Quercetin acts as an antioxidant and downregulates CYP1A1 and CYP1B1 against DMBA-induced oxidative stress in mice.

We investigated the effects of quercetin on 7,12-dimethylbenz(a)anthracene (DMBA)-induced oxidative stress and the expression of CYP1A1 and CYP1B1 in mice. Quercetin was administered orally to mice at 100 or 250 mg/kg BW for 18 days, after which DMBA (34 mg/kg BW) was administered intragastrically twice. Quercetin showed side effects such as increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in DMBA-untreated mice. Also, quercetin induced AST and ALT in DMBA-treated, although this was not significantly different from levels in DMBA-treated controls. The thiobarbituric acid reactive substances (TBARS) value showed a tendency to decrease following quercetin treatment; these decreases were significantly greater in the DMBA-treated compared to the untreated groups. Also, catalase and superoxide dismutase (SOD) activities as well as their mRNA expression were increased by quercetin; this increase was more pronounced in DMBA-treated compared to untreated mice. DMBA induced CYP1 activity as well as expression of CYP1A1 and CYP1B1. Each of these effects was significantly reduced by quercetin; however, this reduction was observed for CYP1A1 at only the higher dose and for CYP1B1 at both doses. These data suggest that quercetin shows antioxidant activity against DMBA-induced oxidative stress. Moreover, its regulation of CYP1A1 and CYP1B1 suggests the potential of quercetin as an anticancer supplement.