Showing papers on "Thiocyanate published in 1984"

Clinical Pharmacokinetics of Nitroprusside, Cyanide, Thiosulphate and Thiocyanate

Abstract: Sodium nitroprusside decomposes within a few minutes after intravenous infusion to form metabolites which are pharmacologically inactive but toxicologically important. Free cyanide, which represents 44% w/w of the sodium nitroprusside molar mass, is formed and must be detoxified in the body into thiocyanate using thisulphate as substrate. Nitroprusside penetrates cell membranes slowly. At therapeutic dose levels its distribution is probably mainly extracellular. Contact with the sulfhydryl groups in the cell walls, however, immediately initiates breakdown of the molecule. Sodium nitroprusside taken orally is not absorbed from the gastrointestinal tract to any appreciable extent. Cyanides in the body form prussic acid, which can rapidly penetrate mucous and cell membranes. In the blood, about 99% of the prussic acid binds to the methaemoglobin of erythrocytes. At normal physiological levels, however, the total body methaemoglobin of an adult human can only bind about 10mg of prussic acid; this is a small fraction of the amounts usually infused therapeutically as sodium nitroprusside. The endogenous detoxification of prussic acid exhibits zero-order kinetics. The limiting factor is a sulphur donor, principally thiosulphate, which is available in the body in only limited amounts. The rate of spontaneous detoxification of prussic acid in humans is only about 1 microgram/kg/min, corresponding to a sodium nitroprusside infusion of about 2 microgram/kg/min. This dose limit set by the prussic acid toxicity of sodium nitroprusside can, however, be increased considerably by simultaneous infusion of thiosulphate. A lack of thiosulphate can be detected early by a rise of the prussic acid concentration in the erythrocytes. Thiosulphate taken orally is not absorbed by the body. After intravenous infusion, its serum half-life is about 15 minutes. Most of the thiosulphate is oxidised to sulphate or is incorporated into endogenous sulphur compounds; a small proportion is excreted through the kidneys. Thiocyanate taken orally is completely absorbed by the body. In healthy persons its volume of distribution is approximately 0.25 L/kg and the serum half-life about 3 days; elimination is mainly renal. Thiocyanate toxicity does not represent a serious therapeutic problem with intravenous infusion of sodium nitroprusside.

Distortion isomerism in a thiocyanate-bridged copper(II) dimer. X-ray structure of .beta.-bis(.mu.-thiocyanato-N,S)-bis[bis(5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine)(thiocyanato-N)copper(II)] and comparison of its spectral and structural properties with those of other copper(II) 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine thiocyanates

Abstract: Le thiocyanate de Cu(II) et la dimethyl-5,7 triazolo-1,2,4 [1,5-a] pyrimidine (C 7 H 8 N 4 , dmtp) forment trois complexes differents: deux isomeres de composition [Cu(NCS) 2 (dmtp) 2 ] 2 et l'espece hydratee Cu(NCS) 2 (dmtp) 2 H 2 O. Etude RX de l'isomere β de [Cu(NCS) 2 (dmtp) 2 ] 2 : cristallisation dans P2 1 /n avec Z=4; affinement jusqu'a R=0,034. Ce compose est un dimere autosymetrique

Effects of Dietary Compounds on α-Hydroxylation of N-Nitrosopyrrolidine and N′-Nitrosonornicotine in Rat Target Tissues

Abstract: Male F344 rats were pretreated with various dietary compounds, and the effects of pretreatment on the in vitro α-hydroxylation of N -nitrosopyrrolidine or N′ -nitrosonornicotine were determined in assays with liver microsomes or cultured esophagus, respectively. Dietary compounds included phenols, cinnamic acids, coumarins, indoles, and isothiocyanates. Pretreatments were carried out either by administering the compound by gavage 2 hr prior to sacrifice (acute protocol) or by adding the compound to the diet for 2 weeks (chronic protocol). Acute pretreatment with benzyl isothiocyanate, allyl isothiocyanate, phenethyl isothiocyanate, phenyl isocyanate, and benzyl thiocyanate but not sodium thiocyanate inhibited formation of α-hydroxylation products of both nitrosamines. When the chronic pretreatment protocol was used, only phenyl isothiocyanate and sodium thiocyanate inhibited formation of α-hydroxylation products of both nitrosamines. Pretreatments with butylated hydroxyanisole, p -methoxyphenol, or N -acetylcysteine had little, if any, effect on the α-hydroxylation of N -nitrosopyrrolidine or N′ -nitrosonornicotine. Chronic pretreatment with p -hydroxycinnamic acid, 4-hydroxy-3-methoxycinnamic acid, coumarin, umbelliferone, limetine, indole, indole-3-carbinol, indole-3-acetonitrile, and l-tryptophan induced activity for the α-hydroxylation of N -nitrosopyrrolidine. The results of this study indicate that isothiocyanates are possible candidates for further study as potential inhibitors of carcinogenesis by N -nitrosopyrrolidine and N′ -nitrosonornicotine.

Lewis Base Adducts of Group 1B Metal(I) Compounds. 9. Synthesis and crystal structures of adducts of copper(I) thiocyanate with substituted pyridine bases

Abstract: The crystal structures of the title compounds, Cu(SCN)L, L = 2-methylpyridme (l),2 ,6-dimethylpyridine (2), and Cu(SCN)b, L = 2-, 3-, and 4-methylpyridine (3-5, respectively), 2,4-dimethylpyridine (6), quinoline (7), have been established by single-crystal X-ray diffraction at 295 K and refined by full-matrix least squares to residuals of 0.026,0.039,0.048,0.032, 0.054,0.058, and 0.029 for 1164, 1339, 1499, 1731, 903, 1748 and 468 independent "observed" reflections, respectively. Crystals of 1 are triclinic, PI, with a = 9.452 (3) A, b = 8.077 (3) A, c = 5.779 (1) A, a = 104.33 (2)O, @ = 96.64 (2)O, y = 100.83 (3)O, and 2 = 2; the structure is a polymer consisting of pairs of CuL(SCN)CuL(SCN) strands linked by centrosymmetric four-membered Cu2S2a nd eight-membered CU(SCN)~CrUin gs. Crystals of 2 are monoclinic, P2,/c, with a = 7.721 (2) A, b = 7.753 (2) A, c = 16.1 13 (4) A, @ = 90.67 (2)O, and 2 = 4; the structure is a single-stranded polymer-CuL(SCN)CuL(SCN). Crystals of 3 are orthorhombic, Fdd2, with a = 43.68 (1) A, b = 16.402 (4) A, c = 8.064 (3) A, and 2 = 16. Crystals of 4 are monoclinic, P2]/n, with a = 17.68 (1) A, b = 5.874 (4) A, c = 14.367 (8) A, @ = 112.91 (4)O, and 2 = 4. Crystals of 5 are monoclinic, El, with a = 14.59 (2) A, b = 5.823 (6) A, c = 8.953 (10) A, @ = 106.44 (lo)', and 2 = 2. Crystals of 6 are monoclinic, P21/c, with a = 28.93 (3) A, b = 5.867 (4) A, c = 20.19 (3) A, @ = 112.70 ( 8 ) O , and 2 = 8. Crystals of 7 are orthorhombic,P 212121wr ith a = 16.219 (4) A, b = 12.838 (3) A, c = 8.032 (2) A, and 2 = 4. In spite of the diverse crystal symmetries found for 3-7, all contain single-stranded CuL2(SCN)CuLz(SCN)CuLpzo lymers, with different conformational types. All complexes were synthesized by reaction of copper(1) thiocyanate with the parent base, with or without the presence of acetonitrile as solvent.

Bactericidal and cytotoxic effects of hypothiocyanite-hydrogen peroxide mixtures.

Abstract: Lactoperoxidase catalyzes the oxidation of thiocyanate by hydrogen peroxide into hypothiocyanite, a reaction which can protect bacterial and mammalian cells from killing by hydrogen peroxide. The present study demonstrates, however, that lactoperoxidase in the presence of thiocyanate can actually potentiate the bactericidal and cytotoxic effects of hydrogen peroxide under specific conditions, such as when hydrogen peroxide is present in the reaction mixtures in excess of thiocyanate. The toxic agent was also formed in the absence of lactoperoxidase in a reaction between hypothiocyanite and hydrogen peroxide. Sulfate, sulfite, cyanate, carbonate, and ammonia, which have been postulated to be formed in the chemical oxidation of hypothiocyanite by hydrogen peroxide, were not bactericidal and did not potentiate the bactericidal effect of hydrogen peroxide. Cyanosulfurous acid, the only other postulated product of the chemical oxidation of hypothiocyanite by hydrogen peroxide, may be the killing agent.

Di-enzymatic dentifrice

Abstract: A di-enzymatic dentifrice is provided which contains an oxidizable substrate and an oxidoreductase enzyme specific to such substrate for producing hydrogen peroxide upon oral application of the dentifrice and further contains a thiocyanate salt and lactoperoxidase for interacting with hydrogen peroxide to produce a hypothiocyanate bacterial inhibitor. An illustrative enzymatic system for this purpose contains glucose, glucose oxidase, potassium thiocyanate and lactoperoxidase.

Simultaneous reaction rate spectrophotometric determination of cyanide and thiocyanate by use of the pyridine-barbituric acid method

Abstract: La methode est basee sur le fait que la vitesse de reaction entre thiocyanate et chloramine T varie fortement avec le pH tandis que la reaction entre cyanure et chloramine T est rapide et est independante du pH dans un grand domaine de pH

The elution of aurocyanide from strong- and weak-base resins

Abstract: Results are presented on the elution of gold cyanide and base-metal cyanide complexes from strong- and weakbase resins. It is shown that thiocyanate anions, zinc cyanide anions, and thiourea in acid solution are effective eluants of strong-base resins, but that it is generally necessary for electrowinning to be incorporated in the elution cycle if fast rates of elution are to be achieved. Weak-base resins are eluted with sodium hydroxide solution, which is shown to be far simpler and far more effective than the elution of strong-base resins. The effects of parameters such as concentration of the eluant, temperature, and electrowinning efficiency on the rate of elution of the resins are examined.

Diazotization and thiocyanate differentiate agonists from antagonists for the high- and low-affinity receptors of γ-aminobutyric acid

Abstract: The differentiation of high- and low-affinity postsynaptic gamma-aminobutyric acid (GABA) receptors was examined in a washed cortical membrane preparation of the rat. The selective elimination of the high- and low-affinity GABA sites by the chaotropic anion thiocyanate and diazotization by p-diazobenzenesulfonic acid (DSA), respectively, offered two model systems for the separate sites. The [3H]GABA displacing potencies of some GABA agonists [GABA, 4,5,6,7-tetrahydro- isoxazole [4,5c]pyridine-3-ol (THIP), and muscimol] and antagonists [bicuculline methiodide (BCM), 3-alpha-hydroxy-16-imino-5 beta-17-aza-androstan-11-one (R-5135), and d-tubocurarine] and their slope factors were examined in these model systems and in control membranes. The displacing potency of the agonists was increased in the DSA-pretreated membranes and decreased in the presence of thiocyanate. The displacing potency of the antagonists was shifted in an opposite manner. The chaotropic effect of thiocyanate was reversible and not additive with the inhibitory effect of diazotization on the specific binding of GABA. Inhibition of specific GABA binding by pyridoxal-5-phosphate (PLP) could not be protected by GABA antagonists (BCM and R-5135) but only by agonists. The results can be interpreted in the framework of a dual (agonist-antagonist) receptor model, postulating a hydrophobic accessory site at the low-affinity GABA receptor. The effect of thiocyanate on the GABA receptor may result in the exposure of the hydrophobic accessory sites.

Evidence for covalent bonding of native hapten–protein complexes to smooth lipopolysaccharide of Brucella abortus

Abstract: Smooth lipopolysaccharide (S-LPS) of Brucella abortus was dissociated from noncovalently attached components by differential centrifugation and exhaustive treatment with guanidinium thiocyanate. Mild alkaline hydrolysis then released ester-linked fatty acids as well as native hapten (NH)-protein complexes. These complexes, comprising 15 to 20% by weight of the S-LPS, failed to dissociate in guanidinium thiocyanate or in boiling SDS, suggesting covalent attachment. Analyses for 2-keto-3-deoxyoctonate demonstrated that the released carbohydrate was NH, rather than degraded O-polysaccharide or intact S-LPS monomers. This provides strong evidence that NH-protein complexes are covalently linked to S-LPS, most likely through ester bonds.

Intramolecular electron transfer at metal surfaces. 2. Comparisons of ligand-bridged chromium(III) reduction kinetics at silver vs. mercury electrodes

Abstract: : Rate parameters have been gathered for the electroreduction of a number of Cr(III) complexes attached to silver electrodes via one or more thiocyanate, azide, chloride, or bromide bridging ligands. Unimolecular rate constants k sub et (per sec) for electron transfer within the adsorbed states as well as the surface concentration of the adsorbates were obtained directly using rapid linear sweep voltammetry. These data are also compared with corresponding kinetics and adsorption measurements at mercury electrodes in order to deduce the structure factors responsible for the substantially greater overall reactivities (i.e., larger apparent rate contents k sub app) seen at silver. Marked differences in k sub et, as well as k sub app, were found between silver and mercury surfaces these differences being sensitive to the nature of the nonbridging as well as the bridging ligands. This indicates that the metal surface exerts a significant influence upon the energetics of the elementary electron-transfer step as well as upon the stability of the precursor intermediate. Explanations for the observed structural influences upon k sub et are sought in terms of 'electronic communication' effects between the redox center and the metal surface.

A convenient method of preparing nickel(II) thiocyanate and its use in synthesis

Abstract: A convenient method for preparing nickel(II) thiocyanate is described. Some new compounds containing nickel thiocyanate and ligands, such as OPPh3, OAsPh3, bipy, Me2NH, Et3N or N2H4 are reported, together with their structures and the nature of the bond between the thiocyanate and the metal, which has been determined by physical and chemical methods.

Surface-enhanced Raman spectroscopy of electrochemically characterized interfaces. Transition-metal isothiocyanate adsorbates at silver electrodes

Abstract: : Surface-enhanced Raman (SER) spectra have been obtained at the silver-aqueous interface for nine Cr III, Co III, Ru II, and Rh III ammine or ethylenediamine complexes containing one or more thiocyanates as surface bridging groups. These complexes provide stereochemically well-defined adsorbates having at least one sulfur surface binding site but with electronic properties that differ substantially from thiocyanate itself. The dependence of the SER spectra were examined in each case over a potential range where the complexes are stable with respect to reduction or oxidation, and where the adsorbate coverage remained close to a monolayer. The adsorbate coverage could be evaluated in several cases from the faradaic charge required for one-electron reduction. SER spectra were obtained using a spectrograph-optical multichannel analyzer (OMA) as well as a conventional scanning spectrometer. This enabled the rapid reversible component of the SERS potential dependence to be separated from the irreversible signal decay associated with surface rearrangement. SERS bands due to metal ammine and internal ammine vibrations were observed in addition to those associated with internal thiocyanate and ligand-surface vibrations.

Thiocyanate cleaves the imidazolate-bridged dicopper(II) center in a binucleating macrocycle to form the copper(II) thiocyanate complex [Cu2(SCN)4 .cntnd. A]. Model chemistry for superoxide dismutase

Abstract: Quand KSCN en exces est ajoute a une solution aqueuse de [Cu 2 (im)A'] 3+ A'=hexaazacyclotetracosane, le pont imidazolate se rompt et on isole [Cu 2 (NCS) 4 A']. Etude RX

Formation of elemental sulfur by Chlorella fusca during growth on L-cysteine ethylester

Abstract: During growth on l-cysteine ethylester, Chlorella fusca (211-8b) accumulated a substance which contained bound sulfide, which could be liberated by reduction with dithioerythritol (DTE) as inorganic sulfide. This substance was extracted with hot methanol and purified by thin layer chromatography. This substance liberated free sulfide when incubated with mono- and dithiols, and thiocyanate was formed after heating with KCN. The isolated substance cochromatographed with authentic sulfur flower using different solvent systems for thin layer chromatography, high pressure liquid chromatography, and the identical spectrum with a relative λmax at 263 nm was found. The chemical structure was confirmed by mass spectrometry showing a molecular weight of 256 m/e for the S8 configuration. No labeled elemental sulfur was detected when the cells were grown on [35S]sulfate and l-cysteine ethylester indicating the origin of elemental sulfur from l-cysteine ethylester. C. fusca seems to have enzymes for the metabolism of elemental sulfur, since it disappeared after prolonged growth into the stationary phase. Cysteine was formed from O-acetyl-l-serine and elemental sulfur in the presence of thiol groups and purified cysteine synthase from spinach or Chlorella.

Cobalt(II) Complexes of Creatinine

Abstract: Cobalt(II) complexes of creatinine [Co(creat)2X2] (X = Cl, Br, I or NCS) and [Co(creat)2X2(H2O)2] (X = HCO2, HOCH2CO2 or CNCH2CO2) have been prepared. Their i.r. spectra show an increase in ν(NH) of the cyclic secondary amine group, compared to free ligand (3300 cm−1), indicating that cyclic nitrogen is involved in coordination. The thiocyanate group coordinates through nitrogen and carboxylates coordinate as univalent unidentate ligands. The electronic spectra and magnetic moments suggest a d7 configuration for cobalt: a tetrahedral geometry (4.4 B.M.) for halide and thiocyanate complexes, and an octahedral geometry (5.0 B.M.) for the carboxylate complexes. On heating, the ligand moiety is lost and the respective cobalt halide or cobalt carboxylate is formed, which is converted finally into Co3O4. There is a correlation between the high intensity electronic transitions and the polarographic half-wave potentials.

Crystal structure and NMR spectral studies of alkali thiocyanate complexes with polyoxa(n)ferrocenophanes.

Abstract: 1H- and 13C-NMR spectra of free ligands and their alkali metal complexes with a new type of crown ethers containing a ferrocene unit have been recorded. The change of chemical shifts in 1H- and 13C-NMR spectra was attributed to an electronic field effect and a conformational change on the metal complexation, respectively. The crystal structure of the complex of 1,4,7,10,13-pentaoxa[13]ferrocenophane with sodium thiocyanate was determined by the X-ray method. The crystals are orthorhombic, space group Cccn, with a=20.579(4), b=25.622(8) c=7.606(1) A, U=4010(2) A3, Z=8, Dc=1.48 g cm−3. The distances between the iron atom of a ferrocene nucleus and the incorporated sodium cation and between the sodium cation and the nitrogen atom of a counter anion are 4.129 and 2.541 A, respectively. The results suggest that the iron atom of the ferrocene does not take part directly in complex formation and that the sodium cation forms a contact ion pair with the nitrogen atom of a counter anion.