The present study was designated to evaluated the antimicrobial activities of methanol, ethanol, hexane, ethyl acetate, aqueous, mixture methanol/water and ethanol/water extracts of Pentadiplandra brazzeana, Erythrina sigmoïdea, Petersianthus macrocarpus, Clerodendrum umbellatum , Sida acuta , Eleusine indica , Bridelia micrantha and Musanga cecropioides which are plants used as traditional folk medicine in Cameroon for the treatment of different infections and disorders as gastrointestinal disorders. The antimicrobial activities of the extracts against 17 laboratory strains belong to 15 bacterial species and 2 yeasts implicated in gastrointestinal disorders were evaluated based on the inhibition zone using the disc diffusion assay, minimal inhibition concentration and minimal bactericidal concentration values. 89.6% of the extracts tested have an inhibitory effect at 1.25 mg against at least one of the microorganism tested with the diameter of inhibition zone values ranging from 8 to 27 mm. 62.5% of the broader spectrum of antimicrobial activity of plant material was obtained with methanol extract. The most susceptible bacterium was Shigella flexneri and Enterobacter cloacae the most resistant. Ethanol/Water extract of Pentadiplandra brazzeana presented a good activity against Proteus vulgaris with MIC and MBC of 78 and 250 µg/ml respectively. The weak activity was obtained with Methanol extract of Musanga cecropioides against Klebsiella pneumonia. The results might explain the ethnobotanical use of the studied species for the treatment of gastrointestinal infections.

The objective of this study was to evaluate in vitro synergy of extracts from Picralima nitida, Cylicodiscus gabunensis, Cassia arereh and Trichilia emetica and known antimicrobial agents against clinical isolate of vibrio cholerae.The in vitro antibacterial activity of plant-extracts was evaluated alone and in combination with standard antibiotics against Vibrio cholerae using disc-diffusion and microdilution method.Only antibiotics acting by inhibiting proteins synthesis shown strong bactericidal activity with inhibition zone diameter ranging from 11 ± 0.0 to 26 ± 0.6 mm. we also noticed that methanolic extract of Cassia arereh and Trichilia emetica and ethyl acetate extract of Cassia arereh contain bioactive compounds. These extracts were effective anticholeric agents with MIC ranging between 12.207 and 97.656 µg/ml and MBC between 48.828 and 781.25 µg/ ml. Cassia arereh extract showed the greatest activity with MIC and MBC values of 12.207 and 48.828 µg/ ml respectively. Synergism was observed between antimicrobial agents and the best anticholeric plant-extract with significant reduction in the MICs of antibiotics against the strains tested. Administration of both compounds together resulted in an MIC ranging from 0.078 to 10 µg/ ml which represents a 2 to 16-fold reduction in the MICs of the antibiotics tested alone. This change in MIC was noticed even with antibiotics showed weak antibacterial activity.