Anti-diarrhoeal evaluation of some medicinal plants used by Zulu traditional healers.

Aqueous and methanolic extracts of several medicinal plants, Psidium guajava (leaves), Aristea spp., Iridaceae family (stem), Bridelia micrantha (bark) and Eleutherina bulbosa (bulb), used by Zulu traditional healers were evaluated for anti-diarrhoeal activity against different experimental models of diarrhoea in rats as well as for anti-microbial activity against different pathogenic microorganisms that cause diarrhoea. The methanolic extract of P. guajava (leaves) was the only agent showing significant inhibitory activities against the growths of Salmonella spp. (two isolates), Shigella spp. (S. flexneri, S. virchow and S. dysenteriae) and enteropathogenic Escherechia coli (two isolates). The methanolic extract of B. micrantha (Bark) demonstrated weak inhibitory activities against S. flexneri and S. plesiomonas. Based on the results in experimental rat models, there were significant reductions in faecal output and frequency of droppings when plant extracts were administered compared with castor-oil treated rats. All plant extracts also significantly retarded the propulsion of charcoal meal and significantly inhibited the PGE(2)-induced enteropooling. The results have confirmed the effectiveness of all these Zulu medicinal plants as anti-diarrhoeal agents.