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Pharmacology Relevance: Baccharis trinervis (Lam, Persoon) leaves are used in the traditional medicine for the treatment of high fevers, edema, inflammation, sores and muscle cramps, snakebites and as antiseptic., Aim of the Study: To investigate the cytotoxic, genotoxic, and mutagenic effects of extracts and fractions of B. trinervis from Brazil and Colombia in Chinese Hamster Ovary (CHO) cells, and to examine the mutagenic activity in Salmonella typhimurium., Material and Methods: Aqueous extracts (AE) of aerial parts of B. trinervis from Brazil (B) and Colombia (C) were fractioned in ethyl acetate fraction (EAF), butanol extract (BF), and aqueous residue fraction (ARF). Qualitative chemical screening and determination of total flavonoid content were made. Identification of chemical constituents was performed by High Performance Liquid Chromatography (HPLC) and High Resolution Mass Spectrometry (HRMS). For the in vitro tests, CHO cells were treated for 3h with extracts and fractions. The cytotoxic activity was evaluated by clonal survival and 3-(4.5-dimethylthiazole-2-yl)-2.5-biphenyl tetrazolium bromide reduction assay (MTT). Genotoxic and mutagenic effects were evaluated by the alkaline comet assay and Cytokinesis-blockage micronucleus test (CBMN), respectively. Additionally, Salmonella/microsome assay was carried out to determinate the mutagenic effects in EAF from Brazil and Colombia., Results: Phytochemical analyses indicated the presence of saponins and flavonoids. AE and EAF were the samples with the highest quantity of total flavonoids. HPLC showed the presence of luteolin only in AEC, and caffeic acid, ellagic acid, rosmarinic acid, and rutin were identified in AEB and AEC (AEC>AEB). The HRMS in positive mode of EAFB and EAFC showed presence of two carboxylic acids, coumarin, and two terpenoids. In addition, were identified one terpenoid and two carboxylic acids in AE, BF and ARF of B. trinervis from both countries in negative mode. Dose-dependent cytotoxic effects were observed in CHO cells treated with B. trinervis extracts and fractions by using clonal survival and MTT at concentrations higher than 0.05mg/mL. All the extracts and fractions induced DNA strand breaks in CHO cells with dose-dependent response, mostly EAFB and EAFC. The EAF from Brazil and Colombia showed mutagenic effect at 0.5mg/mL, while the other fractions did not show a significant difference in relation to the control. No mutagenic effects were found in EAF from both countries by the Salmonella/microsome assay., Conclusions: Cytotoxic and genotoxic effects were demonstrated in all extracts and fractions used, although only EAF showed mutagenic effects by CBMN, but not by Salmonella/microsome assay. Our results suggest that flavonoids, phenylpropanoids, coumarins, and diterpenes may be responsible for the cytotoxic, genotoxic and mutagenic effects observed., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In cancer treatment, chemotherapy is one of the main strategies used. The knowledge of the cellular and molecular characteristics of tumors allows the use of more specific drugs, making the removal of tumors more efficient. Among the drugs of choice in these treatments, topoisomerase inhibitors are widely used against different types of tumors. Topoisomerases are enzymes responsible for maintaining the structure of DNA, altering its topological state temporarily during the processes of replication and transcription, in order to avoid supercoiling and entanglements at the double helix. The DNA damage formed as a result of topoisomerase inhibition can be repaired by DNA repair mechanisms. Thus, DNA repair pathways can modulate the effectiveness of chemotherapy. Homologous recombination (HR) and non-homologous end joining (NHEJ) are the main pathways involved in the removal of double strand breaks (DSBs); while nucleotide excision repair (NER) is mainly characterized by the removal of lesions that lead to significant structural distortions in the DNA double helix. Evidence has shown that DSBs are the main type of damage resulting from the inhibition of the DNA topoisomerase II enzyme, and therefore the involvement of HR and NHEJ pathways in the repair process is well established. However, some topoisomerase II inhibitors induce other types of lesions, like DNA adducts, interstrand crosslinks and reactive oxygen species, and studies have shown that other DNA repair pathways might be participating in removing injury induced by these drugs. This review aims to correlate the involvement of proteins from different DNA repair pathways in response to these drugs, with an emphasis on NER., (Copyright © 2016 Elsevier B.V. All rights reserved.)

By isolating putative binding partners through the two-hybrid system (THS) we further extended the characterization of the specific interstrand cross-link (ICL) repair gene PSO2 of Saccharomyces cerevisiae. Nine fusion protein products were isolated for Pso2p using THS, among them the Sak1 kinase, which interacted with the C-terminal β-CASP domain of Pso2p. Comparison of mutagen-sensitivity phenotypes of pso2Δ, sak1Δ and pso2Δsak1Δ disruptants revealed that SAK1 is necessary for complete WT-like repair. The epistatic interaction of both mutant alleles suggests that Sak1p and Pso2p act in the same pathway of controlling sensitivity to DNA-damaging agents. We also observed that Pso2p is phosphorylated by Sak1 kinase in vitro and co-immunoprecipitates with Sak1p after 8-MOP+UVA treatment. Survival data after treatment of pso2Δ, yku70Δ and yku70Δpso2Δ with nitrogen mustard, PSO2 and SAK1 with YKU70 or DNL4 single-, double- and triple mutants with 8-MOP+UVA indicated that ICL repair is independent of YKu70p and DNL4p in S. cerevisiae. Furthermore, a non-epistatic interaction was observed between MRE11, PSO2 and SAK1 genes after ICL induction, indicating that their encoded proteins act on the same substrate, but in distinct repair pathways. In contrast, an epistatic interaction was observed for PSO2 and RAD52, PSO2 and RAD50, PSO2 and XRS2 genes in 8-MOP+UVA treated exponentially growing cells., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Ultraviolet radiation is known to cause adverse effects to aquatic species and aquatic environments. The fish Colossoma macropomum (tambaqui) and Arapaima gigas (pirarucu) live in the Amazon basin, near the Equator, and thus receive high intensity of ultraviolet radiation. Deforestation further aggravates the situation by reducing shade at ground level. The aim of this study was to evaluate the genotoxic effects of UVA and UVB radiation on erythrocytes of tambaqui and pirarucu fish using Micronuclei test and Comet assay. Our study showed that UV radiation caused DNA damage in both species as detected by Comet assay. In addition, there were differences in response to genotoxicity between both species, which are possibly related to their evolutionary history. Tambaqui fish exposed to ultraviolet radiation for different periods presented clear dose-response in DNA damage profile. Significant damage repair was observed 24h after cessation of ultraviolet radiation exposure. At the test conditions used, no significant increase in micronucleated cells was observed in tambaqui and pirarucu fish. Tambaqui proved to be more sensitive to ultraviolet radiation than Pirarucu, as detected by Comet assay, showing statistically higher baseline DNA damage. The present results demonstrated that alkaline Comet assay was very sensitive for detecting the UV-induced genotoxicity during the short exposure period in our study. In addition, the present study also suggests that tambaqui and pirarucu fish are useful sentinel organisms, as their UV sensitivity allows them to be effective monitors of biological hazards in the Amazon region., (Copyright 2010 Elsevier B.V. All rights reserved.)

This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (γ-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of γ-irradiation (2, 4, and 8 Gγ). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment. Environ. Mol. Mutagen., 2011. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: : To evaluate the antioxidant status and repair capacity in breast cancer patients as well as the relationship between these parameters and expression of critical proteins in breast cancer tissue. Design and methods: : Blood samples were obtained from 25 female breast cancer patients and 19 healthy women. The antioxidant status was determined by the concentration of thiobarbituric-reactive substances (TBARS) and activity of superoxide dismutase (SOD) and catalase (CAT). The basal DNA damage and repair capacity in lymphocytes were evaluated by comet assay. The expression of p53, c-erbB2, Ki-67, estrogen receptor (ER) and progesterone receptor (PR) in cancer tissue was detected by immunohistochemical staining. Results: : The breast cancer patients presented significantly elevated endogenous DNA damage in lymphocytes and lower susceptibility to DNA damage induced by H2O2 when compared to the control group. There is a negative correlation between TBARS and sensitivity to peroxide induced DNA damage in patients. The percentage of residual damage after H2O2 treatment followed by 3h of post-incubation is significantly higher in patients and also correlates positively with SOD activity, ER and PR expression and negatively with the basal DNA damage. Conclusions: : Our results demonstrate low repair capacity in lymphocytes of breast cancer patients and suggest that the regulation of DNA repair is sensitive to cellular redox state and can be modulated by ER/PR status. [Copyright &y& Elsevier]