Antisalmonellal Activity and GC-MS Analysis of Piliostigma thonningii leaf extract

Abstract

Typhoid fever is a serious bacterial infection which causes bacteremia and inflammatory destruction of the intestine and some internal organs in the body. The widespread emergence of multi-drug resistant Salmonella typhi and Salmonella paratyphi has necessitated the search for other therapeutic options. The study was conducted to screen the antisalmonellal activity of Piliostigma thonningii leaf crude extract, fractions and isolated compounds. Methods: The plant leaves were extracted with 70% methanol, the crude extract was partitioned into fractions and was tested for antibacterial activity against S. typhi, S. paratyphi A, S. paratyphi B and Salmonella paratyphi C using agar well diffusion technique. Column and thin layer chromatographic methods were used for phyto-constituent separation of plant extract. The most effective antisalmonellal column chromatography isolated compound was subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Results: The crude extract and the fractions except n-hexane fraction possess antibacterial activity on at least one of the Salmonella strains tested, however, the ethyl acetate fraction (PT1-03) exhibited the widest zone of inhibition on the test bacteria (14-16 mm) at the concentration of 100 mg/ml. The zones of growth inhibition increased with the increasing concentration of the fractions. The corresponding increase in concentration and growth inhibition zone was significant (p<0.05). The isolated compound obtained from the column chromatography also showed significant inhibition on the Salmonella strains (12-15 mm) at the concentration of 50 mg/ml. GC-MS analysis of the column chromatography isolates revealed Levomenthol and hexadecanoic acids as the major compounds. Conclusion: The study clearly indicates that P. thonningii possesses bioactive compounds that are active against some Salmonella species. Therefore, these phytochemicals can be formulated into drugs for the treatment of typhoid and paratyphoid fevers.