Compostos de cobre como clivadores de DNA – Uma ferramenta para fins biotecnológicos

Abstract

Although cisplatin and platinum derivatives are effective anticancer agents, their side effects and its toxicity has limited its use in cancer chemotherapy. Therefore, studies have been made to replace this by new drug compounds based on metals with higher efficacy, lower toxicity and greater specificity. The copper compounds (Cu) are promising candidates for the next generation of anticancer drugs and have been extensively studied, whose activity can occur by the generation of free radicals leading to DNA damage. In order to investigate compounds based on copper which exhibit nuclease activity as a tool for selective degradation of DNA to analytical and therapeutic purposes has been carried out a series of studies using square complex planar Cu2+ containing 4 organic ligands (R1, R2, R3, R4). Plasmid pBR322 was used in the electrophoresis test on agarose gel, it is possible to show that the copper complexes were capable of cleaving the DNA after irradiation with light, interaction with glutathione (GSH) and hydrogen peroxide (H2O2), suggesting potential cytotoxic. Among the cleavage activators, GSH was more active than H2O2, where the DNA damage were quite intense, it is not even possible to observe remaining DNA bands in the gel. In order to elucidate the dynamics of cleavage of the complex of copper and reactive species which are involved in it, tests were made monitoring by absorption spectroscopy in the UV-vis range. For this, we used a mixture mixture under physiological conditions, containing Nitroblue Tetrazolium (NBT), specific agent for superoxide detection, copper complexes and GSH. Also analyzed was a mixture containing NBT copper complex and H2O2. In all assays containing the complex and GSH was noted the formation of NBT formazan by reaction with superoxide. These results suggest that the compounds have nuclease activity, and that one of the promoters would be possible superoxide. In the mixture containing copper complex and H2O2 wasn’t noted the formation of formazan, since the DNA cleavage test in these conditions pointed nuclease activity, the results suggest that the potential of promoter DNA cleavage when added H2O2 would be hydroxyl radical.