FLAVONOIDS OF HONEY AND PROPOLIS - CHARACTERIZATION AND EFFECTS ON HEPATIC DRUG-METABOLIZING-ENZYMES AND BENZO[A]PYRENE-DNA BINDING IN RATS

The influence of dietary sunflower honey, propolis, and a flavonoid ex tract of propolis was examined on drug-metabolizing enzyme activities in rat liver and on microsome-mediated binding of benzo[a]pyrene to DN A. Characterization of flavonoids present in sunflower honey and propo lis was achieved in order to assess the relative effects of different components of honey and propolis. Honey and propolis contained the sam e major flavonoids, pinocembrin, chrysin, galangin, and pinobanksin. T he concentration of flavonoids was higher in propolis. Sunflower honey produced no significant changes on phase I and phase II enzyme activi ties and no modification of in vitro binding of benzo[a]pyrene to DNA. Propolis treatment produced an increase of ethoxyresorufin deethylase , pentoxyresorufin depentylase, ethoxycoumarin deethylase, glutathione transferase, and epoxide hydrolase activities. A flavonoid extract fr om propolis slightly enhanced only few enzyme activities, ethoxycoumar in deethylase and epoxide hydrolase. The induction pattern was similar to that observed with pinocembrin (a major flavonoid of propolis) adm inistered solely. Binding of benzo[a]pyrene to DNA by microsomes from rats fed with propolis or a flavonoid extract from propolis was not si gnificantly modified. These results contribute to identification of fo od or foodstuffs that can modify drug-metabolizing enzymes and binding of carcinogens to DNA.