Antisalmonella Activity and Modes of Action of Extracts, Fractions and Cerevisterol from Impatiens burtonii against Multi-Drug Resistant Salmonella

Background: Typhoid fever is an endemic disease in developing countries, especially throughout Asia and Africa, which may lead to life-threatening conditions in the absence of adequate treatment.

Objective: This study was aimed at determining the in vitro activity of the crude extracts, fractions and compounds of Impatiens burtonii against drug sensitive and multidrug-resistant Salmonella strains.

Methods: Moreover, the modes of action of the most active compound, cerevisterol (1) were investigated on Salmonella TyphiATCC6539.The in vitro antisalmonella activity of the samples was evaluated by the broth microdilution method. Catalase Activity was done by measuring the high of the foam in the presence of hydrogen peroxide. Bacteriolysis, time kill-assay, nucleic acid and protein leakage potential of cerevisterol were carried out through spectrophotometric methods. Finally, time kill-assay and proton-ATPase pump activity were determined by bacterial count and pH measurement, respectively.

Results: The In vitro antisalmonella activity revealed that the hydroethanolic 75% crude extract of Impatiens burtonii showed the highest antisalmonella activity, with minimal inhibitory concentration (MIC) ranging from 32 to 512 μg/mL. Among the fractions of that extract, the dichloromethane (DM) fraction exhibited the highest activity, with MIC ranging from 16 to 32 μg/mL. Cerevisterol (1) isolated from the DM extract was the most active compound (8 ≤ MIC≤ 128 μg/mL). This study showed that cerevisterol is bacteriostatic against Salmonella Typhi. Moreover, cerevisterol induced the release of the nucleotides, inhibited H+-ATPase proton pumps, and reduced the catalase activity of Salmonella Typhi ATCC6539.

Conclusion: Finally, this study allowed to identify cerevisterol as a good candidate to tackle typhoid fever infections and mainly that caused by MDR (multidrug-resistant) strains.