Total phenols from grape leaves counteract cell proliferation and modulate apoptosis-related gene expression in MCF-7 and HepG2 human cancer cell lines

[Grape leaves influence several biological activities in the cardiovascular system, 24 acting as antioxidants. In this study, we aimed at evaluating the effect of ethanolic and water extracts 25 from grape leaves grown in Algeria, obtained by Accelerator Solvent Extractor (ASE), on cell 26 proliferation. The amount of total phenols was determined using the modified Folin-Ciocalteu 27 method, antioxidant activities were evaluated by the 2,2-diphenyl-l-picrylhydrazyl free radical 28 (DPPH*) method and ?OH radical scavenging using Electron Paramagnetic Resonance (EPR) 29 spectroscopy methods. Cell proliferation of HepG2 hepatocarcinoma, MCF-7 human breast cancer 30 cells and vein human umbilical HUVEC cells, as control for normal cell growth, was assessed by 3-31 (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay (MTT). Apoptosis- 32 related molecular events were determined by measuring Bax and Bcl-2 mRNA expression levels. 33 Accelerator solvent extractor yield did not show significant difference between the two solvents 34 (ethanol and water) (p > 0.05). Total phenolic content of water and ethanolic extracts was 55.41 ± 35 0.11 and 155.73 ± 1.20 mg of gallic acid equivalents/g of dry weight, respectively. Ethanolic extracts 36 showed larger amount of total phenols as compared to water extracts and an interesting antioxidant 37 activity. HepG2 and MCF-7 cell proliferation decreased with increasing concentration of extracts 38 (0.5, 1, and 2 mg/ml) added to the culture, during a period of 1-72 hours. In addition, the expression 39 of the pro-apoptotic gene Bax was increased and that of the anti-apoptotic gene Bcl-2 was decreased 40 in a dose-dependent manner, when both MCF-7 and HepG2 cells were cultured with one of the two 41 extracts for 72 hours. None of the extracts elicited toxic effects on vein umbilical HUVEC cells, 42 highlighting the high specificity of the antiproliferative effect, targeting only cancer cells. Finally, 43 our results suggested that ASE crude extract from grape leaves represent a source of bioactive 44 compounds such as phenols, with potential antioxidants activity, disclosing a novel 45 antiproliferative and apoptotic effect affecting only HepG2 and MCF-7 tumor cells.