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81.
82.
Jantová S Koňariková K Letašiová S Paulovičová E Milata V Brezová V 《Journal of photochemistry and photobiology. B, Biology》2011,102(1):77-91
The present study demonstrates photoinduced generation of superoxide radical anion and singlet oxygen upon UVA irradiation of ethyl 1,4-dihydro-8-nitro-4-oxoquinoline-3-carboxylate (DNQC), and its cytotoxic/phototoxic effects on murine leukemia L1210 cells. The formation of reactive oxygen species (ROS) was investigated by EPR spectroscopy using in situ spin trapping technique and 4-hydroxy-2,2,6,6-piperidine (TMP) for singlet oxygen ((1)O(2)) detection. The EPR spectra monitored upon photoexcitation of aerated solutions of DNQC in dimethylsulfoxide evidenced the efficient activation of molecular oxygen via Types I and II mechanisms. The cytotoxic/phototoxic effects of DNQC, analysis of cell cycle, induction of apoptosis/necrosis, DNA damage and molecular mechanism of apoptotic death of L1210 cells in dark and in the presence of UVA irradiation were compared. DNQC induced a different cytotoxic/phototoxic effect, which was concentration- and time-dependent. The four highest tested concentrations of non-photoactivated and photoactivated DNQC induced immediate cytotoxic/phototoxic effect after 24h cultivation of L1210 cells. This effect decreased with the time of treatment. The irradiation increased the sensitivity of leukemia cell line on DNQC, but the cell sensitivity decreased with time of processing. Quinolone derivative DNQC significantly induced direct DNA strand breaks in L1210 cells, which were increased with the irradiation of cells. The DNA damage generated by DNQC alone/with combination of UVA irradiation induced cell arrest in G(0)/G(1) and G(2)/M phases, decrease in the number of L1210 cells in Sphase and apoptotic cell death of certain part of cell population after 24 h of influence. DNQC alone/with combination of UVA irradiation induced apoptosis in L1210 cells through ROS-dependent mitochondrial pathway. 相似文献
83.
The present work illustrates the potential of the capillary zone electrophoresis (CZE) separation technique coupled with the
on-capillary diode array detector (DAD) for highly reliable determination of curcuminoids (curcumin, CUR, demethoxycurcumin,
DCUR, and bisdemethoxycurcumin, BCUR) in substances (commercially available plant extract) and pharmaceutical preparation
(commercial pharmaceutical capsules) with minimal sample preparation; (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) was chosen for an anionic separation of CUR and its structural analogues (DCUR and BCUR) as an appropriate complexing
agent (i) providing complete resolution of the curcuminoids and (ii) reducing adsorption of these hydrophobic analytes onto
the capillary wall. DAD detection was utilised for characterisation of the composition of the separated zones via differences
in the corresponding UV-VIS spectra (scanned at interval of 200–800 nm). Reference and real spectra of the analytes demonstrated
that the proposed separation method was sufficiently selective to produce well-separated (i.e. spectrally homogeneous) analyte
zones with no interfering compounds present. Successful validation and application of the CZE-DAD method proposed here suggest
its routine use in highly effective and reliable analysis of curcuminoids in pharmaceutical samples. 相似文献
84.
Katarína Maráková Juraj Piešt'anský Lucia Veizerová Jaroslav Galba Svetlana Dokupilová Emil Havránek Peter Mikuš 《Journal of separation science》2013,36(11):1805-1816
The present work illustrates potentialities of CE hyphenated with MS/MS for the simultaneous determination and identification of a mixture of simultaneously acting drugs in pharmaceutical and biological matrices. Here, the hyphenation was provided by ESI interface, while the MS/MS technique was based on the triple quadrupole configuration. Three drugs, namely pheniramine, phenylephrine, and paracetamol were determined and identified with high reliability due to their characterization in three different dimensions, i.e. electrophoresis and MS/MS, that prevented practically any interference. Appropriately selected transitions of the analytes (parent ion‐quantifier product ion‐qualifier product ion) provided their selective determination at maximum S/N. The proposed CE‐MS/MS method was validated (LOD/LOQ, linearity, precision, recovery, accuracy) and applied for (i) the multidrug composition pharmaceuticals, namely Theraflu®, and (ii) human urine taken after per‐oral administration of the same pharmaceutical preparation. The method was applied also for the investigation of potential weak associates of the drugs and monitoring of predicted (bio)degradation products of the drugs. Successful validation and application of the proposed method suggest its routine use in highly effective and reliable advanced drug control and biomedical research. 相似文献
85.
Aqueous solutions of ascorbic acid in unsupported and supported aqueous solutions and real samples were studied by the kinetics-sensitive double-step voltcoulommetric method with the aim to contribute to a better understanding of its behavior in biological systems. The data obtained from measurements made on analytes prepared in the laboratory, as well as those made on real samples (some commercial orange drinks, flash of the fresh fruits) point to the redox reaction of L-ascorbic acid (L-AH2) being very sensitive to both the presence of dissolved gaseous species (O2, CO2) and the ionic strenght in the analyte. Either the dissolved gaseous species, or the higher ionic strength caused by both the presence of supporting electrolyte and increased total concentration of ascorbic acid, respectively, give birth to the degradation of L-AH2. Naturally, the highest percentage of L-AH2 was spotted in fresh fruit. 相似文献
86.
Pagáčová Jana Plško Alfonz Papučová Iveta Faturíková Katarína Prnová Anna Valuchová Jana Ondrušová Darina 《Journal of Thermal Analysis and Calorimetry》2020,142(5):1643-1648
Journal of Thermal Analysis and Calorimetry - For utilization of TiO2 in advanced applications, TiO2 after thermal treatment has to be in crystalline phase of anatase, because it gives the desired... 相似文献
87.
Peter Mikuš Lucia Veizerová Juraj Piešťanský Katarína Maráková Emil Havránek 《Electrophoresis》2013,34(8):1223-1231
An analytical method, based on a column coupling capillary ITP and CZE in a hydrodynamically closed separation mode hyphenated with the detection in the modular arrangement, was developed in this work. Analytical possibilities of this approach are demonstrated on the direct and ultrasensitive quantitative determination of quinine (QUI) in diluted real multicomponent ionic matrices (beverages, urine). The detection cell interface, with the rectangular arrangement of the optical channels inside, connected the separation capillary with the LIF detector via optical fibers in the on‐column detection arrangement. ITP enabled the direct large volume (30 μL) injections of the diluted real matrices with an on‐line sample pretreatment (preseparation, preconcentration) so that no external sample preparation (except for the dilution) was necessary for the separation of the analyte in the multicomponent ionic matrices. Due to the ITP sample preconcentration and intrinsic sensitivity of the LIF detection, very low concentration LOD (as low as 77 pg/mL), were reached at the same time. This was ca. two orders lower than the corresponding LOD achieved by the same 2D separation system with UV absorbance detection. Compared to the single column CE‐LIF methods applied for this model analyte and matrix, this method was found to be superior in terms of concentration LOD, with acceptable selectivity and benefits of the on‐line sample preparation. A food control and bioanalytical application clearly illustrates great practical possibilities and routine use of the proposed modular ITP–CZE–LIF technique. 相似文献
88.
Martin Weis Katarína Gmucová Vojtech Nádaždy Ignác Capek Alexander Šatka Martin Kopáni Július Cirák Eva Majková 《Electroanalysis》2007,19(12):1323-1326
Sequential single‐electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir‐Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film (a‐Si:H) is reported. Quantized double‐layer charging of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the excess of negative/positive charged defect states in the a‐Si:H layer. The particular charge states in a‐Si:H are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. 相似文献
89.
Katarína Makovínyiová 《Nonlinear Analysis: Real World Applications》2011,12(2):1213-1222
In this paper we analyze a macroeconomic model derived from Schinasi’s model of a closed economy. Rigorous analysis of the existence and stability of the equilibrium is carried out. We present a formula for the calculation of the focus constant in the bifurcation equation of the model. Thereafter we prove the existence and stability of business cycles by application of the Hopf bifurcation theorem. Finally, we give an example of a model with a stable business cycle and its graphical illustrations. 相似文献
90.
Lenka Findoráková Katarína Győryová Marian Koman Jan Moncol Milan Melník 《Journal of chemical crystallography》2010,40(2):145-150