Olive oil and its principal bioactive compound: Hydroxytyrosol – A review of the recent literature

BackgroundOlive (Olea europaea L.) oil is one of the main ingredients of the Mediterranean diets and as such, it is considered responsible for the overall well being of the Mediterranean populations. With European Food Safety Authority (EFSA) approving the health claims of olive oil in part due to the presence of hydroxytyrosol (HT), there is a global upsurge in the exploration of the different health promoting and disease preventing abilities of this bioactive compound.Scope and approachBesides presenting an overview of the fatty acid and phenolic (minor) profiles of olive oil, the present article reviews the nutraceutical properties of olive oil attributed to the presence of HT, health promoting and disease preventing abilities of pure HT, and the synthesis of HT and its metabolic derivatives of biological interests.Key findings and conclusionsOlive oil contains high profile fatty acids and phenolics. The fatty acid profile changes with maturation of the olives. Oleic acid predominates throughout the maturation period. Palmitic acid is predominantly found in the unripe stage while as, palmitoleic acid, stearic acid, and linoleic acid are chiefly found in ripe olives. Oleuropein is the predominant secoiridoid in the early stages of olive maturation. As the maturation proceeds, oleuropein degrades to yield HT. Over the years, HT has been explored against a number of health complications and shows promising results against diabetes, inflammation, nervous disorders, angiogenesis, cancer, oxidative stress, heavy metal toxicity, hemolysis, LDL oxidation, muscle damage, and nephrotoxicity. The bioactive properties of HT are accomplished through nutrigenomic and immunomodulatory mechanisms. HT, its lipophilic derivatives, and many of its metabolites of biological interests have been synthesized through microbological, biotechnological, and other chemical strategies.