Antimicrobial activity of the methanolic extract, fractions and compounds from the stem bark of Irvingia gabonensis (Ixonanthaceae).

The antimicrobial activity of the methanolic extract from the stem bark of Irvingia gabonensis (IGM), fractions and compounds isolated from IGM [3-friedelanone (1), betulinic acid (2), oleanolic acid (3), 3,3',4'-tri-O-methylellagic acid (4), 3,4-di-O-methylellagic acid (5) and hardwickiic acid (6)] was evaluated against Gram-positive bacteria (6 species), Gram-negative bacteria (13 species) and three Candida species using dilution methods for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC). From the obtained results, IGM prevented the growth of all the species of microorganisms tested at a concentration limit of 312.50 microg/ml. Compounds 4-6 also inhibited the growth of all the tested microbial species while compounds 1-3 showed selective activities. The lowest MIC values (78.12 microg/ml) were obtained with IGM on 13 of the 22 microorganisms tested. The corresponding value of 1.22 microg/ml (4.26 microM) for compounds was recorded with compound 6 on Neisseria gonorrhoeae. The obtained results confirmed the use of Irvingia gabonensis in the treatment of bacterial and fungal infections.

Antimicrobial activity of the methanolic extracts and compounds from Treculia obovoidea (Moraceae).

The crude extract from Treculia obovoidea was subjected to purification by repeated chromatography. Eight compounds were isolated from Treculia obovoidea and identified as Psoralen (1), Bergapten (2), 7-methoxycoumarin (3), 7-hydroxycoumarin (4), 4,2',4'-trihydroxychalcone (5), 4,2',4'-trihydroxy-3-prenylchalcone (6), 3-hydroxy-4-methoxybenzoic acid (7) and O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl) butyl] bergaptol (8). These compounds together with the extract were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and three Candida species using micro-dilution methods for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC). The MIC values obtained with the crude extracts varied from 78.12 to 156.25 microg/ml against 17 (80.95%) of the 21 tested microorganisms. All the isolated compounds showed selective activity. The antimicrobial activity of this plant as well as that of compounds 6 and 8 is being reported for the first time. The obtained results provide promising baseline information for the potential use of these crude extract as well as some of the isolated compounds in the treatment of bacterial and fungal infections.