Comparative Evaluation of Locally Sourced and Commercially Packaged Zingiber officinale Methanolic Extracts against Pathogenic Bacteria

Abstract

Antibiotic resistance has increased interest in plant-derived antibacterial agents. This study compared the antibacterial activity of methanolic extracts prepared from locally sourced dried ginger (Zingiber officinale) and commercially packaged ginger powder. Each sample (50 g) was extracted with 500 mL methanol, concentrated, and prepared at 12.5, 25, 50, 100, 200, and 400 mg/mL in dimethyl sulfoxide. Antibacterial activity was assessed by the agar well diffusion method against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhi, and Salmonella paratyphi. Both extracts produced measurable, generally concentration-dependent inhibition against all tested organisms. The locally sourced extract produced its largest zone of inhibition against S. paratyphi at 400 mg/mL (20.67 ± 0.58 mm), followed by S. aureus (18.00 ± 1.00 mm). At the same concentration, the commercial extract produced its largest zones against S. aureus (17.33 ± 2.08 mm) and E. coli (17.33 ± 0.58 mm). The locally sourced extract showed greater peak activity, whereas the commercial extract displayed comparatively consistent activity across several concentrations, particularly against E. coli and S. typhi. These findings demonstrate that both ginger preparations possess in vitro antibacterial activity and that source and processing conditions may be associated with differences in inhibitory performance. Further evaluation using chemically characterised extracts and additional antibacterial endpoints is required before practical application can be considered.