ESTUDO DA INTERAÇÃO DOS QUIMIOTERÁPICOS ANTINEOPLÁSICOS IFOSFAMIDA E CICLOFOSFAMIDA COM O DNA, UTILIZANDO BIOSSENSORES ELETROQUÍMICOS.

Abstract

The use of the chemotherapy drugs, ifosfamide (IF) and cyclophosphamide (CP) have undesirable effects, such as cell death (cytotoxic) and damage to DNA cells (genotoxic), since DNA is the main target of attack by different types of compounds. Because of such effects, it is necessary to study the interaction of alkylating compounds with DNA. Therefore, the present work is based on the electrochemical interaction between IF and CP with dsDNA (double stranded Desoxyribonucleic Acid) in order to observe the possible damages caused in the dsDNA nitrogen bases. For this study, a modified glass carbon sensor with dsDNA and solutions incubated in dsDNA were employed. The interaction of the IF and CP compounds and their degradation products with dsDNA was investigated in vitro by differential pulse voltammetry (DPV) and evidenced by electrophoresis and alkaline comet. In the electrochemical study, a condensation of the polynucleotide chain, guanosine (dGua) and adenosine (dAdo) was observed, which compacted when interacting with the chemotherapeutic agent, making it difficult to appear on the surface of the electrode. Also, the emergence of new peaks were indicative of a strong interaction and possible intercalation of the IF and CP and their degradation products in the double strand of DNA respectively, in addition to modifying the conformation of the dsDNA bases. Free guanine was also observed in all interaction studies, since it is easily oxidized, being the main target of the damage caused by oxidation to the dsDNA. However, the non-appearance of the 8-oxoGua biomarker from the free guanine oxidation does not indicate that the compounds do not cause oxidative damage to dsDNA under the conditions evaluated, since IF and CP in vitro did not undergo the hepatic metabolization process through enzyme P450, rendering the oxidation of this biomarker inactive on the surface of the electrode. Electrophoresis and comet studies have demonstrated the absence of in vitro fragmentation (damage). The electrochemical behavior of the IF and CP, before and after the degradation in aqueous solution, were then studied; however, such compounds passivate the surface of the electrode, making it difficult to determine and/or to complete the electrochemical study. The dsDNA biosensor, applied at the same time to the study of the interaction with IF and CF, it was sensitive and selective for this study guaranteeing strong interaction with the nucleotides.