Antioxidant and hepatoprotective potentials of phenolic compounds from olive pomace

Olive pomace, a heterogeneous solid waste from olive oil production, is one of the most widespread agroindustrial by-products in Mediterranean area. The amount of organic compounds with high chemical and biological oxygen demands present in olive pomace stresses the related industries to adapt adequate treatments for this by-product. Being rich in bioactive molecules, it could be considered a low-cost and renewable source of high added value compounds, such as polyphenols. Dietary plant polyphenols are the subject of increasing scientific interest because of their possible beneficial effects on human health. Recent studies suggested that action of polyphenols goes beyond the modulation of oxidative stress and can improve several physiopathological conditions. In the present study, we investigated the possible effects of polyphenols extracted from olive pomace (PEOP) and of the main single phenolic compounds present in the extract (tyrosol, apigenin and oleuropein) in protecting hepatocytes against excess fat and oxidative stress. PEOP were extracted using a high pressure-temperature agitated reactor (25 bar, 180 °C for 90 min). A mixture of ethanol:water (50:50 v/v) was used as extraction solvents resulting to total polyphenol concentration of 5.77 mgCaffeic Acid Equivalent/mL. In order to test the biological effects of the extract we used rat hepatoma FaO cells exposed to a mixture of oleate/palmitate (2:1 molar ratio) for 3 h which represent a reliable in vitro model for hepatic steatosis. After lipid-loading, hepatic cells were incubated for 24 h in the absence or in the presence of 10 μg/mL tyrosol, 13 μg/mL apigenin or 50 μg/mL oleuropein. Content of intra-and extra-cellular triglycerides (TGs), and oxidative stress-related parameters were evaluated. The preliminary results showed that PEOP ameliorated lipid accumulation and lipid-dependent oxidative unbalance showing their potential applications as therapeutic agents.