RESUMO
Antibiotic resistance poses a great threat to human, animal and environmental health. ß-Lactam antibiotics have been successful in combating bacterial infections. However, the overuse, inappropriate prescribing, unavailability of new antibiotics and regulation barriers have exacerbated bacterial resistance to these antibiotics. 1,4,7-Triazacyclononane (TACN) is a cyclic organic tridentate inhibitor with strong metal-chelating abilities that has been shown to inhibit ß-lactamase enzymes and may represent an important breakthrough in the treatment of drug-resistant bacterial strains. However, its cytotoxicity in the liver is unknown. This study aimed to determine the effect of TACN on oxidative stress in HepG2 cells. The HepG2 cells were treated with 0 to 500 µM TACN for 24 hours to obtain an IC50 for use in subsequent assays. Free radicals were measured using the thiobarbituric acid reactive substance and nitric oxide synthase assays, respectively, while antioxidant levels were assessed using luminometry (glutathione [GSH] and adenosine triphosphate [ATP]) and Western blot analysis (SOD, catalase, GPx-1, HSP70 and Nrf2). Percentage survival fluctuated as TACN concentration increased with a calculated IC50 of 545 µM. A slight increase in HSP70 and Nrf2 expression indicated the presence of stress and a response against it, respectively. However, free radical production was not increased as indicated by decreased malondialdehyde levels and reactive nitrogen species. Glutathione levels increased slightly, while ATP levels were marginally altered. The results suggest that TACN does not induce oxidative stress in HepG2 cells and can be exploited as a potential inhibitor.
