Full Length Research Paper

Evaluation of efficacy of bitter leaf (Vanonia amygdalina) extract as panacea against diarrhea caused by Escherichia coli O157:H7

Ademokoya, A. A.

Abstract

The challenge of antibiotics resistance by most strains of pathogenic Escherichia coli and the development of hemolytic uremic syndrome when antibiotics are used in the treatment of infections caused by enterohaemorrhagic E. coli especially E. coli O157:H7 have been reported by many authors. Therefore, this study was designed to evaluate the efficacy of bitter leaf (Varnonia amygdalina) extract extracted by different solvents as panacea against diarrhoea caused by E. coli O157:H7. The E. coli O157:H7 used in this study was isolated using standard microbiology technique. On the other hand, the bitter leaf used comprised the leaves, stems and roots were harvested in the vegetable garden in Akungba Akoko, Ondo State. The panacea effect of the extract against the pathogen was carried out using in-vitro and in-vivo assays. In the in-vivo test, albino rats were orogastically dosed with different concentrations of the extract, after the establishment of disease condition in the rats inoculated with the infectious dose (2 × 10² cfu/ml) of E. coli O157:H7. Moreover, the in-vitro test was done using agar diffusion method and the zones of inhibition of different concentration were measured in millimeter after incubation for 24 h at 37°C. For the study data, one way ANOVA was done using statistical software SPSS Version 20. The result of the protection of albino rats by the bitter leaf extract against diarrhoea caused by E. coli O157:H7 infection in the in-vivo test of the extract from the leaf, stem and root increased in ascending order as follow: cooled water extract (leaf and stem 40%, root 20%); hot water extract (leaf 60%, stem and root 40%); five percent ethanolic extract (leaf 80%, stem 60% and root 40%); ten percent ethanolic extract (leaf 80%, stem 60% and root 60%), while the highest was found in fifteen percent ethanolic extract (leaf 100%, stem 80% and root 60%) respectively. On the other hand, the in-vitro test result decreased in descending order as follow: fifteen percent ethanolic extract ( leaf 100%, stem 80% and root 60%); followed by ten percent ethanolic extract (leaf and stem 80%, root 40%); five percent ethanolic extract (leaf 80%, stem 60% and root 20%), hot water extract (leaf 60%, stem 40% and root 20%) while the lowest percentage inhibition of the pathogen was found in cool water extract (leaf and stem 40%, root 20%) respectively. This study shows that bitter leaf extracted with 15% ethanolic water synergistically mediated highest curative ability on diarrhea caused by E. coli O157:H7 compared with ordinary water extraction and other solvents extracts used in both in-vivo and in-vitro assays in this study. Hence, 15% ethanolic water bitter leaf extraction can be used to challenge the diarrhoea infection caused by E. coli O157:H7 in both human and animals.

Key words: Bitter leaf, extract, panacea, E. coli O157:H7, diarrhea.

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