Search results for " Oxygen"
showing 10 items of 1626 documents
1,4-Naphthoquinones as inducers of oxidative damage and stress signaling in HaCaT human keratinocytes.
2010
Selected biological effects of 1,4-naphthoquinone, menadione (2-methyl-1,4-naphthoquinone) and structurally related quinones from natural sources--the 5-hydroxy-naphthoquinones juglone, plumbagin and the 2-hydroxy-naphthoquinones lawsone and lapachol--were studied in human keratinocytes (HaCaT). 1,4-naphthoquinone and menadione as well as juglone and plumbagin were highly cytotoxic, strongly induced reactive oxygen species (ROS) formation and depleted cellular glutathione. Moreover, they induced oxidative DNA base damage and accumulation of DNA strand breaks, as demonstrated in an alkaline DNA unwinding assay. Neither lawsone nor lapachol (up to 100 microM) were active in any of these assay…
Tryptophan catabolism via kynurenine production in Streptomyces coelicolor: identification of three genes coding for the enzymes of tryptophan to ant…
2011
Most enzymes involved in tryptophan catabolism via kynurenine formation are highly conserved in Prokaryotes and Eukaryotes. In humans, alterations of this pathway have been related to different pathologies mainly involving the central nervous system. In Bacteria, tryptophan and some of its derivates are important antibiotic precursors. Tryptophan degradation via kynurenine formation involves two different pathways: the eukaryotic kynurenine pathway, also recently found in some bacteria, and the tryptophan-to-anthranilate pathway, which is widespread in microorganisms. The latter produces anthranilate using three enzymes also involved in the kynurenine pathway: tryptophan 2,3-dioxygenase (TD…
Laccases: structure, reactions, distribution
2004
Laccases (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductases) are multi-copper proteins that use molecular oxygen to oxidize various aromatic and non-aromatic compounds by a radical-catalyzed reaction mechanism. The enzymes are involved in the pathogenicity, immunity and morphogenesis of organisms and in the metabolic turnover of complex organic substances such as lignin or humic matter. Owing to their high non-specific oxidation capacity, laccases are useful biocatalysts for diverse biotechnological applications. Until recently, laccases were only found in eukaryotes (fungi, higher plants, insects), but now there is strong evidence for their widespread distribution in prokaryotes and the fi…
Effect of phosphatydylcholine on spectral properties and photostability of 3,3′-diethyloxadicarbocyanine iodide (DODCI) — a potent anti-tumor photose…
1998
Abstract The potential anti-tumor photosensitizer 3,3′-diethyloxadicarbocyanine iodide (DODCI) has been immobilized in dimyristoyl phosphatidylcholine (DMPC) vesicles. Binding of the dicarbocyanine to the lipid vesicles induces several changes in the electronic absorption, emission and excitation spectra of the dye. The monomeric dye molecules exist in at least two forms when immobilized in the DMPC liposomes and the non-luminescing H-aggregates of the dye show efficient excitation energy transfer to the DODCI monomers. Entrapment of the dye in the liposomes generally decreases the photostability of DODCI. While emission from singlet oxygen (1O2) has not been recorded, indirect results sugg…
Synthesis and characterization of NdNiO3 prepared by low temperature methods
1992
Abstract NdNiO3 has been prepared with an orthorhombic perovskite structure by a low temperature and low oxygen pressure method starting from a nickel(III) oxide precursor, β-NiO(OH). The compound LaNiO3 has also been obtained by this method. This chemical-precursor-based synthesis overcomes problems related to the use of high oxygen pressures in the synthesis.
p38 MAPK: A dual role in hepatocyte proliferation through reactive oxygen species
2013
p38 MAPKs are important mediators of signal transduction that respond to a wide range of extracellular stressors such as UV radiation, osmotic shock, hypoxia, pro-inflammatory cytokines, and oxidative stress. The most abundant family member is p38α, which helps to couple cell proliferation and growth in response to certain damaging stimuli. In fact, increased proliferation and impaired differentiation are hallmarks of p38α-deficient cells. It has been reported that reactive oxygen species (ROS) play a critical role in cytokine-induced p38α activation. Under physiological conditions, p38α can function as a mediator of ROS signaling and either activate or suppress cell cycle progression depen…
0152 : Effects of connexin 43 inhibition on mitochondrial function in cardiac skinned fibers and isolated mitochondria
2015
Connexin 43 (Cx43) is a main component of intercellular gap junction channels in cardiomyocytes. The presence of Cx43 in heart mitochondria has been also reported, where it may participate in energy metabolism and protection against ischemia. Given the key role for mitochondria in pathogenesis of heart diseases, we examined how mitochondrial function could be altered in case of Cx43 pharmacological inhibition by carbenoxolone (CBX). Oxygen consumption rates under various substrate conditions were determined either in ventricles from pig hearts using saponin-permeabilized fibers, or in isolated mitochondria from rat hearts. Measurements of mitochondrial membrane potential (ΔΨ) and reactive o…
Influence of solvents on the antioxidant property of flavonoids.
2003
In polyphenols redox systems, the solvent plays a fundamental role in the chemical behaviour of these compounds. Antioxidants can react in different ways with the prooxidant molecules. We have found differences in the antioxidant capacity of flavonoids such as naringin, neohesperidin, neoericitrin, hesperidin, narirutin didymin and the related flavones naringenin, hesperetin eriodictyol and isosakuratenin, when they are in the presence of radicals and solved in water or in an alcohol mixture.
Sildenafil protects human mammary epithelial cells against ROS production induced by estradiol
2010
Several studies suggest that xanthine dehydrogenase (XDH) and its oxidase form (XO) play an important role in various types of ischemic and vascular injuries. Recently, we have demonstrated that estradiol (E2) induces a significant decrease of the expression and activity of XDH and of its conversion to XO in human mammary epithelial cells. E2 is known to induce upregulation of eNOS gene expression in aortic endothelial cells. Because the XO-derived O2·- combines with ·NO to yield ONOO-, and considering that ONOO- converts XDH to XO, the resulting increase of XO activity and reactive oxygen species production would eventually lead to a further increase of ONOO- production, thus creating a vi…
Water-soluble hyperbranched polyglycerol photosensitizer for enhanced photodynamic therapy
2020
Porphyrin and its derivatives as promising photosensitizers have been widely utilized in photodynamic therapy (PDT). However, the water-solubility and biocompatibility of porphyrins are the typical bottlenecks in clinical PDT processes. Herein, we successfully fabricated a new type of water-soluble, hyperbranched polyglycerol photosensitizer through one-step esterification between water-soluble hyperbranched polyglycerol (hbPG) and fluorophenylporphyrin (FP). Compared with the linear control polymer, i.e., FP covalently connected with linear polyethylene glycol (LPEG), the hyperbranched structures bearing multiple porphyrin units generated more singlet oxygen and exhibited higher cytotoxici…