Induction of Growth Inhibition and Differentiation of Human Leukemia HL-60 Cells by a Tunisian Gerboui Olive Leaf Extract

Abstract

Cancer protection associated with the consumption of olive products is well established, but not for leukemia. The protective effects of olive (Olea europaea L.) leaves were investigated by incubating human promyelocytic leukemia HL-60 cells with olive leaf extracts (OLEs) from seven principal Tunisian olive varieties, namely, Chemchali, Chemlali, Chétoui, Gerboui, Sayali, Zalmati and Zarrazi. The results showed significant growth inhibition of HL-60 cells incubated for 48 h with a 100-fold dilution of each OLE which had been obtained by incubating 10 g of dried leaves in 100 ml of 70% ethanol for one week with subsequent ultrafiltration. DNA fragmentation was observed in the cells incubated for 19 h with a 100-fold dilution of the Chemchali, Chemlali and Zalmati extracts. The results of a nitroblue tetrazolium (NBT) assay revealed NBT reduction, a differentiation marker, by the OLE-treated cells after an overnight incubation. The Gerboui extract showed the highest NBT reduction ability at more than 90%. An HPLC analysis revealed the presence of apigenin 7-glucoside in the extract, which was found in subsequent experiments to be responsible for the Gerboui extract-mediated cell differentiation.

Bioavailability of Bioactive Molecules from Olive Leaf Extracts and its Functional Value

“…Despite the fact that previous research has already tested the anti-proliferative and/or cell killing abilities of different olive leaf extracts against leukemia cells (Abaza et al, 2007;Fares et al, 2011;Samet et al, 2014), none of them has proved whether the extracts maintained their anticancer properties once they entered the gastrointestinal tract. Therefore, olive leaf extracts warrant further investigation into their potential antileukemic benefits.…”

A review: benefit and bioactive properties of olive (Olea europaea L.) leaves

“…Several studies have shown that olive leaf extract exhibits a large spectrum of in vitro and in vivo properties, including antioxidant activity [85,86], radio-protective effects [85], anti-proliferative effect on leukemia cells by inducing apoptosis [39,57,87,88], cytotoxic activity against human breast cancer cells [47,89], anti-HIV virus effect [90], antifungal activity [91], gastroprotective activities [92], attenuation of diabetic neuropathic pain [93] and amelioration of gentamicin nephrotoxicity [94]. Several biological properties such as antioxidant, anti-atherosclerotic, hypoglycemic and cardioprotective effects of olive leaves have been reviewed in the literature [76,82].…”

Wogonoside induces cell cycle arrest and differentiation by affecting expression and subcellular localization of PLSCR1 in AML cells

“…Morphological assessment of differentiation was evaluated by Wright-Giemsa staining. 23 The percentage of cells capable of reducing nitro blue tetrazolium (NBT) was measured as described earlier in Abaza et al 24 The results were determined by examining 200 cells per microscopic field and counting 5 times in each group. The data were expressed as the percentage of blue cells per (blue 1 white cells).…”