Antioxidant Characteristics of Hydroxytyrosol

Hydroxytyrosol itself in pure form is a colorless, odorless liquid. But in addition to its pure form, it is more commonly available as a beige colored powder, which is a natural byproduct of the waste water of the olive oil industry. In addition to these natural forms, hydroxytyrosol can also be produced synthetically in varying concentrations as either a pure white powder or as a clear liquid, depending on the concentration. Both the natural and synthetic forms are used in food stuffs and the cosmetics industry.

Hydroxytyrosol displays much more effective antioxidant characteristics, such as the scavenging of free radicals, breaking peroxidative chain reactions, preventing lipid peroxidation, inhibiting hypochlorous acid derived radicals, and so on, compared with other phenolic compounds in olive oil. It could be used in the dermocosmetic industry for the creation of products for protecting the skin from oxidative stress or used as a preservative in the food technology.

Mechanism of Action

Defense against reactive oxygen species (ROS) is fundamental to protect cellular molecules as lipids, proteins or DNA and avoid the development of degenerative diseases. When the defensive mechanisms are overtaken by the action of the free radicals, the subsequent cellular damage may lead to several diseases, including atherosclerosis, cardiovascular diseases, skin and neurodegenerative diseases, diabetes mellitus and metabolic syndrome. Finally, physiological processes such as aging have been associated with a disequilibrium between the action of ROS and that of antioxidants.

Hydroxytyrosol  behave as antioxidant acting as: a. free radical scavengers and radical chain breaking; b. anti-oxygen radicals; c. metal chelators. With their catecholic structure, they are able to scavenge the peroxyl radicals and break peroxidative chain reactions producing very stable resonance structures.    

Hydroxytyrosol (HXT) is a phenolic compound drawn from the olive tree and its leaves as a by-product obtained from the manufacturing of olive oil. It is considered the most powerful antioxidant compound after gallic acid and one of the most powerful antioxidant compounds between phenolic compounds from olive tree followed by oleuropein, caffeic and tyrosol. Due to its molecular structure, its regular consumption has several beneficial effects such as antioxidant, anti-inflammatory, anticancer, and as a protector of skin and eyes, etc. For these reasons, the use of HXT extract is a good strategy for use in meat products to replace synthetics additives. However, this extract has a strong odour and flavour, so it is necessary to previously treat this compound in order to not alter the organoleptic quality of the meat product when is added as ingredient. The present review exposes the health benefits provided by HXT consumption and the latest research about its use on meat. In addition, new trends about the application of HXT in the list of ingredients of healthier meat products will be discussed.

Health Benifits

Hydroxytyrosol is also known as 2-(3,4-dihydroxyphenyl)-ethanol (3,4-DHPEA) and as DOPET. Hydroxytyrosol is mainly found in olive oil as secoiridoid derivatives, as acetate and in free form. Both hydroxytyrosol and its derivatives arise from oleuropein (hydroxytyro- sol esterified with elenolic acid), present in olives during the extraction of olive oil.    

Hydroxytyrosol is a phenylethanoid, a type of phenolic phytochemical with antioxidant properties in vitro. In nature, hydroxytyrosol is mainly found in olives, olive leaves, and olive oil in the form of its elenolic acid ester, oleuropein.[1] It is a constituent of red and white wines.

Hydroxytyrosol is considered safe as a novel food for human consumption, with a no-observed-adverse-effect level of 50 mg/kg body weight per day, as evaluated by the European Food Safety Authority (EFSA). In the United States, hydroxytyrosol is considered to be a safe ingredient (GRAS) in processed foods at levels of 5 mg per serving.