Structure-biological activity relationship of synthetic trihydroxilated chalcones

The bacteriostatic activity of 2',4',2-trihydroxychalcone; 2',4',3-trihydroxychalcone and 2',4',4-trihydroxychalcone, prepared by condensation of 2,4-dihydroxyacetophenone and benzaldehyde substituted, against Staphylococcus aureus ATCC 25923 was assayed by agar plate method. The three compounds presented important inhibition halos. In order to elucidate structure-activity relationships, the minimal inhibitory concentrations against S. aureus were determined by the broth dilution method and the results obtained were compared to that of 2',4'-dihydroxychalcone. The sequence observed was: MIC 2',4',3-(OH)(3) > MIC 2',4'-(OH)(2) > MIC 2',4',4-(OH)(3) > > MIC 2',4',2-(OH)(3). These results showed that the introduction of an electron donating group (-OH) in the aromatic B-ring causes an increase in bioactivity, and that the intensity of action depends on the position of the OH substitute.