Enhancement of antibacterial efficacy of Norfloxacin through biotransformation by Saccharomyces cerevisiae

Abstract

Fluoroquinolones, a class of synthetic antibiotics for bacterial infections, target DNA replication via topoisomerase IV and DNA gyrase. The emergence of fluoroquinolones marks a notable progress in the field of antibiotic treatment. Despite efficacy of fluoroquinolones, resistance and adverse reactions drive the need for novel antibiotics. This study aims to investigate norfloxacin biotransformation using Saccharomyces cerevisiae. Biotransformation experiments involved fermenting fluoroquinolones (4mg/mL), ciprofloxacin, moxifloxacin, levofloxacin, and norfloxacin with S. cerevisiae in a medium (50 mL) containing 10% W/V glucose as the source of energy for dry S. cerevisiae (3g). Control experiments (fluoroquinolones treated with glucose and fluoroquinolones treated with sterile distilled water) were conducted to eliminate the potential influence of glucose or water exposure on fluoroquinolones. Solutions lacking an antibiotic component served as the negative control which was used to exclude any antibacterial effect of metabolites of S. cerevisiae. Freshly prepared fluoroquinolones (4mg/mL in distilled water) served as the positive controls of antibacterial assay. The antibacterial activity was assessed using the agar disk diffusion method. Antibacterial assays against Staphylococcus aureus demonstrated larger inhibition zones (24.7 mm ± 1.15) for fermented norfloxacin (5 μL per disc) when compared with the inhibition zone diameters (15-16 mm) of positive control and other control experiments of norfloxacin. However, the antibacterial efficacy against S. aureus remained unchanged with other tested fluoroquinolones upon fermentation. The negative control demonstrated no inhibition of S. aureus. This study concluded the role of S. cerevisiae in possible biotransformation of norfloxacin. The observed changes in norfloxacin's potency require further investigations through techniques like NMR spectroscopy, and future research should be extended for antibacterial activity assessments against diverse bacterial strains.