Avaliação da atividade da isatina-3-N4-benziltiossemicarbazona (IBTC) como antioxidante na proteção da LDL contra a oxidação

Abstract

Several lines of evidence support the hypotheses that the oxidation of low density lipoprotein (LDL) is a proatherogenic factor. Oxidative stress is one of the causes of the overproduction of reactive species that increase the formation of oxidized LDL. Thiosemicarbazones are compounds used in anticancer, antiviral and antifungal therapy; however, their redox activities have been controversial. Thus, we tested, in vitro, the possible antioxidant activity of a thiosemicarbazone derivate, the isatin-3-N4-benzilthiosemicarbazone (IBTC). We measured the conjugated diene formation in serum and LDL induced by two oxidant agents, 2,2-azobis(2-amidinopropane dihydrochloride) (AAPH) and Cu2+, as well as the loss of tryptophan fluorescence in LDL induced by Cu2+. The total reactive antioxidant potential (TRAP), Thiobarbituric acid reactive substances (TBARS) formation in human LDL and plasma and in different rat tissues was also assessed. The toxicity of IBTC was measured using aortic slices viability assay. The results show that IBTC reduced the formation of conjugated dienes AAPH and Cu2+- induced increased in a dose-dependent manner the lag phase. IBTC also prevented the tryptophan fluorescence loss, and reduced the TBARS formation in LDL, plasma and rat tissues, showing no toxicity to aortic slices. These data indicate that IBTC is a good antioxidant and a promising antiatherogenic agent for further studies in vivo.