Abstract
Plants are potent biochemists; biologically active compounds present in the medicinal plants have always been of great interest to scientists working in this field. Thus, the aim of the current study was to screen the antimicrobial activity of Acacia nilotica, Ziziphus mauritiana, Bauhinia variegate and Lantana camara against some selected clinical isolated strains. Although previous studies have documented the antimicrobial properties of these plants, this work is designed to evaluate the specific antibacterial activity of different extracts of these plants against tested microorganisms, in order to know the best extract against specific microorganisms. In this study the fresh parts (leaves, barks & pods) of the test medicinal plant were collected and methanol, ethanol and ethyl acetate extracts were prepared. Antibacterial susceptibility test was done by using Agar diffusion assay method. Statistical analysis was carried out with SPSS 17.0 Windows version. The results of the current study showed that a total of 8 extracts from 4 different plant species were investigated including pods of ethyl acetate extracts of Lantana camara, which showed the highest antimicrobial activity against tested clinical isolates (Bacillus subtilus 2 +/- 0.1 mm, Bacillus circulans 2.6 +/- 0.2mm, Bacillus sphaericius 2 +/- 0.1mm, Staphylococcus aureus 2.5 +/- 0.1, and Serratia liquefaciens 2.2 +/- 0.1mm), followed by its ethyl acetate extracts of leaves. Bark extracts of four tested medicinal plants possess a lower zone on inhibitory activity as compared to the leaves extracts of these plants. Noticeably no antimicrobial activity was found in the methonolic bark extract of Acacia nilotica against the tested bacteria except Bacillu ciurlans. The results of the present investigation clearly indicate that the antibacterial activity varies with the species of the plants and plant material used. Thus, the study ascertains the value of plants used in ayurveda, which could be of considerable interest to the development of new drugs. Studies are in progress to further evaluate the mechanisms of action of these active test extracts on study organisms associated with certain human diseases.