Search results for "Free Radical"
showing 10 items of 263 documents
Interplay of oxidants and antioxidants during exercise: Implications for muscle health
2010
Muscle contraction results in generation of reactive oxygen and nitrogen species (RONS) at a rate determined by the intensity, frequency, and duration of the exercise protocols. Strenuous exercise causes oxidation of protein, lipid, and DNA, release of cytosolic enzymes, and other signs of cell damage; however, only exhaustive exercise is detrimental. Indeed, the regulation of vascular tone, the excitation-contraction coupling, growth, and differentiation in skeletal muscle, are governed in part by RONS. This is accomplished by RONS interaction with redox-sensitive transcription factors, leading to increased gene expression of antioxidant enzymes, cytoprotective proteins, and other enzymes …
Anandamide-induced apoptosis in Chang liver cells involves ceramide and JNK/AP-1 pathway
2006
In the present study we demonstrate that anandamide, the most important endogenous cannabinoid, markedly induced apoptosis in Chang liver cells, an immortalized non-tumor cell line derived from normal liver tissue, while it induced only modest effects in a number of hepatoma cell lines. The apoptotic effect was reduced by methyl-beta-cyclodextrin, a membrane cholesterol depletor, suggesting an interaction between anandamide and the membrane microdomains named lipid rafts. Anandamide effects were mediated by the production of ceramide, as demonstrated by experiments performed with the sphingomyelinase inhibitor, desipramine, or with the sphingomyelinase activator, melittin. This conclusion w…
Synthesis and pharmacological evaluation of 2'-hydroxychalcones and flavones as inhibitors of inflammatory mediators generation.
1995
2'-Hydroxy-3,4-dimethoxy-3',4'-dimethylchalcone (3a), 2'-hydroxy-3',4',3,4-tetramethoxychalcone (3b), and their corresponding flavones, 3',4'-dimethoxy-7,8-dimethylflavone (4a) and 3',4',7,8-tetramethoxyflavone (4b), were prepared from 3,4-dimethoxycinnamic acid and the respective phenol. The four compounds inhibited enzymic lipid peroxidation and showed weak peroxyl scavenging activity. They also reduced LTB 4 release from human neutrophils stimulated by A23187. The chalcone 3b was the only compound able to inhibit in a concentration-dependent way, synovial human recombinant phospholipase A 2 activity, human platelet TXB 2 generation, and human neutrophil degranulation. This chalcone exert…
Inhibitory effects of N-acetylcysteine on the functional responses of human eosinophils in vitro
2007
Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N-acetyl-L-cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow c…
Accessibility of Protein-Bound Chlorophylls Probed by Dynamic Electron Polarization
2018
The possibility to probe the accessibility of sites of proteins represents an important point to explore their interactions with specific substrates in solution. The dynamic electron polarization of nitroxide radicals induced by excited triplet states of organic molecules is a phenomenon that is known to occur in aqueous solutions. The interaction within the radical-triplet pair causes a net emissive dynamic electron polarization of the nitroxide radical, that can be detected by means of time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy. We have exploited this effect to prove the accessibility of chlorophylls bound to a protein, namely, the water-soluble chlorophyll protei…
Bioactive Constituents of Juniperus turbinata Guss. from La Maddalena Archipelago.
2018
A comprehensive phytochemical study of Juniperus turbinata (Cupressaceae) collected from La Maddalena Archipelago (Sardinia, Italy) is reported. Both the essential oil and the ethanolic extract obtained from the aerial parts were analyzed. The essential oil appears to belong to a new chemotype compared to other Mediterranean juniper accessions, as it was favored by geographic isolation of the isles. It showed a low content of monoterpene hydrocarbons and -terpineol, ent-manoyl oxide, 1,10-di-epi-cubenol as the major constituents. The ethanolic fraction contained mainly diterpenoids. Among these, 15-formyloxyimbricatolic acid (7) is a new natural product since it has hitherto been obtained o…
DNA damage by peroxynitrite characterized with DNA repair enzymes.
1996
The DNA damage induced by peroxynitrite in isolated bacteriophage PM2 DNA was characterized by means of several repair enzymes with defined substrate specificities. Similar results were obtained with peroxynitrite itself and with 3-morpholinosydnonimine (SIN-1), a compound generating the precursors of peroxynitrite, nitric oxide and superoxide. A high number of base modifications sensitive to Fpg protein which, according to HPLC analysis, were mostly 8-hydroxyguanine residues, and half as many single-strand breaks were observed, while the numbers of oxidized pyrimidines (sensitive to endonuclease III) and of sites of base loss (sensitive to exonuclease III or T4 endonuclease V) were relativ…
Histone carbonylation occurs in proliferating cells
2012
12 páginas, 10 figuras (que no es encuentran en este documento, se pueden ver en: http://www.sciencedirect.com/science/article/pii/S0891584912000664)
Isolation and identification of new anthraquinones from Rhamnus alaternus L and evaluation of their free radical scavenging activity
2018
From the butanolic and the ethyl acetate extracts of Rhamnus alaternus L root bark and leaves, three new anthraquinone glycosides, alaternosides A-C (1,4,6,8 tetrahydroxy-3 methyl anthraquinone 1-O-ß-D-glucopyranosyl-4,6-di-O-α-L-rhamnopyranoside (1); 1,2,6,8 tetrahydroxy-3 methyl anthraquinone 8-O-ß-D-glucopyranoside (2) and 1, 6 dihydroxy-3 methyl 6 [2′-Me (heptoxy)] anthraquinone (3)) were isolated and elucidated together with the two known anthraquinone glycosides, Physcion-8-O-rutinoside (4) and emodin-6-O-α-L-rhamnoside (5) as well as with the known kaempferol-7-methylether (6), β-sitosterol (7) and β-sitosterol-3-O-glycoside (8). Their chemical structures were elucidated using spectr…
Copolymerization of VDF and HFP in Supercritical Carbon Dioxide: A Robust Approach for Modeling Precipitation and Dispersion Kinetics
2012
A kinetic model is developed for the heterogeneous free-radical copolymerization of vinylidene fluoride and hexafluoropropylene in supercritical CO 2. The model accounts for polymerization in both the dispersed (polymer-rich) phase and in the continuous (polymer-free) supercritical phase, for radical interphase transport, diffusion limitations, and chain-length-dependent termination in the polymer-rich phase. A parameter evaluation strategy is developed and detailed to estimate most of the kinetic parameters a priori while minimizing their evaluation by direct fitting. The resulting model predictions compare favorably with the experimental results of conversion and MWD at varying monomer fe…