Monatshefte Fur Chemie最新文献

Abstract: We have investigated the photo-induced reduction of Cu²⁺-Cu⁰ using benzil/triethylamine mixtures. The formation of elemental Cu is indicated by the appearance of its characteristic plasmon absorption peaks at 515 nm and 620 nm. Importantly, the nature of the counterion of the Cu²⁺ salt affects the reduction process. In the presence of Cl^-, the reduction proceeds faster than with SO₄^2-. Photo-induced electron transfer between excited benzil and triethylamine leads to the benzil radical anion, which acts as the reducing agent for Cu²⁺ and generates Cu⁰.

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Abstract: We report the chemical synthesis and characterization of the stable 5,15-bis(pentafluorophenyl)-10-(trimethylsilylethynyl)corrole which serves as a precursor for the subsequent in situ sila-Sonogashira-cross-coupling reaction and metalation with copper(II) acetate. Under ambient conditions and a common catalyst system the reaction with 1-iodopyrene occurred within five hours. Due to the direct conjugation of the 18π-electronic system of the corrole macrocycle over the alkynyl group to the pyrene moiety the optical transitions in the Soret (B-) band Q-band region are significantly altered. The copper corrole exhibited complex hyperfine and superhyperfine structure in the EPR spectrum. The assignment of the EPR spectrum reveals the existence of an axial [CuII-cor^∙+] species.

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Abstract: A new series of 2-alkylthio-N-(quinazolin-2-yl)benzenesulfonamide derivatives have been synthesized and evaluated in vitro for their antiproliferative activity by MTT assay against cancer cell lines HCT-116, MCF-7, and HeLa as well as the NCI-60 human tumor cell lines screen. In NCI screen, three compounds inhibited approximately 50% growth of RPMI-8226 and A549/ATCC cell lines. The mean of IC₅₀ calculated in MTT assays for three tested cell lines was about 45 μM for four compounds. The QSAR allowed finding statistically significant OPLS models for HeLa cell line. Metabolic stability in vitro studies indicated favorable and unfavorable structural elements. The good metabolic stability, with t_1/2 higher than 40 min, was observed for three derivatives, which together with their antiproliferative activity and good ADMET profile, makes them good leading structures for further research.

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Abstract: A hydrazone Schiff base ligand was synthesized by the condensation of 3-formyl-4-hydroxycoumarin and oxalyldihydrazide in the molar ratio 2:1. The Schiff base ligand acts as a mono-, bi-, tri- or even tetradentate ligand with metal cations in the molar ratios 1:1 or 2:1 (M:L) to yield either mono- or binuclear complexes as keto or enol isomers, where M = Co(II), Ni(II), Cu(II), VO(IV), and Fe(III). The ligand and its metal complexes were characterized by elemental analyses, IR, ¹H NMR, mass, and UV-Vis spectroscopy. Furthermore, the magnetic moments were calculated from the measured electric conductivities of the complexes. According to the received data, the dihydrazone ligand contains one or two units of ONO domains and can bind to the metal ions via the azomethine nitrogen, the carbonyl oxygen atoms, and/or the phenolic oxygen atoms. Electronic spectra and the magnetic moments of all complexes show that the complexes' geometries are either octahedral, tetrahedral, square planar, or square pyramidal. Cyclic voltammograms of the mononuclear Co(II) and Ni(II) complexes show quasi-reversible peaks. Tests against two pathogenic bacteria as Gram-positive and Gram-negative bacteria for both, the Schiff base ligand and its metal complexes were carried out. In addition, also one kind of fungi was tested. The synthesized complexes demonstrate mild antibacterial and antifungal activities against these organisms.

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Abstract: The series of new hydrazide derivatives were synthesized in reactions of N³-substituted amidrazones with cyclic anhydrides as potential anti-inflammatory and antibacterial agents. The compounds were characterized by ¹H-¹³C two-dimensional NMR techniques, which revealed the presence of two tautomeric forms in DMSO-d₆ solutions, while the molecular structure of one species was confirmed by single-crystal X-ray diffraction. The anti-inflammatory effects of hydrazides on peripheral blood mononuclear cells were experimentally evaluated. Three compounds showed antiproliferative activity comparable to ibuprofen. One derivative demonstrated strong reduction of lymphocyte proliferation stimulated by anti-CD3 antibody (by 90%) and PHA, as well as low cell toxicity. The obtained compounds exhibited relatively weak antibacterial activity; they were more effective against Gram-positive bacterial strains.

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Abstract: The measurements of double-layer differential capacitance, zero charge potential, and surface tension at that potential allowed us to examine the adsorption properties of adenine on the mercury surface from the neat buffer solution, i.e., the acetate buffer at pH 5 and pH 6. The systems obtained at such pH values were close to physiological fluids in their characteristics. The adsorption energy and interaction constants were determined using Frumkin isotherm and virial isotherm. It was shown that the adenine molecule is adsorbed on the mercury electrode with its negative pole against the electrode surface. Using the cyclic voltammetry technique and measuring Faraday impedance, an increasing effect of adenine on the kinetics of zinc ion electroreduction was found. In both buffer solutions, the neutral adenine molecules can form on the surface of the working electrode, an unstable active complex with depolarizer ions, facilitating electron exchange.

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Abstract: A regioselective synthesis of pyridines by the addition of malonate anions to pyridine N-oxide derivatives, which have been activated by trifluoromethanesulfonic anhydride, is reported. The reaction selectively affords either 2- or 4-substituted pyridines in good yields.

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Abstract: Tablets are often used in splitting process when the appropriated, registered dose is not available on the market or patients exhibit swallowing difficulties caused by the size of the tablet. The aim of the work was to assess the impact of physical division of tablets on the kinetics of in vitro gliclazide release from the intact and divided tablets. Gliclazide was released from prolonged release tablets containing 30 or 60 mg of the drug into a phosphate buffer, pH 7.4 and the amount of the drug in acceptor fluid was determined by UV-Vis spectrophotometry. The dissolution profiles were fit to zero- and first-order kinetics as well as to the Korsmeyer-Peppas equation. The largest discrepancy in the values of rate constants was obtained in the case of the release of gliclazide from intact and from splitting tablets using zero- and first-order kinetics. The values of the rate constants k₀ obtained from the release of the drug from the intact tablets and from fragments with a dose of the drug of 30 mg were (4.2 ± 0.1) × 10^-5 g min^-1 and (5.8 ± 0.1) × 10^-5 g min^-1, respectively, and k₁ were (2.3 ± 0.1) × 10^-3 min^-1 and (4.7 ± 0.6) × 10^-3 min^-1, respectively. These discrepancies were confirmed by the value of f₂ coefficient that was 45.9. The results suggest that physical division of tablets accelerate the release of gliclazide from its prolonged form.

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Abstract: Commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes. It naturally occurs in plant seeds as cyanogenic glycosides. Another relatively common mode of cyanide exposure is inhalation of environmental tobacco smoke. This study concerns importance to determine cyanide ion in human biological samples. Urine and saliva samples were collected healthy volunteers exposed to tobacco smoke (active smokers) and environmental tobacco smoke (passive smokers). Chromatographic separation was achieved with an anion-exchange column and separated ions were detected by a pulsed amperometric detector. The method produced linear response in a specific concentration range of cyanide ion. The limit of detection was estimated at 0.1  and 0.5 µg/dm³ for urine and saliva samples, respectively. Cyanide ion concentrations in samples ranged from not detected (below LOD) to 12.88 µg/dm³. The comparison of results of biological samples analyses shows an increasing trend in cyanide concentration that may suggest that environmental tobacco smoke might have an impact on human health.

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Abstract: Mass methanol poisonings present a serious problem for health systems worldwide, with poor outcome associated with delayed treatment. Positive pre-hospital serum ethanol concentration may have predictive value as the prognostic factor of the treatment outcome. We studied the effect of positive serum ethanol level on admission to hospital on survival in patients treated during the Czech methanol outbreak during 2012-2014. Cross-sectional cohort study was performed in 100 hospitalized patients with confirmed methanol poisoning. Pre-hospital ethanol was administered in 42 patients (by paramedic/medical staff to 30 patients and self-administered by 12 patients before admission); 58 patients did not receive pre-hospital ethanol. Forty-two patients had detectable serum ethanol concentration on admission to hospital [median 18.3 (IQR 6.6-32.2) mmol dm^-3]. Pre-hospital ethanol administration by paramedic/medical staff had a significant effect on survival without visual and CNS sequelae when adjusted for arterial blood pH on admission (OR 8.73; 95 % CI 3.57-21.34; p < 0.001). No patients receiving pre-hospital ethanol died compared with 21 not receiving (p < 0.001). Positive serum ethanol concentration on admission to hospital was a predictor for survival without health sequelae when adjusted for arterial blood pH (OR 8.10; 95 % CI 2.85-23.02; p < 0.001). The probability of visual and CNS sequelae in survivors reduced with increasing serum ethanol concentration on admission.

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