Antioxidant and Antibiotic-modulatory Potential of <i>Teucrium polium</i> Ethanolic Extract Against Genetically-modified Antibiotic-resistant <i>E. coli</i> Strains

Background and Aim:The ethanolic extract of Teucrium (T.) polium (TPE) was investigated for its phenolic and flavonoid content, antioxidant activity, and potential to modulate antibiotic efficacy against antibiotic-resistant E. coli strains. Materials and Methods:Antioxidant properties of TPE were evaluated by chemical-based tests application (total phenolic and flavonoid content, anti-radical activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) test).Antibacterial properties of TPE alone and in combination with antibiotics, as well as their effect on proton flux across the bacterial cell membrane were assessed.Results: TPE demonstrated significant antioxidant activity (IC50 = 73.89g/mL) and contained high levels of phenolic (181.7 2.1 mg GAE/g (gallic acid equivalents)) and flavonoid (95.4 3.1 mg QE/g (quercetin equivalents)) compounds.Although TPE exhibited no direct antibacterial effects against the tested microorganisms, it significantly enhanced the efficacy of ampicillin and kanamycin against these strains by decreasing minimum inhibitory concentration (MIC) of ampicillin and kanamycin twice.TPE reduced MIC values of both antibiotics and affected bacterial growth kinetics by reducing growth rates and prolonging lag phases in resistant E. coli strains.Furthermore, TPE influenced membrane-associated properties, specifically reducing proton flux in bacteria, which likely contributed to its modulatory effects.Moreover, in case of the kanamycin-resistant E. coli pARG-25 strain, proton flux was suppressed up to 50% under TPE influence and almost 70% with kanamycin-TPE combination. Conclusion:These findings demonstrated T. polium ethanolic extract as an effective antibiotic resistance modulator, offering a potential adjuvant therapy to combat bacterial resistance.Future research should be focused on identifying the specific bioactive compounds responsible for these effects and evaluating their therapeutic applicability.