SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
5-Aryl (or alkyl)-8-hydroxyquinoline-7-sulphonic acids have been prepared by the Mannich reaction of 8-hydroxyquinoline-7-sulphonic acid with primary and secondary amines. Their bactericidal activities have been determined.
In this communication we describe a novel procedure for the preparation and purification of diethylenetriaminepentaacetic (DTPA)-acylated and (115)In(3+)-labeled oligopeptides using 8-hydroxyquinoline for the removal and quantification of nonbound indium ions. First the N(alpha)- or N(alpha),N(epsilon)-DTPA oligopeptides containing C-terminal KDEL signal motif were produced by solid-phase synthesis. For this the free carboxyl group of DTPA dianhydride was activated in situ for a short period of time yielding a major product. Reversed-phase HPLC-purified DTPA oligopeptides were labeled with (115)In(3+) in aqueous buffer solution at pH 3.8. For the removal as well as for the detection of uncoordinated (115)In(3+) ions we have utilized the (115)In(3+) complex-forming ability of 8-hydroxyquinoline in chloroform. Following an optimized extraction procedure the free indium ion content was measured by spectrophotometry in the organic phase. Data obtained by this method and verified by total-reflection X-ray fluorescence spectroscopy and thin-layer chromatography demonstrated that free (115)In(3+) could be efficiently removed and sensitively detected in the presence of DTPA oligopeptide chelator. No release of (115)In(3+) from its DTPA complex was observed. This method could be useful for the preparation of indium complexes of peptides and perhaps proteins containing a DTPA moiety and nonradioactive isotope ligand.
A modified synthetic method has been developed for immobilization of 8-hydroxyquinoline on polyacrylonitrile fiber. The synthetic conditions, e.g. reagent concentration, reaction temperature and time, were optimized. The features of the newly-modified fiber are higher exchange capacity compared with most other materials containing immobilized 8-hydroxyquinoline, better mechanic characteristics, high stability at both high and low pH, and ease of synthesis. This modified fiber can concentrate and separate trace metals from matrices with higher concentrations of alkali and alkaline earth elements. To validate the characteristics of the modified fiber, trace metals Ag, Be, Cd, Co, Cu, Mn, Ni, Pb, and Zn in the certified reference materials river water (SLRS-4) and seawater (CASS-4, NASS-5, SLEW-3) were preconcentrated before determination by inductively coupled plasma mass spectrometry. Good agreement was obtained between the data obtained by this method and the certified values.
Polyurethane foam functionalized with 8-hydroxyquinoline has been prepared by coupling the foam matrix with 8-hydroxyquinoline (oxine) through an azo spacer. The oxine-bonded foam (Ox PUF) was characterized by use of different tools (UV-Vis spectra, IR spectra, density, and stability). Ox PUF was found to be very suitable for separation and preconcentration of trace metals, e.g. Zn(II), Cd(II), and Hg(II) ions, from wastewater in the pH ranges 2-12, 9-12, and 3-6, respectively. Various conditions influencing the sorption of these metal ions on to Ox PUF were optimized. Extraction of the metal ions was accomplished in 15 to 20 min. Study of the variation of the sorption of the tested metal ions with temperature yielded average values for DeltaH, DeltaS, and DeltaG of 41.99, 158.23, and -5.1 kJ mol(-1), respectively. The capacities of the foam material were 0.27, 0.16, and 0.09 mmol g(-1) for Zn(II), Cd(II), and Hg(II), respectively. Preconcentration factors >50 were achieved (RSD approximately 6.18). The quantitative results were obtained from experiments performed using certified reference materials.
A new series of potent 8-hydroxyquinolines was designed based on the newly resolved X-ray crystal structure of EGLN-1. Both alkyl and aryl 8-hydroxyquinoline-7-carboxyamides were good HIF-1alpha prolyl hydroxylase (EGLN) inhibitors. In subsequent VEGF induction assays, these exhibited potent VEGF activity. In addition, this class of compounds did show the ability to stabilize HIF-1alpha.
Iridescent organic films consisting of quasi-parallel wire-like microstructures are grown by castings from ethanol solutions containing mixtures of aluminium-tris-hydroxyquinoline and 1,10-phenanthroline. Spectrophotometric measurements carried out in the ultraviolet-visible range indicate that the microstructured films have angular-dependent optical behaviour, which is motivated by a refractive-index modulation over dimensions that are comparable to visible-light wavelengths. According to the results of investigations carried out by means of optical microscopy, atomic force microscopy (AFM), and scanning near-field optical microscopy (SNOM), the refractive-index modulation originates from a thickness modulation and a phase separation that occurs as the aluminium-tris-hydroxyquinoline and phenanthroline co-crystallize, with the former material being arranged to form a green luminescent pattern on the top of the latter one.
Four new hexadendate chelators, three hydroxyquinoline-based, Csox, O-Trensox, Cox750, and one catecholate-based CacCam-which have comparable skeletal structures and pFe, but widely different partition coefficients, (Kpart), 0.01, 0.02, 1 and 3.2 respectively, have been tested for their iron chelating efficacy in vitro by two methods. First, by their ability to remove iron from ferritin in solution or second, to remove iron from iron-loaded hepatocytes in vitro. Our objective was to ascertain the importance of Kpart and pFe, on the biological efficiency of the molecule. Previous studies proposed that an ideal value of Kpart of 1 should give maximum biological activity. Mobilization of iron by Csox and CacCAM from ferritin was similar and furthermore more efficient than desferrioxamine B. In the iron-loaded hepatocyte cultures, the three hydroxyquinoline chelators, although showing diversity in terms of lipophilicity, appeared to be very similar in their capacity to chelate iron. CacCAM, the unique catecholate, was the most efficient of the molecules tested, as well as being the least toxic in the cellular model despite having the lowest value of pFe. In conclusion, the use of the partition coefficient and pFe, as tools for predicting biological activity of iron chelators should be not generalized. Further studies are required in order to understand the influence of the structure on the biological activity of the molecule.
A series of 5-, 6-, 7- and 8-aza analogues of 3-aryl-4-hydroxyquinolin-2(1H)-one was synthesized and assayed as NMDA/glycine receptor antagonists. The in vitro potency of these antagonists was determined by displacement of the glycine site radioligand [(3)H]5,7-dicholorokynurenic acid ([(3)H]DCKA) in rat brain cortical membranes. Selected compounds were also tested for functional antagonism using electrophysiological assays in Xenopus oocytes expressing cloned NMDA receptor (NR) 1A/2C subunits. Among the 5-, 6-, 7-, and 8-aza-3-aryl-4-hydroxyquinoline-2(1H)-ones investigated, 5-aza-7-chloro-4-hydroxy-3-(3-phenoxyphenyl)quinolin-2-(1H)-one (13i) is the most potent antagonist, having an IC(50) value of 110 nM in [(3)H]DCKA binding and a K(b) of 11 nM in the electrophysiology assay. Compound 13i is also an active anticonvulsant when administered systemically in the mouse maximum electroshock-induced seizure test (ED(50)=2.3mg/kg, IP).
The electrochemiluminescence (ECL) of tris(8-hydroxyquinoline-5-sulfonic acid)aluminum(III) in aqueous solution is reported. ECL is generated by complexing aluminum ions with the chelating agent 8-hydroxyquinoline-5-sulfonic acid (HQS) to form Al(HQS)3, followed by oxidation in the presence of tri-n-propylamine (TPrA). The ECL intensity peaks a potential corresponding to oxidation of both TPrA and Al(HQS)3, and the ECL emission spectrum (lambda(max) = 499 nm) matches the photoluminescence emission spectrum, indicating that the emission is from a Al(HQS)3* excited state. ECL efficiencies (phi(ecl), photons generated per redox event) of 0.002 using Ru(bpy)3(2+) (phi(ecl) = 1) as relative standard. Conditions for ECL emission were optimized and used to generate a calibration curve that was linear over the 7 x 10(-6)-4 x 10(-4) M (5-281 mg/L (ppm)) range with a theoretical limit of detection of 1 ppm. The ECL of several metal ions other than aluminum with HQS and effects on Al(HQS)3 ECL were also examined.
Four new silver(I) double salts (L(2)H)(4)[Ag(10)(C(2))(CF(3)CO(2))(12)(L)(2)].5H(2)O (1), [Ag(8)(C(2))(CF(3)CO(2))(6)(L)(6)] (2), [(Ag(2)C(2))(AgC(2)F(5)CO(2))(6)(L)(3)(H(2)O)].H(2)O (3), and (L.H(3)O)(2)[Ag(11)(C(2))(2)(C(2)F(5)CO(2))(9)(H(2)O)(2)].H(2)O (4) incorporating the hitherto unexplored ligand 4-hydroxyquinoline (L) have been synthesized by the hydrothermal method. Compound 1 features an unprecedented bicapped square-antiprismatic Ag(10) silver cage with an embedded C(2)(2-) moiety, whereas the discrete supermolecule 2 bears a rhombohedral Ag(8) core similar to that previously found in Ag(2)C(2).6AgNO(3). Compound 3 contains a discrete supramolecular complex whose core is a (C(2))(2)@Ag(16) double cage constructed from the edge-sharing of two monocapped square antiprisms, which is completely surrounded by 12 pentafluoropropionate, 6 4-hydroxyquinoline, and 2 aqua ligands. The layer structure in 4 is constructed from a sinuous anionic silver column composed of fused irregular monocapped trigonal antiprisms each encapsulating a C(2)(2-) dianion, with L.H(3)O(+) species serving as hydrogen-bond connectors to adjacent columns.
New 5-chloro-8-hydroxyquinoline (CHQ)-substituted aza-18-crown-6 (4), diaza-18-crown-6 (1), diaza-21-crown-7 (2), and diaza-24-crown-8 (3) ligands, where CHQ was attached through the 7-position, and aza-18-crown-6 (11) and diaza-18-crown-6 (10) macrocycles, where CHQ was attached through the 2-position, were prepared. Thermodynamic quantities for complexation of these CHQ-substituted macrocycles with alkali, alkaline earth, and transition metal ions were determined in absolute methanol at 25.0 degrees C by calorimetric titration. Two isomers, 1 and 10, which are different only in the attachment positions of the CHQ to the parent macroring, exhibit remarkable differences in their affinities toward the metal ions. Compound 1 forms very stable complexes with Mg(2+), Ca(2+), Cu(2+), and Ni(2+) (log K = 6.82, 5.31, 10.1, and 11.4, respectively), but not with the alkali metal ions. Ligand 10 displays strong complexation with K(+) and Ba(2+) (log K = 6.61 and 12.2, respectively) but not with Mg(2+) or Cu(2+). The new macrocycles and their complexes have been characterized by means of UV-visible and (1)H NMR spectra and X-ray crystallography. New peaks in the UV spectrum of the Mg(2+)-1 complex could allow an analytical determination of Mg(2+) in very dilute solutions in the presence of other alkali and alkaline earth metal cations. (1)H NMR spectral and X-ray crystallographic studies indicate that ligand 10 forms a cryptate-like structure when coordinated with K(+) and Ba(2+), which induces an efficient overlap of the two hydroxyquinoline rings. Such overlapping forms a pseudo second macroring that results in a significant increase in both complex stability and cation selectivity.
Proton translocation along ammonia wires is investigated in 7-hydroxyquinoline.(NH(3))(n) clusters, both experimentally by laser spectroscopy and theoretically by Hartree-Fock and density functional (DFT) calculations. These clusters serve as realistic finite-size models for proton transfer along a chain of hydrogen-bonded solvent molecules. In the enol tautomer of 7-hydroxyquinoline (7-HQ), the OH group acts as a proton injection site into the (NH(3))(n)cluster. Proton translocation along a chain of three NH(3) molecules within the cluster can take place, followed by reprotonation of 7-HQ at the quinolinic N atom, forming the 7-ketoquinoline tautomer. Exoergic proton transfer from the OH group of 7-HQ to the closest NH(3) molecule within the cluster giving a zwitterion 7-HQ-.(NH(3))(6)H+ (denoted PT-A) occurs at a threshold cluster size of n = 6 in the DFT calculations and at n = 5 or 6 experimentally. Three further locally stable zwitterion clusters denoted PT-B, PT-B', and PT-C, the keto tautomer, and several transition structures along the proton translocation path were characterized theoretically. Grotthus-type proton-hopping mechanisms occur for three of the proton transfer steps, which have low barriers and are exoergic or weakly endoergic. The step with the highest barrier involves a complex proton transfer mechanism, involving structural reorganization and large-scale diffusive motions of the cluster.
Isomeric 5-, 6-, 7-hydroxyquinolines (11-13) and 5-hydroxyisoquinoline (14) gave N,C-diprotonated dications in CF(3)SO(3)H-SbF(5) superacid medium. Compounds 11, 13, 14, and 8-hydroxyquinoline (5) underwent selective ionic hydrogenation with cyclohexane in the presence of aluminum chloride. Compounds 11 and 14 condense with benzene in the presence of aluminum halides. The detailed mechanism of reactions, which involves superelectrophilic dicationic intermediates, is discussed.
A series of macrocyclic tetraazacrown ethers containing two pyridine, quinoline, 8-hydroxyquinoline, or 8-aminoquinoline sidearms has been prepared. Crab-like cyclization of bis(alpha-chloroacetamide)s and diamines followed by reduction of the cyclic diamides was used to synthesize the selected crown ethers containing two unsubstituted macroring nitrogen atoms. The preparation of the macrocycles with sidearms was accomplished by reductive amination of the proper aldehydes with the crown ethers using sodium triacetoxyborohydride (NaBH(OAc)(3)) as the reducing agent. The 8-hydroxyquinoline- and 8-aminoquinoline-containing macrocycles were synthesized by reductive amination of 8-acetoxyquinoline-2-carboxaldehyde or 8-nitroquinoline-2-carboxaldehyde followed by removing the acetate groups or reducing the nitro groups to amino groups, respectively. Complexation of ligand 22 with Cu(2+), Co(2+), Ni(2+), Zn(2+), Cd(2+), and Pb(2+) was evaluated potentiometrically in aqueous solution (0.10 M Me(4)NCl) at 25 degrees C. Ligand 22 formed very stable complexes with these metal ions. The UV-vis spectra of 22 and its complexes were examined in an aqueous acetic acid buffer solution (pH 5). The 22-Cu(2+) complex provided a new absorption band at 258 nm.
A new series of 5-(4'-substituted)phenylazo-8-hydroxyquinolines (H[L-R]; R = N(CH(3))(2), C(2)H(5), n-C(4)H(9), C(CH(3))(3), H, and F, ) has been prepared and the corresponding Zn[L-R](2) (1a-6a) and Al[L-R](3) (1b-6b) complexes successfully synthesized. These compounds have been studied in order to design new molecular materials with enhanced electron transport properties. The obtained species have been extensively characterized by absorption and emission spectra and by cyclic voltammetric measurements. Experimental and computational results show that the Zn[L-N(CH(3))(2)].2H(2)O (1a) and Al[L-N(CH(3))(2)](1b) complexes only feature luminescence (at 620 and 600 nm), respectively. The unique effects, which are induced by the N=N-C(6)H(4)-N(CH(3))(2) group, are further proved by a reversible electron transfer process detected by cyclic voltammetry. These outcomes, discussed on the basis of theoretical calculations performed on the (H[L-N(CH3)2])-, H[L-N(CH3)2] and (H[L-N(CH3)(2)])+ species, suggest that metal complexes formed by 5-(4'-N,N-dimethylamino)phenylazo-8-hydroxyquinoline should be considered as electron transport materials suitable for applications in photonic devices.
Column chelation chromatography on controlled pore glass-8-hydroxyquinoline was demonstrated to be a very efficient method for removing trace metal contaminants from concentrated macronutrient salt solutions used to prepare nutrient media. By using (63)Ni and (65)Zn radio-isotopes as tracers, controlled pore glass-8-hydroxyquinoline column packings were found to retain 99.9% of the radiotracer and quantitative recovery of the radioisotopes from these columns was obtained by eluting with 1.2 n HCl. This method has several advantages over liquid-liquid extraction methods of purification which previously have been used in plant micronutrient research.
A potential approach for activating prodrugs in hypoxic regions of tumors is to use ionizing radiation, rather than bioreductive enzymes, to effect reduction. This study investigates radiolytic release of 8-hydroxyquinoline (8-HQ), as a model for hydroxyaza-chloromethylbenzindoline DNA minor groove alkylators, from Co(III) complexes under hypoxia. 8-HQ release, measured by HPLC, showed higher efficiency (one-electron stoichiometry) when the auxiliary ligand was a tetraazamacrocycle [e.g. 1,4,7,10-tetraazacyclododecane (cyclen)] rather than a triazamacrocycle [1,4,7-triazacyclononane (TACN)]. These complexes differ from the bioreductive cobalt complex SN 24771 in that their reduction provides stable cobalt-containing products rather than free (aquated) Co(2+). Radiolytic release of 8-HQ from Co(cyclen)(8-HQ) and Co(TACN)(CN)(8-HQ) was also demonstrated in deoxygenated human plasma, selectively in the absence of oxygen, again with higher efficiency for the cyclen system. The cobalt complexes were >1000-fold less potent than free 8-HQ as inhibitors of cell proliferation and were metabolically stable in aerobic and hypoxic cell cultures. Investigation of cell uptake of total cobalt, by inductively coupled plasma mass spectrometry, showed that these complexes enter cells but do not accumulate to the high concentrations seen with SN 24771. The results demonstrate the feasibility of masking the cytotoxicity of hydroxyquinoline-based cytotoxins as Co(III) complexes and demonstrate the utility of cyclen-based auxiliary ligands for optimizing radiolytic activation of these novel prodrugs under hypoxia.
8-hydroxyquinoline complexes of Na(I), Ca(II), Mg(II), Zn(II), Cu(II), Mn(II), Al(III), In(III) and La(III) were synthesized. Photoluminescence (PL) and UV-Vis absorption spectra characteristics of these complexes and 8-hydroxyquinoline are reported. Except complexes of Cu and Mn, most of these complexes reveal photoluminescence. With the polarization force of metal cations increasing, the PL peak shows red-shift and two broad absorption peak in UV-Vis (300-400nm) absorption spectra distinctly appears apart.