Antibacterial activity of olive leaf and palm pit extracts against bacterial species related to food poisoning.

Food poisoning is a common cause of illness and death in developing countries. This study evaluates inhibitory, synergistic and cytotoxic effects and antioxidant properties of olive leaves and palm pit extracts. Materials and Methods: Olive leaf and palm pit extracts were tested for antibacterial activity against selected bacterial species (Salmonella pullorum, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus). The well-diffusion method was adopted to study the bacterial inhibition against different concentrations of both plant extracts (25, 50, 75 and 100 mg mL?1). Antioxidant activity of plant extracts was evaluated using (DPPH) assay whereas (MTT) assay was conducted to assess their cytotoxicity in human lymphocytes. Results: The OLE ethanolic extracts exhibited the highest antibacterial activity at a concentration of 100 mg mL?1 against E. coli, whereas, the lowest activity was noted against S. pullorum. Contrarily, a moderate antibacterial activity of palm pit extract was noted against all tested bacteria and S. pullorum species exhibited resistance to the extracts. The OLE and palm pit extracts exhibited significant antioxidant activity by inhibiting 81.3 and 78.5% free radicals, respectively. Conclusion: The results demonstrated that OLE and palm pit extracts can serve as a good source of natural antioxidants. The cytotoxic effects of both extracts were evaluated using human lymphocyte cells. The results depicted significant cell growth inhibition at various concentrations (50, 100, 200 and 250 mg mL?1) of the ethanolic extracts. The cell growth inhibition percentages against different concentrations of OLE remained as 14.1, 30.1, 56.2 and 63.2%, respectively whereas, cell growth inhibitions of 11.5, 20.2, 39.9 and 43.2% were noted against different concentrations of palm pit extract.