In vitro antimicrobial activity of Harungana madagascriensis and Euphorbia prostrata extracts against some pathogenic Salmonella sp.

Abstract

Harungana madagascariensis Lam (Hypericaceae) and Euphorbia prostrata Ait (Euphorbiaceae) are commonly used in Cameroon as traditional medicines for the treatment of typhoid fevers. Aqueous extracts were prepared from the leaves of H. madagascariensis and the whole plant of E. prostrata and tested in vitro for antibacterial activity against Salmonella Typhi, Salmonella Paratyphi A, Salmonella Paratyphi B and Salmonella Typhimurium, using broth dilution technique. Phytochemical screening was performed using standard methods. Acute toxicity study of the various extracts was also done on mice. Results obtained showed that H. madagascariensis extract exhibited minimum inhibitory concentrations (MICs) ranging from 390.625 to 1562.5 μg/ml. The median lethal dose (LD₅₀) of H. madagascariensis extract as shown by the acute toxicity studies were 11.6 g/kg and 13.2 g/kg body weight for female and male mice, respectively. The MIC values of E. prostrata extract varied from 1024 to 2048 μg/ml. The LD₅₀ values obtained for this extract were 23.2 g/kg and 26.4 g/kg body weight for female and male mice, respectively. Phytochemical analysis showed the presence of phenols, tannins, saponins, anthraquinones, anthocyanins, triterpenoids, flavonoids and alkaloids in both plant extracts. These data suggest that the aqueous extracts of H. madagascariensis and E. prostrata contain antibacterial principles which may be non toxic.

Keywords: Harungana madagascariensis, Euphorbia prostrata, antibacterial activity, Salmonella sp., phytochemical screening, acute toxicity.