ABSTRACT
The risk created by infectious microorganisms to humans attracted the development of common medicine. To find an alternative source, medicinal plants with diverse metabolites play an important role in curing the diseases and human disorders caused by microbial pathogens. Medicinal plants namely, Citrullus colocynthis, Hyoscyamus muticus, Ocimum basilicum, Amaranthus lividus, Salvia aegyptiaca and Ruta chalepensis are commonly used as a traditional medicine in Gulf countries. The present study aimed to investigate the antibacterial, antifungal and antioxidant potential of the organic crude extracts obtained from the seeds. Besides, the possible antimicrobial mechanisms of the extracts were evaluated by determining the enzyme activities. The antibacterial and antifungal activities of the crude extracts were evaluated by the broth micro dilution method and the effect of the extracts on the pathogens were determined by quantifying the alkaline phosphatase (ALP), lactate dehydrogenase (LDH) enzymes and intracellular protein leakage. Besides, the antioxidant properties were determined using hydroxyl radical scavenging assay, DPPH radical scavenging assay, reducing power assay and superoxide radical scavenging assay. Results indicated that the extracts of C. colocynthis showed promising activity against all the tested pathogens, especially the MIC values were ranged from 100 to 150 μg/ml for Gram positive bacteria and 100 to 250 μg/ml for Gram negative bacteria respectively. The MIC values of H. muticus, O. basilicum and R. chalepensis against the fungal pathogens were ranged from 100 to 500 μg/mL respectively. The ALP activity was higher in extract treated Klebsiella pneumoniae compared with control, whereas the LDH and protein concentrations for Escherichia coli and Staphylococcus aureus were comparatively higher. Furthermore, all the studied seed extract showed good antioxidant activities. In conclusion, the studied plant seed extracts documented good antimicrobial and antioxidant activities. Therefore, the medicinal plants would be the excellent source for natural antioxidant and antibacterial agents for medical and applications.