Abstract:
In the different parts of Ethiopia Carica papaya is widely used for nutritional purpose and traditionally used to treat disease. The aim of this study was to quantitatively analyze the major secondary compounds of C. papaya and to evaluate antimicrobial properties of its leaf extract against S. aureus and E. coli. The leaf of C. papaya was shade dried, ground to powders, and extracted by using distilled water and ethanol. Total phenolic, alkaloids and terpenoids in the resulting extract were analyzed using standard procedures. Antibacterial activities and minimum inhibitory concentration of extracts against test pathogens were determined using Disc diffusion method and broth dilution method, respectively. The result showed that, ethanol extract of total alkaloids, total phenols and total terpenoids highly significant (P<0.05) which is 1.433±0.99 mg/g, 0.34±0.095 mg/g TAE and 0.14±0.05 mg/g, respectively. All the extracts showed antibacterial activities against the test pathogens. Ethanol and water extracts of C. papaya showed high antibacterial activities with significantly high zone of inhibition against S. aureus (11.91mm and 11.16mm) respectively at 200mg/mL while it showed lower zone of inhibition (7.57mm and 7.58mm) at lower concentration (125mg/mL) against E. coli. The data obtained from this experiment showed that C. papaya ethanol crude extract (against S. aureus) and C. papaya distilled water extract (against S. aureus) showed the least MIC of 30.38mg/mL and 45.14mg/mL, respectively. In contrast to this, C. papaya distilled water crude extract against S. aureus and C. papaya ethanol crude extract against E. coli showed the highest MIC (54.68 mg /ml and 54.88 mg/ml), respectively. Among the two crude extracts, ethanol extract of C. papaya showed relatively low MIC against S. aureus while ethanol crude extract showed relatively high MIC against E. coli. Generally, the results indicated the presence of important secondary metabolites in the plants under study in different quantities and medicinal potential of leaf extracts from the plant in treating some bacterial infections.
