Antibacterial activity of spathe from Phoenix dactylifera L. against some food-borne pathogens

The study aimed to evaluate the in vitro antibacterial activity of extracts from spathe (date palm) against Listeria monocytogenes ATCC 7644, Staphylococcus aureus (ATCC 25923 and 29213), Staphylococcus saprophyticus ATCC 15305, Salmonella enterica subsp. enterica ATCC 13076, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. Results of the agar diffusion assay indicated that the 80% methanolic extract of spathe (ME) was the most active sample against test pathogens, compared to water or petroleum ether extracts. The inhibition zones produced by ME were 11-31 mm against the test bacteria. Minimum inhibitory concentration (MIC), determined by the agar dilution method of ME against gram positive bacteria was 1.5 mg/ml. MIC of ME for gram negative bacteria was 3 mg/ml. Preliminary phytochemical tests revealed that ME contained phenolics and flavonoids. The Folin-Ciocalteu method showed that total phenolics (265.7 mg Gallic acid equivalent/g) were significantly (P < 0.05) higher in ME than other extracts. Total antioxidant capacity (phosphomolybdenum method) of ME was 530 μg ascorbic acid equivalent/g. It could be summarized that spathe contains active phytochemicals which may find applications in the food industry and pharmaceuticals.