Leaf Extracts from Tunisian Olive Cultivars Induce Growth Inhibition and Differentiation of Human Leukemia HL-60 Cells

摘要

Recently a lot of interest is given to the beneficial actions and healthy effects of olive leaves. Thus, this work is an investigation of the antiproliferative activities and other effects of olive leaf extracts (OLEs) from seven principal Tunisian olive varieties on the human promyelocytic cell line HL60.Three in vitro assays were performed for this study: MTT assay to evaluate the cytotoxicity effect of OLE on HL60 cells, double staining esterase assay and nitroblue tetrazolium reduction assay forassessment of cell differentiation. We find that all OLEs exert a cytotoxic effect on HL60 cells which is confirmed by some morphological changes. Despite their apoptotic effect, ethanol extract of Tunisian olive leaves induced differentiation of HL60 cells into granulocytes. The differentiation-inducing activity of G extract was more remarkable than those of the other extracts (NBT reduction greater than 90%). To identify the bioactive components of OLEs the cytotoxicity of oleuropein and luteolin, twomajor phenols of olive leaves, were tested, nevertheless, no statistically significant difference was observed versus control. These results suggest that OLEs probably contain unknown bioactive components that are present in relatively high amounts in the G sample and are responsible for the cell differentiation, or possibly, cell differentiation is the result of synergism between compounds present in OLEs.