Antibacterial Activity of the Phenolic Extract of Wild Virgin Olive Oil In Vitro

Background: The olive tree (Olea europaea L.), the most widespread plant species in the Mediterranean basin, includes two forms: cultivated (var Europaea) and wild (var Sylvestris). Wild olive trees or oleasters cover large areas in Algeria. It has been shown that oil from oleaster has a higher content of phenolic compounds, which could have antimicrobial properties. Objective: The objective of this study was to assess the antibacterial activity of phenolic extracts from four Algerian oleaster oils and an extra virgin olive oil (EVOO) from Chemlal variety. Methods: Phenolic compounds were determined by UHPLC-MS. Antibacterial activity was tested against six referenced human enteropathogenic bacteria by the agar disc diffusion method by measuring the diameters of the zone of inhibition. Results: The results revealed a similarity between the phenolic composition of oleasters 1 and 3 and between oleaster 4 and EVOO; however, the phenolic composition of oleaster 2 that the poorer was markedly different with a higher content of free phenolic alcohols and lower in secoiridoids. Almost all bacteria showed to be sensitive against the antibiotics, with the value of ZOI ranging from 5-32 mm; otherwise, most of the oleaster extracts exhibited higher antibacterial activity than the EVOO with ZOI values of 7-12mm. A significant correlation was noted between phenolic content and antibacterial activity. Conclusion: These results show that oleaster oil can be considered a high potential food.