Phenolic Compounds and Antimicrobial Activity of Olive (Olea europaea L.) Leaves

Abstract

Background: Olive leaves are of great interest, especially in traditional medicine. The polyphenols contained in olive leaves play an important role in this respect, as they have anti-carcinogenic, anti-inflammatory and anti-microbial properties. Olive leaves share phenolic compounds with other plants, but they also contain phenolic compounds belonging to the Oleaceae family. Methods: We report the determination of phenolic compounds in olive leaves by HPLC and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Enterobacter cloacae, Proteus mirabilis and Salmonella typhimurium. Result: The results reveal that the olive leaves may constitute a good source of antimicrobial agents. The high performance liquid chromatography (HPLC) analysis showed the presence of five phenolic compounds: oleuropein, ascorbic acid, rutin, catechinand verbascoside and for the first time ascorbic acid. At low concentrations, olive leaf extracts showed an unusual antibacterial action, which suggests their great potential as nutraceuticals, particularly as a source of phenolic compounds.