Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells.

Physicochemical properties of titanium dioxide nanoparticles (TiO2 NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO2 NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO2 NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO2 NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO2 and Cu in Cu-doped TiO2 NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO2 NPs (24 nm) was lower than pure TiO2 NPs (30 nm). Biological results showed that both pure and Cu-doped TiO2 NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO2 NPs. We further observed that cytotoxicity caused by Cu-doped TiO2 NPs was higher than pure TiO2 NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO2 NPs. This is the first report showing that Cu-doped TiO2 NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO2 NPs.

Interaction of Al(2)O(3) nanoparticles with Escherichia coli and their cell envelope biomolecules.

AIMS: The aim of this study is to investigate the antibacterial activity of aluminium oxide nanoparticles (Al2 O3 NPs) against multidrug-resistant clinical isolates of Escherichia coli and their interaction with cell envelope biomolecules. METHODS AND RESULTS: Al2 O3 NPs were characterized by scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM) and X-ray diffraction (XRD) analyses. Antibacterial activity and interaction of Al2 O3 NPs with E. coli and its surface biomolecules were assessed by spectrophotometry, SEM, HR-TEM and attenuated total reflectance/Fourier transform infrared (ATR-FTIR). Of the 80 isolates tested, about 64 (80%) were found to be extended spectrum ß-lactamase (ESBL) positive and 16 (20%) were non-ESBL producers. Al2 O3 NPs at 1000 µg ml(-1) significantly inhibited the bacterial growth. SEM and HR-TEM analyses revealed the attachment of NPs to the surface of cell membrane and also their presence inside the cells due to formation of irregular-shaped pits and perforation on the surfaces of bacterial cells. The intracellular Al2 O3 NPs might have interacted with cellular biomolecules and caused adverse effects eventually triggering the cell death. ATR-FTIR studies suggested the interaction of lipopolysaccharide (LPS) and L-α-Phosphatidyl-ethanolamine (PE) with Al2 O3 NPs. Infrared (IR) spectral changes revealed that the LPS could bind to Al2 O3 NPs through hydrogen binding and ligand exchange. The Al2 O3 NPs-induced structural changes in phospholipids may lead to the loss of amphiphilic properties, destruction of the membrane and cell leaking. CONCLUSIONS: The penetration and accumulation of NPs inside the bacterial cell cause pit formation, perforation and disorganization and thus drastically disturb its proper function. The cell surface biomolecular changes revealed by ATR-FTIR spectra provide a better understanding of the cytotoxicity of Al2 O3 NPs. SIGNIFICANCE AND IMPACT OF THE STUDY: Al2 O3 NPs may serve as broad-spectrum bactericidal agents to control the emergent pathogens regardless of their drug-resistance mechanisms.

Rotenone-induced oxidative stress and apoptosis in human liver HepG2 cells.

Rotenone, a commonly used pesticide, is well documented to induce selective degeneration in dopaminergic neurons and motor dysfunction. Such rotenone-induced neurodegenration has been primarily suggested through mitochondria-mediated apoptosis and reactive oxygen species (ROS) generation. But the status of rotenone induced changes in liver, the major metabolic site is poorly investigated. Thus, the present investigation was aimed to study the oxidative stress-induced cytotoxicity and apoptotic cell death in human liver cells-HepG2 receiving experimental exposure of rotenone (12.5-250 µM) for 24 h. Rotenone depicted a dose-dependent cytotoxic response in HepG2 cells. These cytotoxic responses were in concurrence with the markers associated with oxidative stress such as an increase in ROS generation and lipid peroxidation as well as a decrease in the glutathione, catalase, and superoxide dismutase levels. The decrease in mitochondrial membrane potential also confirms the impaired mitochondrial activity. The events of cytotoxicity and oxidative stress were found to be associated with up-regulation in the expressions (mRNA and protein) of pro-apoptotic markers viz., p53, Bax, and caspase-3, and down-regulation of anti-apoptotic marker Bcl-2. The data obtain in this study indicate that rotenone-induced cytotoxicity in HepG2 cells via ROS-induced oxidative stress and mitochondria-mediated apoptosis involving p53, Bax/Bcl-2, and caspase-3.

Effect of Trans-resveratrol on Rotenone-induced Cytotoxicity in Human Breast Adenocarcinoma Cells.

Rotenone, a botanical insecticide is known to cause apoptosis in various cell types. Trans-resveratrol, a natural phytophenol present in red grapes and wine, is also well documented for its antioxidant, anti-inflammatory, anti-mutagenic, and anticarcinogenic activities. Therefore, the present investigations were carried out to assess the protective effect of trans-resveratrol against rotenone-induced cell death in human breast adenocarcinoma (MCF-7) cells. MCF-7 cells were exposed with various concentrations of rotenone for 24 h, and the loss in percent cell viability was evaluated by MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] and neutral red uptake (NRU) assays. A significant decrease in percent cell viability in MCF-7 cells was observed at 50 µM and above concentrations of rotenone, as compared to untreated control. Furthermore, various concentrations (5, 10, and 25 µM) of trans-resveratrol were used to see its protective role on cell viability in rotenone-induced cell death in MCF-7 cells. Pre- or post- treatment of trans-resveratrol for 24 h was given to the cells. The data exhibited a significant dose dependent increase in the percent cell viability under pre- and post-treatment conditions. However, post-treatment of trans-resveratrol for 24 h after rotenone exposure to the cells was relatively less effective. Overall, the results suggest that trans-resveratrol significantly protects MCF-7 cells from rotenone-induced cell death. This model can be used as an effective and economical alternative to animal models for screening the antioxidant activity of a variety of natural compounds/drugs.

Salubrious effects of dexrazoxane against teniposide-induced DNA damage and programmed cell death in murine marrow cells.

The intention of the present study was to answer the question whether the catalytic topoisomerase-II inhibitor, dexrazoxane, can be used as a modulator of teniposide-induced DNA damage and programmed cell death (apoptosis) in the bone marrow cells in vivo. The alkaline single cell gel electrophoresis, scoring of chromosomal aberrations, micronuclei and mitotic activity were undertaken in the current study as markers of DNA damage. Apoptosis was analysed by the occurrence of a hypodiploid DNA peak and caspase-3 activity. Oxidative stress marker such as intracellular reactive oxygen species production, lipid peroxidation, reduced and oxidised glutathione were assessed in bone marrow as a possible mechanism underlying this amelioration. Dexrazoxane was neither genotoxic nor apoptogenic in mice at the tested dose. Moreover, for the first time, it has been shown that dexrazoxane affords significant protection against teniposide-induced DNA damage and apoptosis in the bone marrow cells in vivo and effectively suppresses the apoptotic signalling triggered by teniposide. Teniposide induced marked biochemical alterations characteristic of oxidative stress including accumulation of intracellular reactive oxygen species, enhanced lipid peroxidation, accumulation of oxidised glutathione and reduction in the reduced glutathione level. Prior administration of dexrazoxane ahead of teniposide challenge ameliorated these biochemical alterations. It is thus concluded that pretreatment with dexrazoxane attenuates teniposide-induced oxidative stress and subsequent DNA damage and apoptosis in bone marrow cells. Based on our data presented, strategies can be developed to decrease the teniposide-induced DNA damage in normal cells using dexrazoxane. Therefore, dexrazoxane can be a good candidate to decrease the deleterious effects of teniposide in the bone marrow cells of cancer patients treated with teniposide.