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A new procedure for fluorescent detection of intracellular H2O2 in cells transiently expressing the catalyst Horseradish Peroxidase (HRP) is setup and validated. More specific reaction with HRP largely amplifies oxidation of the redox probes used (2',7'-dichlorodihydrofluorescein and dihydrorhodamine). Expression of HRP does not affect cell viability. The procedure reveals MAO activity, a primary intracellular H2O2 source, in monolayers of intact transfected cells. The probes oxidation rate responds specifically to the MAO activation/inhibition. Their oxidation by MAO-derived H2O2 is sensitive to intracellular H2O2 competitors: it decreases when H2O2 is removed by pyruvate and it increases when the GSH-dependent removal systems are impaired. Specific response was also measured after addition of extracellular H2O2. Oxidation of the fluorescent probes following reaction of H2O2 with endogenous HRP overcomes most criticisms in their use for intracellular H2O2 detection. The method can be applied for direct determination in plate reader and is proposed to detect H2O2 generation in physio-pathological cell models. [ABSTRACT FROM AUTHOR]

Selenium-containing compounds have emerged as promising treatment for redox-based and inflammatory diseases. This study aimed to investigate the in vitro and in vivo anti-inflammatory activity of a novel diselenide named as dibenzyl[diselanediyIbis(propane-3-1diyl)] dicarbamate (DD). DD reacted with HOCl (k = 9.2 x 107 M−1s−1), like glutathione (k = 1.2 x 108 M−1s−1), yielding seleninic and selenonic acid derivatives, and it also decreased HOCl formation by activated human neutrophils (IC50=4.6 μM) and purified myeloperoxidase (MPO) (IC50=3.8 μM). However, tyrosine, MPO-I and MPO-II substrates, did not restore HOCl formation in presence of DD. DD inhibited the oxidative burst in dHL-60 cells with no toxicity up to 25 µM for 48h. Next, an intraperitoneal administration of 25, 50, and 75 mg/kg DD decreased total leukocyte, neutrophil chemotaxis, and inflammation markers (MPO activity, lipid peroxidation, albumin exudation, nitrite, TNF-α, IL-1β, CXCL1/KC, and CXCL2/MIP-2) on a murine model of carrageenan-induced peritonitis. Likewise, 50 mg/kg DD (i.p.) decreased carrageenan-induced paw edema over 5h. Histological and immunohistochemistry analyses of the paw tissue showed decreased neutrophil count, edema area, and MPO, carbonylated, and nitrated protein staining. Furthermore, DD treatment decreased the fMLP-induced chemotaxis of human neutrophils (IC50=3.7 μM) in vitro with no toxicity. Lastly, DD presented no toxicity in a single-dose model using mice (50 mg/kg, i.p.) over 15 days and in Artemia salina bioassay (50 to 2000 µM), corroborating findings from in silico toxicological study. Altogether, these results demonstrate that DD attenuates carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting damage from MPO-mediated oxidative burst. [ABSTRACT FROM AUTHOR]

Dolichol, a long-chain polyisoprenoid broadly distributed in all tissues and cellular membranes with unknown function(s), might have a role in free radical metabolism [it accumulates in older tissues and decreases after CCl4 (in liver) or phenylhydrazine (in spleen and liver) administration]. The effects of the NADPH-ADP-Fe system on Dolichol levels in isolated hepatocytes were explored and the time-course of changes was compared with the release of MDA in the incubation medium and the decrease in CoQ 9 and 10 and Vitamin E levels. Results showed that the system increased lipid peroxidation and decreased Dolichol and CoQ levels in_parallel fashions and lowered Vitamin E levels with shorter latency. Meanwhile, no increase in dead cells and no Dolichol release in the medium were detected. In conclusion, an increase in oxidative stress possibly caused a rapid degradation of dolichol by the same (unknown) mechanism responsible for the breakdown of_Ubiquinone isoprenoid chains. [ABSTRACT FROM AUTHOR]