Induction of reactive oxygen species by diphenyl diselenide is preceded by changes in cell morphology and permeability in <i>Saccharomyces cerevisiae</i>

<p>Organoselenium compounds, such as diphenyl diselenide (PhSe)₂ and phenylselenium zinc chloride (PhSeZnCl), show protective activities related to their thiol peroxidase activity. However, depending on experimental conditions, organoselenium compounds can cause toxicity by oxidising thiol groups of proteins and induce the production of reactive oxygen species (ROS). Here, we analysed the toxicity of (PhSe)₂ and PhSeZnCl in yeast <i>Saccharomyces cerevisiae</i>. Cell growth of <i>S. cerevisiae</i> after 1, 2, 3, 4, 6, and 16 h of treatment with 2, 4, 6, and 10 μM of (PhSe)₂ was evaluated. For comparative purpose, PhSeZnCl was analysed only at 16 h of incubation at equivalent concentrations of selenium (i.e. 4, 8, 12, and 20 μM). ROS production (DCFH-DA), size, granularity, and cell membrane permeability (propidium iodide) were determined by flow cytometry. (PhSe)₂ inhibited cell growth at 2 h (10 μM) of incubation, followed by increase in cell size. The increase of cell membrane permeability and granularity (10 μM) was observed after 3 h of incubation, however, ROS production occurs only at 16 h of incubation (10 μM) with (PhSe)₂, indicating that ROS overproduction is a more likely consequence of (PhSe)₂ toxicity and not its determinant. All tested parameters showed that only concentration of 20 μM induced toxicity in samples incubated with PhSeZnCl. In summary, the results suggest that (PhSe)₂ toxicity in <i>S. cerevisiae</i> is time and concentration dependent, presenting more toxicity when compared with PhSeZnCl.</p

Effect of acute ethylmalonic acid (EMA) administration (6 μmol/g) on thiobarbituric acid-reactive species (TBA-RS) levels in cerebral cortex and skeletal muscle from 30-day-old rats.

<p>The experiments were performed in duplicate and the data represent mean ± standard error of the mean and are expressed in nmol. mg protein^-1 (n = 5 per group). ***<i>p</i> < 0.001 compared to control group (Student <i>t</i> test for independent samples).</p

Effect of acute ethylmalonic acid (EMA) administration (6 μmol/g) on carbonyl <i>(A)</i> and sulfhydryl <i>(B)</i> content in cerebral cortex and skeletal muscle from 30-day-old rats.

<p>The experiments were performed in duplicate and the data represent mean ± standard error of the mean and are expressed in nmol. mg protein^-1 (n = 5 per group). ***<i>p</i> < 0.001 compared to control group (Student <i>t</i> test for independent samples).</p

Effect of acute ethylmalonic acid (EMA) administration (6 μmol/g) on DCFH oxidation <i>(A)</i> and superoxide generation <i>(B)</i> in cerebral cortex and skeletal muscle from 30-day-old rats.

<p>The experiments were performed in duplicate and the data represent mean ± standard error of the mean and are expressed as DCFH oxidation: nmol. mg protein^-1; superoxide: nM. min^-1. mg of protein^-1 (n = 5–8 per group). *<i>p</i> < 0.05 compared to control group (Student <i>t</i> test for independent samples).</p

Effect of acute administration of ethylmalonic acid (EMA) on Mn-SOD and CuZn-SOD activities in cerebral cortex and skeletal muscle of rats.

<p>Values are mean ± standard error of mean for five independent experiments (animals) per group. Data were expressed as nmol. min^-1. mg of protein^-1. No differences between groups were detected (Student’s <i>t</i> Test).</p><p>Effect of acute administration of ethylmalonic acid (EMA) on Mn-SOD and CuZn-SOD activities in cerebral cortex and skeletal muscle of rats.</p

Effect of acute administration of ethylmalonic acid (EMA) on respiratory chain complex I-III activity in cerebral cortex and skeletal muscle of rats.

<p>Values are mean ± standard error of mean for five independent experiments (animals) per group. Data were expressed as nmol. min^-1. mg of protein^-1. No differences between groups were detected (Student’s <i>t</i> Test).</p><p>Effect of acute administration of ethylmalonic acid (EMA) on respiratory chain complex I-III activity in cerebral cortex and skeletal muscle of rats.</p