Effects of Antimicrobial Flavonoids Against Representative Bacteria and Fungi: A Review of the Literature.

Introduction:  Effective medications are becoming more necessary to combat the global rise in antimicrobial resistance. The findings that some flavonoids have antibacterial properties have urged interest in flavonoid research. The aim of this work was to investigate the inhibitory properties of fisetin, fisetinidin, 7,3`,4`-trihydroxyflavone (THF), and 7,3`,4`-trihydroxyflavonol (THF-) against selected pathogenic bacteria and fungi and to review the literature on relevant compounds.

Methods:  An in vitro experiment was performed on 19 organisms (gram-positive, gram-negative, and yeast fungi) using varying concentrations (100-1000 ug/mL) of fisetin, fisetinidin, THF, and THF-. Using the agar well diffusion method. The in vitro activity of flavonoid compounds against gram-positive, gram-negative, and yeasts was assessed using a serial dilution of the four compounds against organism suspensions (50 µL of 0.5 McFarland). Inoculated agar plates were incubated aerobically at 37C. The results of inhibition were recorded after 24, 48, and 72 hours.

Results: Various classes of flavonoids from different sources have been reviewed for their antimicrobial effects. They showed various inhibitory reactions against a plethora of gram-positive, gram-negative, and yeast organisms. In the present study, the selected four compounds have shown varying antibacterial effects, as have the reviewed flavonoids from the literature. With minimum inhibitory concentrations (MICs) ranging from 100 ug/mL to 1000 ug/mL, the substances fisetin, fisetinidin, THF, and THF- demonstrated inhibitory action against the examined species. The main activity was against , , , , and species. Fisetin and fisetinidin did not inhibit , whereas THF and THF- exhibited inhibitory action.

Conclusions:  Flavonoids, a readily accessible dietary ingredient, remain a viable treatment option for infectious diseases. This study suggests that THF, THF-, fisetin, and fisetinidin may be helpful in stopping the growth of some pathogens, especially staphylococci. Improvements to flavonoids' pharmacokinetics and diffusion may encourage their use in therapy as an adjuvant to conventional medications.