Examination of growth inhibitory properties of synthetic chalcones for which antibacterial activity was predicted

A large series of chalcones were synthesized and studied against Staphylococcus aureus and Escherichia coli. Chalcones were either unsubstituted in ring A or possessed 4′-chloro or 3′,4′,5′-trimethoxy groups. Their other ring B was variously substituted. It was found that the anti-staphylococcal activity of chalcones was related to the energy difference between the two highest occupied molecular orbitals (HOMO and HOMO-1). Presence of hydroxyl group in ring B was not a determinant factor for the anti-staphylococcal activity, but the lipophilicity of ring A of the hydroxyl chalcones was of importance. ▪Amongst a large series of synthetic chalcones, 2-hydroxychalcone and 3′,4′,5′-trimethoxy chalcones with electron withdrawing substituents at p-position in ring B were the most active towards S. aureus.