Protective role of VitC, Glutathione and Sodium Pyruvate against antibiotic-induced oxidative damage in Escherichia coli.

The increasing prevalence of antibiotic tolerance poses a significant challenge in the treatment of bacterial infections. This study investigates the inhibitory effects of commonly used antibiotics- Ciprofloxacin (CFX), Levofloxacin (LVX), and Ampcillin (Amp)-on exponentially growing Escherichia coli DH5α cells, and further explores the modulatory roles of antioxidants including Vitamin C(VitC), Glutathione, and Sodium pyruvate (Na-Pyr). Minimum inhibitory concentrations (MICs) were determined using the microplate Alamar Blue assay (MABA), revealing that fluoroquinolones (CFX and LVX) exhibited highest potency while Amp demonstrated moderate efficacy. Dose-dependent inhibition was observed for each antibiotic, with near-complete suppression of bacterial growth at higher concentrations. Interestingly, co-treatment with antioxidants significantly altered antibiotic performance. VitC enhanced the efficacy of CFX, LVX, and ampicillin. Glutathione increased the activity of CFX and also enhanced LVX and ampicillin efficacy, but primarily at lower concentrations. Na-Pyr showed minimal effect on CFX, while it increased the efficacy of LVX and Amp at lower concentrations. This suggests that these antioxidants may modulate redox homeostasis and amplify reactive oxygen species (ROS)-mediated stress, thereby boosting antibiotic lethality. Collectively, these findings highlight the contribution of oxidative stress to antibiotic action and suggest that co-treatment with specific antioxidants may serve as a promising strategy to improve therapeutic outcomes. This study adds to our understanding of exponentially growing cells susceptibility and antibiotic tolerance, revealing how metabolic and redox-modulating compounds can be leveraged to enhance bacterial killing.