Inflammation and olive polyphenols A perspective review of supporting literature
Hydroxytyrosol (HT) is a simple phenol compound found mainly in olive oil. Recently has been considered as the main antioxidant of olive oil and the most important player in the Mediterranean Diet. Chemically HT is the elenolic acid ester of oleuropein, with the new extraction techniques (1) is easily and abundantly recovered from olive milling water.
Since olive oil has been extensively studied in these past 10 years, HT has been recognized by the European Food Safety Agency (EFSA) for its ability to prevent LDL oxidation, and therefore to reduce atherosclerosis’ complications. But even though EFSA’s notice of allowance recognizes the indirect effect of HT in inflammatory processes such as those arising from LDL oxidation (2), it is in the prevention (3) and or inhibition (4) of inflammatory processes that HT may find its most potent application. Initially investigated for its unique antioxidant activity (5) HT has become the object of intense research. Although not yet completely clear, its mechanism of action includes the selective inhibition of TNF-α gene expression and NO synthases (3) and provides the down modulation of numerous cytokines and chemokynes (6, 34).
Here we will discuss on various application of HT directed at reducing inflammation and pain both in animal and human model; we will also speculate on a possible mechanism of action by which HT may exert its effects.
Although usually considered for their antioxidant properties, olive polyphenols may exert a more important anti-inflammatory effect. In this direction a 2005 study with a proprietary formulation of hydroxytyrosol (HIDROX by CreAgri, Inc.) reported that olive vegetation water (OVW), at a dose of 125 mg/mouse (500 mg/kg), caused a 95 percent reduction of serum TNF-α in LPS-treated BALB/c mice, an accepted model system of inflammation. In the human monocyte cell line, THP-1, OVW reduced LPS-induced TNF-α production by 50 percent at a concentration of 0.5 g/L (equivalent to approximately 0.03 g/L simple and polyphenols). (3). Since TNF-α (cachexin or cachectin) is one of the most important cytokines involved in systemic inflammation, and is able to stimulate the acute phase reaction, it has been chosen as a marker of inflammation. In fact disregulation of TNF-α production has been implicated in a variety of human diseases such as psoriasis, rheumatoids arthritis, and neurodegenerative disease including Alzheimer's (7), cancer (8) and inflammatory bowel disease (9).
TNF-α is believed to be also a principal mediator in pro-inflammator ...