In Vitro Anti-salmonella Activity of Extracts from Selected Kenyan Medicinal Plants

Abstract

The aim of this study was to determine in vitro anti-salmonella activity of n-hexane, ethyl-acetate, methanol and water extracts of 5 selected Kenyan medicinal plants against 5 Salmonella typhi strains and Salmonella typhimurium which were provided by the Centre of Microbiology Research-Kenya Medical Research Institute (CMR-KEMRI). The 5 plants namely Warburgia ugandesis, Carissa edulis, Tithornia diversifolia, Croton megalocarpus and Launae cornuta that are used traditionally in treatment of typhoid fever and other bacterial diseases were screened. The extracts from these plants were assayed for in vitro anti-salmonella activity using the disc diffusion and microdilution techniques to determine the zones of inhibition and Minimum Inhibitory Concentration (MIC).The results from the present study have shown that out of 36 extracts investigated; only eleven extracts from W. ugendensis, T. diversifolia and C.megalocarpus showed activity against Salmonella strains at 1000mg/ml. The zone of inhibition  range from 8mm to 18.5±0mm while 25 plant extracts that were not sensitive showed zone of inhibition of ≤6mm. MIC of the extracts was in the range of <0.031-15.63 mg/ml. The three plants with anti-salmonella activity can therefore be used to source antibiotic substances for drug development that can be used in the control of typhoid fever. The study therefore provides the scientific basis for its traditional application as a local health remedy.

Keywords: Anti-salmonella activity, medicinal plant extracts, Minimum Inhibitory Concentration, disc diffusion,                        Salmonella organisms