Phytochemical Investigation of the Antisalmonellal Effect of Cyperus sphacelatus Rottb. (Cyperaceae)

Abstract

Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typhoid drugs are becoming more and more unavailable to most patients in Africa due to the increased costs and emerging drug resistance. Therefore, there is a need for the discovery of new antimicrobial agents to combat typhoid fever. Objective: This work aimed to investigate the bioactive components in Cyperus sphacelatus Rottb. (Cyperaceae) and test the antisalmonellal activity of the isolated compounds. Methods: Compound purification was done through column chromatography. Structure elucidation was accomplished based on the 1D and 2D NMR, IR and mass spectra. The biological assay was done using five bacterial strains, including Salmonella enterica subsp. enterica sérovars Typhi ATCC 6539 (STS), S. enterica subsp. enterica sérovars Typhi (ST), S. enteritidis (STE), S. enterica subsp. enterica sérovars Typhimurim (STM), and a resistant isolate of S. enterica subsp. enterica sérovars Typhi (ST566). Results: Three natural products were isolated from the methylene chloride extract of the rhizomes of C. sphacelatus, including a new furanoquinone, scabequinon-6(14)-ene (1) and two known compounds, cyperotundone (2) and vanillin (3). Compound 1 showed moderate antisalmonellal activity, with a minimal inhibitory concentration (MIC) of 32 μg/mL against STM and STS. The best inhibitory result was obtained with compound 2 on STM with a MIC of 8 μg/mL. Compound 2 also gave the best minimum bactericidal concentration (MBC) of 32 μg/mL on the STM strain. Conclusion: The discovery of the three antisalmonellal compounds from C. sphacelatus supports the addition of this plant to typhoid fever preparations.