Background: The rise of antibiotic resistance among pathogenic bacteria, particularly Klebsiella pneumoniae resistant to β-lactam antibiotics, poses a major challenge to global healthcare systems. Natural products with antibacterial properties may offer alternative therapeutic options.
Materials and Methods: This study evaluated the antibacterial activity of ethanolic and propanolic extracts of Terminalia chebula fruit against a β-lactam-resistant K. pneumoniae strain. Catalase inhibitory activity was assessed qualitatively, and phytochemical profiles were determined using gas chromatography–mass spectrometry (GC–MS). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using standard assays.
Results: Antibiotic susceptibility tests confirmed complete resistance of the bacterial strain to all tested β-lactam antibiotics. Both extracts inhibited bacterial growth at a concentration of 12.5 mg/mL dilution (MIC) and eradicated the bacteria at a 25 mg/mL dilution (MBC). Catalase activity was fully inhibited at concentrations as low as 6.25 mg/mL. Gas GC–MS analysis revealed that 1, 2, 3-benzenetriol (pyrogallol) was the dominant compound in the ethanolic extract, while the propanolic extract contained several bioactive compounds, notably D-limonene. Both compounds are known catalase inhibitors, promoting reactive oxygen species (ROS) accumulation and impairing bacterial antioxidant defenses.
Conclusion: T. chebula extracts exhibit potent antibacterial effects against β-lactam-resistant K. pneumoniae, primarily by inhibiting catalase and inducing oxidative stress. The presence of bioactive phytochemicals such as pyrogallol and D-limonene likely contributes to these effects, either individually or synergistically. These findings highlight the potential of T. chebula as a natural adjunct therapy for combating drug-resistant bacterial infections.