Allium cepa root tip assay in assessment of toxicity of magnesium oxide nanoparticles and microparticles.

Allium cepa bioassay had been used from decades for the assessment of toxicants and their harmful effects on environment as well as human health. Magnesium oxide (MgO) particles are being utilized in different fields. However, reports on the adverse effects of MgO nanoparticles on the environment and mankind are scarce. Hence, the toxicity of MgO particles is of concern because of their increased utilization. In the current study, A. cepa was used as an indicator to assess the toxicological efficiency of MgO nano- and microparticles (NPs and MPs) at a range of exposure concentrations (12.5, 25, 50, and 100µg/mL). The toxicity was evaluated by using various bioassays on A. cepa root tip cells such as comet assay, oxidative stress and their uptake/internalization profile. Results indicated a dose dependent increase in chromosomal aberrations and decrease in mitotic index (MI) when compared to control cells and the effect was more significant for NPs than MPs (at p<0.05). Comet analysis revealed that the Deoxyribonucleic acid (DNA) damage in terms of percent tail DNA ranged from 6.8-30.1 over 12.5-100µg/mL concentrations of MgO NPs and was found to be significant at the exposed concentrations. A significant increase in generation of hydrogen peroxide and superoxide radicals was observed in accordance with the lipid peroxidation profile in both MgO NPs and MPs treated plants when compared with control. In conclusion, this investigation revealed that MgO NPs exposure exhibited greater toxicity on A. cepa than MPs.

Biochemical alterations induced by nickel oxide nanoparticles in female Wistar albino rats after acute oral exposure.

CONTEXT: Nickel oxide (NiO) nanoparticles (NPs) with appropriate surface chemistry have been widely used for their potential new applications in biomedical industry. Increased usage of these NPs enhances the chance of exposure of personnel involved in the work place. OBJECTIVE: This study was designed to assess the ability of NiO NPs to cause biochemical alterations post-acute oral exposure in female Wistar rats. MATERIALS AND METHODS: Rats were administered with 125, 250, and 500 mg/kg doses of NiO NPs for haematological, biochemical, and histopathological studies. Biodistribution patterns of NiO NPs in female Wistar rats were also monitored. RESULTS: NiO NPs caused significant (p < 0.01) inhibition of RBC and brain AchE of treated rats at the high dose. Activation of the hepatotoxicity marker enzymes, aminotransferases, was recorded in serum and liver, whereas inhibition was observed in kidney. The activity of antioxidant enzymes was also altered by NiO NPs in a dose-dependent manner and found to be significant at the high dose of exposure. CONCLUSIONS: This study revealed that exposure to nanosized NiO particles at acute doses may cause adverse changes in animal biochemical profiles. Further, the in vivo studies on toxicity evaluation help in biomonitoring of the potential contaminants.

Acute oral toxicity study of magnesium oxide nanoparticles and microparticles in female albino Wistar rats.

Advancements in nanotechnology have led to the development of the nanomedicine, which involves nanodevices for diagnostic and therapeutic purposes. A key requirement for the successful use of the nanoparticles (NPs) in biomedical applications is their good dispensability, colloidal stability in biological media, internalization efficiency, and low toxicity. Therefore, toxicological profiling is necessary to understand the mechanism of NPs and microparticles (MPs). MgO NPs have attracted wide scientific interest due to ease of synthesis, chemical stability and unique properties. However, their toxic effects on humans should also be of concern with the increased applications of nano MgO. The present study was aimed to assess the toxicological potential of MgO NPs in comparison to their micron counterparts in female Wistar rats. Toxicity was evaluated using genotoxicity, histological, biochemical, antioxidant and biodistribution parameters post administration of MgO particles to rats through oral route. The results obtained from the investigation revealed that the acute exposure to the high doses of MgO NPs produced significant (p < 0.01) DNA damage and biochemical alterations. Antioxidant assays revealed prominent oxidative stress at the high dose level for both the particles. Toxicokinetic analysis showed significant levels of Mg accumulation in the liver and kidney tissues apart from urine and feces. Further, mechanistic investigational reports are warranted to document safe exposure levels and health implications post exposure to high levels of NPs.

Repeated oral dose toxicity of iron oxide nanoparticles: biochemical and histopathological alterations in different tissues of rats.

Iron oxide (Fe2O3) nanoparticles are widely used in different fields of nanotechnology. However, studies on its toxicological effects in humans and the environment are scarce. Therefore in this investigation 28 days repeated dose oral toxicity studies were conducted on Fe2O3-30 nanoparticles and its counterpart Fe2O3-Bulk with special reference to target biochemical enzymes and histopathological changes in different tissues of female albino Wistar rats. The alterations observed after Fe2O3-30 treatment in various tissues of exposed rats were dose dependent. Low dose was less effective than medium and high doses with low dose demonstrating "no observed adverse effect" (NOAEL). Further, high dose treated rats showed toxic sign and symptoms but no mortality. Due to the repeated doses of Fe2O3-30 nanoparticles, significant inhibition was observed in total, Na(+)-K+, Mg2+ and Ca(2+)-ATPases in brain of exposed rats. Similarly, significant inhibition was recorded in RBC and brain acetylcholinesterase indicating that both synaptic transmission and nerve conduction were affected by this compound. Fe2O3-30 significantly increased aspartate amino transferase, alanine amino transferase and lactate dehydrogenase in serum and liver, whereas, these enzymes were significantly decreased in kidney indicating tissue necrosis and possible leakage of these enzymes into the blood stream. Increased levels of these enzymes in liver as well as in serum might be an adaptive mechanism due to the stress of iron nanoparticles. High dose treated rats of Fe2O3-30 showed dilated central vein, perivascular round cell collections in liver along with focal areas of necrosis, whereas kidney showed focal tubular damage and red pulp congestion, whereas prominent white pulp indices were observed in spleen. However, histopathological analysis of heart and brain tissues failed to show any adverse changes in their architecture exposed to repeated doses of Fe2O3-30 when compared with controls. Fe2O3-Bulk did not induce any adverse effects in either biochemical parameters or histopathology in the treated rats and the changes observed were near to controls and mostly insignificant, indicating that the counter part of nanoparticles i.e., bulk material is less potent than the nanoparticles in causing toxicity in the exposed animals. These results suggested that as particle size decreases, this iron nanoparticle showed increased toxicity, even though the same material is relatively inert in bulk form. The changes observed in these target enzyme activities could be useful as biomarkers of exposure to nanoparticles.

Development of a cell-based nonradioactive glucose uptake assay system for SGLT1 and SGLT2.

Sodium-dependent glucose cotransporters (SGLT1 and SGLT2), which have a key role in the absorption of glucose in the kidney and/or gastrointestinal tract, have been proposed as a novel therapeutic strategy for diabetes and cardiomyopathy. Here we developed a simple cell-based, nonradioactive method for functional screening of SGLT1 and SGLT2 inhibitors. Stable cell lines expressing human SGLT1 and SGLT2 were established by transfecting HEK293 cells with vectors (pCMV6-Neo) having full-length human SGLT1 and SGLT2 and selecting the positive clones following neomycin treatment. We confirmed the gene expression of SGLT1 and SGLT2 by reverse transcription polymerase chain reaction (RT-PCR) and immunoblotting. Furthermore, to analyze the function of SGLTs, we incubated stable cell lines with 2-deoxyglucose or fluorescent d-glucose analog (2-NBDG) and performed glucose uptake assay. A significant (P<0.001) increase in glucose uptake was observed in both cell lines. The increased glucose uptake in both cell lines was completely inhibited when treated with nonspecific SGLT1/SGLT2 inhibitors and phlorizin (100µM), but not when treated with nonspecific sodium-independent facilitative glucose transporter (GLUT) inhibitors (100µM). Taken together, our data suggest that cell-based methods developed for screening SGLT1/SGLT2 inhibitors are phlorizin sensitive and specific for respective glucose transporters. This assay provides a simple and rapid method for identifying novel and selective SGLT inhibitors.

Oxidative stress induced by aluminum oxide nanomaterials after acute oral treatment in Wistar rats.

This study investigated the oxidative stress induced after acute oral treatment with 500, 1000 and 2000 mg kg⁻¹ doses of Al2O3 -30 and -40 nm and bulk Al2O3 in Wistar rats. Both the nanomaterials induced significant oxidative stress in a dose-dependent manner in comparison to the bulk. There was no significant difference between the two nanomaterials. However, the effect decreased with increase with time after treatment. The histopathological examination showed lesions only in liver with Al2O3 nanomaterials at 2000 mg kg⁻¹.

Genotoxicity in filling station attendants exposed to petroleum hydrocarbons.

OBJECTIVES: Biomonitoring of exposure in workplaces has gained importance in evaluation of human health hazards. Since occupational exposure to petroleum hydrocarbons may have deleterious effects, genotoxicity risk among 200 fuel filling station attendants (FFSAs) and 200 matched controls was investigated. METHODS: The probable genetic damage was determined by comet assay and micronucleus test in peripheral blood lymphocytes (PBL) of study subjects. Air and blood sample analysis was done to estimate the benzene, toluene, and xylene (BTX) concentrations using gas chromatography-mass spectrometry. The effect of exposure on antioxidant enzymes was also studied by determining the levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and rate of lipid peroxidation measured as concentration of malondialdehyde (MDA) formed. RESULTS: The results of the present study suggest that there was a statistically significant increase in mean comet tail length (25.09 versus 10.27 µm) and frequency of micronuclei in PBL (11.83 versus 5.83 per thousand; P < 0.05) of FFSAs as compared to controls. BTX concentrations were found to be significantly higher in ambient air of petrol pumps and FFSAs showed elevated levels of these compounds in their breathing zone in comparison to controls (P < 0.05). Blood BTX levels were found to be significantly enhanced in FFSAs. SOD and GPx were significantly decreased with an increased rate of CAT and MDA in FFSAs as compared to controls. CONCLUSIONS: The results of our study suggest that exposure to BTX has the potential to cause genetic changes in the exposed subjects. The data highlight the need to maintain safety measures and intervention to minimize exposure.

In vitro mutagenicity assessment of aluminium oxide nanomaterials using the Salmonella/microsome assay.

The aim of the current study was to evaluate the potential mutagenicity of aluminium oxide nanomaterials (NMs) (Al(2)O(3)-30 nm and Al(2)O(3)-40 nm). Characterization of the NMs was done before the initiation of the study. The mutagenicity of the NMs was studied by the Ames test with Salmonella typhimurium TA100, TA1535, TA98, TA97a and TA102 strains, in the presence and absence of the S9 mixture. Based on a preliminary cytotoxicity study conducted on the strains, different concentrations of Al(2)O(3)-30 nm, Al(2)O(3)-40 nm and Al(2)O(3)-bulk were selected. At all the concentrations tested, Al(2)O(3)-30 nm and Al(2)O(3)-40 nm did not significantly increase the number of revertant colonies compared to the Al(2)O(3)-bulk and control with or without S9 mixture. Our findings suggest that Al(2)O(3) NMs were devoid of any size and concentration dependent mutagenicity compared to the Al(2)O(3)-bulk and control.

Evaluation of genotoxic effects of oral exposure to aluminum oxide nanomaterials in rat bone marrow.

Nanomaterials have novel properties and functions because of their small size. The unique nature of nanomaterials may be associated with potentially toxic effects. The aim of this study was to evaluate the in vivo genotoxicity of rats exposed with Aluminum oxide nanomaterials. Hence in the present study, the genotoxicity of Aluminum oxide nanomaterials (30 and 40 nm) and its bulk material was studied in bone marrow of female Wistar rats using chromosomal aberration and micronucleus assays. The rats were administered orally with the doses of 500, 1000 and 2000 mg/kg bw. Statistically significant genotoxicity was observed with Aluminum oxide 30 and 40 nm with micronucleus as well as chromosomal aberration assays. Significantly (p < 0.05 or p < 0.001) increased frequency of MN was observed with 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (9.4 +/- 1.87 and 15.2 +/- 2.3, respectively) and Aluminum oxide 40 nm (8.1 +/- 1.8 and 13.9 +/- 2.21, respectively) over control (2.5 +/- 0.7) at 30 h. Likewise, at 48 h sampling time a significant (p < 0.05 or p < 0.001) increase in frequency of MN was evident at 1000 and 2000 mg/kg bw dose levels of Aluminum oxide 30 nm (10.6 +/- 1.68 and 16.6 +/- 2.66, respectively) and Aluminum oxide 40 nm (9.0 +/- 1.38 and 14.7 +/- 1.68, respectively) compared to control (1.8 +/- 0.75). Significantly increased frequencies (p < 0.05 or p < 0.001) of chromosomal aberrations were observed with Aluminum oxide 30 nm (1000 and 2000 mg/kg bw) and Aluminum oxide 40 nm (2000 mg/kg bw) in comparison to control at 18 and 24 h. Further, since there is need for information on the toxicokinetics of nanomaterials, determination of these properties of the nanomaterials was carried out in different tissues, urine and feces using inductively coupled plasma mass spectrometry (ICP-MS). A significant size dependent accumulation of Aluminum oxide nanomaterials occurred in different tissues, urine and feces of rats as shown by ICP-MS data. The results of our study suggest that exposure to Aluminum oxide nanomaterials has the potential to cause genetic damage.

In vivo assessment of genotoxic effects of Annona squamosa seed extract in rats.

Widespread use of pesticides represents a potential risk to human and environmental health. Hence, biopesticides from plants are some of the future strategies for plant protection. In this regard, a seed extract of Annona squamosa was prepared and found to be a promising pesticide. In order to establish the inherent toxicity and non-target safety required for registration and marketing of pesticides, toxicological studies are conducted. The genotoxicity potential was evaluated in rats with 75, 150 and 300 mg/kg Annona squamosa by the comet assay in leucocytes, micronucleus and chromosomal aberration tests in bone marrow. We also studied the effects of 300 mg/kg of extract on lipid peroxidation, reduced glutathione level and glutathione S transferase activity in liver, lungs, brain, kidneys, heart and spleen of treated rats. The comet assay showed a statistically significant dose related increase in DNA migration. The micronucleus and chromosomal aberration tests revealed a significant induction in frequency of micronuclei and chromosomal aberrations at 150 and 300 mg/kg. Annona squamosa treatment significantly enhanced lipid peroxidation, decreased glutathione and glutathione S transferase levels revealing the oxidative stress condition. Our results warrant careful use of Annona squamosa seed extract as a biopesticide till more tests are carried out.

In vivo genotoxicity assessment of aluminium oxide nanomaterials in rat peripheral blood cells using the comet assay and micronucleus test.

Advances in nanotechnology and its usage in various fields have led to the exposure of humans to engineered nanomaterials (NMs) and there is a need to tackle the potential human health effects before these materials are fully exploited. The main purpose of the current study was to assess whether aluminium oxide NMs (Al(2)O(3)-30 nm and Al(2)O(3)-40 nm) could cause potential genotoxic effects in vivo. Characterization of Al(2)O(3)-30 nm and Al(2)O(3)-40 nm was done with transmission electron microscopy, dynamic light scattering and laser Doppler velocimetry prior to their use in this study. The genotoxicity end points considered in this study were the frequency of micronuclei (MN) and the percentage of tail DNA (% Tail DNA) migration in rat peripheral blood cells using the micronucleus test (MNT) and the comet assay, respectively. Genotoxic effects were evaluated in groups of female Wistar rats (five per group) after single doses of 500, 1000 and 2000 mg/kg body weight (bw) of Al(2)O(3)-30 nm, Al(2)O(3)-40 nm and Al(2)O(3)-bulk. Al(2)O(3)-30 nm and Al(2)O(3)-40 nm showed a statistically significant dose-related increase in % Tail DNA for Al(2)O(3)-30 nm and Al(2)O(3)-40 nm (P < 0.05). However, Al(2)O(3)-bulk did not induce statistically significant changes over control values. The MNT also revealed a statistically significant (P < 0.05) dose-dependent increase in the frequency of MN, whereas Al(2)O(3)-bulk did not show any significant increase in frequency of MN compared to control. Cyclophosphamide (40 mg/kg bw) used as a positive control showed statistically significant (P < 0.001) increase in % Tail DNA and frequency of MN. The biodistribution of Al(2)O(3)-30 nm and Al(2)O(3)-40 nm and Al(2)O(3)-bulk in different rat tissues, urine and feces was also studied 14 days after treatment using inductively coupled plasma mass spectrometry. The data indicated that tissue distribution of Al(2)O(3) was size dependent. Our findings suggest that Al(2)O(3) NMs were able to cause size- and dose-dependent genotoxicity in vivo compared to Al(2)O(3)-bulk and control groups.