The investigation on the potency of unripe banana (Musa sapientum L.), lemon grass (Cymbopogon citratus S.) and turmeric (Curcuma longa L.) was carried out against pathogens. The formulations were in the powder form as used locally. The antimicrobial activity of these plants was examined using different solvents and efficacy was compared. The solvents were ethanol (70%, v/v) and water. Antimicrobial activity was carried out by the agar well diffusion method. The clinical isolates include aerobic, facultative bacteria namely: Stapyhlococcus aureus ATCC 25921, S. aureus, Salmonella paratyphi, Shigella flexnerii, Escherichia coli ATCC 25922, E. coli, Klebsiella pneumoniae, Bacillus subtilis and Pseudomonas aeruginosa. Crude extracts of the solvents varied in zones of inhibition. All the Gram-positive bacteria (S. aureus, S. aureus ATCC 25921 and B. subtilis) and all Gram-negative bacteria (E. coli ATCC 25922, E. coli, P. aeruginosa, S. paratyphi,S. flexneri and K. pneumonia) were susceptible to ethanolic extracts of unripe banana, lemon grass and turmeric while some namely E. coli ATCC 25922, E. coli,P. aeruginosa and S. flexneri were not susceptible to aqueous extracts of the three medicinal plants. The minimum inhibition concentration (MIC) ranged from 4 – 512 mg/ml while the minimum bactericidal concentration (MBC) ranged from 32 – 512 mg/ml depending on isolates and extracting solvent. Ethanolic extracts showed greater antimicrobial activity than aqueous extracts. The killing rate of the extracts varied. Unripe banana had less than 2 h killing time for S. aureus ATCC 25921, turmeric less than 3 h for E. coli while lemon grass had more than 3 h killing time for S. paratyphi.
Key words: Antimicrobial activity, unripe banana, lemon grass, turmeric, death rate.