Carbon tetrachloride induced hepato/renal toxicity in experimental mice: antioxidant potential of Egyptian Salvia officinalis L essential oil

The present research designed to assess the protective role of Salvia officinalis essential oil (SO) against carbon tetrachloride (CCl₄)-induced liver and kidney damage in mice. This is evidenced by estimation of antiradical scavenging activity of SO using DPPH assay, biochemical markers, histological investigation of liver and kidney sections, and comet assay. Mice were given CCl₄ (1.2 mL/kg for 24 h or 0.8 mL/kg for 2 weeks, 3 times/week) and with or without SO (0.1, 0.2, and 0.4 mL/kg, for 2 week, 5 times/week). The findings demonstrated that both acute and subacute treatment with CCl₄ alone had adverse side effects on liver and kidney of mice. These effects were evidenced by a significant increase in serum hepatic enzymes (ALT, AST, ALP, LDH, and G-GT), bilirubin, and renal function markers (blood urea, creatinine). Toxic effect of CCl₄ was accompanied by a decline in the serum total protein, albumin, globulin, and prothrombin (%). CCl₄ induced oxidative stress as evidenced by increasing serum lipid peroxidation (LPO) along with decreasing serum total glutathione S transferase (GST). A remarkable increase in hepatic DNA strand breakages and histopathological distortion in liver and kidney specimens were observed in CCl₄-intoxicated groups. Ultrastructurally, hepatocytes exhibited irregular nuclei, vacuolated cytoplasm, and distorted microorganelles. Essential oil form S. officinalis possessed antiradical scavenging (EC₅₀ = 4602 μg/mL) lower than ascorbic acid (EC₅₀ = 5.9 μg/mL). This oil was effectively exhibited hepato-nephroprotective activity especially at its higher concentrations in co-treated groups (SO plus CCl₄). The activity of SO was associated with lowering the liver enzymes, bilirubin, urea, and creatinine, along with increasing total protein, albumin, globulin, and prothrombin. The increase in GST content and the decrease in LPO and DNA breakage levels, alongside repairing the histo-architectural distortions further confirmed the protective activity of SO. SO is a potential candidate for counteracting hepato/renal injury associating CCl₄. This effect may occur via antioxidant defense mechanism which in part related to the complexity of its chemical constituents.

The essential comet assay: a comprehensive guide to measuring DNA damage and repair

The comet assay (single cell gel electrophoresis) is the most common method for measuring DNA damage in eukaryotic cells or disaggregated tissues. The assay depends on the relaxation of supercoiled DNA in agarose-embedded nucleoids (the residual bodies remaining after lysis of cells with detergent and high salt), which allows the DNA to be drawn out towards the anode under electrophoresis, forming comet-like images as seen under fluorescence microscopy. The relative amount of DNA in the comet tail indicates DNA break frequency. The assay has been modified to detect various base alterations, by including digestion of nucleoids with a lesion-specific endonuclease. We describe here recent technical developments, theoretical aspects, limitations as well as advantages of the assay, and modifications to measure cellular antioxidant status and different types of DNA repair. We briefly describe the applications of this method in genotoxicity testing, human biomonitoring, and ecogenotoxicology.

Genotoxic effects of the water-soluble fraction of heavy oil in the brackish/freshwater amphipod Quadrivisio aff. lutzi (Gammaridea) as assessed using the comet assay

Amphipod crustaceans have been widely used as invertebrate models in ecotoxicology due to their importance in the food chain. However, few studies have evaluated the genotoxic effects of pollutants in this model using the comet assay. The main obstacle to using amphipods in the comet assay is the difficulty in obtaining enough blood cells from a single individual. In this study, we evaluated the genotoxic effects of the water-soluble fraction (WSF) of heavy oil on the brackish/freshwater amphipod Quadrivisio aff. lutzi, which is common in the coastal lagoons of southeastern Brazil, using hemocytes obtained from single amphipods (without pooling) after optimizing hemolymph extraction. The comet assay revealed significantly higher DNA damage levels (2- to 6-fold higher) in treated amphipods compared to untreated ones with a sublethal concentration of 17.6 % of the WSF within 72 h of treatment. Two independent experiments confirmed an "up and down" pattern of DNA damage, measured as the % of DNA contained in the tail of the comets. Elevations in DNA damage levels were observed at the 6 and 48 h time points, while very low levels of DNA damage were observed at the 24 and 72 h time points. Furthermore, the comet assay revealed gender variability in the levels of DNA damage after short-term exposure.

Application of comet assay for the assessment of DNA damage caused by chemical genotoxins in the dairy yeast Kluyveromyces lactis

Kluyveromyces lactis, also known as dairy yeast, has numerous applications in scientific research and practice. It has been approved as a GRAS (Generally Recognized As Safe) organism, a probiotic, a biotechnological producer of important enzymes at industrial scale and a bioremediator of waste water from the dairy industry. Despite these important practical applications the sensitivity of this organism to genotoxic substances has not yet been assessed. In order to evaluate the response of K. lactis cells to genotoxic agents we have applied several compounds with well-known cyto- and genotoxic activity. The method of comet assay (CA) widely used for the assessment of DNA damages is presented here with new special modifications appropriate for K. lactis cells. The comparison of the response of K. lactis to genotoxins with that of Saccharomyces cerevisiae showed that both yeasts, although considered close relatives, exhibit species-specific sensitivity toward the genotoxins examined.