In-vitro anti-salmonella activity of methanol and aqueous extracts and their associations of Psidium guajava and Carica papaya leaves

Abstract

Background: Typhoid fever is a major public health problem and endemic especially in some developing countries. The present study was aimed at determining the anti-salmonella potentials of Psidium guajava (PG) and Carica papaya (CP) leaves extract association in-vitro. Methods: The plant materials were extracted both in methanol and water separately. The methanol extract was concentrated using a rota-evaporator while the aqueous was dried in an oven. Phytochemical screening was done for the presence of alkaloids, phenols, flavonoids, steroids, triterpenoids, tannins, saponins, anthocyanins, and anthraquinons. The Salmonella strains were screened for susceptibility to P. guajava and C. papaya extracts using micro well dilution checkerboard test with colorimetric para-iodonitrotetrazolium chloride (INT) as revelator to obtain the Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC). Results: The results obtained showed the presence of alkaloids, phenols, flavonoids, steroids, triterpenoids, tannins, saponins, and anthraquinons secondary metabolites. The MIC of the methanol extract was 64 µg/mL for CP+PG and its MBC was 128 µg/mL. CP methanol extracts showed higher salmonella activities than PG methanol extracts with the most sensitive Salmonella typhi isolate S66 exhibiting the lowest MIC of 64 µg/mL. Synergic effects were observed with the association of CP + PG in 4 of the 10 salmonella studied strains/isolates. The FICCP was lower than FICPG in all the studied strains/isolates. Conclusion: This study demonstrated that the CP methanol extract used in single or in association with PG could be used to develop phytomedicines against salmonella infections which are natural, readily available to all citizens, cheap, non-toxic with minimal side effects but contain active ingredients which can be used in the pre-formulation of phytodrug to fight against typhoid in our community.