Antibacterial effect of crude methanol Carica papaya L. (papaya) extract and amoxicillin combination.

Bridge Mwesigwa, Genny Dominguez Montero, Miriela Betancourt Valladares, Victoria Katawera, David Nkwangu, Joseph Openy Oweta Noah

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Background: the emergence of multi-drug resistant bacteria and the diseases caused by them are a serious threat to global health necessitating an urgent need for new approaches to combat them. Synergy studies of conventional antimicrobial drugs and medicinal plants with antibacterial effects are important to establish whether it is prudent to recommend their concurrent administration to get successful treatments.

Objective: evaluate the antibacterial effect resulting from the combination of Carica papaya (papaya) and amoxicillin.

Methods: the papaya methanol extract was obtained from seeds and phytochemical screening was done. Checkerboard assay was used to determine the Minimum Inhibitory Concentration. Combined effect of both Carica papaya methanol extract and amoxicillin was determined by calculating the Fractional Inhibitory Concentration index. Strains of Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 were used in the tests.

Results: phenols and tannins were found in the Carica papaya seed methanol extract. The minimum inhibitory concentration of Carica papaya extract was 100 µg/mL for both microorganisms studied which was higher than the Minimum Inhibitory Concentration of amoxicillin being 3.12 µg/mL for Escherichia coli and 0.2 µg/mL for Staphylococcus aureus. The Fractional Inhibitory Concentration of the combination of drugs was 0.99 for Escherichia coli and 2.51 for Staphylococcus aureus.

Conclusions: the antibacterial effect of Carica papaya extract may be attributed to the presence of phenolic compounds. There was no interaction between amoxicillin and Carica papaya extract on Staphylococcus aureus, but the antimicrobial activity against Escherichia coli of both drugs can be potentiated by their additive interaction.