The contribution of cytotoxicity to DNA-effects in the single cell gel test (comet assay)
ABSTRACT We evaluated genotoxic and cytotoxic effects of the three non-mutagenic and non-carcinogenic compounds p-nitrophenol, d-menthol and sodium N-lauroyl sarcosine which have previously been shown to induce DNA double strand breaks (DNA dsb) secondary to induced cytotoxicity. We tested wheter genotoxic effects in the alkaline single cell gel test (comet assay) may be confounded by cytotoxicity-induced DNA dsb. Cell viability was determined at the end of the treatment using the fluorescein diacetate/ethidium bromide-assay and plating efficiency was used as an indicator of long-term survivability. Experiments with V79 Chinese hamster cells and human white blood cells revealed negative results in the comet assay despite strong cytotoxic effects. However, cells with extremely fragmented DNA (‘clouds’) occured but were excluded from the evaluation under the principle that they represent dead cells. We also noticed a significant loss of cells at cytotoxic concentrations that might be attributed to the induction of highly fragmented DNA which is lost during electrophoresis. Since the comet assay allows the determination of DNA effects on the single cell level, a confounding effect of cytotoxicity on test results can be avoided.
SourceAvailable from: Nevena Stankovic[Show abstract] [Hide abstract]
ABSTRACT: Two chroman-2,4-dione derivatives, namely 2a and 2f, were tested as in vivo anticoagulants by seven days of continuous per os application to adult male Wistar rats in a concentration of 20 mg/kg of body weight. Derivatives were selected from a group of six previously intraperitoneally applied compounds on the basis of presenting remarkable activity in a concentration of 2 mg/kg of body weight. The derivatives 2a and 2f are VKORC1 inhibitors, and comparison of the absorption spectra, association, and dissociation constants suggested that the compounds will be bound to serum albumin in the same manner as warfarin is, leading to transfer towards the molecular target VKORC1. After oral administration, the compounds proved to be anticoagulants comparable with warfarin, inasmuch as the measured prothrombin times for 2a and 2f were 56.63 and 60.08 s, respectively. The INR values of 2a and 2f ranged from 2.6 to 2.8, recommending them as useful therapeutics in the treatment of patients suffering from thromboembolic events and atrial fibrillation. The high percentage of binding and high binding affinity of 2a and 2f towards serum albumin reduced the risk of induced internal bleeding. Several kinds of toxicity studies were performed to investigate whether or not 2a and 2f can cause pathological changes in the liver, kidneys, and DNA. The catalytic activity of serum enzymes, concentration and catalytic activity of liver and kidney oxidative stress markers and enzymes, respectively, as well as the observed hepatic and renal morphological changes indicated that the compounds in relation to warfarin induced irrelevant hepatic toxicity, no increment of necrosis, and inconsiderable oxidative damage in the liver and kidneys. Estimation of DNA damage using the comet assay confirmed that 2a and 2f caused no clinically significant genotoxicity. The higher activity and lower toxicity of 2f recommended this compound as a better drug candidate than 2a.Chemico-Biological Interactions 12/2014; 227. DOI:10.1016/j.cbi.2014.12.005 · 2.98 Impact Factor
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ABSTRACT: Rubus niveus Thunb. plant belongs to Rosaceae family and have been used traditionally to treat wounds, burns, inflammation, dysentery, diarrhea and for curing excessive bleeding during menstrual cycle. The present study was undertaken to investigate the in vivo genotoxicity of R. niveus aerial parts extract and its possible chemoprotection on doxorubicin (DXR)-induced DNA damage. In parallel, the main phytochemicals constituents in the extract were determined. The animals were exposed to the extract for 24 and 48h, and the doses selected were 500, 1000 and 2000mg/Kg b.w. administered by gavage alone or prior to DXR (30mg/Kg b.w.) administered by intraperitoneal injection. The endpoints analyzed were DNA damage in bone marrow and peripheral blood cells assessed by the alkaline alkaline (pH > 13) comet assay and bone marrow micronucleus test. The results of chemical analysis of the extract showed the presence of tormentic acid, stigmasterol, quercitinglucoronide (miquelianin) and niga-ichigoside F1 as main compounds. Both cytogenetic endpoints analyzed showed that there were no statistically significant differences (p > 0.05) between the negative control and the treated groups with the two higher doses of R. niveus extract alone, demonstrating absence of genotoxic and mutagenic effects. Aneugenic/clastogenic effect was observed only at 2000mg/Kg dose. On the other hand, in the both assays and all tested doses were observed a significant reduction of DNA damage and chromosomal aberrations in all groups co-treated with DXR and extract compared to those which received only DXR. These results indicate that R. niveus aerial parts extract did not revealed any genotoxic effect, but presented some aneugenic/clastogenic effect at higher dose; and suggest that it could be a potential adjuvant against development of second malignant neoplasms caused by the cancer chemotherapic DXR. Copyright © 2015. Published by Elsevier Ireland Ltd.Journal of Ethnopharmacology 02/2015; 164. DOI:10.1016/j.jep.2015.02.013 · 2.94 Impact Factor
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ABSTRACT: PURPOSE: To characterize the anatomy of the fruit and leaf and the presence of phytocompounds. To evaluate the antitumor and antimicrobial activity of ethanolic extract of Garcinia mangostana L. (mangosteen) cultivated in southeastern Brazil. METHODS: Anatomical characterization and histochemical reactions were performed for structural identification and the presence of phytocompounds. Preparation of ethanolic extract of the fruit, leaf and resin of mangosteen. Culture B16-F10 melanoma cells for treatment with mangosteen ethanolic extract to determine cell viability by MTT and genotoxic effect by comet assay. Evaluation by antimicrobial activity against Staphylococcus aureus and Escherichia coli by agar diffusion test and by determination of Minimum Inhibitory Concentration (MIC). RESULTS: Our results showed many secretory canals in resin fruit and leaf; identifying lipids, starch, lignin and phenolic compounds. The leaf extract induced genotoxicity and apoptosis in B16-F10 cells, since the fragmentation of DNA in the comet assay. The ethanolic extract of mangosteen obtained in the resin, leaf and fruit showed antimicrobial activity against Staphylococcus aureus and Escherichia coli with a MIC at 0.1 mg/mL. CONCLUSION: In conclusion, we have demonstrated both antimicrobial and antitumor activity of ethanol extract of mangosteen emphasizing its therapeutic potential in infectious diseases and in cancer, such as melanoma.Acta cirurgica brasileira / Sociedade Brasileira para Desenvolvimento Pesquisa em Cirurgia 01/2014; 29(Suppl 2):21-28. DOI:10.1590/S0102-86502014001400005 · 0.48 Impact Factor