RESUMO
We examined the effect of trimidox (3,4,5-trihydroxybenzamidoxime) on the production of nitric oxide (NO) by lipopolysaccharide (LPS) in mouse RAW 264.7 macrophages. Trimidox (50 - 300 microM) concentration-dependently inhibited NO production by LPS (0.01, 0.1, or 1 microg/ml) after incubation for 24 h. LPS-induced expression of inducible NO synthase (iNOS) and degradation of IkappaBalpha were prevented by trimidox. The protective effect against NO production by LPS was not only observed in prior incubation but also later incubation with trimidox until iNOS was activated by LPS. These results suggest that trimidox has a predominantly protective effect against LPS-induced production of NO via iNOS expression.
Assuntos
Benzamidinas/farmacologia , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Óxido Nítrico/biossíntese , Actinas/metabolismo , Animais , Western Blotting , Proteínas I-kappa B/metabolismo , Macrófagos/efeitos dos fármacos , Camundongos , NF-kappa B/metabolismo , Óxido Nítrico Sintase Tipo II/biossíntese , Sais de Tetrazólio , TiazóisRESUMO
Trimidox (3,4,5-trihydroxybenzamidoxime) is one of the most potent ribonucleotide reductase inhibitors, revealing an antitumor effect in several experimental studies. We have examined the effect of trimidox on the induction of cytotoxicity and apoptosis via oxidative stress by typical free radical inducers, hydrogen peroxide (H(2)O(2)), tert-butylhydroperoxide (tBuOOH) or ultraviolet (UV) irradiation in a human diffuse histiocytic lymphoma U937 cell line. Trimidox showed strong radical scavenging activity by the DPPH reduction assay. The 50% rate inhibited the DPPH reduction concentration of trimidox, and its derivates didox, or gallic acid were 8.8 microM, 117.5 microM, or 41.8 microM, respectively. Induction of cytotoxicity by H(2)O(2) (500 microM) or tBuOOH (100 microM) was concentration-dependently attenuated by incubation with Trimidox (10-150 microM). Trimidox also prevented the effect of UV-induced apoptosis estimated by both nuclear morphological change and DNA fragmentation. This effect was due to inhibition of the production of reactive oxygen species. Moreover, the activity and mRNA expression of catalase, an antioxidant enzyme, was significantly increased by trimidox. These results indicate that trimidox has radical scavenging activity and prevents exogenous oxidative stress and increase in catalase; therefore, trimidox is suggested as an anticancer agent exhibiting potent antioxidant properties in this study.
