Phenolic profile (HPLC-UV) of olive leaves according to extraction procedure and assessment of antibacterial activity

Abstract

The aim of the present study is to firstly study the effect of the extraction solvents (ethanol, acetonitrile, distilled water), pH, temperature, and the extraction method (maceration, sonication, maceration in two steps) on the flavonoid and phenolic contents of olive leaves. Furthermore, qualitative and quantitative analyzes of phenolic compounds by (HPLC) were performed. Results showed that the extract macerated in two steps by ethanol followed by distilled water of dried leaves showed high contents of phenolic compounds and flavonoids compared to the extracts obtained by the other studied techniques and solvents. On the other hand, the macerated extracts were studied for their antibacterial activity against five pathogenic bacteria (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Listeria monocytogenes). The results showed a strong antibacterial activity of the same macerated extract in two steps for dried leaves, which could be attributed to its richness in bioactive compounds such as oleuropein. Keywords: Olea europaea, Antibacterial activity, Extraction methods, HPLC, Olive leaves, Phenolic compounds