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 (LD 50 ) 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 LD 50 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.
Background
A. cordifolia is a plant widely used in Africa to solve many health problems. In Cameroon, it is used in the treatment of urogenital infections. As a continuation of our search for pharmacologically active agents from natural sources, the antimicrobial activity of A. cordifolia leaf extracts against E. coli and the toxicity of this extract were investigated.MethodsThe antibacterial activity of the aqueous extract from leaves of Alchornea cordifolia was carried out in vitro on Escherichia coli, as well as in vivo on E. coli-infected rat model. Phytochemical screening was performed using standard methods. The acute toxicity was investigated in mice, while at the end of treatment of infected rats, some biochemical, hematological and histological markers of toxicity were evaluated.ResultsThe extract exhibited a bacteriostatic activity with MIC value of 1500 μg/ml. Phytochemical screening revealed the presence of phenols, tannins, triterpens, flavonoids, alkaloids, anthraquinones, anthocyanins, saponins and coumarins in the extract. The acute toxicity study showed LD50 values of 8.6 g/kg and 3.8 g/kg in male and female mice respectively. In vivo, the oral administration of the extract showed a dose-dependent decrease of the bacterial load as the extract at 232, 112 and 58 g/kg were able to eradicate the infection after 9, 11 and 13 days of treatment. The infected rats showed a significant (p < 0.05) increase in the level of serum creatinine, ALAT, white blood cells, and a significant (p < 0.05) decrease in the level of food and water intake, the relative weight of lungs, heart and spleen. In the treated rats, a significant (p < 0.05) increase in food and water intake and ALAT was observed at the doses of 116 and 232 mg/kg. A decrease in the red blood cells count and serum protein levels was also observed. These observations corroborate liver damages as revealed by the histopathological examination of the cross sections of this organ.ConclusionThe results of this assay thus showed that the extract of A. cordifolia is bacteriostatic, therapeutic at 58 g/kg bw and may be considered as slightly and almost non-toxic on females and males mice respectively.
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