However,

they strongly suggest additional targets because while NAC abolished ROS generation induced by QPhNO2 at 1 and 2 μM (Fig. 2), it did not inhibit the appearance of apoptotic features at the equal concentrations (Fig. 3 and Fig. 4). DNA is also recognized as a target of quinones. The cytotoxic effects of doxorubicin are generally related to its ability to damage cancer cell DNA, which is a consequence of its interaction and inhibition of DNA topoisomerase II, its induction of double-stranded DNA breaks, and its direct intercalation into selleck DNA, modifying helical torsion (Ozben, 2007). The comet assay is a sensitive and relatively simple technique to quantify DNA damage in individual cells (Singh et al., 1988). HL-60 cells treated with nor-beta

did not display any DNA damage in the tested time frame and dosage. QPhNO2 showed a different profile, with concentration-dependent damage and frequency of damage after 3 and 24 h of treatment, especially at higher concentrations (10 μM) (Fig. 6). Doxorubicin, as expected, was a very strong genotoxic compound, increasing the DNA damage index and frequency at 0.5 μM (Fig. 6). Thus, QPhNO2 directly interacts with DNA but at higher concentrations than those necessary to induce apoptosis. Electrochemical methods (analytical and preparative) and electrochemical (thermodynamic VE-821 clinical trial and kinetic) parameters have been shown to be extremely useful in biomedical chemistry with respect to the mechanisms of biological electron-transfer processes. The high versatility of electrochemical methodologies allows the mimicking of a large spectrum of biological environments (Hillard et al., 2008). With this in mind, electrochemical Adenosine proof of the pro-oxidant activity of QPhNO2 and nor-beta was assayed using cyclic voltammetry in the presence of oxygen in aprotic media, which provided a good model of the membrane environment in which peroxidation processes take place (Ossowski et al., 2000). The electrochemistry of both quinones

in aprotic media on GCE and mercury has already been reported (de Souza et al., 2010 and Hernández et al., 2008). A detailed study of the influence of oxygen concentration on EpIc and IpIc of both quinones was performed, as described previously for lapachol and isolapachol ( Goulart et al., 2003 and Goulart et al., 2004). The addition of O2 to the system caused remarkable changes to the position of the first reduction peak potential (EpIc) as well as to the shape of the other waves of QPhNO2 ( Fig. 7A). The peak of oxygen reduction (EpO2) in this medium occurred at −0.894 V. These effects include a) an increase in the height and anodic shift of the first cathodic wave (Ic) (inset, Fig. 7A, which is related to the generation of the semiquinone, and b) a disappearance of the corresponding anodic wave (Ia) ( Fig. 7A).