Abstract
The aim of this study was to determine in vitro anti-Salmonella activity of extracts of five selected Kenyan medicinal plants against Salmonella ser. Typhi and Salmonella ser. Typhimurium. The extracts from Tithonia diversifolia, Warburgia ugandesis, Croton megalocarpus, Carissa edulis and Launae cornuta plants traditionally used in treatment of typhoid fever were screened for anti-Salmonella activity using disc diffusion and microdilution techniques. The results from the present study have shown that out of thirty six extracts investigated, only nine extracts from T. diversifolia and W. ugendensis showed activity against Salmonella ser. Typhi and Salmonella ser. Typhimurium at 1000 mg/ml. The inhibition zone of ethyl acetate, hexane and methanol extracts of T. diversifolia leaves, ethyl acetate and hexane extracts of T. diversifolia flowers, ethyl acetate and hexane extracts of W. ugandensis stem barks, ethyl acetate and hexane extract of W. ugandensis roots ranged from 8 to 18.5 ± 0 mm. These results were comparable with those of ciprofloxacin (19.67 to 26 mm) and chloramphenicol (6.67 to 24.33 mm). The minimum inhibitory concentration (MIC) of the active extracts were in the range of 0.031 to 15.63 mg/ml which compared very well with ciprofloxacin (0.015 to 0.02) and chloramphenicol (0.022 to 0.03 mg/ml). Extracts with anti-Salmonella activity can be used to source antibiotic substances useful in the treatment of typhoid fever. The study provides the scientific basis for the traditional application against typhoid fever. Key words: Anti-Salmonella activity, medicinal plant extracts, minimum inhibitory concentration, disc diffusion technique, microdilution technique, Salmonella strains, typhoid.
Highlights
INTRODUCTIONTyphimurium), is a Gram-negative bacterial pathogen that infects humans and animals, causing significant morbidity and mortality worldwide (Fink and Cookson, 2007)
The minimum inhibitory concentration (MIC) was defined as the lowest concentration of plant extract that completely suppress the growth of Salmonella strains
It was noted from this study that plant extracts tested by microdilution technique showed higher anti-Salmonella activity compared to values obtained from disc diffusion technique
Summary
Typhimurium), is a Gram-negative bacterial pathogen that infects humans and animals, causing significant morbidity and mortality worldwide (Fink and Cookson, 2007). The nine plant parts obtained from 5 selected medicinal plants indicated in Table 1 were extracted using four solvent systems namely; hexane, ethyl acetate, methanol and water. The nine plant materials were extracted using selected solvents. Each plant material was extracted sequentially using hexane, ethyl acetate and methanol in the order of increasing polarity. Single extraction was carried out using water for each of the nine plant materials. The ethyl acetate residues were re-soaked in 1500 ml of methanol and kept for 36 h away from direct sunlight undisturbed.
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