The use of dietary
flavonoids as potential chemopreventive agents is a concept of increasing interest. Recent findings indicate that methylated
flavones have the advantage of increased metabolic stability. One such compound, the naturally-occurring
5,7-dimethoxyflavone (5,7-DMF), has been shown to be a potential chemopreventive agent in human
cancer originating from the liver, mouth, esophagus and lung. As bioavailability is a key issue for potential in vivo effects, the tissue accumulation and biliary elimination of 5,7-DMF and its non-methylated analog
chrysin were examined in a small fish model (Fundulus heteroclitus). The fish were exposed to 5,7-DMF,
chrysin or vehicle control (
DMSO<0.01%) in seawater for 8h. Toxicity was not observed at the 5microM exposure level. Tissues and bile were harvested and analyzed by HPLC and LC/MS for quantitation and identification of parent compound and metabolites. 5,7-DMF accumulated 20-fold to 100-fold in all tissues examined, with the highest accumulation in liver and brain, whereas
chrysin was barely detectable in any tissues except the liver. The bile of
chrysin-exposed fish contained very low concentrations of unchanged
chrysin but high concentrations of two
glucuronic acid conjugates. In the bile of 5,7-DMF-exposed fish, the parent compound was detectable in significant amounts along with
glucuronic acid conjugates of O-demethylated 5,7-DMF. In conclusion, our study demonstrated high tissue accumulation and limited metabolism of 5,7-DMF compared to
chrysin in vivo, making this
flavone a promising chemopreventive molecule.