Antibacterial and Antifungal Activities of Extracts of Some Medicinal Plants of Ethiopia

Abstract

Four Ethiopian medicinal plants, viz. Clerodendrum myricoides (Lamiaceae), Ficus plamata (Moraceae), Grewia ferruginea (Tiliaceae) and Periploca linearifolia (Asclepediaceae) were selected based on their ethnomedicinal profiles and screened for antibacterial and antifungal activities. The antimicrobial activity of the total extracts of these plants obtained by maceration with 80% (v/v) methanol was tested by agar-well diffusion method. Further, the antimicrobial activities of petroleum ether, chloroform, acetone and methanol fractions of C. myricoides were also examined similarly and the minimum inhibitory concentration (MIC) of the total extract of C. myricoides was determined by agar dilution method. The plants were generally more active against the test bacterial strains than the fungal strains. C. myricoides exhibited a significant broad spectrum inhibitory effect against all the test bacteria. The total extracts of all the plants inhibited the growth of Pseudomonas aeruginosa at all concentration levels employed. On the other hand, only C. myricoides was active against Escherichia coli. The MICs of C. myricoides were 5 mg/ml against the Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes and 10 mg/ml against the Gramnegative bacteria P. areuginosa and E. coli. Among the test fungal strains, only Trichophyton mentagrophytes was sensitive to the plants studied. The strongest antifungal activity was also demonstrated by C. myricoides. All the solvent fractions of C. myricoides except the petroleum ether fraction were active against all the bacterial species tested. Conversely, the petroleum ether fraction was the most active against T. mentagrophytes. The results generated from this study could substantiate, at least partly, the popular traditional use of these medicinal plants for different indications including wound infections and skin diseases. Keywords: Clerodendrum myricoides, Ficus plamata, Grewia ferruginea, Periploca linearifolia, antimicrobial activityEthiopian Pharmaceutical Journal Vol. 25 (2) 2007: pp. 111-120