Anti-Staphylococcus aureus activity of methanol extracts of 12 plants used in Cameroonian folk medicine.

BACKGROUND: The emergence of bacterial infections including those associated with Staphylococcus aureus causes a benefit of interest to medicinal plants as an effective means of control. The present study was designed to investigate the activities of 12 selected Cameroonian medicinal plants against S. aureus isolates. METHODS: The plant extracts were prepared by maceration in methanol at laboratory temperature. Qualitative phytochemical analysis was performed by chemical reaction methods. The broth microdilution method was used to evaluate the activities of plant extracts against 11 S. aureus clinical isolates. RESULTS: Dacryodes edulis was found to have significant antibacterial activity on all the S. aureus isolates (MIC = 64-256 µg/ml). Occimum gratissimum revealed significant inhibitory activity on 9 of the 11 isolates while Commelina erecta and Spilanthes filicaulis revealed similar results on 6 of the 11 clinical isolates. CONCLUSION: The present findings showed that D. eduli, O. gratissimum, C. erecta and S. filicaulis possess interesting inhibitory properties against S. aureus species. These plants could therefore be good candidates to overcome infectious diseases associated with these microorganisms.

Antibacterial activity of ethanolic extract and compounds from fruits of Tectona grandis (Verbenaceae).

BACKGROUND: Well known as teak, Tectona grandis is widely used in African folk medicine for its pharmacological relevance. In Cameroon, this species is a reputed laxative in the Northern Region while in the Western Region, it is used in the treatment of skin diseases and diarrhoea. MATERIALS AND METHODS: Separation and isolation of compounds were performed using different chromatographic methods while their structures were elucidated by spectroscopic techniques including MS and NMR, and by comparison of data with those reported in the literature. Isolated compounds as well as crude ethanol extract were tested for their antibacterial activities using broth micro-dilution method against four Gram negative bacteria strains Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (PA 01), Klebsiella pneumonia (ATCC 11296) and Escherichia aerogenes (ATCC 13048). RESULTS: Three known compounds were isolated, including two quinones and one triterpene. They were identified as tectograndone (1), 6-methyl-1,4-dihydroxyanthraquinone (2), and 2ß-hydroxyursolic acid (3) respectively. Crude ethanol extract showed good activity against the bacteria strains tested with MIC of 64-256 µg/mL. Among the isolated metabolites, 6-methyl-1,4-dihydroxyanthraquinone exhibited a strong activity against Escherichia aerogenes with MIC of 16 µg/mL, while tectograndone showed a moderate activity against Escherichia coli with MIC of 32 µg/mL. The antibacterial screening of the fruits of this plant as well as that of compounds 1 and 2 is reported herein for the first time. CONCLUSION: The research work presented here shows that Tectona grandis fruits possess compounds which could be developed in the treatment of bacterial diseases.