Comparative Antibacterial Efficacy and Phytochemical Characterization of Camellia Sinensis (Green Tea) Extracts against Clinically Important Bacterial Pathogens

Abstract

The increasing prevalence of antibacterial resistance has sped up the search for safe and effective natural alternatives to conventional antibiotics. Bioactive phytochemicals with antibacterial and antioxidant properties, such as polyphenols, flavonoids, and catechins, are abundant in green tea, or Camellia sinensis. The goal of the current study was to evaluate the phytochemical composition and in vitro antibacterial activity of green tea extracts in aqueous, methanolic, acetone, and hexane against clinically important bacterial pathogens, namely Escherichia coli, Pseudomonas spp., and Staphylococcus aureus. Qualitative phytochemical analysis revealed proteins, flavonoids, and tannins but not carbohydrates or saponins. Antibacterial activity at different extract concentrations was measured using the agar well diffusion technique. Acetone and methanolic extracts demonstrated comparatively greater antibacterial activity against all three bacterial strains, while hexane extract had the least inhibitory effect of the extracts under investigation. The aqueous extract also showed significant antibacterial activity, particularly against S. aureus and E. coli. The increased inhibitory activity with increasing extract concentration showed a concentration-dependent antimicrobial response. The reported antibacterial action is likely related to the presence of bioactive polyphenolic compounds that may prevent bacterial growth. These findings indicate that green tea extracts have strong antibacterial activity and may be effective natural antimicrobial agents against both Gram-positive and Gram-negative bacteria. To confirm their therapeutic potential, more research comprising the isolation of active compounds, the calculation of minimum inhibitory concentrations (MIC), toxicity assessment, and in vivo tests is advised.