A flavonoid, quercitrin restores flavin-containing monooxygenase suppressed by nitric oxide in rats.

초록

It was shown that overproducing nitric oxide (NO) decreased the expressions and activities of flavin-containing monooxygenase (FMO), a hepatic drug metabolizing enzyme, in rats. Quercitrin (QCT), an edible flavonoid, was known to induce the expression of FMO. Therefore, we hypothesized that QCT restores FMO activity that has been suppressed by NO in rats. FMO activity was measured in rats by administering ranitidine (100 mg/kg), an in vivo probe for FMO activity. Urinary ranitidine N-oxide collected for 12 hr periods was analyzed by HPLC and indexed as the FMO activity. QCT (5 mg/kg), 4hr before administration of ranitidine, increased the FMO activity to 300% and lipopolysaccharide (LPS; 1 mg/kg), 6hr before administration of ranitidine, decreased to 50% in comparison to the levels measured in control animals. Treatments of both QCT and LPS restored the suppressed FMO activities to control levels. These results suggest that QCT-rich foods such as onions and tomatoes may be beneficial for individuals who suffer from hepatitis, cirrhosis or hepatic cancers with increased production of NO.