ABSTRACT
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'-(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.