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CpIr complex-catalyzed N-heterocyclization of primary amines with diols: a new catalytic system for environmentally benign synthesis of cyclic amines.

[reaction: see text] A new efficient method for the N-heterocyclization of primary amines with diols catalyzed by a CpIr complex was developed. A variety of five-, six-, and seven-membered cyclic amines were synthesized in good to excellent yields with the formation of only water as a byproduct. A two-step asymmetric synthesis of (S)-2-phenylpiperidine was also achieved using (R)-1-phenylethylamine as a starting primary amine.

Alcohols↗

Marked amine and amine metabolite changes in Norrie disease patients with an X-chromosomal deletion affecting monoamine oxidase.

Urinary and plasma amines and amine metabolites were quantified in two individuals with Norrie disease resulting from a deletion in chromosomal region Xp11.3, recently reported to be associated with absence of the gene encoding monoamine oxidase (MAO)-A and nondetectable MAO-A activity in fibroblasts and MAO-B activity in platelets. Marked (four-to 100-fold) elevations in levels of urinary phenylethylamine, o-tyramine, and m-tyramine (which are preferential substrates for MAO-B) and marked reductions (90%) in levels of 3-methoxy-4-hydroxyphenylglycol (a deaminated metabolite of norepinephrine, a preferential substrate for MAO-A) in urine and plasma confirmed the presence of a systemic, functionally significant reduction in the activities of both MAO isozymes. The magnitude of these changes, which are equivalent to those found in subjects taking MAO-inhibiting antidepressants, suggests that early initiation of dietary and drug restrictions may be clinically important in these and other patients with X-chromosomal mutations involving MAO. These findings further support the proposition that the MAOA and MAOB genes are located in close proximity on the X chromosome. Negligible changes in the metabolites of dopamine and serotonin raise the possibility that other metabolic pathways are of importance for their production, that dietary or intestinal bacterial sources contribute substantially to the presence of these amine metabolites in urine, or both.

Adolescent↗

In-vivo effects of (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine (MDL 72145) on amine oxidase activities in the rat. Selective inhibition of semicarbazide-sensitive amine oxidase in vascular and brown adipose tissues.

One hour after MDL 72145 ((E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine) (2.5 mg kg-1) was given by intraperitoneal injection, the semicarbazide-sensitive amine oxidase (SSAO) activity of rat aorta and brown adipose tissue measured in-vitro was reduced by more than 95% of its control value, whereas the monoamine oxidase (MAO-A) activity remained virtually unaffected. The action of this drug on amine oxidases in the liver at this dose was less selective. The in-vitro effect of MDL 72145 on the soluble enzyme diamine oxidase from rat intestine was 100 fold less potent than that of semicarbazide but about equipotent with semicarbazide on sheep plasma amine oxidase. Overall MDL 72145 was selectively more active against membrane bound SSAO enzymes that deaminate primary monoamines. Although MDL 72145 does inhibit MAO-B activity these results suggest that this compound may be used to study the effect of selective inhibition of SSAO activity on the pharmacological responses of appropriate preparations in-vitro.

Adipose Tissue, Brown↗

Anti-inflammatory effects of inhibiting the amine oxidase activity of semicarbazide-sensitive amine oxidase.

Human semicarbazide-sensitive amine oxidase (SSAO) or vascular adhesion protein-1 (VAP-1) is a copper-containing amine oxidase (AOC3, EC 1.4.3.6) that has both enzymatic and adhesive function. SSAO catalyzes the oxidative deamination of primary amines, resulting in the formation of the corresponding aldehyde and release of hydrogen peroxide and ammonia. Membrane-bound SSAO is an inflammation-inducible endothelial cell adhesion molecule that mediates the interaction between leukocytes and activated endothelial cells in inflamed vessels. Both the direct adhesive and enzymatic functions seem to be involved in the adhesion cascade. LJP 1207 [N'-(2-phenyl-allyl)-hydrazine hydrochloride] is a potent (human SSAO IC(50) = 17 nM), selective, and orally available SSAO inhibitor that blocks both the enzymatic and adhesion functions of SSAO/VAP-1. In a mouse model of ulcerative colitis, LJP 1207 significantly reduces mortality, loss of body weight, and colonic cytokine levels. Quantitative histopathological assessment of colitis activity in this model showed a highly significant suppression of inflammation, injury, and ulceration scores in the animals treated with the SSAO/VAP-1 inhibitor. LJP 1207 also reduced serum levels of tumor necrosis factor-alpha and interleukin 6 in lipopolysaccharide (LPS)-challenged mice and prolonged survival post-LPS-induced endotoxemia. Therapeutic and prophylactic administration of LJP 1207 in the rat carrageenan footpad model also markedly inhibited swelling and inflammation. Overall, the data suggest that small molecule SSAO/VAP-1 inhibitors may provide clinical benefit in the treatment of acute and chronic inflammatory diseases.

Amine Oxidase (Copper-Containing)↗

In situ fluoride retention in enamel and dentine after the use of an amine fluoride dentifrice and amine fluoride/sodium fluoride mouthrinse.

The aim of this in situ investigation was to study the effect of an amine fluoride/sodium fluoride mouthrinse (total F = 250 ppm) in addition to an amine fluoride dentifrice (F = 1,250 ppm) on the amount of acquired fluoride in enamel and dentine. In the partial prosthesis of 12 participants a combined specimen of slightly demineralized enamel and dentine was placed. During two consecutive experiments, each lasting 3 weeks, the participants used an amine fluoride dentifrice alone or in combination with a fluoride mouthrinse. After the in situ period the specimens were retrieved and both the enamel and the dentine specimens were analysed for the amount of KOH-soluble fluoride and structurally bound fluoride. The results showed a significant increase in both KOH-soluble and structurally bound fluoride in enamel and dentine when a fluoride mouthrinse was used. Whether the rinsing procedure was performed immediately after toothbrushing or with a delay of 2 h did not influence the results. Furthermore it was shown that dentine acquired substantially more fluoride than enamel during the experimental period. The results indicate that a fluoride mouthrinse used in addition to a fluoride dentifrice may have a beneficial effect on the protection of enamel and dentine against caries.

Adsorption↗

Biogenic amine and amine precursor uptake by mast cells.

The mast cell population is heterogeneous concerning its amine precursor and amine uptake. The immature cells incorporate amine precursors, but in more advanced stages of their maturation they take up only 5-HTP. The mature cells do not take up precursors only 5-HT. The thyroid gland and heart muscle mast cells take up the highest amount of 5-HT; this may be related with some specific function of the mast cells in these two organs. Neither of the mast cells would take up histamine, the compound is synthetised by the cells.

5-Hydroxytryptophan↗

Control of the mutagenicity of aromatic amines by protein kinases and phosphatases. I. The protein phosphatase inhibitors okadaic acid and ortho-vanadate drastically reduce the mutagenicity of aromatic amines.

The role of protein kinase C and protein phosphatases was examined in the control of mutagenic metabolites of aromatic amines. Various metabolic activating systems derived from rat liver were treated with: 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C modulator; okadaic acid (OA), a potent inhibitor of serine/threonine protein phosphatases (PP1 and PP2A); and ortho-vanadate (OV), an inhibitor of tyrosine phosphatases. TPA used over a wide concentration range (10(-9)-10(-6) M) did not affect the bacterial mutagenicity of the aromatic amines and of the aromatic amide investigated, 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene (2AAF). At the molecular level, TPA did not affect the function of cytochrome P450s 1A1 or 1A2, which are known key factors for the activation and inactivation of aromatic amines/amides. By contrast the OA and OV treatment of rat hepatocytes, rat liver homogenate, fraction S9 and the nuclear fraction drastically reduced (by > 80%) the mutagenicity of the aromatic amines/amide investigated. This is by far the most pronounced change in genotoxicity observed to date via modulation of phosphorylation. Whilst the mutagenicity of the primary toxication product 2-N-OH-acetylaminofluorene (2-N-OH-AAF) in the presence of exogenous activating systems (hepatocytes, S9-fraction, nuclear fraction) was also reduced by OV, OA had no influence. Thus the tyrosine protein phosphatase inhibitor and the serine/threonine protein phosphatase inhibitor influence the genotoxicity of aromatic amines/amides on different levels. Moreover, this shows that the drastic reduction in mutagenicity by OA was due to its influence on a step prior to the presence of the primary toxication product 2-N-OH-AAF. This reduction could be due to changes in the activity of cytochrome P4501A1 and/or 1A2. However, no incorporation of 32P-labelled phosphate from intracellularly prelabelled [32P]-ATP into cytochromes P450 1A1 or 1A2 nor any change in their catalytic activities was observed in the presence of OA. Furthermore, a phosphorylation dependent change in the function of P-glycoprotein (known for its role in the transport of diverse xenobiotic substances and their metabolites) was shown not to contribute to the observed decrease in mutagenicity. Our results reveal an important role for protein phosphatase 1 and/or 2A and tyrosine phosphatase(s) in the control of the genotoxicity of aromatic amines and amides. However, the present study does not distinguish between effects mediated by individual proteins affected by these protein phosphatases.

2-Acetylaminofluorene↗

Pancreatic carcinogenic effect of N-nitrosobis (2-oxobutyl) amine and N-nitroso (2-oxobutyl) (2-oxopropyl) amine in Syrian hamster.

A single subcutaneous injection of N-nitrosobis(2-oxobutyl)amine (BOB) and N-nitroso(2-oxobutyl)(2-oxopropyl)amine (OBOB) induced a high incidence of pancreatic ductular neoplasms in Syrian hamsters. Both compounds showed a cytotoxic effect on pancreatic islet cells in toxic doses. Since both compounds, like N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), can form cyclic structures resembling the hexose sugars and the glucose-moiety of the streptozotocin, it can be assumed that the ability of these 2 carcinogens to cyclize is important in their affinity for the pancreas. However, OBOP had a greater pancreatic carcinogenic effect than BOB, the primary target tissue of which was the liver. Hence factors other than cyclization, such as the presence of the 2-oxo group in the aliphatic chains, also appear to be important for the pancreatic carcinogenicity of this class of nitrosamines.

Animals↗

1,5-benzodiazepines. Part XIII. Substituted 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines and 4H-imidazo[1,2-a][1,5]benzodiazepin-5-amines as analgesic, anti-inflammatory and/or antipyretic agents with low acute toxicity.

The reaction of proper N,N-dialkyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amines (1) with N-chlorosuccinimide afforded their 4-chloroderivatives 3 which in turn were treated with cyclic amines to give the corresponding 4,5-diaminoderivatives 4. The N,N-dialkyl-4H-imidazo[1,2-a][1,5]benzodiazepin-5-amines (5) were prepared starting from suitable 4-(dialkylamino)-1,3-dihydro-2H-1,5-benzodiazepin-2-ones (8), through multistep synthetic routes. At the 200 mg kg(-1) os dose, some compounds 3 and 4 showed notable analgesic or anti-inflammatory activity but no antipyretic properties, whereas the 5-(dibutylamino) derivatives 5b and 5f proved to be significantly endowed with all these activities. Almost all the compounds 3, 4 and 5 did not show acute toxicity in mice up to 800 mg kg(-1) os dose.

Analgesics↗

Regulation of N-arginine dibasic convertase activity by amines: putative role of a novel acidic domain as an amine binding site.

Peptide sequence analysis and cDNA cloning indicate that a previously described mouse arginine-specific dibasic cleaving enzyme (dynorphin converting enzyme) [Csuhai et al. (1995) Biochemistry 34, 12411] is the homologue of N-arginine dibasic convertase (NRDc) isolated from rat testis [Chesneau et al. (1994) J. Biol. Chem. 269, 2056]. A mouse NRDc cDNA exhibited 98% amino acid identity with the rat cDNA. However, within a 74 residue acidic stretch, this identity drops to 82%. Likewise, the corresponding acidic stretch of human NRDc is only 73% identical with that of rat NRDc. To reconcile previously observed kinetic differences between rat and mouse NRDc, the hydrolysis of peptide substrates by the rat, human, and mouse enzymes was compared using phosphate and Tris as buffers. Although the three NRDc's behaved similarly, Tris had a pronounced effect on the kinetics of peptide hydrolysis. With BAM-8, alpha-neoendorphin, and dynorphin B as substrates, Tris increased KM up to 40-fold with little change in Vmax, while with dynorphin A or somatostatin 28 as substrate, Tris caused a decrease in KM of up to 100 fold, again with only a modest change in Vmax. Other amines, including the polyamines putrescine, spermidine, and spermine, all affected NRD convertase activity. It is proposed that amines bind to the acidic stretch found in NRDc, and that quantitative differences in the sensitivity to amines between the rat, mouse, and human enzymes can be at least partially accounted for by differences in their acidic stretch. The role of polyamines as physiological modulators of N-arginine dibasic convertase is considered.

Amino Acid Sequence↗

Fluoro-substituted N-nitrosamines. 7. Non-genotoxic N-nitroso-bis(2,2,2-trifluoroethyl)amine and N-nitroso-bis(2,2,3,3,4,4,4-heptafluorobutyl)amine: binding to cytochrome P-450, acidity of alpha-protons and pharmacokinetic investigations.

The biologically inactive fluorinated nitrosamines N-nitroso-bis(2,2,2-trifluoroethyl)amine (NDEA-F6) and N-nitroso-bis-(2,2,3,3,4,4,4-heptafluorobutyl)amine (NDBA-F14) were investigated for binding affinity to cytochrome P-450 and for ease of alkali-induced proton abstraction at the alpha-C atom, in comparison with biologically active analogues (N-nitroso-diethylamine, NDEA; N-nitroso-2,2,2-trifluoroethylethylamine, NDEA-F3; N-nitrosodibutylamine, NDBA; N-nitroso-4,4,4-trifluorobutylbutylamine, NDBA-F3; N-nitroso-bis(4,4,4-trifluorobutyl)amine, NDBA-F6). Binding to cytochrome P-450 was studied by spectroscopic measurements (optical difference spectra with microsomal fractions); base-catalyzed deuterium exchange of alpha-hydrogen atoms was followed by 1H n.m.r. measurements. Additionally the excretion of NDEA-F6 and NDBA-F14 in expired air, urine and faeces was studied after oral application to the rat. Compared with the biologically active nitrosamine analogues, NDEA-F6 and NDBA-F14 showed higher binding affinity to cytochrome P-450. N.m.r. spectroscopy showed that NDEA-F6, NDBA-F14 and NDEA-F3 (at the fluorinated alkyl chain) were rapidly deprotonated at the alpha-C-position in sodium perdeutero methylate, in contrast to the other analogues tested. In vivo, NDEA-F6 and NDBA-F14 were excreted unchanged, mainly via exhalation. The biological inactivity of NDEA-F6 and NDBA-F14, together with the observed blocking of their microsomal activation can be reconciled with the experimental findings which indicate that homolytic alpha-C-H bond fission is more likely to be involved in alpha-C-hydroxylation of dialkylnitrosamines, than alpha-proton abstraction.

Animals↗

Metabolism of the pancreatic carcinogens N-nitroso-bis(2-oxopropyl)amine and N-nitroso-bis(2-hydroxypropyl)amine in the Syrian hamster.

Metabolisms of the potent pancreatic carcinogens N-nitroso-bis(2-oxopropyl)amine (BOP) and N-nitroso-bis(2-hydroxypropyl)amine (BHP) were studied in male Syrian hamsters. BHP and a new metabolite, N-nitroso-(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), were detected in the urine of hamsters administered BOP and BHP. The rates of HPOP formation from BOP and BHP were determined by the measurement of blood and urine levels at various times after each compound was administered: HPOP was formed readily from BOP, but slowly from BHP. This may explain the different organotropic spectra and carcinogenic potencies of BOP and BHP.

Animals↗

Expedited palladium-catalyzed amination of aryl nonaflates through the use of microwave-irradiation and soluble organic amine bases.

[reaction: see text] Microwave-assisted, palladium-catalyzed C-N bond-forming reactions with aryl/heteroaryl nonaflates and amines using the soluble amine bases DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or MTBD (7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene) and ligands (1-3) resulted in good to excellent yields (71-99%) of arylamines in short reaction times (1-45 min).

Amination↗

Biomonitoring of aromatic amines II: Hemoglobin binding of some monocyclic aromatic amines.

Covalent binding of 13 monocyclic aromatic amines to hemoglobin was studied in female Wistar rats and hemoglobin binding indices were determined. The hemoglobin adducts were hydrolyzed under alkaline conditions. In all cases the parent amine could be identified by gas chromatography and with one exception represented the only cleavage product. The binding index varied considerably and was highest with p-chloroaniline (569) and lowest with 2,4,5-trimethylaniline (0.7). Five compounds were also studied in female B6C3F1 mice. Hemoglobin binding was lower than in rats, but to varying degrees. Hemoglobin binding correlated remarkably well with the maximum methemoglobin level achieved with the six examples studied. The results support the notion that the reaction of nitrosoarenes, as metabolites of arylamines, with hemoglobin represents a general pathway in vivo. The analysis of such hemoglobin adducts is recommended as a dosimeter in biological monitoring of humans in order to control exposure. It is too early, however, to assess the carcinogenic risk from hemoglobin binding data with these compounds.

Amines↗

The activity of amitriptyline as a differential inhibitor of amine secretion from rat peritoneal mast cells: the contribution of amine uptake.

Amitriptyline, at a concentration of 10(-4) M, significantly inhibited the release of histamine from purified peritoneal rat mast cells in response to compound 48/80, but was without effect upon the output of 5-HT. The reduction was not extensive, and concentrations of the drug above or below 10(-4) M were without effect. Amitriptyline (10(-8)-10(-4) M) inhibited uptake of exogenous 5-HT in a concentration dependent manner. Paradoxically, however, histamine uptake was significantly increased in the presence of this drug, but only at a concentration of 10(-4) M. This effect was observed at 4 degrees C for both amines. Concentrations of amitriptyline in excess of 10(-4) M caused lysis of the mast cells. These results suggest that the observed selective inhibitory effect of amitriptyline upon histamine output may be a function of altered amine uptake rather than differential inhibition and 5-HT secretion.

Amitriptyline↗

Biomonitoring of aromatic amines V: acetylation and deacetylation in the metabolic activation of aromatic amines as determined by haemoglobin binding.

Aromatic amines are metabolically activated by N-oxidation of either the amine or the acetamide as a first step and esterification of the resulting N-hydroxyl derivatives as a second step. Both pathways may lead to DNA-adducts and subsequently to DNA lesions and mutations. Since the accumulation of non-acetylated adducts has been associated with tumour initiating properties, the balance between acetylation and deacetylation may greatly influence the biological effect. Hydrolysable haemoglobin adducts representing the bioavailability of N-hydroxylamines and the corresponding nitroso-derivatives were analysed following oral administration to female Wistar rats of two arylamine-acetamide couples: 4-aminobiphenyl and 2-aminofluorene, and two arylamine-acetamide-diacetamide triples: benzidine and 3,3'-dichlorobenzidine. The results show that the monoacetamides are readily deacetylated in vivo whereas the diacetamides are not. A dynamic equilibrium is indicated to exist between acetylation and deacetylation, which depends on substrate specificity, and the role of deacetylation is emphasised. In addition, acetylation polymorphism was studied with 4-chloroaniline and 3,3'-dichlorobenzidine in slow acetylating A/J and rapid acetylating C57BL/6J mice. The slow acetylator genotype was associated with significantly higher haemoglobin-adduct levels for both arylamines. The results provide additional support for the use of haemoglobin adducts in biomonitoring as a dosimeter for the biologically active dose of arylamines/arylacetamides. Moreover, biomonitoring of haemoglobin adducts may provide information about an individual's susceptibility to the toxic and carcinogenic effects of these chemicals.

Acetylation↗

Use of statistical design of experiments to evaluate the sorption capacity of 7-amine-4-azaheptylsilica and 10-amine- 4-azadecylsilica for Cu(II), Pb(II), and Fe(III) adsorption.

7-Amine-4-azaheptylsilica (AAH Si) and 10-amine-4-azadecylsilica (AAD Si) were prepared and used for removal of Cu(II), Pb(II), and Fe(III) from aqueous solutions. Full 2(3) factorial designs with two pseudo-central points were carried out in order to achieve the best conditions of the batch adsorption procedure for metallic ion uptake by the adsorbents. To continue the optimizations, central composite surface design was also employed. These two independent statistical designs of experiments lead to the following conditions: m=30.0 mg of adsorbent; pH 6.0 for Cu(II) and Pb(II), pH 4.0 for Fe(III); t of contact 180 min to guarantee equilibration at higher adsorbate concentration. After optimization of the conditions, isotherms of the metallic ions adsorbed on the AAH Si and AAD Si adsorbents were obtained, which were fitted to nonlinear Langmuir and Freundlich isotherm models.

Adsorption↗

Electrooxidation mechanism of biogenic amines at amine oxidase modified graphite electrode.

Amine oxidase (AO, EC. 1.4.3.6) was previously shown to be a very efficient biological recognition element of amperometric biosensors for monitoring biogenic amines. The enzyme was effectively working in both mono- and bienzyme electrode designs, based on either a direct or a mediated electron-transfer pathway. This work focuses on the elucidation of the electron-transfer mechanism of the monoenzymatic unmediated AO-modified biosensor. The observed unmediated catalytic currents were assumed to be caused by (i) a direct electron-transfer process, (ii) the electrooxidation of the formed product, or (iii) their combination. Experiments supporting these assumptions are discussed in detail.

Amine Oxidase (Copper-Containing)↗