In vitro antimicrobial activity of extracts and compounds of some selected medicinal plants from Cameroon

Aim of the studySeven extracts and eight compounds from four selected Cameroonian medicinal plants, Solanecio mannii Hook f. (Asteraceae), Monodora myristica Dunal (Annonaceae), Albizia gummifera (J.F. Gmel) C.A. Smith (Fabaceae/Mimosoideae) and Glyphaea brevis (Spreng) Monachino (Tiliaceae), traditionally used for the treatment of hepatitis, parasites and other infectious diseases, were tested in vitro for their antimicrobial activity against Gram-positive (5 species) and Gram-negative (4 species) bacteria species and pathogenic yeasts (2 Candida species), to establish whether or not they have antimicrobial activity and to validate scientifically their use in traditional medicine.Materials and methodsThe agar disc diffusion and the microbroth dilution methods were used to determine the zone of inhibition between the edge of the filter paper and the edge of the inhibition area (IZ) and the minimal inhibitory concentration (MIC) respectively.ResultsThe most active extracts against Candida albicans and Candida krusei were respectively the cyclohexane extract from the fruits of Monodora myristica and the ethyl acetate extract from the stem bark of Albizia gummifera (MIC = 6.3 μg/ml for both extracts). The lowest MIC value (1.6 μg/ml) for purified compounds was obtained on Candida albicans with a mixture of linear aliphatic primary alcohols (n-C24H50O to n-C30H62O), with n-hexacosanol (1b) as major compound and mixture of fatty acid esters of diunsaturated linear 1,2-diols (6).ConclusionThese results afford ground informations for the potential use of the crude extracts of these species as well as of some of the isolated compounds in bacterial and fungal infections.

Four selected Cameroonian medicinal plants were investigated for their antimicrobial activity. The most active extracts with MIC = 6.3 μg/ml were obtained from the ethyl acetate extract from the stem bark of Albizia gummifera and the hexane extracts from the fruits of Monodora myristica, the leaves of Solanecio manni and the leaves of Glyphaea brevis. The mixture (1b) with n-hexacosanol as major compound and the mixture of linear unsaturated fatty acid esters (6) exhibited the best activity (MIC = 1.6 μg/ml) for isolated compounds.Figure optionsDownload as PowerPoint slide