Antibacterial Activity of Papaya (Carica papaya) Leaf and Seed Extracts Against Some Selected Gram-Positive and Gram- Negative Bacteria

Abstract

Background: Medicinal plants are well-known natural sources of remedies, used in the treatment of innumerable diseases since antiquity. Wide range of medicinal plant extracts are used to treat several infections as they have potential antimicrobial activity. Objectives: This study was aimed to investigate antibacterial activity of Carica papaya leaf and seed with different solvents against Gram negative and Gram positive bacteria. The leaves and seeds of Carica papaya were dried, powdered and extracted with 80% of Acetone, Ethanol, Methanol and water. Disc diffusion method was used for the antibacterial assay and measuring the zone of inhibition, and the MIC was determined by broth macro dilution method. Results: The highest percent yield of crude extract72.5% was obtained from Carica papaya leaf with Methanol, Ethanol and Acetone as solvents while, the lowest yield 24% was obtained from Carica papaya seed with Acetone extract. All Crude extracts from the different plant parts showed antibacterial activity. Accordingly, Carica papaya Seed with Ethanol extract exhibited the highest antibacterial activity 14.3±1.2 (mm) against P. aeruginosa which was lower than standard antibiotic disc Ciprofloxacin with inhibition zone of 25.9 ±0.00 (mm), while the lowest inhibition of 3.8±0.5 (mm) was recorded from Carica papaya leaf with Ethanol crude extract against E. coli. The MIC of 12.5mg/ml was observed from Ethanol crude extract of Carica papaya seed on P. aeruginosa. Crude seed extract of Ethanol showed the highest antibacterial activity. The results of the antibacterial assay of the crude extract of Carica papaya (leaf and seed) with four different solvents showed zone of inhibition against all tested bacteria. However, among the plant parts of Carica papaya included in the current study, the seed of Carica papaya were found to be the best source of antibacterial agents. Conclusion: In this study, limited (only leaf and seed parts) of Carica papaya was tested for its antimicrobial activity. So, the same work should be carried out on different parts of Carica papaya plant like; bark, root, flower and fruits on antibacterial activities so, as to have a clear picture of the spectrum of antibacterial activity of the plant.