A. Rama Narsimha Reddy

Pulmonary toxicity assessment of multiwalled carbon nanotubes in rats following intratracheal instillation

In this study, we have evaluated the pulmonary toxicity of intratracheally (i.t.) instilled two multi walled carbon nanotubes (MWCNT) in rats. The lungs of rats were instilled with phosphate buffered saline + 1% of Tween 80 or MWCNT or carbonyl iron or quartz particles at a dose of 0.2, 1, and 5 mg/kg b.w. Following exposure, bronchoalveolar lavage (BAL) fluid was collected from the lungs to analyze lactate dehydrogenase (LDH), alkaline phosphatase (ALP), lipid peroxidation products (MDA; malondialdehyde), and total microprotein (MTP) levels at 24 h, one week, one month, and three months post instillation periods. The lungs of particle exposed rats were also collected at the same intervals to evaluate for histopathology. Exposures of MWCNT and quartz particles to rats produced transient dose dependant increase in BAL fluid LDH, ALP, MDA, and MTP values than control at all post exposure periods. Results of lung histopathology revealed that exposure of MWCNT produced a dose dependant focal peribronchiolar lymphoid aggregates, foamy alveolar macrophage accumulation, lymphoplasmocytic infiltration, fibrosis and diffuse alveolar damage. In conclusion, instillation of MWCNT produced a greater pulmonary toxicity in rats and was comparable with that of quartz.

Translocation and extra pulmonary toxicities of multi wall carbon nanotubes in rats

This study evaluated the ability of the multi wall carbon nanotubes (MWCNT) to induce extra pulmonary toxicities in rats following intra-tracheal (IT) instillation of two MWCNT. Two carbon nanoparticles were instilled into the lungs of rats (0.2, 1, and 5 mg/kg b.w.) and at different post-exposure intervals, blood and organs like liver, kidney, etc. were collected. The histopathological examination of liver tissues revealed a dose-dependent periportal lymphocytic infiltration, ballooning, foamy degeneration, and necrosis at all post-instillation periods. However, examination of kidney revealed the tubular necrosis and interstitial nephritis with 5 mg/kg dose at 1 month of post-instillation of both MWCNT. These liver and kidney toxicities were further confirmed by the elevated levels of respective tissue damage biomarkers. These results suggest the extra pulmonary toxicities of these carbon nanoparticles might be due to the translocation into the liver and kidney.

Evaluation of oxidative stress and anti-oxidant status in rat serum following exposure of carbon nanotubes.

The aim of the present study was to evaluate the oxidative stress and anti-oxidant status in rat serum following intra-tracheal instillation of multi wall carbon nanotubes (MWCNT). The lungs of rats were intra-tracheally instilled with (single dose of) Phosphate-buffered saline (PBS)+1% of Tween 80 (Solvent Control) or MWCNT or carbonyl Iron (negative control) or quartz particles (positive control) at a dose of 0.2, 1 and 5 mg/kg body weight. Following exposure, the blood samples were collected at 1, 7, 30 and 90 days of post instillation of nanoparticles and different parameters were estimated to assess the oxidative stress induced by the instillation of MWCNT. Exposure of MWCNT to rats produced a significant (p<0.05) dose dependent reduction of blood total anti-oxidant capacity, glutathione, superoxide dismutase, catalase activity and increased lipid peroxidation product, (Malondialdehyde) levels than PBS+1% Tween 80 control group. This reduction in the total anti-oxidant capacity in nanotubes exposed rats indicates the reduction in anti-oxidant deference mechanisms due to the instillation of MWCNT. These results indicate that, exposure of multi wall carbon nanotubes induces oxidative stress by reducing the total anti-oxidant capacity in rats. The findings suggest possible occupational health hazard in chronic exposures.

Induction of oxidative stress and cytotoxicity by carbon nanomaterials is dependent on physical properties.

In this study, we investigated the mechanisms involved in multi-wall carbon particles/nanomaterials (MWCNM) induced cytotoxicity using human embryonic kidney (HEK293) cells and to assess the effect of physicochemical properties on the cytotoxicity and oxidative stress induced by the carbon nanomaterials (CNM). To elucidate the possible mechanisms of CNM-induced cytotoxicity, cell viability (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide [MTT assay]), cell membrane damage (lactate dehydrogenase enzyme [LDH] assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation levels were quantitatively assessed under carbon nanomaterials exposed (48 h) conditions. Exposure of different sizes of four CNM at dosage levels between 3 and 300 μg/mL decreased cell viability in a concentration- and size-dependent manner. Exposure of CNM (10-100 μg/mL) to HEK cells resulted in size-, surface area- and concentration-dependent cell membrane damage, increased production of IL-8, increased thiobarbituric acid reactive substances (TBARS) and decreased intracellular glutathione levels. In summary, the physical properties of carbon nanoparticles may alter the CNM-induced concentration-dependent cytotoxicity and oxidative stress.

Antioxidant status in MgO nanoparticle-exposed rats

In this present study, antioxidant status was evaluated in rat serum following exposure to magnesium oxide (MgO) nanoparticles. The lungs of rats were intratracheally instilled with (single dose) phosphate-buffered saline (PBS) + 1% of Tween 80 (solvent control) or MgO or carbonyl iron (negative control) or quartz particles (positive control) at a dose of 1 and 5 mg/kg of body weight. The blood samples were collected at 1, 7, and 30 days of postinstillation of nanoparticles after their exposure, and different parameters were estimated to assess the oxidative stress induced by the instillation of MgO. Exposure of rats to MgO produced a significant (p < 0.05) dose-dependent reduction in blood total antioxidant capacity, superoxide dismutase, and catalase activity levels than PBS + 1% Tween 80 control group. This reduction in the antioxidant capacity in MgO nanoparticle-exposed rats indicates the reduction in antioxidant defense mechanisms due to the instillation of MgO. These results indicate that exposure to MgO nanoparticles induces oxidative stress by reducing the total antioxidant capacity in rats. The findings suggest possible occupational health hazard in chronic exposures.

Single walled carbon nanotubes induce cytotoxicity and oxidative stress in HEK293 cells

The aim of the present study was to evaluate the potential toxicity and general mechanisms involved in single walled carbon nanotubes (SWCNTs)-induced cytotoxicity using human embryonic kidney cell line (HEK293) cells. Carbon nanotubes (coded as CNT) used in this study were synthesized by the chemical vapor deposition method. To elucidate the possible mechanisms underlying SWCNT-induced cytotoxicity, cell viability, cell membrane damage (lactate dehydrogenase activity (LDH) assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation products levels were quantitatively assessed following SWCNT exposure for 48 hr using HEK293 cells. Exposure of cells to SWCNT at 3–300 μg/ml produced significant reduction in cell viability in a concentration-dependent manner. The IC50 value of SWCNT was found to be 87.58 μg/ml. Exposure of HEK cells to SWCNT at 10–100 μg/ml resulted in concentration-dependent cell membrane damage, increased production of IL-8, elevated levels of thiobarbituric acid reactive substances like malondialdehyde and decreased intracellular GSH levels. In summary, exposure to SWCNT resulted in a concentration-dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.

Antihyperlipidemic and Antioxidant Activity of Methanolic Extract of Trianthema portulacastrum in Rats Fed a High-Fat Diet

The methanolic extract of Trianthema portulacastrum (Aizoaceae) was evaluated for antihyperlipidemic and antioxidant activity in high-fat-diet–induced hyperlipidemic rats. It was found that the extract caused a significant reduction in the lipid levels in hyperlipidemic rats and was comparable with the standard anti-hyperlipidemic drug atorvastatin. It was also found that the plant extract increased the liver antioxidant enzyme (catalase, superoxide dismutase, glutathione) levels while reducing the lipid peroxide (malondialdehyde) levels.

Hepatoprotective activity of methanolic extract of Hiptage bengalensis leaves against CCl4-induced hepatotoxicity in rats

The objective of the present study was to evaluate hepatoprotective activity of methanolic extract of Hiptage bengalensis (L.) kurz (MEHB) in rats. Hepatic damage was induced by administration of carbontetrachloride(1 ml/kg, b.w, p.o.) in combination with liquid paraffin (1:1) as a single dose on 7th day. The extent of liver damage was studied by estimating biochemical parameters. Administration of MEHB (200 mg & 400 mg/kg) for 6 days before carbontetrachloride administration showed a significant reduction (p < 0.01) of serum liver damage enzymes markers-aspartate transaminase, alanine transaminase, total bilirubin and alkaline phosphatase (ALP). Histopathological changes of hepatic tissue were also evaluated in control and MEHB treated groups. Results also indicated that MEHB possessed potential antioxidant effect by increasing the levels of glutathione and also possessed free radical scavenging activities. The hepatoprotective effect of Hiptage bengalensis (L.) kurz was comparable to standard drug silymarin (50 mg/kg).

Novel extractive colorimetric and UV spectrophotometric estimation of etizolam in bulk and tablet by forming ion association complex with methyl orange and bromocresol green

A novel, sensitive, and rapid UV spectrophotometric and colorimetric method was developed for estimation of etizolam (ETZ) in bulk and tablet. The UV spectrophotometric method (method I) is based on quantitative estimation of ETZ using 0.1N NaOH as the solvent which exhibits maximal absorption at 378 nm. Colorimetric methods (method II and III) were based on the formation of color complex in association with ions between basic nitrogen of the drug with methyl orange (MO) and bromocresol green (BCG) in acidic medium. The formed color complexes were quantitatively extracted with chloroform and measured at 509 nm for Drug–MO complex and at 442 nm for Drug–BCG complex, respectively. Beers law was obeyed over the linear ranges 2–16 µg/ml (method I), 5–45 µg/ml (method II), and 2–20 µg/ml (method III). The correlation coefficient (r2) for ETZ was 0.999, 0.997, and 0.998 for method I, II, and III, respectively. All methods were successfully applied for the assay of the drug in tablet. The % purity was found to be 98.52 (method I), 98.72 (method II), and 99.18 (method III). These developed methods were fully validated with % relative standard deviation (RSD) for accuracy less than 2 for all methods. The % RSD of the intra-day and inter-day variations was found to be less than 2%. The limit of detection and quantitation were as follows: 0.108 µg/ml and 0.327 µg/ml (method I), 0.24 µg/ml and 0.75 µg/ml (method II), 0.1 µg/ml and 0.5 µg/ml (method III) indicating marked method sensitivity. Empirical evidence from all three methods concludes that developed methods are simple, sensitive, and reliably validated for useful routine quality control analysis of ETZ.