The Antibacterial Activity of Dioscorea alata L. Tuber Extract Using the Agar Well Diffusion Method

Abstract

The growing emergence of antibiotic-resistant pathogens highlights the need for alternative antimicrobial agents from plant sources. This study evaluated the in vitro antibacterial activity of the tuber extract of Dioscorea alata L. using the agar well diffusion method. A crude extract (100 mg/mL in DMSO) was tested at concentrations of 0.5–2.5 mg per well (5–25 µL) against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella sp., and Salmonella typhi. Streptomycin and DMSO served as positive and negative controls, respectively.

The extract exhibited selective antibacterial activity. No inhibition was observed against S. aureus and Klebsiella sp. Moderate activity was recorded against B. subtilis (maximum 10 mm at 25 µL), P. aeruginosa (maximum 11 mm at 20 µL), and S. typhi (maximum 13 mm at 25 µL), showing a generally concentration-dependent response. Streptomycin produced larger inhibition zones (18–22 mm), while DMSO showed no activity.  Although the activity was lower than that of streptomycin, the extract showed promising antibacterial effects, suggesting its potential as a natural antimicrobial source and the need for phytochemical investigation to identify the active principles responsible for the observed activity.