Antimicrobial Activity of Carica Papaya (Pawpaw Leaf) on Some Pathogenic Organisms of Clinical Origin from South-Western Nigeria

The bioactive compound of leaf and root extracts of Carica papaya was extracted, using water and organic solvents, and were investigated for antibacterial activity against some human pathogenic bacteria using the agar diffusion method. The aqueous extracts of the root extracts did not show significant activity, but the organic extracts had significant activity with the methanol extracts demonstrating the highest activity against the test bacteria. The root extracts demonstrated higher activities against all the gram-positive bacteria than the gram-negative bacteria tested, with the highest activity (14 mm zone of inhibition) demonstrated against Pseudomonas aeruginosa while the aqueous leaf extract showed pronounced inhibition demonstrating higher activities against the test bacteria than the organic solvents. The extracts demonstrated higher activities against all the gram-positive bacteria than the gram-negative bacteria tested, with the highest activity (4.2 mm zone of inhibition) demonstrated against Pseudomonas aeruginosa. Increase in temperature enhanced the activity of the extracts, while alkaline pH decreased the activity. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the root extracts ranged between 50-200 mg/ml. Preliminary phytochemical analyses showed that the extracts contain alkaloids, tannins, saponins, glycosides and phenols. Carica papaya may be used for the treatment of gastroenteritis, uretritis, otitis media and wound infections.