The influence of halogen substituents on the biological properties of sulfur-containing flavonoids

Abstract A series of halogen-substituted tricyclic flavonoids containing a 1,3-dithiol-2-ylium moiety has been synthesized from the corresponding 3-dithiocarbamic flavanones. The influence of halogen substituents on the antibacterial properties of the tricyclic flavonoids has been investigated against Staphylococcus aureus and Escherichia coli . On going from fluorine to iodine, these compounds exhibit good to excellent inhibitory properties against both Gram-positive and Gram-negative pathogens. These results suggest that size is the main factor for the change in potency rather than polarity/electronics.