Biological Properties and Chemical Composition of Essential Oils from Fresh and Shade Dried Olive Leaves of Olea europaea L. Chemlali Cultivar.

This study focuses on the variation of the contents, chemical profiling and biological activities among fresh and dried leaves essential oils of Olea europaea L. Chemlali cultivar. The essential oils (EO) of the fresh and shade dried leaves of O. europaea were obtained by hydro-distillation and analyzed by gas chromatography-mass spectrometry. Antimicrobial activities were assessed by the evaluation of MICs and MCCs standards. Both oils showed significant quantitative and qualitative differences in their chemical composition. Indeed, 25 and 47 components were identified in the fresh and shade dried leaves essential oils, respectively. The fresh leaves essential oils were dominated by α-farnesene (17.85 %) and β-maaliene (17.16 %) while n-hexadecanoic acid (7.44%) was the major component of shade dried leaves essential oils. Moderate antioxidant activity was shown for both essential oils. The essential oils of dried leaves exhibited higher antimicrobial activity with MICs values ranging between 1 and 2 mL L-1 and MFCs ranging between 1 and 4 mL L-1, whereas the MBCs of oils of fresh leaves ranged between 3.25 and 26 mL L-1, and MFCs ranged between 3.25 and 6.5 mL L-1. The detected reduction in the viability of standard bacteria, higher than 5 log units within a contact time of 5 min, was obtained by 0.75 % (v/v) dried and 1.25 % (v/v) fresh leaves essential oils. Concentrations of 3 % (v/v) dried and 6 % (v/v) fresh leaves essential oils resulted in a reduction in viability higher than 4 log units for the standard fungi, within a contact time of 5 min. [ABSTRACT FROM AUTHOR]