Results 1 - 10 of 1834
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[en] Diverse flavonoid compounds are widely distributed in angiosperm families. Flavonoids absorb radiation in the ultraviolet (UV) region of the spectrum, and it has been proposed that these compounds function as UV filters. We demonstrate that the DNA in Zea mays plants that contain flavonoids (primarily anthocyanins) is protected from the induction of damage caused by UV radiation relative to the DNA in plants that are genetically deficient in these compounds. DNA damage was measured with a sensitive and simple assay using individual monoclonal antibodies, one specific for cyclobutane pyrimidine dimer damage and the other specific for pyrimidine(6,4)pyrimidone damage. (author)
[en] A series of 2',3'-dideoxy-3'-fluoro-D-apiosyl nucleosides 15, 16, 17 and 18 were synthesized enantiomerically with L-Gulonic-γ-lactone as the starting material. The reduction of butenolide 1 with DIBAL-H followed by the Luche procedure afforded the allylic alcohol 2. Ozonolysis and the reduction of compound 4 induced the cyclized lactol, which was acetylated to give the acetate 7. Condensation of the acetate 7 with silylated pyrimidine (N4-benzoyl cytosine) and a purine base (6-chloropurine) under Vorbruggen conditions and deblocking afforded a series of fluorinated apiosyl nucleosides
[en] Full text: The increase of ultraviolet radiation reaching the earth's surface, caused by the depletion of the stratospheric ozone layer shows the importance of investigating the effects of UV-induced DNA damage. DNA is very sensitive to UV radiation since the absorption maximum of DNA is in the UV region. UV-radiation is known to induce mutagenic and cytotoxic DNA lesions: e.g. the cyclobutane -pyrimidine dimers. DNA damage is then also induced by secondary processes which occur after irradiation, their nature is either physical or chemical. Among them the action by low energy electrons turned out be highly relevant. This secondary species interact with molecules by DEA (Dissociative Electron Attachment). Here we study DEA to a 1,2-dimethylcyclobutane pyrimidine dimer methylated at the nitrogen atoms. The apparatus used for the presented measurements is a crossed electron/molecule beams-instrument consisting of a neutral molecular beam source, a Nier-type ion source and a double-focusing two sector instrument in reverse BE-geometry with high sensitivity. The electron attachment measurements show a surprising fragmentation pattern at electron energies only slightly above 0 eV. The mass spectra reveal that the highest anion fragment is mass 139 which corresponds to a symmetric cleavage minus one methyl group. This fragmentation pattern which reminds of fragmentation patterns of explosives like TNT could perhaps be one reason for the DNA damage caused by these molecules. (author)
[en] The review is dedicated to discussing the literature data and our own research results regarding the synthesis and biological activity (in particular, antitumor, antimicrobial, antifungal, antiviral, anti-inflammatory, anticonvulsant, etc.) of pyrazolo[1,5- a]pyrimidines. Schemes and methods for the synthesis of various derivatives containing substituents in both the pyrazole and pyrimidine rings are presented, as well as their effect on individual receptors and biological activity. The review provides insights into the study of organic dyes and other substances of the pyrazolo[1,5-a]pyrimidine series, which have been studied as tumor imaging agents. The review presents an original method for the preparation of polysubstituted pyrazolo[1,5-a]pyrimidines by recycling 2-alkylpyrimidinium salts. The reaction of 4,6-dimethylpyrimidinyl-2-acetic acid ethyl ester iodomethylate with carboxylic acid hydrazides leads to the formation of pyrazolo[1,5-a]pyrimidines. In this transformation, the triatomic fragment C-N-N of the hydrazide is included in the pyrazolopyrimidine molecule, and the nitrogen atom of the N-alkyl group is eliminated from the pyrimidine ring
[en] Ultraviolet (UV) radiation in sunlight can result in DNA damage and an inflammatory reaction of the skin commonly known as sunburn, which in turn can lead to cutaneous tissue disorders. However, little has been known about how UV-induced DNA damage mediates the release of inflammatory mediators from keratinocytes. Here, we show that UVB radiation intensity-dependently increases NLRP3 gene expression and IL-1β production in human keratinocytes. Knockdown of NLRP3 with siRNA suppresses UVB-induced production of not only IL-1β, but also other inflammatory mediators, including IL-1α, IL-6, TNF-α, and PGE_2. In addition, inhibition of DNA damage repair by knockdown of XPA, which is a major component of the nucleotide excision repair system, causes accumulation of cyclobutane pyrimidine dimer (CPD) and activation of NLRP3 inflammasome. In vivo immunofluorescence analysis confirmed that NLRP3 expression is also elevated in UV-irradiated human epidermis. Overall, our findings indicate that UVB-induced DNA damage initiates NLRP3 inflammasome activation, leading to release of various inflammatory mediators from human keratinocytes. - Highlights: • UVB radiation induces NLRP3 inflammasome activation in human keratinocytes. • NLRP3 knockdown suppresses production of UVB-induced inflammatory mediators. • UVB-induced DNA damage triggers NLRP3 inflammasome activation. • NLRP3 expression in human epidermis is elevated in response to UV radiation.
[en] The published data on the Biginelli reaction are generalised and systematised. The major attention is focused on the publications of the last seven years. Possible reaction mechanisms and its application for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives are considered. Examples of rare versions of this reaction are given.
[en] Present article is devoted to scientific activity of Professor M.A. Kukaniev. The main areas of activity of scientist were: synthesis of sulphur containing heterocyclic compounds; synthesis of active biological preparations containing in their cycle nitrogen, sulphur and other elements; chemistry of natural compounds.
[en] A series of novel oxacalixarenepyrimidine derivatives were synthesized, and their antitumor activities against HeLa, MCF7, HepG2, and A549 human cancer cell lines were evaluated using an MTT assay. Some of the synthesized compounds exhibited considerable anti-proliferative activity against the human cancer cell lines. Compound 5l, which contains an ethanolamine moiety, exhibited the strongest inhibitory activity against HepG2 with an IC50 value of 12.37 μM. Moreover, a cell apoptosis assay indicated that the anti-proliferative activity of 5l might be attributed to its induction of apoptosis. Our report highlights the potential anticancer efficacy of novel oxacalixarenepyrimidines.