Comparative evaluation of oxidative stress status and manganese availability in plants growing on manganese mine.

This study pioneered an approach that determined the effects of excess manganese (Mn) on three species; Datura stramonium, Alhagi camelthorn and Chenopodium ambrosioides. We investigated their levels of Mn, antioxidative enzymes and oxidative damage biomarkers in plants (zone 1) in and outside (zone 2) the Mn mine. The results showed that total and available Mn were at toxic levels for plants growing on zone 1. The Mn levels in each plant species were higher in leaves, stems and roots. Mn was only accumulated significantly in leaf vacuoles of A. camelthorn. Antioxidative enzyme activities of C. ambrosioides and/or D. stramonium in zone 1 were higher in leaves, stems and then in their roots. Malondialdehyde (MDA) and dityrosine levels were insignificantly higher in tissues of the studied plants in zone 1 with respect to zone 2. The roots of studied plants showed significantly higher levels of these biomarkers in comparison with their leaves in zone 1. Accordingly, antioxidative enzymatic response to Mn-stress in D. stramonium and C. ambrosioides and possibly accumulation of Mn in leaf vacuoles of A. camelthorn, protected them from oxidative damages and involved in their tolerance in Mn mine.

On the cytotoxicity and status of oxidative stress of two novel synthesized tri-aza macrocyclic diamides as studied in the V79 cell lines.

Two tri-aza macrocycles as diamide derivatives of macrocyclic compounds possess a hydrophilic cavity surrounded by hydrophobic ring, which enables them to diffuse cell membrane and interfere with different living systems. In this study, we comparatively evaluated cytotoxicity effects of tri-aza dibenzo sulfoxide (TSD) and dibenzo sulfide (TTS) macrocyclic diamides in a range of doses (0.5-8mM) and the role of oxidative stress in V79 cell culture. We assessed the effects of these substances on ROS level, cellular viability, apoptosis events, activity of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), and on some macromolecules' oxidative damage end-products: malondialdehyde (MDA), dityrosine, and 8-hydroxy-deoxyguanosine (8-OH-dG) that were assessed by spectrometry and HPLC methods. Both compounds revealed cytotoxicity effects on cell culture particularly at doses >1mM after 24-h incubation. They decreased cellular viability and significantly promoted ROS generation, increased enzyme activities, and enhanced oxidative damages in which TSD was more effective. Treatment of cells with each compound alone increased significantly the percent of apoptotic events at 2 and then 4mM. Co-treatment with alpha-tocopherol (alpha-TCP) drastically reduced these events. Cells' exposure with mixture of 30 microM alpha-tocopherol and 8mM of each compound exerted significant decrease in the levels of ROS, enzyme activities, and oxidative damage biomarkers. As conclusion, our study documented the oxidative radical forming ability of the studied compounds and further strengthened the documentation of their cytotoxicity effects through lipids, proteins and DNA oxidation damages.

The copper tolerance strategies and the role of antioxidative enzymes in three plant species grown on copper mine.

This study was undertaken to identify the strategies and the status of antioxidant enzyme activities involved in three plant species tolerance against Cu-toxicity in copper mine. The following methods were used for evaluations in three wild type species; Datura stramonium, Malva sylvestris and Chenopodium ambrosioides. The level of chlorophyll and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) by spectrometry, malondialdehyde (MDA) and dityrosine by HPLC and the levels of Cu in tissues and soils by atomic absorption spectrometry (AAS). Analysis showed that total and available copper were at toxic levels for plants growing on contaminated soil (zone 1). However, there were not any visual and conspicuous symptoms of Cu toxicity in plant species. Among three species, excess copper was transferred only into the D. stramonium and C. ambrosioides tissues. The C. ambrosioides accumulated Cu in roots and then in leaves, in which the leaves chloroplasts stored Cu around two times of vacuoles. In D. stramonium most of Cu was accumulated in leaves in which the storage rate in vacuoles and chloroplasts were 42% and 8%, respectively. In zone 1, the chlorophyll levels increased significantly in leaves of C. ambrosioides with respect to the same plant growing on uncontaminated soil (zone 2). There was insignificant decrease in chlorophyll content of D. stramonium leaves, collected from zone 1 with respect to zone 2. The D. stramonium and C. ambrosioides in zone 1, both revealed significant increase in their tissues antioxidant enzyme activities in comparison with the same samples of zone 2. There was significant elevation in oxidative damage biomarkers; MDA and dityrosine, when the aerial parts of D. stramonium in zone 1 were compared with the same parts of zone 2. We concluded that there were different tolerance strategies in studied plant species that protected them against copper toxicity. In M. sylvestris, exclusion of Cu from the roots or its stabilization in the soil restricted Cu toxicity effects. On the other hand D. stramonium and C. ambrosioides, elevated their antioxidative enzyme activities in response to cu-toxicity. In addition, the species D. stramonium accumulated excess of Cu in leaves vacuoles.

Oxidative response of rat lung tissue after crown ethers exposure and the effects of alpha-tocopherol treatment.

BACKGROUND: Ionophoric properties of crown ethers enable them ideally to transport across membranes and interfere with different living systems. We studied cytotoxicity effects of 18-crown-6 and 15-crown-5 and the role of oxidative stress in rat lung tissue culture. METHODS: We assayed the effects of these crown ethers in a range of doses (0.1 to 2 mmol/l) on lipids and proteins oxidative damages end products; malondialdehyde (MDA) and dityrosine and on the activity of antioxidant enzymes; superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), in rat lung tissue culture by spectrometry and HPLC. RESULTS: Both compounds significantly increased the levels of MDA, dityrosine and enzyme activities at doses >0.5 mmol/l after 48-h incubation in the lung tissue, representing promotion of ROS generation with respect to control. These effects were more considerable for 18-crown-6 than 15-crown-5. Treatment of lung tissue with 30 microm of alpha-tocopherol in addition to 2 mmol/l of crown ethers showed significant decrease on the levels of enzyme activities, MDA and dityrosine. CONCLUSION: We showed the oxidative radicals forming ability of crown ethers as documented in their toxicity effects through lipid and proteins oxidation damages.

Cytotoxicity and the levels of oxidative stress parameters in WI38 cells following 2 macrocyclic crown ethers treatment.

BACKGROUND: Crown ethers as macrocyclic polyethers possess a hydrophilic cavity surrounded by hydrophobic ring which enable them to diffuse cell membrane. We evaluated cytotoxicity effects of 15-crown-5 and 18-crown-6 and the role of oxidative stress in WI38 cells culture. METHODS: The effect of these ethers in a range of doses (0.1 to 2 mmol/l) on the activity of antioxidant enzymes; superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), and on some macromolecules oxidative damages end products; malondialdehyde (MDA) and dityrosine were assessed by spectrometry and HPLC methods. RESULTS: Both compounds markedly inhibited the viability of cells with respect to control particularly at doses >0.5 mmol/l after 24- or 48 h incubation. The survivals of cells were measured using MTT assay. They lowered cell's viability and significantly promoted ROS generation, increased enzyme activities and enhanced oxidative damages in which 18-crown-6 was more effective. Treating cells with 30 microm of alpha-tocopherol in addition to 2 mmol/l of crown ethers showed significant decrease on the levels of ROS, enzyme activities, MDA and dityrosine. CONCLUSION: We document the oxidative radicals forming ability of the studied crown ethers and further strengthens the documentation of their cytotoxicity effects through lipid and proteins oxidation damages.

A longitudinal follow-up of pulmonary function and respiratory symptoms in workers exposed to manganese.

The purpose of the investigation was to study the effects on the respiratory system in mine workers with long-term exposure to manganese (Mn) in the workplace. The study included a follow-up of pulmonary function and respiratory symptoms among 145 workers employed in a large Mn mine and 65 matched controls, and the assessment of Mn concentrations in environment and biological samples. Lung function was measured by recording spirometric parameters. The Mn-exposed workers reported more respiratory symptoms and a significantly higher prevalence of all grades of pulmonary function impairment. All predicted symptoms except for asthma increased significantly in the current smoking group compared with the non-smoking group. There was a significant decrease in FEV1, FVC, and FEV1% values in exposed workers compared with controls at stages 2 and 3, with an additive effect of the smoking habit. The Mn concentrations in blood, urine, and hair were significantly higher in the exposed workers than in the controls. The level of cumulative exposure index of workplace Mn was notable and did not change significantly over this study. The respiratory effects found in Mn-exposed workers were probably caused by the Mn in the workplace and the synergistic effect of smoking. These effects indicate a need for respiratory protection and improvements in the work environment.

Long-term follow-up of workplace and well water manganese effects on iron status indexes in manganese miners.

The authors assessed the effect of water reconstitution in the workplace by evaluating the iron status of manganese mine workers during a long-term study. Subsequent analyses and biological monitoring were performed in a group of 150 manganese miners before, and 2.8 yr after, reconstitution of drinking water in the miners' workplace. The authors found significantly high concentrations of manganese in the workplace well water, as well as in the miners' blood, urine, and hair. There was a considerable prevalence of epithelial lesions, which resulted from iron deficiency, in the miners, compared with controls. The authors assessed the prevalence of iron deficiency grades (i.e., I > II > III > IV) before and after water reconstitution. Reconstitution of drinking water for the ultimate attainment of healthy levels of manganese and other minerals resulted in a significant improvement in the miners' iron status and a decreased prevalence of epithelial lesions. The authors concluded that alterations in iron status may result from the cumulative effect of high levels of manganese in consumed water, as well as in airborne dust, in the workplace. Such elevated levels should be considered as an occupational hazard because they have an ability to interfere with iron absorption.