Induction of monooxygenase and transferase activities in rat by dietary administration of flavonoids

Xenobiotica. 1989 Dec;19(12):1379-86. doi: 10.3109/00498258909043189.


1. The influence of the dietary flavonoids, chrysin, quercetin, tangeretin, flavone and flavanone, on the components of the rat liver drug-metabolizing enzyme system was examined and compared with two well-known synthetic flavonoids 7,8-benzoflavone and 5,6-benzoflavone. 2. Polyhydroxylated molecules such as quercetin and chrysin, produced no significant changes on phase I and phase II enzyme activities. 3. Flavone was the most potent inducer, and resulted in a mixed type of induction. 7-Ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin depentylase (PROD) activities were increased 2, 30 and 15-fold respectively. p-Nitrophenol UDP-glucuronyltransferase (UDPGT 1), p-hydroxybiphenyl UDP-glucuronyltransferase (UDPGT 2) and glutathione transferase (GST) activities were also induced. 4. Flavanone, which differs from flavone only by the degree of unsaturation of the pyrone ring, produced only a weak increase in monooxygenase activity, but the increase in phase II enzyme activities was as great as that for flavone treatment. 5. Tangeretin displayed a mixed pattern of induction, with increases in ECOD, EROD and PROD, and UDPGT 1 and UDPGT 2 activities, but these were less than with flavone treatment. 6. 7,8-Benzoflavone and 5,6-benzoflavone showed induction patterns similar to those of 3-methylcholanthrene. Nevertheless dietary treatment with 5,6-benzoflavone caused changes which were not as great as those usually described when this compound is administered i.p.

MeSH terms

  • Animals
  • Cytochrome P-450 CYP1A1
  • Cytochrome P-450 CYP2B1
  • Cytochrome P-450 Enzyme System / biosynthesis
  • Cytosol / drug effects
  • Cytosol / enzymology
  • Diet*
  • Enzyme Induction / drug effects
  • Flavonoids / pharmacology*
  • Glucuronosyltransferase / biosynthesis
  • Liver / drug effects
  • Liver / enzymology
  • Male
  • Microsomes, Liver / drug effects
  • Microsomes, Liver / enzymology
  • Mixed Function Oxygenases / biosynthesis*
  • Organ Size / drug effects
  • Oxidoreductases / biosynthesis
  • Rats
  • Rats, Inbred Strains
  • Transferases / biosynthesis*


  • Flavonoids
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Oxidoreductases
  • Cytochrome P-450 CYP1A1
  • Cytochrome P-450 CYP2B1
  • Transferases
  • Glucuronosyltransferase