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A new coprecipitation procedure was improved for preconcentration-separation and detection of trace propineb. In order to coprecipitate propineb, 8-hydroxyquinoline (8HQ) and copper (II) were used as a precipitating agent and a carrier element, respectively. Using the stoichiometric relationship with zinc, propineb was determined. The critical parameters on the quantitative recoveries of analyte such as pH, mass of precipitating agent, mass of carrier element, and sample volume were studied. The influences of the matrix components were also tested. The preconcentration factor was 80. The limit of detection (LOD), and the limit of quantification (LOQ) for propineb were 0.114 mg L−1 and 0.38 mg L−1, respectively. Copper(II)-8-hydroxyquinoline coprecipitation was applied to determine propineb in vegetable and fruit samples from Kayseri-Turkey with satisfactory results. Flame atomic absorption spectrometry (FAAS) was utilized for measurements of model and real sample solutions. [ABSTRACT FROM AUTHOR]

A series of new unique acetylene derivatives of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonamide 3a–f and 6a–f were prepared by reactions of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonyl chlorides with acetylene derivatives of amine. A series of new hybrid systems containing quinoline and 1,2,3-triazole systems 7a–h were obtained by reactions of acetylene derivatives of quinoline-5-sulfonamide 6a–d with organic azides. The structures of the obtained compounds were confirmed by 1H and 13C NMR spectroscopy and HR-MS spectrometry. The obtained quinoline derivatives 3a–f and 6a–f and 1,2,3-triazole derivatives 7a–h were tested for their anticancer and antimicrobial activity. Human amelanotic melanoma cells (C-32), human breast adenocarcinoma cells (MDA-MB-231), and human lung adenocarcinoma cells (A549) were selected as tested cancer lines, while cytotoxicity was investigated on normal human dermal fibroblasts (HFF-1). All the compounds were also tested against reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and representatives of multidrug-resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis. Only the acetylene derivatives of 8-hydroxyquinoline-5-sulfonamide 3a–f were shown to be biologically active, and 8-hydroxy-N-methyl-N-(prop-2-yn-1-yl)quinoline-5-sulfonamide (3c) showed the highest activity against all three cancer lines and MRSA isolates. Its efficacies were comparable to those of cisplatin/doxorubicin and oxacillin/ciprofloxacin. In the non-cancer HFF-1 line, the compound showed no toxicity up to an IC50 of 100 µM. In additional tests, compound 3c decreased the expression of H3, increased the transcriptional activity of cell cycle regulators (P53 and P21 proteins), and altered the expression of BCL-2 and BAX genes in all cancer lines. The unsubstituted phenolic group at position 8 of the quinoline is the key structural fragment necessary for biological activity. [ABSTRACT FROM AUTHOR]

The complex [Pt(C9H6NO)Cl(C2H4)], (I), was synthesized and structurally characterized by ESI mass spectrometry, IR, NMR spectroscopy, DFT calculations and X-ray diffraction. The results showed that the deprotonated 8-hydroxyquinoline (C9H6NO) coordinates with the PtII atom via the N and O atoms while the ethylene coordinates in the η2 manner and in the trans position compared to the coordinating N atom. The crystal packing is characterized by C—H...O, C—H...π, Cl...π and Pt...π interactions. Complex (I) showed high selective activity against Lu-1 and Hep-G2 cell lines with IC50 values of 0.8 and 0.4 µM, respectively, 54 and 33-fold more active than cisplatin. In particular, complex (I) is about 10 times less toxic to normal cells (HEK-293) than cancer cells Lu-1 and Hep-G2. Furthermore, the reaction of complex (I) with guanine at the N7 position was proposed and investigated using the DFT method. The results indicated that replacement of the ethylene ligand with guanine is thermodynamically more favorable than the Cl ligand and that the reaction occurs via two consecutive steps, namely the replacement of ethylene with H2O and the water with the guanine molecule.

AbstractIn this study, two 8-hydroxyquinoline derivatives, HAPAQ and EAPAQ, were first synthesized, and their molecular structures were confirmed by 1H and 13C NMR. The effects of HAPAQ and EAPAQ on corrosion processes were investigated using weight loss, electrochemical, and theoretical methods. Overall, the data unmistakably demonstrate that the inhibition performance (η %) increases with an increase as HAPAQ and EAPAQ concentrations rise, peaking at 96.08% (HAPAQ) and 94.37% (EAPAQ) at the optimal concentration (10−3 M) for PPD technology. The two 8-hydroxyquinoline derivatives exhibit inhibitory behavior, as seen by the polarization curve impedance tests; however, they demonstrate that adsorption promotes protective action on metal surfaces, creating a geometric blocking effect and a protective coating that impedes metal breakdown. HAPAQ and EAPAQ's inhibitory efficacy may be reduced by the rising temperature. Furthermore, it adheres to Langmuir’s single-layer adsorption isotherm, and the physisorption and chemisorption mechanisms are linked to the corresponding value of the adsorption energy (ΔGads). Additionally, the MS scanning electron microscope (SEM) has been studied and discussed. The possibility of complex organization between the inhibitor molecules, 8-hydroxyquinoline derivatives (HAPAQ and HAPAQ), and the Fe2+ ions generated during the oxidation process was established by examining the test solutions using UV–visible spectroscopy. Consequently, it is evident from DFT simulations that the surface recovery is dependent on the local reactivity descriptors. The theoretical outcomes derived from DFT are aligned with the findings of the experimental studies. [ABSTRACT FROM AUTHOR]

An efficient and stable palladium species catalyst immobilized on functionalized hyper–cross-linked polymers (HCPs-Pd) has been successfully developed and applied in the Suzuki–Miyaura coupling reaction of diverse types of aromatic halides with aryl boronic acid in this work. The results demonstrated that HCPs-Pd exhibited high catalytic activity, which benefited from the microporous structure of the catalyst guaranteed high dispersibility of active palladium, and high specific surface area, large pore volume, good chemical stability. Under optimal reaction conditions, 93.0% of biphenyl yield in the Suzuki–Miyaura reaction with bromobenzene (C6H5Br) and phenylboronic acid (C6H7BO2) as raw material was obtained. The good stability of the HCPs-II-Pd catalyst was verified by five cycles experiments. Perhaps this work provides new insights into the high-yield preparation of aromatic biphenyl compounds employing HCPs-Pd as an efficient and stable catalyst in the Suzuki–Miyaura reaction. [ABSTRACT FROM AUTHOR]

The complex [Pt(C9H6NO)Cl(C2H4)], (I), was synthesized and structurally characterized by ESI mass spectrometry, IR, NMR spectroscopy, DFT calculations and X-ray diffraction. The results showed that the deprotonated 8-hydroxyquinoline (C9H6NO) coordinates with the PtII atom via the N and O atoms while the ethylene coordinates in the η² manner and in the trans position compared to the coordinating N atom. The crystal packing is characterized by C--H...O, C--H...π, Cl...π and Pt...π interactions. Complex (I) showed high selective activity against Lu-1 and Hep-G2 cell lines with IC50 values of 0.8 and 0.4 mM, respectively, 54 and 33-fold more active than cisplatin. In particular, complex (I) is about 10 times less toxic to normal cells (HEK-293) than cancer cells Lu-1 and Hep-G2. Furthermore, the reaction of complex (I) with guanine at the N7 position was proposed and investigated using the DFT method. The results indicated that replacement of the ethylene ligand with guanine is thermodynamically more favorable than the Cl ligand and that the reaction occurs via two consecutive steps, namely the replacement of ethylene with H2O and the water with the guanine molecule. [ABSTRACT FROM AUTHOR]

The interaction between 8-hydroxyquinoline (8HQ, C9H7NO) and naphthalene-1,5-disulfonic acid (H2NDS, C10H8O6S2) in aqueous media results in the formation of the salt hydrate bis(8-hydroxyquinolinium) naphthalene-1,5-disulfonate tetrahydrate, 2C9H8NO+·C10H6O6S22−·4H2O. The asymmetric unit comprises one protonated 8HQ+ cation, half of an NDS2– dianion symmetrically disposed around a center of inversion, and two water molecules. Within the crystal structure, these components are organized into chains along the [010] and [10\overline{1}] directions through O—H...O and N—H...O hydrogen-bonding interactions, forming a di-periodic network parallel to (101). Additional stabilizing interactions such as C—H...O, C—H...π, and π–π interactions extend this arrangement into a tri-periodic network structure

A series of new unique acetylene derivatives of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonamide 3a–f and 6a–f were prepared by reactions of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonyl chlorides with acetylene derivatives of amine. A series of new hybrid systems containing quinoline and 1,2,3-triazole systems 7a–h were obtained by reactions of acetylene derivatives of quinoline-5-sulfonamide 6a–d with organic azides. The structures of the obtained compounds were confirmed by 1H and 13C NMR spectroscopy and HR-MS spectrometry. The obtained quinoline derivatives 3a–f and 6a–f and 1,2,3-triazole derivatives 7a–h were tested for their anticancer and antimicrobial activity. Human amelanotic melanoma cells (C-32), human breast adenocarcinoma cells (MDA-MB-231), and human lung adenocarcinoma cells (A549) were selected as tested cancer lines, while cytotoxicity was investigated on normal human dermal fibroblasts (HFF-1). All the compounds were also tested against reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and representatives of multidrug-resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis. Only the acetylene derivatives of 8-hydroxyquinoline-5-sulfonamide 3a–f were shown to be biologically active, and 8-hydroxy-N-methyl-N-(prop-2-yn-1-yl)quinoline-5-sulfonamide (3c) showed the highest activity against all three cancer lines and MRSA isolates. Its efficacies were comparable to those of cisplatin/doxorubicin and oxacillin/ciprofloxacin. In the non-cancer HFF-1 line, the compound showed no toxicity up to an IC50 of 100 µM. In additional tests, compound 3c decreased the expression of H3, increased the transcriptional activity of cell cycle regulators (P53 and P21 proteins), and altered the expression of BCL-2 and BAX genes in all cancer lines. The unsubstituted phenolic group at position 8 of the quinoline is the key structural fragment necessary for biological activity.

Cutaneous leishmaniasis exhibits a wide spectrum of clinical manifestations; however, only a limited number of drugs are available and include Glucantime® and amphotericin B, which induce unacceptable side effects in patients, limiting their use. Thus, there is an urgent demand to develop a treatment for leishmaniasis. Recently, it was demonstrated that 8-hydroxyquinoline (8-HQ) showed significant leishmanicidal effects in vitro and in vivo. Based on that, this work aimed to develop a topical formulation containing 8-HQ and assess its activity in experimental cutaneous leishmaniasis. 8-HQ was formulated using a Beeler base at 1 and 2% and showed an emulsion size with a D50 of 25 and 51.3 µm, respectively, with a shear-thinning rheological behaviour. The creams were able to permeate artificial Strat-M membranes and excised porcine skin without causing any morphological changes in the porcine skin or murine skin tested. In BALB/c mice infected with L. (L.) amazonensis, topical treatment with creams containing 1 or 2% of 8-HQ was found to reduce the parasite burden and lesion size compared to infected controls with comparable efficacy to Glucantime® (50 mg/kg) administered at the site of the cutaneous lesion. In the histological section of the skin from infected controls, a diffuse inflammatory infiltrate with many heavily infected macrophages that were associated with areas of necrosis was observed. On the other hand, animals treated with both creams showed only moderate inflammatory infiltrate, characterised by few infected macrophages, while tissue necrosis was not observed. These histological characteristics in topically treated animals were associated with an increase in the amount of IFN-γ and a reduction in IL-4 levels. The topical use of 8-HQ was active in decreasing tissue parasitism and should therefore be considered an interesting alternative directed to the treatment of leishmaniasis, considering that this type of treatment is non-invasive, painless, and, importantly, does not require hospitalisation, improving patient compliance by allowing the treatment to be conducted. [ABSTRACT FROM AUTHOR]

Aluminum alloys play a significant role in aviation, medical equipment, electronic device and automotive industry. Nevertheless, the corrosion is a critical problem that must be solved before applications. In this work, synergistic effect of an organic hydrophobic film (2-mercaptobenzothiazole (MBT), sodium stearate (SS) or 8-hydroxyquinoline (8-HQ)) deposited on micro-arc oxidation (MAO) which was post-sealing treated by NaH2PO4 was investigated on corrosion resistance. The morphology and composition of the resulting organic hydrophobic films were analyzed by FESEM, EDS and FTIR. The results revealed that the organic hydrophobic films were successfully deposited on the MAO coating with NaH2PO4 (MAO-NaH2PO4), and the pores and cracks of the MAO layer were effectively sealed. Moreover, the contact angle of the sample with 8-HQ treating reached the hydrophobic level (136.8°), which was much higher than that of the MAO-NaH2PO4 (58.06°). The PDP and EIS measurements showed that the sample with 8-HQ treating possessed superior corrosion resistance with a low corrosion current (1.924 × 10−8 A cm−2) and the decreased corrosion rate (1.8 × 10−4 mm·a−1), which was two order of magnitude higher than that of the MAO-NaH2PO4 sample (3.8 × 10−2 mm·a−1). This facile and low-cost strategy to form organic-inorganic composite coatings could have promising application in the corrosion protection for the light alloys.

KP46 (tris(hydroxyquinolinato)gallium(III)) is an experimental, orally administered anticancer drug. Its absorption, delivery to tumours, and mode of action are poorly understood. We aimed to gain insight into these issues using gallium-67 and gallium-68 as radiotracers with SPECT and PET imaging in mice. [67Ga]KP46 and [68Ga]KP46, compared with [68Ga]gallium acetate, were used for logP measurements, in vitro cell uptake studies in A375 melanoma cells, and in vivo imaging in mice bearing A375 tumour xenografts up to 48 h after intravenous (tracer level) and oral (tracer and bulk) administration. 68Ga was more efficiently accumulated in A375 cells in vitro when presented as [68Ga]KP46 than as [68Ga]gallium acetate, but the reverse was observed when intravenously administered in vivo. After oral administration of [68/67Ga]KP46, absorption of 68Ga and 67Ga from the GI tract and delivery to tumours were poor, with the majority excreted in faeces. By 48 h, low but measurable amounts were accumulated in tumours. The distribution in tissues of absorbed radiogallium and octanol extraction of tissues suggested trafficking as free gallium rather than as KP46. We conclude that KP46 likely acts as a slow releaser of gallium ions which are inefficiently absorbed from the GI tract and trafficked to tissues, including tumour and bone. [ABSTRACT FROM AUTHOR]

Aim: This study evaluates the in vitro efficacy of 8-hydroxyquinoline (8HQ) derivatives in controlling the phytopathogenic fungus Phaeomoniella chlamydospora. Methods and results: The in vitro tests assessed the susceptibility to the minimum inhibitory concentration (MIC), checkerboard assay, mycelial growth (MG) inhibition, and EC50 determination. Among the seven agricultural fungicides tested, tebuconazole (TEB) displayed the lowest MIC, 1.01 µg mL−1, followed by captan (CAP), thiophanate methyl (TM), and mancozeb with MICs of 4.06, 5.46, and 10.62 µg mL−1, respectively. The 8HQ derivatives used in this study were clioquinol and PH 151 (PH) with MICs of 1.09 and 2.02 µg mL−1, respectively. PH associated with TEB and CAP showed synergism and inhibited 95.8% of MG at the highest dose. TEB inhibited 100% of MG at the three highest doses, while associated with PH exhibited the lowest EC50 (0.863 + 0.0381 µg mL−1). Conclusions: We concluded that the 8HQ derivatives tested controlled effectively the P. chlamydospora in vitro. PH associated with CAP and TEB exhibited a synergistic effect. The association between PH and TM was considered indifferent. Impact Statement: This study expands the list of active ingredients tested against P. chlamydospora, with the PH 151 and clioquinol derivatives being tested for the first time. The in vitro efficacy and synergistic action with other fungicides suggest a potential use as a grapevine wound protectant. This association makes it possible to reduce doses and increase the potency of both drugs, reducing the risk of resistance development and harm to humans and the environment. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of uranyl ion (UO2+2 ) onto kaolinite mineral from its aqueous solutions has been investigated using the batch experiment method under different parameters. Uranyl ions were measured spectrophotometrically using 8-hydroxy quinoline as a chromogen. The effect of contact time, pH, initial ion concentration, adsorbent amount, and ionic strength has been designated to establish this study. The adsorbed percentage increased dramatically as the pH increased from 1 to 5; from 28% to 70% at well-known parameters of contact time, pH value, adsorbent amount, and initial ion concentration. Above pH 5, the adsorption affinity was virtually unchanged. On the other hand, the adsorbed percentage decreased from 68% to 57% when the initial uranyl ion concentration increased from 90 to 120 mg/L. The overall results showed that the maximum uranyl ion adsorption percentage reached at the initial concentration of 90 ppm, pH 4.5, contact time of 5 h, and an adsorbent dosage of 4.0 g/L. The adsorption behavior of the uranium ion on kaolinite obeys Langmuir (1918) and Freundlich isotherm models, with R² value above 0.998 for both. [ABSTRACT FROM AUTHOR]

The adsorption analysis of some organic inhibitors consisting of benzotriazole, 8-hydroxyquinoline, 2-mercaptobenzothiazole onto aluminum alloy surface based on optimized coordination of binding on the Al–X (Mg, Ga, Si) surface has been accomplished. In this work, the ONIOM approach has been performed with a three-layered level of high level of DFT method using EPR-III, 6-31+G(d,p) and LANL2DZ basis sets by the physico-chemical software of Gaussian 16 revision C.01 program, a medium semi-active part that includes important electronic contributions, and a low level part that has been handled using MM2 force field approaches. The physico-chemical properties of adsorption -surface complexes are one of the principal parameters for determining and choosing the Langmuir adsorption through IR, NMR, UV–Vis, HOMO/LUMO and charge distribution results. Comparing to amounts approved a good agreement among computed results, as well as the correctness of the selected isotherm for the adsorption process of benzotriazole → Al–Mg, benzotriazole → Al–Ga, benzotriazole → Al–Si, 8-hydroxyquinoline → Al–Mg, 8-hydroxyquinoline → Al–Ga, 8-hydroxyquinoline → Al–Si, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole → Al–Mg, 2-mercaptobenzothiazole → Al–Ga, and 2-mercaptobenzothiazole → Al–Si. Nuclear magnetic resonance has certainly has focused on the aluminum shielding in the intra-atomic interaction with magnesium, gallium and silicon and simultaneously interatomic interaction with other atoms in organic inhibitors through variety of high, medium and low layers of ONIOM method. Al–Si with highest fluctuation in the shielding tensors of NMR spectrum generated by intra-atomic interaction leads us to the most influence in the neighbor atoms generated by interatomic reaction. Moreover, based on the computed amounts of UV–Vis spectra for benzotriazole, 8-hydroxyquinoline and 2-mercaptobenzothiazole adsorb on the Al(111)-alloy surface, there are maximum adsorption bands between 200–280 nm for benzotriazole, 225–350 nm for 8-hydroxyquinoline and 210–280 nm for 2-mercaptobenzothiazole, respectively; and maximum adsorption bands for benzotriazole, 8-hydroxyquinoline, and 2-mercaptobenzothiazole has observed around 230, 300, and 240 nm, respectively. [ABSTRACT FROM AUTHOR]

A rapid, conventional reflux and efficient procedure is used to synthesize a series of ternary metal complexes derived from Schiff base of 2-aminobenzimidazole with 2-chloroacetophenone and secondary ligands (8-hydroxy quinoline or L-histidine). Our present work focuses on the potential of the synthesized Schiff base, its metal complexes and the study of their antimicrobial activity. All these compounds are characterized by elemental analysis, melting point, magnetic moment measurement, molar conductance measurement and various spectral techniques such as FTIR, ¹H NMR, and mass spectra. Among these synthesized complexes, Ni(II) complex having 8-hydroxyquinoline as a secondary ligand exhibits excellent antifungal activity against Aspergillus niger compared to standard Ketoconazole whereas other metal complexes show good to moderate activity against gram-positive bacteria i.e. Staphylococcus aureus and gram-negative bacteria i.e. Escherichia coli compared to standard Ciprofloxacin. [ABSTRACT FROM AUTHOR]

The inhibition behavior of the promising eco-friendly inhibitor 8-hydroxyquinoline (8HQ) in two concentrations of sodium chloride solution was studied by hydrogen evolution, scanning electron microscope (SEM), three-dimensional morphology, electrochemical testing, and computational calculations. The results indicated that the 8HQ inhibitor showed satisfactory inhibition effect due to its fast, excellent adsorption capacity and self-healing ability. The corrosion inhibition effect is related to the concentration of the inhibitor. There was a competitive adsorption relationship between 8HQ and [Cl−], and the adsorption morphology was obviously affected by the concentration of [Cl−]. At the lower concentration of NaCl solution, the adsorption of 8HQ was more orderly, faster, and the adsorption amount was larger, which led to the formation of a denser protective layer. Density functional theory (DFT) results showed that the most stable adsorption configuration of 8HQ was NO-Top. N and O atoms are the active sites, and there is a strong coupling between them and Mg atoms, which is consistent with the experimental results. [ABSTRACT FROM AUTHOR]

A series of manganese(I) tricarbonyl complexes formulated as [Mn(8‐HQ)(CO)3Imd] (HQ = hydroxyquinoline and Imd = imidazole derivatives) was synthesized and fully characterized. These structures could be easily accessed from a common dimeric edifice formulated as [Mn2(8‐HQ)2(CO)6]. The structure of this complex has been confirmed by X‐ray diffraction studies. Its reaction with a range of imidazole derivatives (Imd) yielded the monomeric complexes [Mn(8‐hydroxyquinoline)(CO)3Imd] with various functional groups as an anchoring point for a vector. Photoactivation of all these complexes by blue‐light irradiation led to the liberation of 3 mol of CO per mol of complex as determined experimentally. Spectroscopic and computational methods were employed to explore the mechanism of CO release. Finally, a manganese complex including the more elaborate imidazole ligand N‐ and C‐di‐protected histidine was successfully synthesized, opening the way to its direct incorporation in peptides. [ABSTRACT FROM AUTHOR]

The ligand namely N-(8-hydroxyquinolin-5-yl)-2,4,6-trimethylbenzene sulfonamide (8HQTBS) and its complexes with transition metals were synthesized using transition metal ions. Prepared ligand and their metal complexes were examined by the study of physicochemical properties, various spectral techniques, and magnetic susceptibility. Octahedral geometry of the transition metal complexes was proposed by spectral studies. The antimicrobial profile of prepared ligands and complexes (In vitro) showed better activity of ligands after metal complexation. Strong binding of transition metal complexes with CT-DNA was observed through the intercalation mechanism. A comparative molecular docking study between bacterial proteins and a DNA helix was performed, and the docking results obtained were in good agreement with the spectroscopic results. Some of the compounds showed good to moderate antimalarial activity. [ABSTRACT FROM AUTHOR]

The isoelectronic relationship of 1,2-azaborinine (B=N structural motif) and benzene (C=C) is well documented. Upon deprotonation of the former, the anionic 1,2-azaboratabenzene is obtained, which is isosteric with pyridine (C=N) and has a similar capability as an aromatic N-donor. We present the complexation of boron and aluminum precursors with a κ2-N,O-donating 8-hydroxy-BN-naphthalene ligand (H2(BQ), 1). Six chelate complexes with 1:1 and 2:1 stoichiometries were isolated and characterized by X-ray diffraction analysis and NMR spectroscopy. Comparing the isosteric dimethylaluminum complexes of H2(BQ) and an 8-hydroxyquinoline (HQ', 2) as a reference allowed us to quantify the influence of a formal substitution of carbon by boron on the structure and the electronic properties: While the structural parameters of the ligands were similar, the electropositive boron atom affected the electron density distributions within the complexes substantially. As the consequence, the Al–N bond was significantly shortened, and the aluminum atom showed a different coordination geometry than in the quinoline analog. Moreover, strong hypsochromic shifts of both the absorption and the emission were observed. The results highlight that the differences between CN and BN polyaromatic complexes are more distinct than between equally charged BN and CC congeners. [ABSTRACT FROM AUTHOR]

The separation and preconcentration for trace cobalt(II), copper(II), lead(II), and zinc(II) were investigated with magnetic solid phase extraction using Fe3O4 nanoparticles coated with 8-hydroxyquinoline as a new adsorbent prior to their microinjection sampling–flame atomic absorption spectrometric (MIS–FAAS) determination. The synthesized 8-hydroxyquinoline-coated Fe3O4 magnetic nanoparticles (Fe3O4-8HQ MNPs) were characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The analytical parameters including pH, type of eluent, eluent volume, eluent concentration, adsorption and desorption times, mass of adsorbent, and foreign ion effects were investigated. The analyte ions were quantitatively recovered at pH 8.0 and eluted with 1 M nitric acid. The developed method was applied to pharmaceuticals, wastewater, and a composite material with recoveries from 92% to 98%. The method was validated using NIST certified reference material (CRM) QCP-QCS-1. The results of the CRM solution were compared with those obtained by inductively coupled plasma–mass spectrometry (ICP–MS) and shown to be compatible. [ABSTRACT FROM AUTHOR]

The metal chelator PBT2 (5,7-dichloro-2-[(dimethylamino)methyl]-8-hydroxyquinoline) acts as a terdentate ligand capable of forming binary and ternary Cu2+ complexes. It was clinically trialed as an Alzheimer's disease (AD) therapy but failed to progress beyond phase II. The β-amyloid (Aβ) peptide associated with AD was recently concluded to form a unique Cu(Aβ) complex that is inaccessible to PBT2. Herein, it is shown that the species ascribed to this binary Cu(Aβ) complex in fact corresponds to ternary Cu(PBT2)NImAβ complexes formed by the anchoring of Cu(PBT2) on imine nitrogen (NIm) donors of His side chains. The primary site of ternary complex formation is His6, with a conditional stepwise formation constant at pH 7.4 ( K c [M−1]) of log K c = 6.4 ± 0.1, and a second site is supplied by His13 or His14 (log K c = 4.4 ± 0.1). The stability of Cu(PBT2)NImH13/14 is comparable with that of the simplest Cu(PBT2)NIm complexes involving the NIm coordination of free imidazole (log K c = 4.22 ± 0.09) and histamine (log K c = 4.00 ± 0.05). The 100-fold larger formation constant for Cu(PBT2)NImH6 indicates that outer-sphere ligand–peptide interactions strongly stabilize its structure. Despite the relatively high stability of Cu(PBT2)NImH6, PBT2 is a promiscuous chelator capable of forming a ternary Cu(PBT2)NIm complex with any ligand containing an NIm donor. These ligands include histamine, L-His, and ubiquitous His side chains of peptides and proteins in the extracellular milieu, whose combined effect should outweigh that of a single Cu(PBT2)NImH6 complex regardless of its stability. We therefore conclude that PBT2 is capable of accessing Cu(Aβ) complexes with high stability but low specificity. The results have implications for future AD therapeutic strategies and understanding the role of PBT2 in the bulk transport of transition metal ions. Given the repurposing of PBT2 as a drug for breaking antibiotic resistance, ternary Cu(PBT2)NIm and analogous Zn(PBT2)NIm complexes may be relevant to its antimicrobial properties. [ABSTRACT FROM AUTHOR]

In this study, we investigated the abilities of nitrogen and sulfur heterocyclic carbenes of benzotriazole, 2-mercaptobenzothiazole, 8-hydroxyquinoline, and 3-amino-1,2,4-triazole-5-thiol regarding adsorption on an Al-Mg-Si alloy toward corrosion inhibition of the surface. Al-Si(14), Al-Si(19), and Al-Si(21) in the Al-Mg-Si alloy surface with the highest fluctuation in the shielding tensors of the "NMR" spectrum generated by intra-atomic interaction directed us to the most influence in the neighbor atoms generated by interatomic reactions of N → Al, O → Al, and S → Al through the coating and adsorbing process of Langmuir adsorption. The values of various thermodynamic properties and dipole moments of benzotriazole, 2-mercaptobenzothiazole, 8-hydroxyquinoline, and 3-amino-1,2,4-triazole-5-thiol adsorbed on the Al-Mg-Si increased by enhancing the molecular weight of these compounds as well as the charge distribution between organic compounds (electron donor) and the alloy surface (electron acceptor). Finally, this research can build up our knowledge of the electronic structure, relative stability, and surface bonding of various metal alloy surfaces, metal-doped alloy nanosheets, and other dependent mechanisms such as heterogeneous catalysis, friction lubrication, and biological systems. [ABSTRACT FROM AUTHOR]

Heterocyclic compounds with multiple bonds and heteroatoms of nitrogen, oxygen and sulfur can be notable as corrosion inhibitors for metal surfaces. In this work, Ge-doped Al–Mg nanoalloy has been investigated based on Langmuir adsorption and density functional theorey method (DFT) method. The partial electron density states (PDOS) have confirmed an obvious charge accumulation between the Al–Mg alloy and doped atom of Ge through the recognition of the conduction band region. The infrared (IR) spectrums for complexes of inhibitors adorbed on Ge-doped Al–Mg alloy have been reported in the frequency between 500–3500 cm–1 for (benzotriazole/2-mercaptobenzothiazole/8-hydroxyquinoline) → Al–Mg–Ge, and around 500–4000 cm–1 for 3-amino-1,2,4-triazole-5-thiol → Al–Mg–Ge with the sharpest peak approximately around 2000 cm–1, 3000 cm–1 for (benzotriazole/2-mercaptobenzothiazole/8-hydroxyquinoline) → Al–Mg–Ge and 2000 cm–1, and 4000 cm–1 for 3-amino-1,2,4-triazole-5-thiol → Al–Mg–Ge. Nuclear magnetic reonance (NMR) spectrocopy has focused on the intra-atomic and interatomic interactions with ONIOM model with three levels of high, medium and low by using LANL2DZ/6-31+G(d, p), semi-empirical and MM2 functions. Al–Ge(14), Al–Ge(19) and Al–Ge(21) in the Al–Mg–Ge alloy surface with the highest fluctuation in the shielding tensors of NMR spectrums generated by intra-atomic interaction direct us to the most influence in the neighbor atoms generated by interatomic reactions of N → Al, O → Al, S → Al through the coating and adsorbing process of Langmuir adsorption. This work indicated that proper monitoring of the coating mechanism by Langmuir adsorption can illustrate inhibiting the ternary aluminum nanoalloy of Al–Mg–Ge corrosion through an investigation of their structural and physicochemical analysis. Furthermore, it has been illusstrated the effect of the substitution of aluminum atoms in Al–Al nanosheet with Mg and Ge through resulted electric potential by using Nuclear quadrupole resonance (NQR) analysis. [ABSTRACT FROM AUTHOR]

In a "smart" corrosion-protective coating system, both the active anti-corrosion and the early corrosion detection of underlying metals are highly required. It is practical significant to develop materials that possess self-detecting of the early local corrosion and self-healing of coating defects simultaneously. The organic compound 8-hydroxyquinoline (8HQ) is an effective inhibitor and a fluorescent sensor probe for corrosion of aluminum alloy. Therefore, a layer double hydroxide (LDH) nanocontainer film loaded with the 8HQ was developed for the active corrosion protection purpose of aluminum alloy AA2024. In corrosive environments, the 8HQ are released from LDH film to inhibit the corrosion process, leading to the loss of the complexation with Al3+ ions in LDH laminates, thus turning off fluorescence. Results show that the LDH film loaded with 8HQ composites can improve the anti-corrosion performance of the film by releasing corrosion inhibitors on demand. Simultaneously, due to the complexation of 8HQ and Al3+ ions, the LDH film is fluorescent at the initial stage under ultraviolet light, and then becomes non-fluorescent at the corrosion sites, indicating the corrosion evolution process of the coating. The 8HQ-loaded LDH film with self-healing and self-detecting dual functions provides promising opportunities for the effective corrosion protection of aluminum alloy due to its "smart" and multifunctional properties. [ABSTRACT FROM AUTHOR]

8-hydroxyquinoline (oxine) is a widely known and frequently used chelating agent, and the pharmacological effects of the core molecule and its derivatives have been studied since the 19th century. There are several synthetic methods to modify this core. The Mannich reaction is one of the most easily implementable examples, which requires mild reaction conditions and simple chemical reagents. The three components of the Mannich reaction are a primary or secondary amine, an aldehyde and a compound having a hydrogen with pronounced activity. In the modified Mannich reaction, naphthol or a nitrogen-containing naphthol analogue (e.g., 8-hydroxyquinoline) is utilised as the active hydrogen provider compound, thus affording the formation of aminoalkylated products. The amine component can be ammonia and primary or secondary amines. The aldehyde component is highly variable, including aliphatic and aromatic aldehydes. Based on the pharmacological relevance of aminomethylated 8-hydroxyquinolines, this review summarises their syntheses via the modified Mannich reaction starting from 8-hydroxyquinoline, formaldehyde and various amines. [ABSTRACT FROM AUTHOR]

Abstract A highly sensitive spectrofluorimetric method is developed for the determination of prucalopride succinate (PRU). The method depends on lanthanide-sensitized luminescence due to complex formation between the drug and terbium chloride (Tb+3) which is enhanced by the addition of 8 hydroxyquinoline (8HQ) and phosphate buffer (0.02 M, pH 3.2). The calibration curve was constructed over the linear range 10–300 ng/mL after excitation at 226 nm and measuring the emission of the ternary complex at 544 nm. The method was validated according to ICH Q2 (R1) guidelines and showed a good recovery ± RSD of 100.41% ± 1.26, the limits of detection and quantitation were found to be 2.81 and 8.53 ng/mL, respectively. The proposed method was successfully applied for the determination of the drug marketed tablet dosage form and the results were in good agreement with the reference method. Also, the method greenness was evaluated according to Complex-GAPI and analytical Eco-Scale.

The fabrication of pH-sensitive lignin-based materials has received considerable attention in various fields, such as biomass refining, pharmaceuticals, and detecting techniques. However, the pH-sensitive mechanism of these materials is usually depending on the hydroxyl or carboxyl content in the lignin structure, which hinders the further development of these smart materials. Here, a pH-sensitive lignin-based polymer with a novel pH-sensitive mechanism was constructed by establishing ester bonds between lignin and the active molecular 8-hydroxyquinoline (8HQ). The structure of the produced pH-sensitive lignin-based polymer was comprehensively characterized. The substituted degree of 8HQ was tested up to 46.6% sensitivity, and the sustained release performance of 8HQ was confirmed by the dialysis method, the sensitivity of which was found to be 60 times slower compared with the physical mixed sample. Moreover, the obtained pH-sensitive lignin-based polymer showed an excellent pH sensitivity, and the released amount of 8HQ under an alkaline condition (pH = 8) was obviously higher than that under an acidic condition (pH = 3 and 5). This work provides a new paradigm for the high-value utilization of lignin and a theory guidance for the fabrication of novel pH-sensitive lignin-based polymers. [ABSTRACT FROM AUTHOR]

The intercalation of 8-hydroxyquinoline (HQ) organic chelating ligand onto the structure of Na+-montmorillonite (MMT) was prepared and investigated by using Fourier transform infrared spectrometry (FT-IR), X-ray diffraction spectrometry (XRD), elemental analysis, and scanning electron microscope with energy X-ray dispersive (SEM–EDS) techniques; the results indicated that 8-hydroxyquinoline was successfully intercalated in the interlayer space of montmorillonite. This intercalation compound was used to construct a potentiometric electrode. Potentiometric results showed the best response to Cu2+ ion with a slope of 30.45 ± 0.36 mV decade−1 (R2 = 0.9987) and provided a good linearity within a concentration range of 10−5–0.5 M. The limit of detection of the electrode was determined as 1.99×10−6 mol L−1. The selectivity coefficient of electrode was evaluated by a separate solution method (SSM), and the resulting values of the selectivity coefficient were small which indicated the electrode gave the best response to Cu2+ ion. This electrode also showed good precision, repeatability, durability, fast response time, and selective to copper ion. Cyclic voltametry and electrochemical impedance spectroscopy (EIS) analysis exhibited that 8-hydroxyquinoline could help enhance the specificity of the montmorillonite to form with Cu2+ ion in solution. The proposed potentiometric electrode was successfully applied to determine Cu2+ in a real micronutrient fertilizer sample by the standard addition method. [ABSTRACT FROM AUTHOR]

We report the time-efficient synthesis of quinolin-8-yl 4-chlorobenzoate (3) via an O-acylation reaction between 8-hydroxyquinoline (1) and 4-chlorobenzoyl chloride (2) mediated by triethylamine in acetonitrile under heating at 80 °C for 20 min in the Monowave 50 reactor. This protocol is distinguished by its short reaction time, operational simplicity, and clean reaction profile. The structure of 3 was fully characterized through a combination of analytical techniques, including NMR, IR, and UV–Vis spectroscopy, MS spectrometry, differential scanning calorimetry (DSC), thermogravimetry (TG), and crystallographic studies. Interestingly, X-ray diffraction analyses of 3 show that the crystal structure is characterized by C-H···N, C-H···O, Cl···π, and π···π interactions. The molecular conformation presents an orthogonal orientation between aromatic rings in the solid state. The calculated interaction energies using the CE-B3LYP model show that dispersion forces act in a higher proportion to build the crystal, which is consistent with the few short hydrogen interactions detected. Electrostatic potential maps suggest the formation of σ-holes over the Cl atoms. Although they can behave as both Lewis acid and base sites, Cl··Cl interactions are absent due to the shallow depth of these σ-holes. Quantum chemical descriptors and global reactivity descriptors were examined using the B3LYP method with the 6-31G(d,p) basis set implemented in CrystalExplorer. Finally, compound 3 exhibited low activity against HOP-92 and EKVX non-Small-cell lung and UO-31 Renal cancer cell lines, with a growth inhibition percentage (GI%) ranging from 6.2% to 18.1%. [ABSTRACT FROM AUTHOR]

The increase of corrosion resistance of magnesium and its alloys by forming the smart self-healing hybrid coatings was achieved in this work in two steps. In the first step, using the plasma electrolytic oxidation (PEO) treatment, a ceramic-like bioactive coating was synthesized on the surface of biodegradable MA8 magnesium alloy. During the second step, the formed porous PEO layer was impregnated with a corrosion inhibitor 8-hydroxyquinoline (8-HQ) and bioresorbable polymer polycaprolactone (PCL) in different variations to enhance the protective properties of the coating. The composition, anticorrosion, and antifriction properties of the formed coatings were studied. 8-HQ allows controlling the rate of material degradation due to the self-healing effect of the smart coating. PCL treatment of the inhibitor-containing layer significantly improves the corrosion and wear resistance and retains an inhibitor in the pores of the PEO layer. It was revealed that the corrosion inhibitor incorporation method (including the number of steps, impregnation, and the type of solvent) significantly matters to the self-healing mechanism. The hybrid coatings obtained by a 1-step treatment in a dichloromethane solution containing 6 wt.% polycaprolactone and 15 g/L of 8-HQ are characterized by the best corrosion resistance. This coating demonstrates the lowest value of corrosion current density (3.02 × 10−7 A cm−2). The formation of the hybrid coating results in the corrosion rate decrease by 18 times (0.007 mm year−1) as compared to the blank PEO layer (0.128 mm year−1). An inhibitor efficiency was established to be 83.9%. The mechanism of corrosion protection of Mg alloy via smart hybrid coating was revealed. [ABSTRACT FROM AUTHOR]

8‐Hydroxyquinoline and its derivatives consist of a group of metal‐binding ligands capable of reaching complexes that present several biological activities. In the present study, we collate and discuss data regarding the antileukemia activities of 8‐hydroxyquinoline (8HQ) compounds to provide an overview of their mechanisms of actions, and a compilation of cytotoxicity data against diverse leukemia cell lines. The pharmacological activities of this class of agents are associated primarily with their ability to coordinate metals and interact with multiple biological targets. We found consistent evidence that 8HQ exerts promising proapoptotic features through its direct interaction with deoxyribonucleic acid (DNA) and inhibition of multiple targets, such as the proteasome, nuclear factor kappa B (NF‐κB), histone deacetylase (HDAC), bromodomain and extra terminal (BET) proteins and janus kinases (JAKs), in addition to inducing autophagy associated cell death. Thus, we provide substantial evidence for the repositioning potential of the 8HQ class for the treatment of leukemia, a hematological malignancy for which urgent advances in therapeutic approaches are needed to overcome conventional therapy limitations. [ABSTRACT FROM AUTHOR]

Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride (TCH) over a metal-free 8-hydroxyquinoline (8-HQ) functionalized carbon nitride (CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth. This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation. [Display omitted]. [ABSTRACT FROM AUTHOR]

The 5‐(4‐aryl azo)‐8‐hydroxyquinolines (L1–L3) and their metal complexes with Ni2+ and Zn2+ have been produced. Various spectroscopic techniques have been employed to analyze the ligand and complexes. The structures of the prepared compounds have been confirmed by Fourier transform infrared (FT‐IR), proton nuclear magnetic resonance (1H NMR), molar conductance, magnetic measurements, thermal gravimetric and differential thermal analyses (TG and DTA), and electronic transition. The FT‐IR spectra showed that the ligands are coordinated to the metal ions in a bidentate manner with donor sites of the azomethine‐N and phenolic‐OH. The FT‐IR and UV–Visible spectra were compared with the calculated results and showed a good agreement. The mass spectra concluded that the ligands' molecular weights and the calculated estimated m/z values match well. The complexes contain coordinated and hydrated water as confirmed by the TG results. The complexes are tetrahedral, trigonal bipyramid, and octahedral geometrical structures and act as non‐electrolytes in dimethylformamide (DMF) solvent. Using density functional theory (DFT) at the B3LYP level of theory and the 6‐311G** basis set for the C, H, N, Cl, and O atoms and the LANL2DZ basis set for the Ni and Zn atoms. Natural bond orbital (NBO) analysis was used to compute and describe the natural charge population and precise electronic configuration. The small energy gap between HOMO and LUMO energies suggests that charge transfer occurs within Ni2+ and Zn2+ complexes. The first‐order hyperpolarizability (β) of the complexes and the anisotropy of polarizability (α) values show promising optical properties. The electronic transitions of the prepared complexes were computed by time‐dependent density functional theory (TD‐DFT/PCM) with the B3LYP method using a 6‐31G** basis set. The ethanol polarizable continuum model (PCM) was used to simulate the solvent effect. Utilizing a computer virtual screening technique through molecular docking, the anticipation of binding of 8‐quinolinolazodye derivatives and their complexes with human CORONA virus protein (PDB ID: 5epw) was done. [ABSTRACT FROM AUTHOR]

Two tetranuclear [Zn4Cl2(ClQ)6]·2DMF (1) and [Zn4Cl2(ClQ)6(H2O)2]·4DMF (2), as well as three dinuclear [Zn2(ClQ)3(HClQ)3]I3 (3), [Zn2(dClQ)2(H2O)6(SO4)] (4) and [Zn2(dBrQ)2(H2O)6(SO4)] (5), complexes (HClQ = 5-chloro-8-hydroxyquinoline, HdClQ = 5,7-dichloro-8-hydroxyquinoline and HdBrQ = 5,7-dibromo-8-hydroxyquinoline) were prepared as possible anticancer or antimicrobial agents and characterized by IR spectroscopy, elemental analysis and single crystal X-ray structure analysis. The stability of the complexes in solution was verified by NMR spectroscopy. Antiproliferative activity and selectivity of the prepared complexes were studied using in vitro MTT assay against the HeLa, A549, MCF-7, MDA-MB-231, HCT116 and Caco-2 cancer cell lines and on the Cos-7 non-cancerous cell line. The most sensitive to the tested complexes was Caco-2 cell line. Among the tested complexes, complex 3 showed the highest cytotoxicity against all cell lines. Unfortunately, all complexes showed only poor selectivity to normal cells, except for complex 5, which showed a certain level of selectivity. Antibacterial potential was observed for complex 5 only. Moreover, the DNA/BSA binding potential of complexes 1–3 was investigated by UV-vis and fluorescence spectroscopic methods. [ABSTRACT FROM AUTHOR]

Cutaneous leishmaniasis exhibits a wide spectrum of clinical manifestations; however, only a limited number of drugs are available and include Glucantime® and amphotericin B, which induce unacceptable side effects in patients, limiting their use. Thus, there is an urgent demand to develop a treatment for leishmaniasis. Recently, it was demonstrated that 8-hydroxyquinoline (8-HQ) showed significant leishmanicidal effects in vitro and in vivo. Based on that, this work aimed to develop a topical formulation containing 8-HQ and assess its activity in experimental cutaneous leishmaniasis. 8-HQ was formulated using a Beeler base at 1 and 2% and showed an emulsion size with a D50 of 25 and 51.3 µm, respectively, with a shear-thinning rheological behaviour. The creams were able to permeate artificial Strat-M membranes and excised porcine skin without causing any morphological changes in the porcine skin or murine skin tested. In BALB/c mice infected with L. (L.) amazonensis, topical treatment with creams containing 1 or 2% of 8-HQ was found to reduce the parasite burden and lesion size compared to infected controls with comparable efficacy to Glucantime® (50 mg/kg) administered at the site of the cutaneous lesion. In the histological section of the skin from infected controls, a diffuse inflammatory infiltrate with many heavily infected macrophages that were associated with areas of necrosis was observed. On the other hand, animals treated with both creams showed only moderate inflammatory infiltrate, characterised by few infected macrophages, while tissue necrosis was not observed. These histological characteristics in topically treated animals were associated with an increase in the amount of IFN-γ and a reduction in IL-4 levels. The topical use of 8-HQ was active in decreasing tissue parasitism and should therefore be considered an interesting alternative directed to the treatment of leishmaniasis, considering that this type of treatment is non-invasive, painless, and, importantly, does not require hospitalisation, improving patient compliance by allowing the treatment to be conducted.

The genus Avicennia contains of 8 species which show a great extent of morphological and genetic variability, which make taxonomy of the genus difficult. Molecular barcoding along with advancement in computational approaches may be proper methods to investigate and assess the efficiency of different molecular genetic regions in Avicennia species delineation and also produce data on species evolution and divergence. The aims of present study were to utilize multiple genetic data for the species delineation and study the phylogeny of the genus. Moreover, we developed a hypothesis on biogeography of these species with respect to barcode divergence. The results showed that both Internal transcribed spacer (ITS) and trnHG–psbA intergenic spacer (trnHG-psbA) sequences may be used in Avicennia species delineation. Barcode gap analysis and nucleotide difference of the studied taxa showed significant Fst for pair-wise species comparison and the role of nucleotide changes in Avicennia speciation.

Due to the high cation exchange capacity, depressed permeability, low cost, and massive specific surface area, bentonite has crucial importance in the disposal of radioactive waste from their aqueous solutions. Here, the intercalation of 8-hydroxyquinoline onto the surface of Na-bentonite was carried out and the obtained material was used to explore the sorption conduct of lanthanides metal ions from their solutions. X-ray fluorescence, X-ray powder diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy spectra were done to characterize unmodified and modified bentonite. The changes in the environmental parameters such as contact time, solution pH, sorbent mass, initial concentration, and temperature were optimized. Sorption isotherm was simulated by Langmuir and Freundlich equations and the outcomes revealed that the Langmuir model was appropriate for the sorption of lanthanides onto 8-hydroxyquinoline bentonite (HQ-bentonite) and the maximum sorption capacities values were found to be 26.1, 47.6, 32.6, 39.2, and 40.9 mg/g for Y3+, Nd3+, Gd3+, Sm3+, and Lu3+, respectively, at 303 K. On the other hand, the regeneration studies were investigated with various reagents. [ABSTRACT FROM AUTHOR]

Multidrug resistance (MDR) in cancer is one of the major obstacles of chemotherapy. We have recently identified a series of 8-hydroxyquinoline Mannich base derivatives with MDR-selective toxicity, however with limited solubility. In this work, a novel 5-nitro-8-hydroxyquinoline-proline hybrid and its Rh(η5-C5Me5) and Ru(η6-p-cymene) complexes with excellent aqueous solubility were developed, characterized, and tested against sensitive and MDR cells. Complex formation of the ligand with essential metal ions was also investigated using UV-visible, circular dichroism, 1H NMR (Zn(II)), and electron paramagnetic resonance (Cu(II)) spectroscopic methods. Formation of mono and bis complexes was found in all cases with versatile coordination modes, while tris complexes were also formed with Fe(II) and Fe(III) ions, revealing the metal binding affinity of the ligand at pH 7.4: Cu(II) > Zn(II) > Fe(II) > Fe(III). The ligand and its Rh(III) complex displayed enhanced cytotoxicity against the resistant MES-SA/Dx5 and Colo320 human cancer cell lines compared to their chemosensitive counterparts. Both organometallic complexes possess high stability in solution, however the Ru(II) complex has lower chloride ion affinity and slower ligand exchange processes, along with the readiness to lose the arene ring that is likely connected to its inactivity. [ABSTRACT FROM AUTHOR]

8-hydroxyquinoline is a plant natural compound, but it can be also obtained by synthesis, with a wide range of applications. An extensive theoretical investigation of 8-hydroxyquinoline, performed by quantum-mechanical modeling, give important information on the physical properties of this molecule. A solvatochromic study of 8-hydroxyquinoline was also performed, the results of which allowed to estimate the contribution of each type of intermolecular interactions to the total spectral shift of the absorption band. Also, the electric dipole moment in the excited state of this molecule was estimated by the variational method and by Abe's model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Small library of 8-hydroxyquinoline (8HQ) was evaluated against M. tuberculosis. • 9 derivatives were active against the mycobacteria. • 5a , 5c , 5d and 5i were active against the mycobacteria and inhibited in vitro Mt InhA. • 7-substituted 8HQ but not the 5-substituted were able to inhibit in vitro Mt InhA. • First report of 8HQ derivatives that inhibit in vitro Mt InhA. The increasing prevalence of drug-resistant Mycobacterium tuberculosis strains stimulates the discovery of new drug candidates. Among them are 8-hydroxyquinoline (8HQ) derivatives that exhibited antimicrobial properties. Unfortunately, there is a lack of data assessing possible targets for this class mainly against Mycobacterium tuberculosis enoyl-acyl carrier protein reductase (Mt InhA), a validated target in this field. Thus, the main purpose of this study was to identify 8HQ derivatives that are active against M. tuberculosis and Mt InhA. Initially, the screening against the microorganism of a small antimicrobial library and its new derivatives that possess some structural similarity with Mt InhA inhibitors identified four 7-substituted-8HQ (series 5 – 5a , 5c , 5d and 5i) and four 5-substituted-8HQ active derivatives (series 7 – 7a , 7c , 7d and 7j). In general, the 7-substituted 8-HQs were more potent and, in the enzymatic assay, were able to inhibit Mt InhA at low micromolar range. However, the 5-substituted-8-HQs that presented antimycobacterial activity were not able to inhibit Mt InhA. These findings indicate the non-promiscuous nature of 8-HQ derivatives and emphasize the significance of selecting appropriate substituents to achieve in vitro enzyme inhibition. Finally, 7-substituted-8HQ series are promising new derivatives for structure-based drug design and further development. [ABSTRACT FROM AUTHOR]

By combining 2-((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L 1) and 8-hydroxyquinoline (L 2), mixed ligand complexes of Ni(II), Co(II), and Mn(II) were synthesized. L 1 's crystal structure was established via single crystal X-ray. Lastly, the MTT assay assessed mixed-ligand complex toxicity to human lung cancer and bronchial epithelial cell lines (A549 and BEAS-2B). [Display omitted] This study focuses on the preparation of mixed ligand complexes of Ni(II), Co(II), and Mn(II) by combining the co-ligands 2-(((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L 1) and 8-hydroxyquinoline (L 2). The chemical structures of the all compounds were examined using various techniques, including 1H and 13C NMR, FT-IR, UV–Vis, TGA, molar conductivity, LC-MS/MS, elemental analysis and magnetic susceptibility. The crystal structure of the ligand L 1 was determined using single crystal X-ray analysis revealing that the ligand favors the phenol-imine tautomeric form in the solid state. All complexes are suggested to have an octahedral structure. Finally, the MTT assay was used to determine the toxicity level of the mixed ligand complexes in human non-small cell lung cancer (A549) and normal bronchial epithelial cell lines (BEAS-2B). The results showed that the [Ni(L 1)(L 2).(H 2 O) 2 ] complex (IC 50 : 5.97 µM) exhibited high cytotoxic activity at a lower dose than cisplatin compared to the other compounds. In contrast, the [Ni(L 1)(L 2).(H 2 O) 2 ] complex was shown to exhibit significantly lower cytotoxic activity (IC 50 > 100 s µM) in the BEAS-2B (normal bronchial epithelial cell) cell line. The other compounds [Co(L 1)(L 2).(H 2 O) 2 ] and [Mn(L 1)(L 2).(H 2 O) 2 ] were shown to have no significant anticancer activity in A549 cells due to their cytotoxic activity at higher doses than cisplatin (IC 50 > 100 s µM). [ABSTRACT FROM AUTHOR]

KP46 (tris(hydroxyquinolinato)gallium(III)) is an experimental, orally administered anticancer drug. Its absorption, delivery to tumours, and mode of action are poorly understood. We aimed to gain insight into these issues using gallium-67 and gallium-68 as radiotracers with SPECT and PET imaging in mice. [67Ga]KP46 and [68Ga]KP46, compared with [68Ga]gallium acetate, were used for logP measurements, in vitro cell uptake studies in A375 melanoma cells, and in vivo imaging in mice bearing A375 tumour xenografts up to 48 h after intravenous (tracer level) and oral (tracer and bulk) administration. 68Ga was more efficiently accumulated in A375 cells in vitro when presented as [68Ga]KP46 than as [68Ga]gallium acetate, but the reverse was observed when intravenously administered in vivo. After oral administration of [68/67Ga]KP46, absorption of 68Ga and 67Ga from the GI tract and delivery to tumours were poor, with the majority excreted in faeces. By 48 h, low but measurable amounts were accumulated in tumours. The distribution in tissues of absorbed radiogallium and octanol extraction of tissues suggested trafficking as free gallium rather than as KP46. We conclude that KP46 likely acts as a slow releaser of gallium ions which are inefficiently absorbed from the GI tract and trafficked to tissues, including tumour and bone.

In this study, the recyclable heterogeneous cluster bud Fe-MOF@Fe3O4 ‘nanoflower’ composite (CB Fe-MOF@Fe3O4 NFC) was successfully synthesized using Fe(NO3)3·9H2O, 8-hydroxyquinoline sulfate monohydrate, and Fe3O4 nanoparticles by microwave irradiation. The as-prepared CB Fe-MOF@Fe3O4 NFC was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrational sampling magnetometry (VSM), and Fourier transform infrared spectroscopy (FTIR). The CB Fe-MOF@Fe3O4 NFC samples proved to have excellent catalytic activity. The activity of the CB Fe-MOF@Fe3O4 NFC nanocatalyst was explored in the synthesis of dihydropyrano[3, 2-c]chromene derivatives via a three-component reaction of 4-hydroxycoumarin, malononitrile, and a wide range of aromatic aldehyde compounds. Optimized reaction conditions had several advantages, including the use of water as a green solvent, environmental compatibility, simple work-up, reusability of the catalyst, low catalyst loading, faster reaction time, and higher yields.

A highly sensitive spectrofluorimetric method is developed for the determination of prucalopride succinate (PRU). The method depends on lanthanide-sensitized luminescence due to complex formation between the drug and terbium chloride (Tb+3) which is enhanced by the addition of 8 hydroxyquinoline (8HQ) and phosphate buffer (0.02 M, pH 3.2). The calibration curve was constructed over the linear range 10–300 ng/mL after excitation at 226 nm and measuring the emission of the ternary complex at 544 nm. The method was validated according to ICH Q2 (R1) guidelines and showed a good recovery ± RSD of 100.41% ± 1.26, the limits of detection and quantitation were found to be 2.81 and 8.53 ng/mL, respectively. The proposed method was successfully applied for the determination of the drug marketed tablet dosage form and the results were in good agreement with the reference method. Also, the method greenness was evaluated according to Complex-GAPI and analytical Eco-Scale. [ABSTRACT FROM AUTHOR]