Chalcones are potent inhibitors of aromatase and 17β-hydroxysteroid dehydrogenase activities

Chalcones were tested for estimating anti-aromatase, anti-3 beta -hydroxysteroid dehydrogenase Delta (5)/Delta (4) isomerase (3 beta -HSD) and anti-17 beta -hydroxysteroid dehydrogenase (17 beta -HSD) activities in human placental microsomes. In the present study, we have demonstrated for the first time that chalcones are potent inhibitors of aromatase and 17 beta -hydroxysteroid dehydrogenase activities: these enzymes being considered as important targets in the metabolic pathways of human mammary hormone-dependent cells. Our results showed that naringenin chalcone and 4-hydroxychalcone were the most effective aromatase and 17 beta -hydroxysteroid dehydrogenase inhibitors with IC50 values of 2.6 and 16 muM respectively. In addition, inhibitory effects of some flavones and flavanones were compared to those of the corresponding chalcones. A structure-activity relationship was established and regions or/and substituents essential for these inhibitory activities were determined. (C) 2001 Elsevier Science Inc. All rights reserved.