| dc.description.abstract | Herbals have been used for decades to treat gastrointestinal infections across the world, including
in Tharaka-Nithi County, Kenya. Crude extracts from herbs have long been prescribed by traditional
healers for treatment of typhoid, cholera, and shigellosis. However, the effectiveness of extracts
obtained using different extraction solvents such as methanol, acetone, and hexane have not fully
been evaluated. This study aimed at evaluating the effect of solvents (Ethanol, hexane, and
methanol) on the yield of crude extract from plants (Erythrinna abyssinica, Aspilia pluriseta,
Vangueria infausta, Ficus sycomorus, and Carissa edulis), assessing the effect of the solvents on
extracted active metabolites, and determining the effect of these solvents on extract’s bioactivity against Vibrio cholerae, Shigella flexneri, and Salmonella typhimuriumi and, Escherichia coli that
served as a model organism for screening plant extracts against Gram-negative bacteria. Crude
extracts were obtained by soaking dried ground plant parts in individual solvents, which were then
concentrated by a rotary evaporator. The phytochemical screening to detect plant metabolites was
done qualitatively. Bioassays to analyze the efficacy of the plant crude extracts against the
microbes were carried out in 4×3×3×5 factorial experiment laid out in a completely randomized
design. The determination of bioactivity of herbal extracts was carried out using minimal inhibition
concentration and minimum bactericidal concentration methods. Data obtained on the bioactivity
assay (Count of the bacteria colony forming units) was analyzed using the Kruskal-Wallis test at α =
0.05, and medians were compared by the Wilcoxon rank sum test in Scientific Analysis System
version 9.4. Methanol solvent produced higher quantities of crude extracts for all the herbal
samples used with, Vangueria infausta producing the highest extract (5.06g). Most phytochemicals
were present in Methanolic extracts compared to hexane and acetone extracts. There was a
significant (p < 0.05) difference in the bioactivity of different herbal plants against bacterial
pathogens at different concentrations of crude extract. The efficacy of plant extract increased
progressively from 100ppm to 1000ppm concentration. Methanol is recommended for use in the
extraction of medicinal plant extracts as it leads to improved potency as compared to hexane and
acetone. | en_US |
