Aim/Background: The development of resistance to synthetic drugs by target organism is a major challenge facing medicine, yet locked within plants are phytochemicals used in herbal medicine (especially in the Arabian Peninsula) that may find application in this regard. In pursuit of unlocking these hidden treasures the methanol extracts of leaves, aerial parts, fruits and resins of seventeen plants used in the Arabian Peninsula were screened for antimicrobial activities. Methods: The nematicidal, antibacterial and antifungal activities using appropriate assays. Steinernema feltiae, Staphylococcus carnosus, Escherichia coli and Saccharomyces cerevisiae were used as test organisms. Concentrations of the extracts ranging from 0.5 to 20 mg/ml were tested and appropriate statistical tests performed on the data generated. Results: The results show that extracts from S. incanum, C. murale, C. myrrha, A. nobilis and A. biebersteinii were the most active, and had very high activities against two or more of the test organisms at low concentrations. Extracts of the leaves of S. incanum and resins of F. asafoetida were the most active nematicides, with significant activity at 0.5 mg/ml. Extracts of C. myrrha and C. murale had the most active antibacterial activity with inhibition zones of 12-15 mm and minimum inhibitory concentrations (MICs) of 2.5 mg/ml for both bacteria. Extracts of the leaves of A. biebersteinii were the most active fungicide, giving an MIC of 1.5 mg/ml. Conclusion: The results validate the use of these plants in ethnopharmacology, and open new vistas of opportunities for the development of cheap but effective agents that may be useful against infectious diseases.
Key words: antimicrobials, nematicides, medicinal plants, Solanum incanum, Commiphora myrrha, phytochemicals
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