Antimicrobial Activities and Mode of Flavonoid Actions.

The emergence of antibiotics-resistant bacteria has been a serious concern for medical professionals over the last decade. Therefore, developing new and effective antimicrobials with modified or different modes of action is a continuing imperative. In this context, our study focuses on evaluating the antimicrobial activity of different chemically synthesized flavonoids (FLAV) to guide the chemical synthesis of effective antimicrobial molecules. A set of 12 synthesized molecules (4 chalcones, 4 flavones and 4 flavanones), bearing substitutions with chlorine and bromine groups at the C6' position and methoxy group at the C4' position of the B-ring were evaluated for antimicrobial activity toward 9 strains of Gram-positive and Gram-negative bacteria and 3 fungal strains. Our findings showed that most tested FLAV exhibited moderate to high antibacterial activity, particularly against with minimum inhibitory concentrations (MIC) between the range of 31.25 and 125 μg/mL and that chalcones were more efficient than flavones and flavanones. The examined compounds were also active against the tested fungi with a strong structure-activity relationship (SAR). Interestingly, leakage measurements of the absorbent material at 260 nm and scanning electron microscopy (SEM) demonstrated that the brominated chalcone induced a significant membrane permeabilization of .