Antisamonellal Property and Modes of Action of Leaf Extracts of Dracaena deisteliana Engl. (Dracaenaceae)

Abstract

Background: In Cameroon, typhoid fever is after malaria, the disease with which health workers are most confronted because its incidence is constantly increasing. Salmonella has become over time multiresistant to antibiotics available on the market, for this reason, it becomes imperative to use drugs made from extracts of parts of medicinal plants consisting of several secondary metabolites at the origin of their good efficacity. Objective: Determine whether the aqueous and hydroethanolics leaf extract of Dracaena deisteliana have in vitro antisalmonellal activities, and to determine the site of action of the most active extract on Salmonella Typhi strain (ATCC6539). Methods: To do this, the in vitro antisalmonellal activity of aqueous and hydroethanolics leaf extracts of Dracaena deisteliana was evaluated by the liquid microdilution method. The modes of action of the 55% hydroethanolic leaf extract of Dracaena deisteliana was also done in order to verify the sites of action of this extract. Results: The in vitro antisalmonellal activity revealed that the decocted and 55% hydroethanolic leaf extract of Dracaena deisteliana presented MICs of 256 and 128 μg/ml respectively on the Salmonella Typhi (ATCC6539) strain on which they were tested. Phytochemical analysis revealed the presence of steroids, terpenoids, tannins, phenols, and saponins in aqueous and hydroethanolics leaf extracts of Dracaena deisteliana. The modes by which the 55% hydroethanolic leaf extract of Dracaena deisteliana inhibits the growth of Salmonella, were studied by following bacterial decay, bacteriolysis, inhibition of biofilms, inhibition of ATPASES-H+ proton pumps, protein synthesis and biofilm formation. The study of growth kinetics on the Salmonella Typhi strain (ATCC6539) showed that at all concentrations (2MIC, MIC and 1/2MIC), the 55% hydroethanolic leaf extract of Dracaena deisteliana induced the inhibition of bacterial ATPASES-H+ proton pumps. This extract also inhibits the formation of biofilms from 28 to 72% and prevents the synthesis of Salmonella Typhi strain (ATCC6539) proteins. Conclusion: Aqueous and Hydroethanolics leaf extracts of Dracaena deisteliana possess in vitro antisalmonellal activities.