Results 1 - 10 of 19579
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[en] This study aims to examine the antioxidant effects of some Mannich bases containing bis-1, 2, 4 triazole, which are synthesized afresh. The antioxidant activities of the derivatives were measured using different methods in this study, including reducing power capacity, metal chelating activity, superoxide anion radicals scavenging activity, H/sub 2/ O/sub 2/ scavenging activity and hydroxyl radical scavenging. As a result, derivatives had efficient antioxidant and free radical scavenging activity when compared to ascorbic acid, BHT and alpha-tocopherol as associated antioxidants. (author)
[en] The mechanism of enhanced radiosensitization by nitroheterocyclics after a preincubation period under hypoxic conditions was investigated. The hypothesis that this phenomenon was caused by glutathione depletion was tested. The phenomena of enhanced radiosensitization by nitroheterocyclics after a preincubation period under hypoxic conditions is potentially of importance therapeutically because essentially nonlethal preradiation exposures to the electron affinic drugs cause a much larger radiation sensitization than would otherwise be expected. We have investigated this interesting property of several 2-nitroimidazoles to determine its possible cause and to test various hypotheses about maximizing its possible therapeutic benefit. In view of many observations that thiols are depleted by incubation of cells with nitroimidazoles under hypoxic conditions, we have specifically investigated this aspect of the preincubation effect. Depletion of glutathione was either enhanced by an overnight incubation with buthionine sulfoximine or minimized by preincubation with a 2-nitroimidazole which is sterically inhibited from causing thiol depletion. When conditions were chosen which minimized variations in cellular glutathione content during the preincubation period, no preincubation effect was observed. At low, therapeutically relevant radiation doses, where 2-nitroimidazoles are less efficient sensitizers, the preincubation effect may be even more important, but thiol depletion still minimizes its impact in this region of the dose-response curve. These results suggest that the preincubation effect is caused by a open-quotes self-sensitizationclose quotes involving the known enhancement of radiation sensitization by thiol depletion. 16 refs., 5 figs
[en] The data on the synthesis, structures and chemical properties of pyrido- and pyrimidoisoindole derivatives with an azine ring annelated to a pyrrole ring, which have been published over the last two decades, are generalised. The structure of the π-electron system and the high reactivities of azinoisoindoles are discussed. Special attention is given to aromatic pyrido- and pyrimidoisoindoles.
[en] Data on the synthetic routes to substituted 1,2,3-triazoles, including those containing functional groups, based on cyclisation of various nitrogen compounds published during the last 15 years are described. Examples of using new triazole derivatives in agrochemistry, medicine and engineering are given.
[en] Results are presented which demonstrate that the sensitising effects of two nitroimidazole radio-sensitisers are additive, and that the cellular uptake of the combined compounds is not significantly different from that for each compound alone, using Chinese hamster V79 37 A cells. (author)
[en] For targeted synthesis of new biologically active compounds among 1,2,4-triazole derivatives a preparative procedure of synthesis was elaborated and derivatives of 3-mercapto-4-amino-5-aryl-1,2,4-triazole-4 H were obtained. By Paal-Knorr reaction the modification of the amino group in the first position into the pyrrole ring was carried out. Prognosis of pharmacological activity allowed to plan screening of synthesized compounds as potential central nervous system agents. (author)
[en] DFT calculations have been carried out on 6,6-dimethyl-7-nitroso-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine concerning energies, absolute shieldings (GIAO) and moleculargraphs (AIM) to determine the molecular structureof the compound (tautomerism and conformation of thenitroso group). (Author)
[en] A series of new polymers containing 1,2,3-triazoles were synthesized and their structures and properties were characterized by FT-IR, "1H NMR, TGA, DSC and GPC. The results showed that the polymers modified by alkyl groups had good solubility, thermal stability and reasonable molecular weights. It was also demonstrated that the properties of fluorine-containing polymers were seriously affected by fluorine atoms with hydrophobic and chemical proof properties
[en] Published data on the synthesis, structure, properties and applications of metal derivatives of tetrazoles are generalised and described systematically. Compounds based on the anionic and neutral tetrazole forms, C- and N-mono- and C,N-disubstituted tetrazoles are considered.
[en] We fabricated an IMI-O polymer containing an imidazole group that could form a complex structure between the monolayer and the metal ions at the air-water interface. Also, the monolayer behavior at the air-water interface and the electrical properties of metal-complexed Langmuir-Blodgett (LB) films were investigated by using Brewster angle microscopy (BAM) and current-voltage(I-V) measurements. The difference in the BAM images between the pure water and the aqueous metal ions is attributed to the interactions of the copolymers with the metal ions at the interface and the consequent change of the monolayer organization. In the I-V characteristics, the current for LB films with different metal ion depended on the quantity of the metal-ion complexed with the LB film due to the interaction between the metal ion and the IMI-O polymer