Aromatase and 17beta-hydroxysteroid dehydrogenase inhibition by flavonoids

Cancer Lett. 1998 Nov 13;133(1):101-6. doi: 10.1016/s0304-3835(98)00211-0.


A method for estimating in the same assay both aromatase and 17beta-hydroxysteroid dehydrogenase activities in human placental microsomes using radiolabelled [1,2,6,7-3H]4-androstene-3,17-dione was proposed. In this assay, estrone (E1) and estradiol (E2) produced were separated by HPLC and estimated using a radioactive flow detector. Using this method, the inhibitory effect of various flavonoids, including flavone, flavanone and isoflavone, on the human placental aromatase and 17beta-hydroxysteroid dehydrogenase was studied. Flavonoids were shown to be potent inhibitors of both aromatase and 17beta-hydroxysteroid dehydrogenase activities. We found that 7-hydroxyflavone and apigenin are the most effective aromatase and 17beta-hydroxysteroid dehydrogenase inhibitors, respectively. Experiments showed that a hydroxyl group in position 7 was essential for anti-17beta-hydroxysteroid dehydrogenase activity. However, flavonoids with 7-methoxy or 8-hydroxyl groups on the A ring showed only anti-aromatase activity. Structure-activity relationships were discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 17-Hydroxysteroid Dehydrogenases / antagonists & inhibitors*
  • Aromatase Inhibitors*
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology*
  • Female
  • Flavonoids / pharmacology*
  • Humans
  • Pregnancy
  • Structure-Activity Relationship


  • Aromatase Inhibitors
  • Enzyme Inhibitors
  • Flavonoids
  • 17-Hydroxysteroid Dehydrogenases