RESUMO
Vanadium and vanadium salts cause genotoxicity and elicit variable biological effects depending on several factors. In the present study, we analyzed and compared the DNA damage and repair processes induced by vanadium in three oxidation states. We used human blood leukocytes in vitro and in a single cell gel electrophoresis assay at two pH values. We observed that vanadium(III) trioxide and vanadium(V) pentoxide produced DNA single-strand breaks at all of the concentrations (1, 2, 4, or 8 µg/ml) and treatment times (2, 4, or 6 h) tested. Vanadium(IV) tetraoxide treatment significantly increased DNA damage at all concentrations for 4 or 6 h of treatment but not for 2 h of treatment. The DNA repair kinetics indicated that most of the cells exposed to vanadium III and V for 4 h recovered within the repair incubation time of 90 min; however, those exposed to vanadium(IV) repaired their DNA within 120 min. The data at pH 9 indicated that vanadium(IV) tetraoxide induced DNA double-strand breaks. Our results show that the genotoxic effect of vanadium can be produced by any of its three oxidation states. However, vanadium(IV) induces double-strand breaks, and it is known that these lesions are linked with forming structural chromosomal aberrations.
Assuntos
Quebras de DNA , Reparo do DNA/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Óxidos/toxicidade , Compostos de Vanádio/toxicidade , Adulto , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ensaio Cometa , DNA/efeitos dos fármacos , DNA de Cadeia Simples/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Leucócitos/efeitos dos fármacos , Leucócitos/metabolismo , MasculinoRESUMO
Sulfentrazone is an herbicide used as a pre-plant incorporated or pre-emergence treatment. The electrochemical oxidation of sulfentrazone was studied, by cyclic, differential and square-wave voltammetry on unmodified and on glassy carbon nanotube-modified electrodes, and by controlled-potential coulometry and electrolysis. The voltammograms of sulfentrazone showed a main irreversible diffusion-controlled pH-dependent oxidation peak. The in situ DNA-damaging capacity of sulfentrazone was also investigated, employing double stranded ds-DNA-modified glassy carbon electrode, without evidence of interaction. On the other hand, in a solution of sulfentrazone and single stranded ss-DNA, the oxidation signals of the respective bases decreased concentration-dependently, indicating binding of sulfentrazone to guanine and adenine. The electro-Fenton method was employed to promote decontamination by eliminating the herbicide, resulting in almost 60% of mineralization.
Assuntos
DNA de Cadeia Simples/efeitos dos fármacos , Herbicidas/química , Sulfonamidas/química , Triazóis/química , Quebras de DNA de Cadeia Simples , DNA de Cadeia Simples/química , Eletrólise , Herbicidas/toxicidade , Peróxido de Hidrogênio/química , Ferro/química , Sulfonamidas/toxicidade , Testes de Toxicidade/métodos , Triazóis/toxicidadeRESUMO
Propolis, a natural product derived from plant resins collected by honeybees, has been used for thousands of years in traditional medicine all over the world. The composition of the propolis depends upon the vegetation of the area from where it was collected and on the bee species. In this study, we investigated the antioxidant activity of a propolis sample, provided by NATURANDES-CHILE, collected in a temperate region of central Chile. In addition, this natural compound was tested for its antiproliferative capacity on KB (human mouth epidermoid carcinoma cells), Caco-2 (colon adenocarcinoma cells) and DU-145 (androgen-insensitive prostate cancer cells) human tumor cell lines. Results showed that this Chilean propolis sample exhibits interesting biological properties, correlated with its chemical composition and expressed by its capacity to scavenge free radicals and to inhibit tumor cell growth.
Assuntos
Antioxidantes/farmacologia , Proliferação de Células/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , DNA de Cadeia Simples/efeitos dos fármacos , Sequestradores de Radicais Livres/farmacologia , Própole/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Chile , Meios de Cultura , Radicais Livres/metabolismo , Humanos , Peróxido de Hidrogênio/toxicidade , FotóliseRESUMO
Tinidazole (TNZ), ornidazole (ONZ) and metronidazole (MTZ) are antiparasitic drugs (nitroimidazole derivatives) that have proven to be effective against Trichomonas vaginalis, Entoamoeba histolytica, Giardia lamblia and Helicobacter pylori. The reduction of the nitro group and the generation of short-lived reactive intermediates are the basis of its parasiticidal activity. This reduction is associated with its mutagenic activity in bacteria, although in mammalian cells DNA damage seems to be related to the production of reactive oxygen species (ROS). Using alkaline single cell electrophoresis, a significant increase in single strand breaks and alkali labile sites in human peripheral blood lymphocytes (PBL) exposed to MTZ, ONZ and TNZ at 10, 100 and 500 microg/ml is observed. MTZ causes less damage, especially at higher concentrations, when compared with TNZ, the most harmful of the drugs tested. These findings suggest that primary damage is induced under aerobic conditions and confirms that these nitroimidazoles are DNA damaging agents.
Assuntos
Antitricômonas/toxicidade , Dano ao DNA/genética , DNA de Cadeia Simples/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Nitroimidazóis/toxicidade , Adulto , Células Cultivadas , Ensaio Cometa , Relação Dose-Resposta a Droga , Humanos , Linfócitos/sangue , Masculino , Metronidazol/toxicidade , Ornidazol/toxicidade , Tinidazol/toxicidadeRESUMO
Stannous ion (Sn) has been employed in nuclear medicine and in food industry. We described that Stannous Chloride (SnCl2) inactivation effect in Escherichia coli is mediated by a Fenton-like reaction. The effect of SnCl2 was studied through: (i) the alteration of plasmid topology in neutral and acidic pH by gel electrophoresis; and (ii) the transformation efficiency of an wild type E. coli strain. Treatment of plasmid DNA pUC 9.1 with SnCl2, at pH 7.4, results in DNA single-strand breaks (SSB), in a dose-dependent manner. Addition of sodium benzoate partly inhibited the DNA damage, while EDTA completely abolishes DNA-SSB. Furthermore, the ability of the plasmid to transform E. coli was reduced. At pH 1.3, SnCl2 exerts a protective effect on plasmid against HCI depurination. Our results suggest the generation of ROS, such as *OH by a Fenton-like reaction, close to the site of the lesions due to a possible complexation of stannous ion to DNA.
Assuntos
Dano ao DNA , DNA de Cadeia Simples/efeitos dos fármacos , Compostos de Estanho/toxicidade , Relação Dose-Resposta a Droga , Concentração de Íons de Hidrogênio , Plasmídeos , Espécies Reativas de OxigênioRESUMO
The aim of this investigation is the evaluation of DNA interaction of with tetraruthenated porphyrin (TRP) and of DNA damage in the presence of light. Direct-fluorescence and electronic absorption measurements after incubation of DNA with TRP indicate strong binding between pBR322 DNA or calf thymus DNA with the modified porphyrin. Exposure of pBR322 DNA to TRP (up to 3 microM) and light leads to single-strand break formation as determined by the conversion of the supercoiled form (form I) of the plasmid into the nicked circular form (form II). Oxidative DNA base damage was evaluated by the detection of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) after irradiation of calf thymus DNA in the presence of the TRP. The data demonstrated a dose and time dependence with each type of DNA damage. These data indicate (1) a specificity of the binding mode and (2) type I and II photoinduced mechanisms leading to strand scission activity and 8-oxodGuo formation. Accordingly, singlet molecular oxygen formation, after TRP excitation, was confirmed by near-infrared emission. From these investigations a potential application of TRP in photodynamic therapy is proposed.
Assuntos
Dano ao DNA , DNA/efeitos dos fármacos , DNA/metabolismo , Desoxiguanosina/análogos & derivados , Compostos Organometálicos/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/farmacologia , 8-Hidroxi-2'-Desoxiguanosina , Animais , Cátions , Bovinos , DNA/efeitos da radiação , DNA de Cadeia Simples/efeitos dos fármacos , DNA de Cadeia Simples/metabolismo , Desoxiguanosina/biossíntese , Luz , FotoquimioterapiaRESUMO
All organisms have the ability to respond and adapt to a myriad of environmental insults. The human respiratory epithelium, when exposed to oxidant gases in photochemical smog, is at risk of DNA damage and requires efficient cellular adaptative responses to resist the environmentally induced cell damage. Ozone and its reaction products induce in vitro and in vivo DNA single strand breaks (SSBs) in respiratory epithelial cells and alveolar macrophages. To determine if exposure to a polluted atmosphere with ozone as the main criteria pollutant induces SSBs in nasal epithelium, we studied 139 volunteers, including a control population of 19 children and 13 adult males who lived in a low-polluted Pacific port, 69 males and 16 children who were permanent residents of Southwest Metropolitan Mexico City (SWMMC), and 22 young males newly arrived to SWMMC and followed for 12 weeks. Respiratory symptoms, nasal cytology and histopathology, cell viabilities, and single-cell gel electrophoresis were investigated. Atmospheric pollutant data were obtained from a fixed-site monitoring station. SWMMC volunteers spent >7 hr/day outdoors and all had upper respiratory symptoms. A significant difference in the numbers of DNA-damaged nasal cells was observed between control and chronically exposed subjects, both in children (p<0.00001) and in adults (p<0.01). SSBs in newly arrived subjects quickly increased upon arrival to the city, from 39.8 +/- 8.34% in the first week to 67.29 +/- 2.35 by week 2. Thereafter, the number of cells with SSBs remained stable in spite of the continuous increase in cumulative ozone, suggesting a threshold for cumulative DNA nasal damage. Exposure to a polluted urban atmosphere induces SSBs in human nasal respiratory epithelium, and nasal SSBs could serve as a biomarker of ozone exposure. Further, because DNA strand breaks are a threat to cell viability and genome integrity and appear to be a critical lesion responsible for p53 induction, nasal SSBs should be evaluated in ozone-exposed individuals.
Assuntos
Dano ao DNA , DNA de Cadeia Simples/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Mucosa Nasal/efeitos dos fármacos , Ozônio/efeitos adversos , População Urbana , Adulto , Sobrevivência Celular , Criança , Exposição Ambiental/análise , Feminino , Humanos , Masculino , México , Mucosa Nasal/citologia , Doenças Nasais/induzido quimicamente , Ozônio/análiseRESUMO
5-Aminolevulinic acid (ALA), a heme precursor accumulated in chemical and inborn porphyrias, has been demonstrated to produce reactive oxygen species upon metal-catalyzed aerobic oxidation and to cause oxidative damage to proteins, liposomes and subcellular structures. Exposure of plasmid pBR322 DNA to ALA (0.01-3 mM) in the presence of 10 microM Fe2+ ions causes DNA single-strand breaks (ssb), revealed by agarose gel electrophoresis as an increase in the proportion of the open circular form (75 +/- 7.5% at 3 mM ALA) at the expense of the supercoiled form. Addition of either anti-oxidant enzymes such as superoxide dismutase (10 micrograms/ml) and catalase (20 micrograms/ml), or a metal chelator (DTPA, 2.5 mM), or a HO. scavenger (mannitol, 100 mM) inhibited the damage (by 30, 45, 55, and 81%, respectively), evidencing the involvement of O2-., H2O2 and HO. (by the Haber-Weiss reaction) in this process. Hydrogen peroxide (100 microM) or Fe2+ (10 microM) alone were of little effect on the extent of DNA ssb. The present data may shed light on the correlation reported between primary liver-cell carcinoma and intermittent acute porphyria.
Assuntos
Ácido Aminolevulínico/farmacologia , DNA de Cadeia Simples/efeitos dos fármacos , Compostos Ferrosos/farmacologia , Plasmídeos/efeitos dos fármacos , Antioxidantes/farmacologia , Dano ao DNA , DNA Circular/análise , DNA Super-Helicoidal/análise , DNA Super-Helicoidal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Escherichia coli/genética , Sequestradores de Radicais Livres , Humanos , Fígado/metabolismo , Ácido Pentético/farmacologia , Porfiria Aguda Intermitente/etiologiaRESUMO
In vitro DNA synthesis on single stranded templates damaged by singlet oxygen was investigated in the supF tRNA gene sequence, using several DNA polymerases. Singlet oxygen was generated by the thermal decomposition of the water soluble with the endoperoxide of disodium 3,3'-(1,4-naphthylidene) dipropionate (NDPO2). The data demonstrated that damage at deoxyguanosine residues interrupts DNA polymerization. Modified T7 phage and Thermus aquaticus DNA polymerases were found to synthesize DNA fragments which terminated opposite deoxyguanosine, while T4 phage DNA polymerase and avian myeloblast virus reverse transcriptase were blocked one nucleotide 3' to deoxyguanosine positions on the template. DNA polymerase I (Klenow fragment) from Escherichia coli was inhibited at both positions, before and at the putative damaged sites. The blocking lesions, induced by 5 mM NDPO2, were estimated to be approximately 1.5 per 260 nucleotides, corresponding to 2% of deoxyguanosines. The distribution of lesions in the supF gene did not reveal any specific sequence context which showed distinct susceptibility to the attack of singlet oxygen.