Antitumor Effects of Chemlali and Wild Olive Tree Extracts: Role in Cell Proliferation and Apoptosis in Prostate (PC3) and Breast (MDA‐MB‐231) Cancer Cell Lines

Cancer remains a major global health challenge, requiring natural therapeutic solutions. Olive tree by-products, like leaves and pomace, are rich in bioactive phenolics with antioxidant and anticancer potential. This study explores the chemical composition and anticancer potential of the hexane fraction of olive leaf extracts and the dichloromethane fraction of olive pomace extracts from two <i>Olea europaea</i> varieties: e cultivated Chemlali (var. <i>europaea</i>) and the wild olive (<i>var. sylvestris</i>). GC-MS analysis identified stigmast-5-en-3-ol, erythrodiol, and phytol as the predominant compounds in wild olive leaf extracts, whereas Chemlali leaf extracts contained only the first two. Analysis of olive pomace extracts revealed four major compounds: coniferyl alcohol, glyceryl monooleate, stigmast-5-en-3-ol, and methylursolate, present in both varieties, with significant variations in their peak areas. Cytotoxic evaluation showed that olive waste extracts significantly inhibited cancer cell growth and viability in both prostate (PC3) and breast (MDA-MB-231) cancer cell lines. Specifically, pomace extracts exhibited the strongest effect against PC3 prostate cancer cells, while leaf extracts were more effective against MDA-MB-231 breast cancer cells. These extracts inhibited cell proliferation, induced morphological and phenotypic alterations, modified the cell cycle progression, promoted apoptotic nuclear changes, and triggered apoptosis. Notably, wild olive extracts demonstrated stronger cytotoxic effects than those derived from the Chemlali cultivar. These findings highlight olive by-products as promising sources of natural anticancer agents for pharmaceutical applications.