Quantification of canavanine, 2-aminoethanol, and cyanamide in Aphis craccivora and its host plants, Robinia pseudoacacia and Vicia angustifolia: effects of these compounds on larval survivorship of Harmonia axyridis.

The cowpea aphid Aphis craccivora that infests the black locust Robinia pseudoacacia shows toxicity to its predator, the multicolored Asian ladybird beetle, Harmonia axyridis. In contrast, the same aphid species that infests the common vetch, Vicia angustifolia, is suitable prey for H. axyridis larvae. Previously, it was reported that the toxicity of A. craccivora infesting R. pseudoacacia was due to canavanine and 2-aminoethanol, but there was some doubt about the toxicity of these compounds and their concentrations in the aphids. In the present study, we determined the concentrations of cyanamide, canavanine, and 2-aminoethanol in A. craccivora infesting the two host plants. In the extracts of A. craccivora that infested either of the host plants, canavanine was undetectable, and 2-aminoethanol was detected at the concentration of 3.0-4.0 µg/g fresh weight. Cyanamide was detected in the extract of A. craccivora that infested R. pseudoacacia (7.7 µg/g fresh weight) but not in that infesting V. angustifolia. The toxicity of canavanine, 2-aminoethanol, and cyanamide was evaluated against H. axyridis larvae in a bioassay by using an artificial diet containing these compounds at various concentrations. Cyanamide exhibited 10-100 times stronger toxicity than canavanine and 2-aminoethanol. These results indicate that the toxicity is at least partly due to cyanamide, which is present in the toxic A. craccivora that infests R. pseudoacacia but absent from the non-toxic A. craccivora that infests V. angustifolia.

Acetaldehyde and the hypothermic effects of ethanol in mice.

BACKGROUND: Acetaldehyde, the first metabolite of ethanol, has been suggested to be involved in many behavioral effects of ethanol. However, few studies have investigated the hypothermic effects of acetaldehyde or the contribution of acetaldehyde to ethanol-induced hypothermia. The aim of the present study is to better understand the hypothermic effects of acetaldehyde and the possible contribution of acetaldehyde in ethanol-induced hypothermia, especially under conditions leading to acetaldehyde accumulation. METHODS: Female Swiss mice were injected intraperitoneally with ethanol and acetaldehyde and their rectal temperatures were measured with a digital thermometer at various time points after the injections. Experiment 1 compared the hypothermic effects of various acetaldehyde doses (0 to 300 mg/kg) with a reference dose of ethanol (3 g/kg). Experiment 2 tested the effects of a pretreatment with the aldehyde dehydrogenase (ALDH) inhibitor cyanamide (25 mg/kg) on ethanol- and acetaldehyde-induced hypothermia. In experiments 3 and 4, mice received a combined pretreatment with cyanamide and the alcohol dehydrogenase (ADH) inhibitor 4-Methylpyrazole (10 mg/kg) before the injection of ethanol or acetaldehyde. RESULTS: Acetaldehyde at doses between 100 and 300 mg/kg induced significant hypothermic effects, but of shorter duration than ethanol-induced hypothermia. The inhibition of ALDH enzymes by cyanamide induced a strong potentiation of both ethanol- and acetaldehyde-induced hypothermia. The pretreatment with 4-MP prevented the potentiation of ethanol-induced hypothermia by cyanamide, but slightly increased the potentiation of acetaldehyde-induced hypothermia by cyanamide. CONCLUSIONS: The results of the present study clearly show that acetaldehyde has hypothermic properties in mice at least at relatively high concentrations. Furthermore, the accumulation of acetaldehyde following ALDH inhibition strongly enhanced the hypothermic effects of ethanol. These latter results confirm the hypothermic properties of acetaldehyde and show that acetate, the next step in ethanol metabolism, is not involved in these hypothermic effects. Finally, the experiment with 4-MP indicates that the potentiating effects of cyanamide are mediated by the peripheral accumulation of acetaldehyde, which then reaches the brain to induce a severe hypothermia.

Update: hydrogen cyanamide-related illnesses--Italy, 2002-2004.

Hydrogen cyanamide is used in agriculture as a plant growth regulator and is applied to many deciduous plants to stimulate uniform budbreak after dormancy, resulting in uniform flowering and maturity. Hydrogen cyanamide is highly toxic, and adverse health effects from contact include severe irritation and ulceration of the eyes, skin, and respiratory tract. The substance also inhibits aldehyde dehydrogenase and can produce acetaldehyde syndrome (e.g., vomiting, parasympathetic hyperactivity, dyspnea, hypotension, and confusion) when exposure coincides with alcohol use. After Dormex (Degussa AG, Trostberg, Germany), a pesticide product containing hydrogen cyanamide (49% by weight), was introduced in Italy in 2000, a total of 23 cases of acute illness associated with exposure to this chemical were identified in early 2001. This led to a temporary suspension of sales and usage of Dormex on February 23, 2002, and strengthening of protective measures, as specified on the pesticide label when sales were resumed on June 20, 2003. This report describes 28 additional cases of hydrogen cyanamide-related illness that occurred during 2002-2004, 14 of which occurred after sales resumed. These illnesses suggest that the preventive measures adopted in Italy in 2003 to protect workers using hydrogen cyanamide are inadequate. Workers exposed to hydrogen cyanamide should be provided adequate information, training, personal protective equipment (PPE), and engineering controls.

Cyanamide phytotoxicity in soybean (Glycine max) seedlings involves aldehyde dehydrogenase inhibition and oxidative stress.

The phytotoxic effect of the allelochemical cyanamide has been well-documented yet the underlying mechanism for this phenomenon has not been fully characterized. Cognizant of the putative inhibitory effect of cyanamide on aldehyde dehydrogenases (ALDHs), we hereby show that the capacity of mitochondrial preparations from cyanamide-treated soybean seedlings to oxidize acetaldehyde and succinic-semialdehyde was dose-dependently reduced to at most 55% and 70%, respectively. Cyanamide-treated plants exhibited oxidative stress (i.e. increased lipid peroxidation and H2O2 accumulation) that was exacerbated upon exposure to UV-A--symptoms reminiscent of ALDH and succinic-semialdehyde dehydrogenase (SSADH) knock-out Arabidopsis mutants. We suggest that the inhibition of mitochondrial ALDH and SSADH may be a contributory mechanism to the burst in oxidative stress mediated by cyanamide.

Role of catalase in the smooth muscle relaxant actions of sodium azide and cyanamide.

The aim of this study was to determine the role of catalase in the smooth muscle relaxant actions of sodium azide and cyanamide. The effects of 3-amino-1,2,4-triazole suggested a role for this enzyme in the relaxant actions of sodium azide on rat aorta and bovine retractor penis muscle and cyanamide on rat aorta. Moreover, results obtained using a difference spectrophotometric assay based upon the oxidation of haemoglobin were consistent with the catalase-dependent oxidation of sodium azide to nitric oxide (NO) and of cyanamide to nitroxyl anion. Surprisingly, however, no free nitric oxide or nitroxyl was detected in solution using a sensitive electrode. This anomaly might be explained if the stable complexes of catalase with nitric oxide or nitroxyl do not release their respective ligand except to sites of high affinity, such as the haemoglobin employed in the difference spectrophotometric assay, or indeed, the soluble guanylate cyclase within the smooth muscle.

Effect of cyanamide on toxicity and glutathione depletion in rat hepatocyte cultures: differences between two dichloropropanol isomers.

The effect of aldehyde dehydrogenase inhibition by cyanamide pre-treatment in vitro on dichloropropanol-dependent toxicity and glutathione depletion was investigated in 24 h rat hepatocyte cultures. Cyanamide pre-treatment had no effect on nitrophenol hydroxylase, 7-methoxy-, 7-ethoxy- or 7-benzyloxyresorufin O-dealkylase activities in 24 h cultures from untreated rats, and had no effect on intracellular glutathione content in cultures from untreated rats, or in cultures from isoniazid-treated rats in which cytochrome P4502E1 (CYP2E1) is increased. In cultures from untreated animals the primary alcohol, 2,3-dichloropropanol, was not toxic and did not significantly deplete glutathione. Cyanamide pre-treatment however, potentiated both toxicity and glutathione depletion. Induction of CYP2E1 also potentiated the toxicity of 2,3-dichloropropanol, and in these cultures cyanamide pre-treatment significantly increased both toxicity and glutathione depletion. Cyanamide did not alter the toxicity or glutathione depletion due to the secondary alcohol, 1,3-dichloropropanol, irrespective of CYP2E1 induction. These results indicate that the primary alcohol isomer is metabolised to an aldehyde intermediate which depletes glutathione. Under basal conditions this metabolite appears to be effectively detoxified, but increased CYP2E1 activity and/or decreased aldehyde dehydrogenase activity promotes accumulation of metabolite, and therefore increases glutathione depletion and toxicity.

Urinary excretion of biomarkers for radical-induced damage in rats treated with NDMA or diquat and the effects of calcium carbimide co-administration.

The urinary excretion of seven aldehydes, acetone, coproporphyrin III and 8-hydroxy-2'-deoxyguanosine (8-OH-dG) as non-invasive biomarkers of oxidative damage was measured in rats treated with diquat or N-nitrosodimethylamine (NDMA), two compounds causing hepatic damage by different mechanisms. Furthermore, the effect of co-administration of the aldehyde dehydrogenase inhibitor, calcium carbimide (CC) on the urinary excretion of the aldehydes was determined. Slight hepatotoxicity was found at the end of the experiment after treatment with NDMA (0.5, 4 and 8 mg/kg at t = 0, 48 and 96 h, respectively) or diquat (6.8 and 13.6 mg/kg at t = 0 and 48 h, respectively). In diquat treated rats slight nephrotoxicity was also found. Urinary excretion of aldehydes, acetone and coproporphyrin III remained largely unchanged in rats treated with NDMA. In the rats treated with diquat, the urinary excretion of several aldehydes was several-fold increased. An increase was also found in the urinary excretion of 8-OH-dG after the second dose of diquat. Treatment of rats with CC did not significantly influence the urinary excretion of aldehydes in control and NDMA rats. However, in rats treated with diquat, CC caused a potentiating effect on the excretion of acetaldehyde, hexanal and malondialdehyde (MDA), indicating that oxidation of aldehydes to carbonylic acids by aldehyde dehydrogenases (ALDHs) might be an important route of metabolism of aldehydes. In conclusion, increased urinary excretion of various aldehydes, acetone, coproporphyrin III and 8-OH-dG was observed after administration of diquat, probably reflecting oxidative damage induced by this compound. No such increases were found after NDMA administration, which is consistent with a different toxicity mechanism for NDMA. Therefore, excretion of aldehydes, acetone, coproporphyrin III and 8-OH-dG might be used as easily accessible urinary biomarkers of free radical damage.

An evaluation of the mutagenic potential of cyanamide using the micronucleus test.

The bone-marrow micronucleus assay was used in mice to evaluate the mutagenic potential of cyanamide administered per os at doses of 10, 49 and 247 mg/kg. Bone-marrow smears were examined to find the incidence of micronucleated cells in 1000 polychromatic erythrocytes (PCE) and 1000 normochromatic erythrocytes ( NCE ). The ratio of NCE /PCE was also scored. No increase in the incidence of micronucleated polychromatic erythrocytes and no difference in the ratio NCE /PCE for the groups treated with cyanamide (10 and 49 mg/kg) were observed. The group treated with the highest dose of cyanamide (247 mg/kg) did, however, show an NCE /PCE ratio lower than the control group (p less than 0.05).

Safe transport of cyanamide.

For many years cyanamide (CAS no. 420-04-2) was not commercially available due to its unstable nature. Since about 1965 the former "Süddeutsche Kalkstickstoffwerke AG" (current name: AlzChem Trostberg GmbH) developed a special stabilizing system. It was to be investigated to which Class (e.g. "Corrosive Substances", Class 8) or Division (e.g. "Self-reactive Substances", Division 4.1) of the International Regulations for the Transport of Dangerous Goods cyanamide (pure or as a 50% solution in water) should be assigned and based on this which maximum quantities are allowed to transport e.g. in tanks. Cyanamide is used for the synthesis of pharmaceutical and agrochemical actives, biocides, dyestuffs and fine chemicals. During the last years cyanamide was tested at BAM and AQura. The results and an appraisal are presented in this paper. Thus, cyanamide should be classified according to the UN Recommendations on the Transport of Dangerous Goods in Class 8, UN number 2922 (50% solution in water) and UN number 2923 (pure substance) respectively, packaging group III, danger labels 8+6.1. Cyanamide, 50% solution in water, can be transported in portable tanks under specific conditions.

Differential phosphorylation of translation initiation regulators 4EBP1, S6k1, and Erk 1/2 following inhibition of alcohol metabolism in mouse heart.

Acute alcohol intoxication leads to an inhibition of protein synthesis in heart that results in part through altered phosphorylation of protein factors controlling mRNA translation initiation. The purpose of the present set of experiments was designed to examine the effects of inhibitors of ethanol metabolism on the phosphorylation of 4E-binding protein (4EBP1) and S6k1(Thr(389)), two factors regulating mRNA translation initiation. Phosphorylation of 4E-BP1, S6k1(Thr(389)), and Erk 1/2 was reduced 2 h following IP injection of alcohol. Pretreatment with 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase (ADH), did not attenuate the ethanol-induced decrease in phosphorylation of 4EBP1 and S6k1(Thr(389)). In contrast, 4-MP prevented the decrease in Erk 1/2 phosphorylation observed with acute ethanol intoxication. Pretreatment with cyanamide, an inhibitor of aldehyde dehydrogenase, did not attenuate the ethanol-induced decrease in phosphorylation S6k1(Thr(389)), but partially prevented the ethanol-induced lowering of 4EBP1 phosphorylation. The studies indicate that modulation of ethanol metabolism through inhibition of ADH or aldehyde dehydrogenase leads to preferential modulation of the phosphorylation of distinct myocardial signaling systems involved in regulating protein synthesis.

Mechanisms of fetal alcohol effects: role of acetaldehyde.

Pregnant rats were treated from day 9 through 12 of gestation with 12.5% ethanol, 25% ethanol, 1% acetaldehyde, cyanamide (an inhibitor of the enzyme aldehyde dehydrogenase), or a combination of cyanamide and ethanol. Embryos were recovered on gestational day 12 and were quantitatively assessed on the basis of 16 recognizable developmental endpoints (morphological scores). The head and the crown-rump lengths of the embryos were also measured. Total resorption occurred in two animals treated with cyanamide and two treated with cyanamide and ethanol. Acetaldehyde and ethanol (at both concentrations) were found to reduce the head length of the embryos but had no significant effects on morphological scores and crown-rump length. The combination of ethanol with cyanamide caused a greater reduction in head length and also significantly reduced crown-rump length, as well as the morphological scores. The results suggest that the deleterious effects of ethanol could be attributed to acetaldehyde, its primary metabolite, although other underlying factors cannot be ruled out.

Potentiation of ethanol toxicity by cyanamide in relation to acetaldehyde accumulation.

The possibility that acetaldehyde accumulation potentiates the acute toxicity of ethanol was studied by pretreating rats with cyanamide, an aldehyde dehydrogenase inhibitor. At 30 min after administration of ethanol (7 to 9 g/kg, po), the levels of acetaldehyde in femoral venous blood of cyanamide-treated rats were increased from 10 to 20 to 600 mumol/liter and at death the concentrations of acetaldehyde in heart blood and cerebrospinal fluid were still 7 to 9 and 4 to 9 times higher, respectively, than in rats given ethanol only. The cyanamide pretreatment (25 mg/kg) significantly increased the mortality of rats given 6.5 to 7.0 g/kg ethanol and decreased the LD50 of ethanol from 7.3 to 5.9 g/kg. Cyanamide increased the late mortality, possibly because of sustained acetaldehyde accumulation. Although administration of the alcohol dehydrogenase inhibitor, 4-methylpyrazole (4-MP, 10 mg/kg), prevented the accumulation of acetaldehyde, it only partly counteracted the effect of cyanamide on mortality. After coadministration of cyanamide and 4-MP, the LD50 of ethanol was 6.5 g/kg, and after 4-MP alone, 6.7 g/kg. 4-MP by itself seemed to increase the early mortality of rats to ethanol poisoning. The results suggest that the potentiating effect of cyanamide on ethanol toxicity can partly be explained by acetaldehyde accumulation and that 4-MP can be used to inhibit this accumulation providing its central depressant effect is taken into account.

A review of the clinical use of disulfiram and calcium carbimide in alcoholism treatment.

The role of disulfiram and calcium carbimide in alcoholism treatment is currently under critical review. Evidence supporting the efficacy of these drugs is unclear: although many alcoholism therapists are of the opinion that the alcohol deterrents are useful in the treatment of the chronic alcoholic, clinical studies with disulfiram that use proper evaluation methodologies report no or only low improvement rates, and there have been no controlled studies with calcium carbimide. Although disulfiram is thought to be safe when administered in therapeutic dosages, toxicity can occur in alcoholics treated with this drug. Information concerning the toxicity of calcium carbimide in alcoholics is incomplete. In this article, the efficacy and toxicity of disulfiram and calcium carbimide are reviewed, and guidelines for their safe and effective use in alcoholism treatment are presented.

[Field study of workers with longterm exposure to calcium cyanamide (author's transl)]. / Felduntersuchung von Personen mit langjähriger Exposition gegenüber Kalkstickstoff.

"Kalkstickstoff" (calcium cyanamide) is extensively used as a fertilizer and a herbicide and also as a chemical intermediate. Its main compounds are calcium cyanamide (CaCN2) (60%) and calcium oxide (15%). In earlier times cauterized damages of the skin and the mucous membranes caused by the content of calcium oxide were common. A certain effect of CaCN2 is the reaction of intolerance after alcohol intake, which expresses as a so-called burning, a flush with redness and feeling of heat of the head, the neck and the upper part of the body often combined with tachycardia and dyspnea. Further health impairments, sometimes with fatal end, were reported repeatedly in the older literature. Convincing evidences for the causal connections between the exposure to CaCN2 and these damages are missed. They exclusively concerned farmers but not workers in the production of CaCN2. Except of the damages of the skin also diseases of the respiratory and gastrointestinal tract, the kidneys, the nervous and circulatory system as well as favoring of infectious complications and goitrogenic effects are in discussion. Furthermore it was suggested that CaCN2 causes a lack of reduced glutathione in the organism. On the occasion of establishing a preliminary MAC-value for CaCN2 in the F.R.G. an occupationally medical field study was performed on 65 workers of a calcium cyanamide factory with long-term exposure to CaCN2. The maximal CaCN2 concentration measured at the working places was 8.3 mg/m3. No signs of diseases or health impairments, which are possibly caused by CaCN2, were found with the medical examination in the above mentioned organs and organ systems. There also was no decrease of the glutathione content of the total blood detectable. With an alcohol load of 22 voluntary workers 1 till 7 hours after the working shift in 6 cases modest and in 7 cases weak flush reactions were observed. As result of the study an elevation of the MAC-value from 1 to at least 2.5 mg/m3 is proposed.

[Free amino acids of the liver and the characteristics of the amino acid metabolism in the liver and brain after cyanamide administration to rats]. / Svobodnye aminokisloty pecheni i osobennosti obmena aminokislot pecheni i mozga pri vvedenii tsiamida krysam.

A single administration to rats of cyanamide (60 mg/kg, for 1 hour) was found to decrease the contents of cysteate, serine, glutamate, glycine, alanine, valine, methionine, isoleucine, tyrosine, ethanolamine, ornithine and histidine that may be considered as a manifestation on the drug hepatotoxicity. The activities of transaminases, glutamate dehydrogenase, pyruvate dehydrogenase remained unchanged. Cyanamide effects were considerably abolished by the supplementary ethanol administration (0.5 g/kg). Cyanamide failed to affect vitamin-dependent enzymes reflecting thiamine pyrophosphate, pyridoxal phosphate and flavine adenine dinucleotide status of the rat organism.

Effect of cyanamide on transaminases and other serum proteins in the rat.

The changes of the serum biochemical features induced by cyanamide, a drug used in the pharmacological treatment of alcoholism, were studied in Wistar rats. Sixty five Wistar rats were divided into 6 groups, 4 experimental and 2 control. Two experimental groups received cyanamide intraperitoneally, at a dose of 1 and 16 mg per kg of body weight, for 8 weeks. One experimental group received CCl4 and the other one CCl4 and cyanamide for 13 weeks. In addition to a delay in the increase of body weight as compared with the control group, the rats receiving cyanamide underwent a marked dispersion of the transaminase and LDH values. This could be explained by the double effect of cyanamide: its capacity to depress the cellular activity (lowered synthesis of proteins, transaminase and LDH among them) and cellular damage. Therefore, some animals showed a marked depression of protein synthesis, causing low enzyme values while cytolysis prevailed in the rest as seen in higher enzyme values. When cyanamide and CCl4 were employed simultaneously, the cyanamide tended to diminish the higher enzyme values caused by CCl4 when used alone. These findings can explain why patients on cyanamide may develop severe liver damage without serious alterations in tests for liver function.

A two-generation reproduction-fertility study of cyanamide in the rat.

A two-generation reproduction-fertility study of cyanamide in the rat has been carried out. After oral administration of 2, 7 and 25 mg/kg/day of the drug, relevant changes have been noted at the highest dose level. Decrease in dam weight gain, in number of corpora lutea, in number of implantations and in number of neonates have been observed in rats of the Fo generation after treatment with 25 mg/kg/day. This group showed a reduced fertility rate and decreases in the weight of several reproductive organs male rats. In contrast to the findings noted in the Fo generation, changes related to cyanamide treatment have not been observed in the F1 generation. Histopathology of these organs has disclosed a low incidence of bilateral testicular atrophy. Decreased fertility rate due to non-specific toxicity associated with a diminished food intake cannot be discarded.

Failure of ethanol and acetaldehyde to alter in vivo norepinephrine release in the striatum and hippocampus of rats.

The effect of ethanol (EtOH) and acetaldehyde (AcH) on norepinephrine (NE) release was examined in the striatum and hippocampus of freely moving rats by means of in vivo microdialysis coupled with high-performance liquid chromatography and an electrochemical detector. Rats were treated intraperitoneally with EtOH (1 g/kg) or cyanamide (CY, 50 mg/kg, a potent aldehyde dehydrogenase inhibitor) plus EtOH (1 g/kg). No significant difference in NE levels in the dialysates was observed in the striatum and hippocampus in either the EtOH or CY+EtOH groups. NE levels in the hippocampal dialysates were about fivefolds higher than those in the striatum. The concentration of EtOH and AcH in the striatal dialysate reached a peak at 30 min after EtOH dosing and then gradually decreased in the CY+EtOH group. In the EtOH group the striatal concentration of EtOH also reached a peak at 30 min after EtOH dosing, and then gradually decreased while AcH was not detected. The present study suggests that there is no in vivo effect of brain EtOH or AcH on NE release in the striatum and hippocampus of awake rats.