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PubMed1980

[On the problems in respect ot the formation of N-nitroso compound precursors when using alkylating agents in the fumigation of foodstuffs. I. Investigations of the formation of secondary amines by the action of ethylene oxide on primary amines and amino acids (author's transl)].

Special attention must be paid to the formation of secondary amines as precursors of nitrosamines as a possible consequence of the fumigation of foodstuffs with ethylene oxide. Investigations carried out in vitro show that secondary amines can result in various ways by reaction of the amine groups with ethylene oxide: 1. directly, by reaction of ethylene oxide with primary amines, 2. by reaction with amino acids followed by decarboxylation. Identification of the secondary amines produced by the reaction of ethylene oxide with primary amines or amino acids was carried out by means of thin layer chromatography. In this manner, the formation of methylamino ethanol, ethylamino ethanol and diethanolamine was demonstrated by the reaction of ethylene oxide with methylamine, ethylamine and ethanolamine. Furthermore, the reaction of ethylene oxide with glycine and serine followed by decarboxylation produced, depending upon the pH value, the compounds methylamino ethanol and diethanolamine.

Amines↗
PubMed2002

DFT investigation of the tri(amino)amine N(NH(2))(3)(2+) and the tri(azido)amine N(N(3))(3)(2+) dications and related mixed amino(azido)ammonium ions (N(3))(x)N(NH(2))(4-x)(+) (x = 0-4)(1).

Structures of the tri(amino)amine N(NH(2))(3)(2+) and the tri(azido)amine N(N(3))(3)(2+) dications were calculated at the density functional theory (DFT) B3LYP/6-311+G level. The tri(amino)amine dication (NH(2))(3)N(2+) (1) was found to be highly resonance stabilized with a high kinetic barrier for deprotonation. The structures of diamino(azido)amine dication (NH(2))(2)N(N(3))(2+) (2), amino(diazido)amine dication (NH(2))N(N(3))(2)(2+) (3), and tri(azido)amine dication (N(3))(3)N(2+) (4) were also found to be highly resonance stabilized. The structures and energetics of the related mixed amino(azido)ammonium ions (N(3))(x)N(NH(2))(4-x)(+) (x = 0-4) were also calculated.

Journal Article↗
PubMed2004

Solvothermal syntheses, crystal structures, and thermal properties of new manganese thioantimonates(III): The first example of the thermal transformation of an amine-rich thioantimonate into an amine-poorer thioantimonate.

Two new neutral thioantimonates(III) were first prepared by the reaction of elemental manganese, antimony, and sulfur in tren (tren = tris(2-aminoethyl)amine, C6H18N4) at 140 degrees C. In the amine-rich compound [Mn(tren)]2Sb2S5 (1) the trigonal SbS3 pyramids are connected via common corners (S(3)) into the tetradentate [Sb2S4]4- anion. Four S atoms have bonds to the manganese atoms of the [Mn(tren)2+] cations. A special structural feature is the large Sb-S(3)-Sb(a) angle of 134 degrees. Density functional calculations clearly demonstrate that this large angle results from the steric interactions between the two Mn(tren) subunits. In the crystal structure of the amine-poorer compound [Mn(tren)]2Mn2Sb4S10 (2), MnS4 tetrahedra and SbS3 pyramids are linked via common corners and edges to form a new heterometallic [Mn2Sb4S10] core. The [Mn(C6H18N4)2+] cations are located at the periphery of the core and are bound to the [Mn2Sb4S10] unit via two S atoms. The thermal behavior of both compounds was investigated using simultaneous thermogravimetry (TG), differential thermoanalysis, and mass spectroscopy. The amine-richer compound 1 decomposes in three steps upon heating. After the first TG step an intermediate phase is formed, which was identified as the amine-poorer compound 2 by X-ray diffraction. Reaction of compound 2 at 140 degrees C with an excess of tren forms the amine-rich compound 1.

Journal Article↗
PubMed2000

Formal hydride transfer mechanism for photoreduction of 3-phenylquinoxalin-2-ones by amines. Association Of 3-phenylquinoxalin-2-one with aliphatic amines

The photophysical and photochemical behavior of 1-methyl-3-phenylquinoxalin-2-one (MeNQ) and 3-phenylquinoxalin-2-one (HNQ) in the presence of amines is reported. While HNQ fluorescence shows an auxochromic effect and a bathochromic shift with added amines, explained by association of HNQ with amine in the ground state and emission from both excited species HNQ and [HNQ-amine], both MeNQ and HNQ are photoreduced efficiently on irradiation in the presence of amines, leading to the semireduced quinoxalin-2-ones, MeNQH(-) and HNQH(-), respectively, via an electron-proton-electron transfer, with unit quantum yields at high amine concentrations. The semireduced quinoxalin-2-ones XNQH(-) (X = H, Me) revert almost quantitatively to the parent XNQ in a dark thermal reaction with an activation free energy for MeNQH(-) of 17.4 and 25.9 kcal/mol in acetonitrile and benzene, respectively. Kinetic and spectroscopic (UV and NMR) evidence supports the proposed reaction mechanism for the reversible photoreduction.

Journal Article↗
PubMed1994

The amine-donor substrate specificity of tissue-type transglutaminase. Influence of amino acid residues flanking the amine-donor lysine residue.

The amine-donor substrate specificity of tissue-type transglutaminase has been studied in a series of recombinant alpha A-crystallin mutants. These mutant proteins have been provided with a potential substrate lysine residue, flanked by different amino acid residues, in the C-terminal extended arm of alpha A-crystallin. A biotinylated amine-acceptor hexapeptide was used as a probe for labelling the amine-donor sites. Wild-type bovine alpha A-crystallin does not function as an amine-donor substrate for tissue-type transglutaminase. Yet, upon introduction of a lysine residue at the C-terminal or penultimate position, all mutant alpha A-crystallins act as amine-donor substrates, although to different extents. This shows that accessibility is the primary requirement for a lysine residue to function as an amine-donor substrate for transglutaminase and that the enzyme has a broad tolerance towards the neighbouring residues. However, the nature of the flanking amino acid residues does clearly affect the reactivity of the substrate lysine residue. Notably, we found that a proline or glycine residue in front of the substrate lysine has a strong adverse effect on the substrate reactivity as compared to a preceding leucine, serine, alanine or arginine residue.

Amino Acid Sequence↗
PubMed1989

Semicarbazide-sensitive amine oxidase (SSAO) of the rat aorta. Interactions with some naturally occurring amines and their structural analogues.

The influence of a number of naturally occurring amines and their structural analogues has been examined on the metabolism of radiolabelled benzylamine (BZ) by the membrane bound semicarbazide-sensitive amine oxidase (SSAO) of the rat aorta. Only primary monoamines were effective in reducing the deamination of BZ. In the phenylethylamine series, addition of hydroxyl groups to the benzene ring decreased their potency as inhibitors while addition of a hydroxyl group at the beta position increased the inhibitory potency. Stereoselectivity of action was shown with octopamine, the L-isomer being the more active form. Kinetic analysis of these interactions showed predominantly competitive inhibition and kynuramine had the lowest Ki of 5.4 microM. The aliphatic monoamines, isoamylamine and isobutylamine both competed with BZ. 5-Hydroxytryptamine (5-HT) was the only amine that inhibited non-competitively. Direct evidence for metabolism by SSAO of some of the competing amines such as isoamylamine, phenylethylamine, tyramine and tryptamine was obtained by fluorimetric or radiochemical assays. The inhibitors clorgyline and (E)-2-(3',4'-dimethoxyphenyl)-3-fluoroallylamine (MDL 72145) were used to characterise the amine oxidase activity responsible for the deamination. Octopamine and phenylethanolamine (PeOH) were not SSAO substrates and inhibited BZ metabolism in the fluorimetric assay. It is possible that the activity of SSAO is controlled by octopamine released from sympathetic nerve endings or 5-HT released from platelets.

Allosteric Regulation↗
PubMed1994

Food-derived heterocyclic amines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and related amines, as inhibitors of monoamine metabolism.

The effects of heterocyclic amines, pyrolysis products of tryptophan, on monoamine metabolism were examined. Among these amines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) are potent inhibitors of the enzymes related to amine metabolism. They inhibited type A monoamine oxidase more markedly than type B. After culture of a dopamine cell model, clonal pheochromocytoma PC12h cells, with Trp-P-1 activity of tyrosine hydroxylase was decreased by reduction of its affinity to the biopterin cofactor. Trp-P-1 and Trp-P-2 inhibited tryptophan hydroxylase competitively with the substrate and non-competitively with biopterin. These results suggest that food-derived heterocyclic amines may perturb the monoamine levels in the brain through the inhibition of the biosynthesis and metabolism of biogenic amines.

Amines↗
PubMed1992

Quantitative correlation of mutagenic and carcinogenic potencies for heterocyclic amines from cooked foods and additional aromatic amines.

Aromatic amines have long been recognized as animal and human carcinogens. Recently heterocyclic aromatic amines (thermic amines) have been found in small amounts in cooked foods, primarily meats, and have proven to be potent mutagens and rodent carcinogens. Availability of quantitative databases for mutagenic potency in Salmonella and for carcinogenic potency in rodents has made possible a study of ten heterocyclic thermic amines and 24 aromatic amines. Potencies on mutagenic and carcinogenic scales were significantly correlated. By multiple linear regression analysis and multivariate analysis of variance, two descriptive structural factors were found to modulate the two modes of biological response. These factors were number of rings and methyl substitution at carbon atoms. The quantitative correlation between mutagenic and carcinogenic potencies and the modulating structural factors suggest a significant similarity of molecular mechanisms and support the utility of the short-term bacterial assay in evaluating hazard levels.

Amines↗
PubMed2006

Coated wire potentiometric detection for capillary electrophoresis studied using organic amines, drugs, and biogenic amines.

Capillary electrophoresis was coupled successfully and reliably to potentiometric sensors, which are based on an ionically conductive rubber phase coating, applied on a 250 microm diameter metal substrate. The membrane components included potassium tetrakis(p-chlorophenyl)borate (TCPB), bis(2-ethylhexyl)sebacate (DOS), and high molecular mass poly(vinyl chloride) (PVC). Potentiometry reveals a very sensitive CE detection mode, with sub-micromolar detection limits for amines and the randomly chosen drugs quinine, clozapine, cocaine, heroine, noscapine, papaverine, and ritodrine. The lowest detection limit, 1 x 10(-8) M injected concentration, was obtained for the quaternary ammonium compound tetrahexylammonium chloride. The more polar lower aliphatic amines and the biogenic amines dopamine, adrenaline, and cadaverine have much higher detection limits. The detection limits are log P dependent. Addition of a commercially available calixarene molecule or a synthetic macrocyclic amphiphilic receptor molecule to the electrode coatings enhanced the sensitivity respectively for the lower aliphatic amines and for the biogenic amines. A transpose of the Nikolskii-Eisenman-type function was suggested and used to convert the signal of the detector to a concentration-dependent signal.

Biogenic Amines↗
PubMed2005

Efficient synthesis of 1,2,4-dithiazolidine-3,5-diones [dithiasuccinoyl-amines] from bis(chlorocarbonyl)disulfane plus bis(trimethylsilyl)amines.

The 1,2,4-dithiazolidine-3,5-dione heterocycle, also referred to as a dithiasuccinoyl (Dts)-amine, serves as a readily removable amino protecting group for building blocks used in syntheses of peptides, glycopeptides, and PNA; it is also useful as a masked isocyanate and (inversely) as a sulfurization reagent for trivalent phosphorus. Bis(chlorocarbonyl)disulfane, the two-sulfur analogue of succinyl chloride, has been envisioned as a reagent for facile single-step elaboration of the heterocycle. However, reactions of bis(chlorocarbonyl)disulfane directly with primary amines fail to yield Dts-amines for reasons that are discussed. Inspired by several precedents from the organosilicon chemistry literature that a trimethylsilyl group may serve as a "large proton," a successful, high-yield preparation of Dts-amines through reactions of bis(chlorocarbonyl)disulfane with bis(trimethylsilyl)amines has been developed. Studies aimed at elucidating mechanistic reasons for these observations are also presented.

Amines↗
PubMed2002

Metamodulation of the biogenic amines: second-order modulation by steroid hormones and amine cocktails.

An evolutionarily conserved feature of neural systems is that they can be modified by neuromodulators. These modulatory chemical signals include the biogenic amines, octopamine (OA), serotonin (5-HT) and dopamine (DA). Such modulation effectively broadens the operational range in which specific neural circuits can function adaptively. This report discusses how these amines are themselves modulated; for example, by the steroid hormone 20-hydroxyecdysone (20-E) or by the addition of a second biogenic amine. Such second-order neuromodulation, termed metamodulation, is discussed in the context of two well-studied invertebrate systems: the tobacco hornworm moth Manduca sexta, a model of neurodevelopment and plasticity, and the medicinal leech Hirudo medicinalis, a long-favored preparation used to study neural circuits at the level of identified neurons. A portion of this article reviews our previous research of M. sexta that shows that the 'preadult' rise in 20-E is both necessary and sufficient for the increased levels of octopamine observed in the adult. Such elevated levels likely play an important role in the production and modulation of adult behaviors. The somatic growth of median octopaminergic neurons and the late expression of OA-immunoreactivity by novel lateral neurons are also demonstrated to be dependent on 20-E. New immunocytochemical results of stained dopaminergic neurons in the larval and adult moth brain are provided as well, and the potential influence of 20-E on the developmental expression of this neuromodulator is presented. Turning attention to the leech, data indicate that the actions of OA are dramatically altered when 5-HT is combined with OA in the bath surrounding the isolated nervous system. Although either OA or 5-HT alone induces fictive swimming behavior, a cocktail of these two amines strongly inhibits the generation of swimming. Subsequent removal of such a mixture induces nearly continuous swimming and constitutes the best swim-inducing stimulus encountered to date. To understand better how these nonadditive effects are achieved, new results are discussed that indicate that the leech brain is the target of metamodulation by the two amines. Both the arthropod and annelid systems presented here highlight the multiple levels of metamodulation that can exist in nervous systems, and the diverse ways that a modulator's actions can become altered over short or long time periods.

Animals↗
PubMed2004

Electron transfer interaction of dihydroxyquinones with amine quenchers: dependence of the quenching kinetics on the aliphatic and aromatic nature of the amine donors.

Studies on the electron transfer (ET) interaction of 1,4-dihydroxy-9,10-anthraquinone and 6,11-dihydroxy-5,12-naphthacenequinone with aliphatic and aromatic amine (AlA and ArA, respectively) donors have been investigated in acetonitrile solutions. Steady-state (SS) measurements show quenching of the quinone fluorescence by amines, without indicating any change in the shape of the fluorescence spectra. No significant change in the absorption spectra of the quinones is also observed in the presence of the amines. For all the quinone-amine pairs, the bimolecular quenching constants (kq) estimated from SS and time-resolved measurements are found to be similar. Variation in the kq values with the oxidation potentials of the amines indicates the involvement of the ET mechanism for the quenching process. A reasonably good correlation between the kq values and the free energy changes (deltaG0) for the ET reactions following Marcus' outer-sphere ET theory also supports this mechanism. It is seen that for both the quinone-ArA and quinone-AlA systems, the kq values initially increase and then get saturated at some diffusion-controlled limiting values (kqDC) as deltaG0 values gradually become more negative. Interestingly, however, it is seen that the kqDC value for the quinone-AlA systems is substantially lower than that for quinone-ArA systems. Such a large difference in the kqDC values between quinone-AlA and quinone-ArA systems is quite unusual. Present results have been rationalized based on the assumption that an orientational restriction is imposed for the encounter complexes in quinone-AlA systems to undergo ET reactions, which arises because of the localized (at amino nitrogen) shapes of the highest-occupied molecular orbitals (HOMO) of AlA in comparison to the pi-like HOMO of the ArA.

Amines↗
PubMed1999

Sensitive amperometric biosensor for the determination of biogenic and synthetic amines using pea seedlings amine oxidase: a novel approach for enzyme immobilisation.

We prepared a new inorganic sorbent based on modified triazine (2-[4,6-bis (aminoethylamine)-1,3,5-triazine]-Silasorb; BAT-Silasorb) which binds pea seedlings amine oxidase (PSAO) very tightly without loss of its catalytic activity. This unique feature as well as the wide substrate specificity of PSAO was successfully utilised in the construction of an amperometric biosensor based on a carbon paste electrode for the fast and sensitive detection of various amines at a formal potential 0 mV versus Ag/AgCl reference electrode. The reaction layer of the biosensor is created by the direct immobilisation of PSAO at the electrode surface via affinity carrier BAT-Silasorb. Used arrangement facilitates a simple restoration of the inactive biosensor. An amperometric signal results from horseradish peroxidase catalysed reduction of H2O2, a secondary product of the oxidative deamination of amines, catalysed by PSAO. The sensor was used for the basic characterisation of 55 biogenic and synthetic amines, from numerous mono-, di- and polyamines to various hydroxy-, thio-, benzyl- and aromatic derivatives in order to establish its suitability as a postcolumn detector. Its high sensitivity to putrescine 20.0 +/- 0.64 mA l-1 per mol (636.9 +/- 2.03 mA l-1 per mol per cm2), a limit of detection of 10 nmol l-1 (determined with respect to a signal-to-noise ratio 3:1), a linear range of current response to 0.01-100 mumol l-1 concentration of substrate and good reproducibility all indicate that the sensor could be applied to future industrial and clinical analyses.

Amine Oxidase (Copper-Containing)↗
PubMed2007

Amination of [60]fullerene by ammonia and by primary and secondary aliphatic amines--preparation of amino[60]fullerene peroxides.

Ammonia and aliphatic amines react readily in the oxygen-rich regions of the Cs symmetric fullerene peroxides C60(O)(OOtBu)4 (1) and C60(OH)(Br)(OOtBu)4 (2 c). Michael addition-type hydroamination of the 1,4-diene moiety on the central skew-pentagon was observed when 1 was treated with ammonia or with nonbulky primary amines, while sterically demanding primary amines opened the epoxy moiety to form vicinal aminohydroxy fullerene compounds with the amino group on the central pentagon. In 2 c the bromo group was replaced under similar conditions by ammonia and primary amines. Cyclic secondary amines showed different reaction patterns, forming hydrogenation products or aminoketal-fullerenes when treated with 1 and 2 c, respectively. Single-electron transfer (SET) is the key step in all the proposed mechanisms. The compounds were characterized by their spectroscopic data, and in addition, three single-crystal X-ray structures were obtained.

Journal Article↗
PubMed1996

Syntheses and Crystal Structures of Ruthenium Complexes of 1,4,8,11-Tetraazacyclotetradecane, Tris(2-aminoethyl)amine (tren), and Bis(2-aminoethyl)(iminomethyl)amine. A Microporous Layered Structure Consisting of {[K(tren)](2)[RuCl(6)]}(n)()(n)()(-) and {(H(5)O(2))(4)[RuCl(6)]}(n)()(n)()(+).

The second method for the synthesis of cis-[Ru(III)Cl(2)(cyclam)]Cl (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane), with use of cis-Ru(II)Cl(2)(DMSO)(4) (DMSO = dimethyl sulfoxide) as a starting complex, is reported together with the synthesis of [Ru(II)(cyclam)(bpy)](BF(4))(2).H(2)O (2) (bpy = 2,2'-bipyridine) from 1. The syntheses of Ru complexes of tris(2-aminoethyl)amine (tren) are also reported. A reaction between K(3)[Ru(III)(ox)(3)] (ox = oxalate) and tren affords fac-[Ru(III)Cl(3)(trenH)]Cl.(1)/(2)H(2)O (3) (trenH = bis(2-aminoethyl)(2-ammonioethyl)amine = monoprotonated tren) and (H(5)O(2))(2)[K(tren)][Ru(III)Cl(6)] (4) as major products and gives fac-[Ru(III)Cl(ox)(trenH)]Cl.(3)/(2)H(2)O (5) in very low reproducibility. A reaction between 3 and bpy affords [Ru(II)(baia)(bpy)](BF(4))(2) (6) (baia = bis(2-aminoethyl)(iminomethyl)amine), in which tren undergoes a selective dehydrogenation into baia. The crystal structures of 2-6 have been determined by X-ray diffraction, and their structural features are discussed in detail. Crystallographic data are as follows: 2, RuF(8)ON(6)C(20)B(2)H(34), monoclinic, space group P2(1)/c with a = 12.448(3) Å, b = 13.200(7) Å, c = 17.973(4) Å, beta = 104.28(2) degrees, V = 2862(2) Å(3), and Z = 4; 3, RuCl(4)O(0.5)N(4)C(6)H(20), monoclinic, space group P2(1)/a with a = 13.731(2) Å, b = 14.319(4) Å, c = 13.949(2) Å, beta = 90.77(1) degrees, V = 2742(1) Å(3), and Z = 8; 4, RuKCl(6)O(4)N(4)C(6)H(28), trigonal, space group R&thremacr; with a = 10.254(4), c = 35.03(1) Å, V = 3190(2) Å(3), and Z = 6; 5, RuCl(2)O(5.5)N(4)C(8)H(22), triclinic, space group P&onemacr; with a = 10.336(2) Å, b = 14.835(2) Å, c = 10.234(1) Å, alpha = 90.28(1) degrees, beta = 90.99(1) degrees, gamma = 92.07(1) degrees, V = 1567.9(4) Å(3), and Z = 4; 6, RuF(8)N(6)C(16)B(2)H(24), monoclinic, space group P2(1)/c, a = 10.779(2) Å, b = 14.416(3) Å, c = 14.190(2) Å, beta = 93.75(2) degrees, V = 2200.3(7) Å(3), and Z = 4. Compound 4 possesses a very unique layered structure made up of both anionic and cationic slabs, {[K(tren)](2)[Ru(III)Cl(6)]}(n)()(n)()(-) and {(H(5)O(2))(4)[Ru(III)Cl(6)]}(n)()(n)()(+) (n = infinity), in which both sheets {[K(tren)](2)}(n)()(2)(n)()(+) and {(H(5)O(2))(4)}(n)()(4)(n)()(+) offer cylindrical pores that are occupied with the [Ru(III)Cl(6)](3)(-) anions. The presence of a C=N double bond of baia in 6 is judged from the C-N distance of 1.28(2) Å. It is suggested that the structural restraint enhanced by the attachment of alkylene chelates at the nitrogen donors of amines results in either the mislocation or misdirection of the donors, leading to the elongation of the Ru-N(amine) distances and to the weakening of their trans influence. Such structural strain is also discussed as related to the spectroscopic and electrochemical properties of the cis-[Ru(II)L(4)(bpy)](2+) complexes (L(4) = (NH(3))(4), (ethylenediamine)(2), and cyclam).

Journal Article↗
PubMed2001

Palladium catalysed 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodides, allene and primary amines.

A 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodide, allene and primary aliphatic amines is described; chiral amines give analogous products with no detectable racemisation; mixtures of two different aryl iodides can be utilised to give the mixed tertiary amines as the sole, or major, product; the reaction is sensitive to stereoelectronic effects which lead to mono(2-arylallyl) secondary amines.

Journal Article↗