DNA damage and repair following In vitro exposure to two different forms of titanium dioxide nanoparticles on trout erythrocyte

TiO(2) has been widely used to promote organic compounds degradation on waste aqueous solution, however, data on TiO(2) nanotoxicity to aquatic life are still limited. In this in vitro study, we compare the toxicity of two different families of TiO(2) nanoparticles on erythrocytes from Oncorhynchus mykiss trout. The crystal structure of the two TiO(2) nanoparticles was analyzed by XRD and the results indicated that one sample is composed of TiO(2) in the anatase crystal phase, while the other sample contains a mixture of both the anatase and the rutile forms of TiO(2) in a 2:8 ratio. Further characterization of the two families of TiO(2) nanoparticles was determined by SEM high resolution images and BET technique. The toxicity results indicate that both TiO(2) nanoparticles increase the hemolysis rate in a dose dependent way (1.6, 3.2, 4.8 μg mL(-1) ) but they do not influence superoxide anion production due to NADH addition measured by chemiluminescence. Moreover, TiO(2) nanoparticles (4.8 μg mL(-1) ) induce DNA damage and the entity of the damage is independent from the type of TiO(2) nanoparticles used. Modified comet assay (Endo III and Fpg) shows that TiO(2) oxidizes not only purine but also pyrimidine bases. In our experimental conditions, the exposure to TiO(2) nanoparticles does not affect the DNA repair system functionality. The data obtained contribute to better characterize the aqueous environmental risks linked to TiO(2) nanoparticles exposure. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011

Lymphocyte DNA damage in rats exposed to pyrethroids: effect of supplementation with Vitamins E and C.

Pesticides have been considered potential chemical mutagens. In fact, some studies show that various agrochemical ingredients possess mutagenic properties inducing mutations, chromosomal alterations or DNA damage. Experimental evidence shows a marked correlation between mutagenicity and carcinogenicity and indicates that short-term mutagenicity tests are useful for predicting carcinogenicity. The present study on rat exposed to two pyrethroids, cypermethrin and permethrin, showed different lymphocyte DNA damage depending on the type of pyrethroid, the dose, and the period of treatment. Data obtained from comet assay showed that oral treatment with 150 mg/kg body weight/day of permethrin (corresponding to 1/10 of LD50) for 60 days, induced a significant increase in all comet parameters. No lymphocyte DNA damage was measured after treatment with 25 mg/kg body weight/day of cypermethrin (corresponding to 1/10 of LD50) for the same period. A higher dose of permethrin (300 mg/kg body weight/day), for a shorter period (22 days), did not induce lymphocyte DNA damage, while supplementation with 200 mg/kg of Vitamins E and C protected erythrocytes against plasma membrane lipids peroxidation. Moreover, treatment with Vitamins E and C maintained the activity of glutathione peroxidase, which was reduced in the presence of permethrin, and reduced the osmotic fragility, which had increased following permethrin treatment

Fluorescence study on rat epithelial cells and liposomes exposed to aromatic nitroxides

This study was performed to evaluate the effects, if any, of aromatic nitroxides, namely, indolinic nitroxides, on membrane fluidity of rat epithelial cells using steady-state fluorescence. These nitroxides are being increasingly considered as new and versatile compounds to reduce oxidative stress in biological systems. Hence, the results obtained in this study will give more insights on the interaction of these compounds with biological structures which at present is lacking, especially in view of their possible application as antioxidant therapeutic agents. The probes DPH and Laurdan which give information on the hydrophobic and hydrophilic-hydrophobic regions of the membrane bilayer, respectively, showed that nitroxide 1 (1,2-dihydro-2-methyl-3H-indole-3-one-1-oxyl) significantly increases membrane fluidity, whereas the corresponding phenylimino nitroxide derivative 2 (1,2-dihydro-2-methyl-3H-indole-3-phenylimino-1-oxyl) leads to membrane rigidification. The aliphatic nitroxide TEMPO included in this study for comparison produced no modifications. Consequently, it appears that the structure of the heterocyclic rings (aromatic or aliphatic) and the substituents may affect membrane fluidity differently. (C) 2004 Elsevier Inc. All rights reserved

Antioxidant and Anti-Inflammatory Activities of Extracts from Cassia alata, Eleusine indica, Eremomastax speciosa, Carica papaya and Polyscias fulva Medicinal Plants Collected in Cameroon

Abstract Background: The vast majority of the population around the world has always used medicinal plants as first source of health care to fight infectious and non infectious diseases. Most of these medicinal plants may have scientific evidence to be considered in general practice. Objective: The aim of this work was to investigate the antioxidant capacities and anti-inflammatory activities of ethanol extracts of leaves of Cassia alata, Eleusine indica, Carica papaya, Eremomastax speciosa and the stem bark of Polyscias fulva, collected in Cameroon. Methods: Chemiluminescence was used to analyze the antioxidant activities of plant extracts against hydrogen peroxide or superoxide anion. Comet assays were used to analyze the protection against antioxidant-induced DNA damage induced in white blood cells after treating with hydrogen peroxide. Flow cytometry was used to measure cd T cells proliferation and anti-inflammatory activity of cd T cells and of immature dendritic cells (imDC) in the presence of different concentrations of plant extracts. Results: Ethanol extracts showed strong antioxidant properties against both hydrogen peroxide and superoxide anion. Cassia alata showed the highest antioxidant activity. The effect of plant extracts on cd T cells and imDC was evidenced by the dose dependent reduction in TNF-a production in the presence of Cassia alata, Carica papaya, Eremomastax speciosa Eleusine indica, and Polyscias fulva. cd T cells proliferation was affected to the greatest extent by Polyscias fulva. Conclusion: These results clearly show the antioxidant capacity and anti-inflammatory activities of plant extracts collected in Cameroon. These properties of leaves and stem bark extracts may contribute to the value for these plants in traditional medicine and in general medical practice

Divergent effects of quinolinic aminoxyls on mitochondrial ultrastructure and localisation in osteosarcoma 143 B cells

In the present study we have shown that quinolinic aromatic aminoxyls are very efficient in protecting lipids of endoplasmic reticulum membranes against hydroperoxide- induced oxidation. The efficacy of these aminoxyls as protectors of lipids was much higher than the water-soluble 4-OH-TEMPO. We have also shown that QAL causes distinct changes of the morphology of mitochondria: from filamentous to granular enlarged structure via the folding of the former. QAL induces also perinuclear clustering of mitochondria. C-QAL as well as 4-OH-TEMPO treated cells revealed filamentous and scattered pattern of mitochondria. Antioxidant activity of QAL as well as morphological changes of mitochondrial raise the possibility that this drug can affect cell physiology via changes of mitochondrial function

Diallyl trisulfide-induced prostate cancer cell death is associated with Akt/PKB dephosphorylation mediated by P-p66shc

PURPOSE: P66Shc, an isoform of adaptor proteins, is known to mediate various signals including those leading to apoptosis or cell proliferation. Previously, we have shown that diallyl trisulfide (DATS)-induced prostate cancer cell death was mediated by increased ROS formation. In this study, we investigated the role of p66Shc protein and its serine 36 phosphorylation in DATS induced decrease in prostate cancer cell viability (PC-3). METHODS: PC-3 prostate cancer cells were used in this study. Stable cell lines expressing p66ShcS36A or an empty vector have been obtained. Cell viability, concentration of ROS, changes in P-p66Shc and P-Akt and DNA damage were determined. RESULTS: We observed that DATS treatment increased p66Shc phosphorylation at serine 36. Importantly, the phosphorylation was abolished by JNK inhibitor SP600125. Cells expressing plasmid-encoded variant of p66ShcS36A showed much higher resistance to DATS-induced cells death. In addition to that, we observed that DATS-induced ROS formation was completely abolished in cells expressing the p66ShcS36A variant. Interestingly, SP600125 proved to prevent DATS-induced Akt inactivation. In order to confirm that the observed effect is related to phosphorylation of p66Shc, we performed experiments on a stable cell line expressing p66ShcS36A. In such cells, DATS-induced Akt dephosphorylation was significantly reduced. On the other hand, hydrogen peroxide induced Akt activation in PC-3 cells, which was abrogated in cells expressing p66ShcS36A. CONCLUSIONS: Our results uncover a novel signaling pathway with p66Shc being indispensable for DATS-induced inactivation of Akt due to hypophosphorylation

Antioxidant activities of different hemoglobin derivatives

The antioxidant activity of hemoglobin was examined by studying both its peroxidase activity and its interaction with the superoxide anion. The peroxidase activity of both the subunits (α and β) was reduced with respect to the α2β2 tetramer and heme-oxidation was found to be associated with a decrease in this activity. Lucigenin-amplified chemiluminescence experiments have shown that at low pH, the presence of hemoglobin reduces the level of superoxide anion generated by the xanthine/xanthine oxidase system (met-Hb is more efficient in reducing the level of O2 - than oxy-hemoglobin). These results confirm that hemoglobin may be of importance in providing protection against oxidative damage to erythrocytes

DNA damage and repair following in vitro exposure to two different forms of titanium dioxide nanoparticles on trout erythrocyte

TiO2 has been widely used to promote organic compounds degradation on waste aqueous solution, however, data on TiO2 nanotoxicity to aquatic life are still limited. In this in vitro study, we compare the toxicity of two different families of TiO2 nanoparticles on erythrocytes from Oncorhynchus mykiss trout. The crystal structure of the two TiO2 nanoparticles was analyzed by XRD and the results indicated that one sample is composed of TiO2 in the anatase crystal phase, while the other sample contains a mixture of both the anatase and the rutile forms of TiO2 in a 2:8 ratio. Further characterization of the two families of TiO2 nanoparticles was determined by SEM high resolution images and BET technique. The toxicity results indicate that both TiO2 nanoparticles increase the hemolysis rate in a dose dependent way (1.6, 3.2, 4.8 lg mL21) but they do not influence superoxide anion production due to NADH addition measured by chemiluminescence. Moreover, TiO2 nanoparticles (4.8 lg mL21) induce DNA damage and the entity of the damage is independent from the type of TiO2 nanoparticles used. Modified comet assay (Endo III and Fpg) shows that TiO2 oxidizes not only purine but also pyrimidine bases. In our experimental conditions, the exposure to TiO2 nanoparticles does not affect the DNA repair system functionality. The data obtained contribute to better characterize the aqueous environmental risks linked to TiO2 nanoparticles exposure