Aims: 

Hydroxytyrosol is a natural polyphenol present in table olives and olive oil. Over the recent years it has been well described for its properties in relation to disease prevention, such as cardiovascular disease and cancer. The anti-proliferative and pro-apoptotic activities of hydroxytyrosol were evaluated in human colorectal carcinoma HT-29 cells.

Methods: 

Proliferation, necrosis and caspase-3 were measured by fluorescence-based techniques. Proliferation was measured over 72 hours in the absence (control) or presence of hydroxytyrosol at different concentrations and cell numbers were determined subsequently using SYTOX-Green nucleic acid stain. Caspase-3-like activities, measured by the cleavage rate of a fluorogenic tetrapeptide substrate served as indicators of apoptosis.

Results: 

HT-29 cells incubated with hydroxytyrosol at 50 and 75 mM suffered a reduction in cell number of 30 and 73%, respectively. Hydroxytyrosol displayed anti-proliferative activities with an EC50 value of 58.5 2.7 mM. No signs of necrosis were detected. Hydroxytyrosol did not show pro-apoptotic effects since this polyphenol failed to activate caspase-3, at any of the concentrations studied.

Conclusions: 

Hydroxytyrosol may exert cancer chemopreventative effects in the large intestine by inhibiting cell proliferation.

Supported by grants AGL2005-05728 (MCT) and 2005-SGR-00632 (Generalitat de Catalunya).