The Chemo-preventive Ability of Quercetin and Isorhamnetin on Bromate- induced Cytotoxicity and Oxidative Stress May Involve Modulation of the Inflammatory Response

Abstract

The protective/preventive effects of quercetin and isorhamnetin on bromate-induced aberrations were studied. Cells were first incubated with either quercetin or isorhamnetin before exposure to bromate. Subsequently, cell viability and production of reactive oxygen species (ROS) were assessed. In the other investigation, U937-derived macrophages were incubated with either flavonoid before exposure to bromate. Subsequently, the production of pro-inflammatory markers and expression of the antioxidant enzymes; superoxide dismutase (SOD) and catalase (CAT) were also investigated. The findings reveal that bromate caused significant cytotoxicity, production of ROS, nitric oxide and cytokines when compared to untreated controls (p < 0.05). Bromate also reduced the expression of the antioxidant enzymes SOD and CAT. However, chemoprevention was observed when the cells were pre-incubated with either flavonoid which was concentration-dependent (p < 0.05). Pre-incubation of the cells with the flavonoids also reduced bromate-induced production of reactive oxygen species. The flavonoids also reduced bromate-induced production of nitric oxide and the cytokines in the U937-derived macrophages. The expression of the antioxidant enzymes was also enhanced following the pre-treatment of the macrophages with the flavonoids. Quercetin tends to be more active than isorhamnetin at reducing bromate-induced cytotoxicity and production of ROS. However, isorhamnetin tends to be better at reducing bromate-induced alterations on the production of NO and the pro-inflammatory cytokines but largely not significant. Isorhamnetin was also better at enhancing the expression of antioxidant enzymes than quercetin (p < 0.05).