kiwifruit Buds during Budbreak.

Buds, and resultant shoots, were collected from kiwifruit (Actinidia deliciosa [A. Chev.] CF Liang et AR Ferguson var deliciosa cv Hayward) vines from late autumn until late spring with and without hydrogen cyanamide treatment. Those samples were weighed and analyzed for total nitrogen and free amino acids. By 7 days after hydrogen cyanamide treatment, the amount of proline had risen to nearly one-quarter of the total amino acid pool in the treated buds and that proportion was maintained for at least 14 days before it declined. The maximum concentration detected in treated buds was 25.8 micromoles per gram dry weight, 6.6 times that detected in untreated buds. By 95 days after treatment, the relative amounts of proline were not significantly different.

Journal Article↗

Inhibition of brain dopa-decarboxylase by RO 4-4602 infused ICV blocks alcohol drinking induced in rats by cyanamide.

Following the stereotaxic implantation of chronic cannulae for intracerebroventricular (ICV) infusion, rats were given an alcohol preference test to establish their preferred concentration in comparison with water. After alcohol was removed, 15 mg/kg cyanamide was then injected subcutaneously for 4 days in order to maximize volitional intake of single solutions of alcohol, which in these animals ranged from 7 to 15%. The L-dopa-decarboxylase inhibitor benserazide (Ro 4-4602) injected subcutaneously twice daily in doses of 50-100 mg/kg failed to alter the rats' alcohol consumption either in terms of g/kg or proportional values. However, when given ICV twice daily in concentrations of 10 ng-2.0 micrograms per 5.0 microliters volume, benserazide attenuated the rats' alcohol drinking significantly. This reduction occurred in a dose-dependent manner in terms of both absolute and proportional intakes of alcohol. Pre-treatment of the animals with 1.0 microgram benserazide given ICV, when alcohol was removed from the test situation, did not abolish the subsequent ingestion of alcohol but its peripheral administration (50 mg/kg) enhanced drinking. These results suggest that the interference with the metabolic pathway of dopamine or serotonin synthesis, possibly through the mechanism of reduced formation of aldehyde adducts in the brain, markedly alters the pattern of voluntary drinking in the rat. Alternatively, benserazide could act by its central inhibition of aldehyde dehydrogenase, which in turn would concomitantly elevate levels of acetaldehyde and thereby reduce alcohol drinking.

Alcohol Drinking↗

Cyanamide mediated synthesis under plausible primitive earth conditions. VI. The synthesis of glycerol and glycerophosphates.

The formation of glycerol occurs when a solution of DL-glyceraldehyde is heated in the presence of hydrogen sulfide at room temperature. DL-glyceraldehyde and dihydroxyacetone treated with hydrazine, as well as DL-glyceraldehyde incubated with formaldehyde are also partially converted to glycerol. The yields of the above reactions are from approximately 1% to about 3%. The formation of glycerophosphates occurs when glycerol is heated with ammonium dihydrogen phosphate and either urea or cyanamide. The yield of glycerophosphates is about 30%, most of which is sn-glycero-1 (3)-phosphate. These findings indicate that glycerol and sn-glycero-3-phosphate, which are moieties of glycerolipids, could have been formed under conditions which may have prevailed on the primitive Earth.

Biological Evolution↗

Cyanamide mediated syntheses under plausible primitive earth conditions. V. The synthesis of phosphatidic acids.

A mixture of ammonium palmitate, 14C-sn-glycero-1(3)-phosphate, cyanimide and imidazole when heated for several hours formed significant quantities of phospholipids. These reaction products were shown by chromatographic, chemical and enzymatic procedures to be monopalmitoylglycerophosphate (MPGP), dipalmitoylglycerophosphate (DPGP) and monopalmitoyl cyclic glycerophosphate (cMPGP). A portion of the MPGP and DPGP possessed the same steric configuration as naturally occurring lysophosphatidic acid and phosphatidic acid. The yield of total phospholipid was maximal at temperatures between 60 degrees and 90 degrees after 8 h. When ratios of reactants were varied, up to 45% of radioactive glycerophosphate was converted into phospholipids. The average proportions of individual phosphatidic acids were: 60% MPGP, 27% DPGP and 13% cMPGP. Evidence was obtained for a synergistic relationship between cyanamide and imidazole in promoting the formation of phosphatidic acids. These results suggest that phosphatidic acids, which are essential precursors for the biochemical synthesis of more complex membrane phospholipids, could have been produced on the primitive Earth.

Cyanamide↗

Effects of high hepatic acetaldehyde level following simultaneous administration of ethanol and cyanamide on liver function in rats.

Extremely high concentrations of hepatic acetaldehyde were induced in rats by the intragastric administration of ethanol and cyanamide, an aldehyde dehydrogenase inhibitor; and these high levels were maintained for 4 weeks. Liver function tests, including mitochondrial ornithine carbamoyltransferase (OCT) and GOT activities, were within normal limits, and no increase in either hepatic triglyceride or collagen contents was observed. These results suggest that hepatotoxic effects of ethanol are not derived from the high acetaldehyde levels in the liver.

Acetaldehyde↗

Ethanol metabolism in isolated hepatocytes. Effects of methylene blue, cyanamide and penicillamine on the redox state of the bound coenzyme and on the substrate exchange at alcohol dehydrogenase.

Ethanol metabolism in hepatocytes increases the NADH/NAD+ ratio. The mechanism was investigated by measurements of the redox state of the coenzyme bound to alcohol dehydrogenase and of ethanol-acetaldehyde exchange and concomitant hydrogen transfer between ethanol molecules. Isolated hepatocytes from fed rats were incubated with cyclohexanone and cyclohexanol or with [1,1-2H2]-and [2,2,2-2H3]ethanol, followed by gas chromatographic determination of the redox state and isotope analysis of the ethanol by gas chromatography-mass spectrometry, respectively. Cyanamide and methylene blue decreased the redox shift caused by ethanol and increased the rates of acetaldehyde reduction during the exchange. Both drugs increased the extent of hydrogen transfer between ethanol molecules during oxidoreduction. Penicillamine had no significant effect on the ethanol-induced change in redox state of the bound coenzyme although it decreased the rate of acetaldehyde reduction. The results indicate that methylene blue inhibits aldehyde dehydrogenase and that accumulation of acetaldehyde decreases the redox effects of ethanol. The redox effect appears to result primarily from rapid elimination of acetaldehyde and equilibration with the NAD system on the alcohol dehydrogenase, but is not enhanced by further decreases in acetaldehyde concentration. Thus, penicillamine could probably be used to decrease the concentration of acetaldehyde without increasing the redox effects.

Acetaldehyde↗

Selective reduction by the 5-HT antagonist amperozide of alcohol preference induced in rats by systemic cyanamide.

This investigation was undertaken to determine the effect of a unique psychotropic agent on the volitional drinking of alcohol induced pharmacologically in the rat by an inhibitor of aldehyde dehydrogenase. Following administration of cyanamide in a dose of 10 mg/kg twice daily for 3 days, the pattern of drinking of ethyl alcohol was determined in each of 12 Sprague-Dawley rats by means of a standard preference test for 3-30% alcohol vs. water. Then, each rat was offered water and its maximally preferred concentration of alcohol, which ranged from 7-15%. After a 4-day predrug test, either the saline control vehicle or the diphenylbutylpiperazinecarboxamide derivative, amperozide, was administered subcutaneously. The injections of amperozide were given b.i.d. at 1600 and 2200 h over 3 days in a dose of 0.5, 1.0, or 2.5 mg/kg. The intake of alcohol during the sequence of amperozide injections was significantly reduced in a dose-dependent manner in terms of both absolute g/kg and proportion of alcohol to water intake, whereas the saline control vehicle was without any effect on alcohol consumption. Although the highest dose of amperozide reduced the total intake of fluid due to the sharp decline in alcohol drinking, neither the consumption of food nor level of body weight was affected by any dose of the drug either during or after its administration. Because amperozide acts centrally on the synaptic activity of dopaminergic and serotonergic neurons in limbic system structures, it is envisaged that the drug ameliorates the aberrant drinking of alcohol by virtue of a direct effect on either one or both of these classes of neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗

5-Hydroxyindoleacetic acid and 5-hydroxytryptophol levels in rat brain: effects of ethanol, pyrazole, cyanamide and disulfiram treatment.

The two serotonin metabolites 5-hydroxyindoleacetic acid (5HIAA) and 5-hydroxytryptophol (5HTOL) were measured in two regions of rat brain (pons medulla and diencephalon) using a gas chromatographic-mass spectrometric (GC-MS) method. Acute ethanol intoxication effected an elevation of 5-hydroxytryptophol levels, while 1 week of treatment with ethanol appeared to have no effect on either metabolite when measured 24 h after the last dose. Disulfiram and cyanamide treatment produced an approximately 2-fold increase in 5-hydroxytryptophol and a slight reduction in 5-hydroxyindole-acetic acid. Pyrazole treatment produced an increase in both metabolites. This effect was, however, counteracted by the simultaneous administration of ethanol.

Animals↗

Cyanamide injections during alcohol deprivation increase alcohol drinking.

Long-Evans male rats were given 7 weeks of choice between 10% ethanol and water and then were divided into 6 matched groups, 3 of which were then deprived of alcohol for 6 days. Subcutaneous cyanamide injections (10 mg/kg, 3 times daily, for 4 days) during alcohol deprivation produced a long lasting, significant increase in subsequent alcohol selection, over and above the increase produced by alcohol deprivation alone. The same injections given to a group not deprived of alcohol caused a significant suppression of alcohol drinking during the treatment and had disappeared 4 days after the last injection. Thereafter the drinking remained at the control level and did not rise to that of the group given the injections during deprivation. The groups did not differ in their subsequent selection of saline solutions.

Alcohol Drinking↗

1-Methyl-tetrahydro-beta-carboline-3-carboxylic acid is present in the rat brain and is not increased after acute ethanol injection with cyanamide treatment.

We conducted analyses of 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (1Me3C-THBC) by gas chromatography-mass spectrometry (negative chemical ionization mode) to investigate its presence and the in vivo condensation between tryptophan and AcH. 1Me3C-THBC was found in the cerebellum and the cerebrum of normal rat [117.0 +/- 41.7 and 46.5 +/- 13.9 pmol/g tissue (mean +/- SEM), respectively]. The concentrations of 1Me3C-THBC and tryptophan were higher in the cerebellum than those in the cerebrum. The level of 1Me3C-THBC in both regions remained unchanged following a single oral ethanol administration alone or with cyanamide pretreatment. These data suggest that acetaldehyde is an unlike precursor of 1Me3C-THBC as a result of ethanol ingestion. 1Me3C-THBC also existed in the rat chow (282.0 +/- 24.2 pmol/g), so that most of brain 1Me3C-THBC detected in the rat brain might have originated from dietary sources. However, the possibility of a biosynthesis from tryptophan and alpha-keto acid still remained, especially after long-term ethanol treatment.

Acetaldehyde↗

An N-hydroxylated derivative of cyanamide that inhibits yeast aldehyde dehydrogenase.

A stable, N,O-dibenzoyl derivative (DBHC) of N-hydroxycyanamide, the latter the postulated bioactivation product of the alcohol deterrent agent, cyanamide, has been synthesized. DBHC was an effective inhibitor of yeast aldehyde dehydrogenase (AIDH) in vitro and inhibited this enzyme in a concentration-dependent manner with an IC50 of 25 microM. Hydrolysis of the benzoate moiety of DBHC with dilute NaOH gave rise to the formation of nitroxyl (HN = O), detected by gas chromatography as nitrous oxide (N2O), the end-product of nitroxyl dimerization and disproportionation. It is postulated that the nitroxyl liberated by esterase action on DBHC by yeast AIDH may be the reactive species that inhibits AIDH.

Aldehyde Dehydrogenase↗

Irreversible suppression of alcohol drinking in cyanamide-treated rats after sustained delivery of the 5-HT2 antagonist amperozide.

The purpose of this study was to evaluate the long-term effect of sustained treatment with amperozide, which has been shown to attenuate the volitional drinking of ethyl alcohol in the rat without side effects. Preference for alcohol first was induced pharmacologically in Sprague-Dawley rats by the inhibitor of aldehyde dehydrogenase, cyanamide, administered in a dose of 10 mg/kg twice daily for 3 days. Then following a standard preference test, each rat was offered water and its maximally preferred concentration of alcohol which ranged from 7% to 15%. Following a 4-day pre-drug test, saline control vehicle or amperozide was administered for 7 days by an osmotic minipump implanted in the intrascapular space. A single dose of 208 micrograms/kg/h (i.e., 5.0 mg/kg/day) was selected on the basis of a prior dose response study of amperozide. During the interval of sustained release of amperozide, the consumption of alcohol declined significantly in terms of both absolute g/kg intake and proportion of alcohol to water. When the preference of the rats was retested at 4, 30, 70, 110, and 140 day intervals after the pump had exhausted amperozide, the absolute g/kg consumption of alcohol continued to decline significantly. Unlike other drugs, amperozide did not produce any side effects, particularly on the intake of food or water or on body weight, which suggests a pharmacological specificity of its action.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗

Physicochemical characterisation of residual hemicelluloses isolated with cyanamide-activated hydrogen peroxide from organosolv pre-treated wheat straw.

Seven residual hemicellulosic preparations (19.6-45.0% of the original hemicelluloses) were extracted from wheat straw pre-treated with various organic solvents using 1.8% H2O2-0.18% cyanamide at 50 degrees C and pH 10.0 for 4 h. Their chemical compositions and physicochemical properties were determined using GC, HPLC, GPC, FT-IR and 13NMR spectroscopy. The results indicated that all the residual hemicellulosic preparations were heteropolysaccharides containing xylose, glucose, arabinose, galactose, mannose, rhamnose and 4-O-methyl-alpha-D-glucopyranosyluronic acid. The predominant monosaccharide was xylose, ranging between 67.7% and 81.9% of the total neutral sugars, composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylan. The content of contaminant lignin in the isolated residual hemicelluloses was 2.89-5.31%. The Mw values of the two residual hemicellulosic preparations H6 and H7 (42,710 and 44,080 g mol-1, respectively) obtained from the aqueous-alcohol pre-treated straw were much higher than those of H1-H5 (12,980-15,950 g mol-1) extracted from the organic acid pre-treated straw.

Carbohydrates↗

Mechanisms of inhibition of aldehyde dehydrogenase by nitroxyl, the active metabolite of the alcohol deterrent agent cyanamide.

Nitroxyl, produced in the bioactivation of the alcohol deterrent agent cyanamide, is a potent inhibitor of aldehyde dehydrogenase (AIDH); however, the mechanism of inhibition of AlDH by nitroxyl has not been described previously. Nitroxyl is also generated from Angeli's salt (Na2N2O3) at physiological pH, and, indeed, Angeli's salt inhibited yeast AlDH in a time- and concentration-dependent manner, with IC50 values under anaerobic conditions with and without NAD+ of 1.3 and 1.8 microM, respectively. Benzaldehyde, a substrate for AlDH, competitively blocked the inhibition of this enzyme by nitroxyl in the presence of NAD+, but not in its absence, in accord with the ordered mechanism of this reaction. The sulfhydryl reagents dithiothreitol (5 mM) and reduced glutathione (10 mM) completely blocked the inhibition of AlDH by Angeli's salt. These thiols were also able to partially restore activity to the nitroxyl-inhibited enzyme, the extent of reactivation being dependent on the pH at which the inactivation occurred. This pH dependency indicates the formation of two inhibited forms of the enzyme, with an irreversible form predominant at pH 7.5 and below, and a reversible form predominant at pH 8.5 and above. The reversible form of the inhibited enzyme is postulated to be an intra-subunit disulfide, while the irreversible form is postulated to be a sulfinamide. Both forms of the inhibited enzyme are derived via a common N-hydroxysulfenamide intermediate produced by the addition of nitroxyl to active site cysteine thiol(s).

Alcoholism↗

Convenient syntheses of symmetrical and unsymmetrical glycosyl carbodiimides and N,N-bis(glycosyl)cyanamides.

Reaction of glycosyl trimethylphosphinimides with carbon disulfide under mild conditions (room temperature, short reaction time) leads to symmetrical glycosyl carbodiimides. Addition of bis(trimethylsilyl)carbodiimide to peracetylated aldoses under the influence of SnCl(4) afforded N,N-bis(glycosyl)cyanamides for the first time. Readily accessible unsymmetrical N,N'-bis(glycosyl)thioureas can be desulfurated and transformed into the corresponding carbodiimides using HgO in CHCl(3)/water at room temperature.

Carbodiimides↗

Effect of different doses of cyanamide on striatal salsolinol formation after ethanol treatment.

To assess the dose-dependent effect of cyanamide (CY, a potent aldehyde dehydrogenase inhibitor) on salsolinol release in the striatum, rats were treated with CY (25, 50 and 100 mg/kg) plus ethanol (EtOH,1 g/kg) intraperitoneally. Striatal salsolinol was detected using in vivo microdialysis coupled with high-performance liquid chromatography with an electrochemical detector in free-moving rats, and blood acetaldehyde (AcH) and EtOH were detected using the head-space gas chromatographic method. With the increase in the doses of CY following EtOH, the peak concentrations of striatal salsolinol and blood AcH were increased significantly. Our study indicated that the magnitude of striatal salsolinol levels may depend on the concentration of blood AcH, and that there is a correlation between the blood AcH and striatal salsolinol.

Acetaldehyde↗