Human absorption of a supplement containing purified hydroxytyrosol, a natural antioxidant from olive oil, and evidence for its transient association with low-density lipoproteins

Hydroxytyrosol supplementation increases vitamin C levels in vivo. A human volunteer trial

“…It has been proposed that the hydrophilic properties of vitamin C facilitate their localization at the interface of the lipid bilayers in membranes, thereby producing effective inhibition of attack by free radicals in the aqueous phase, and effective repair of lipophilic antioxidants [44]. A previous study in humans carried out in our laboratory demonstrated absorption of the HT supplement and a transient but measurable association of HT with LDL particles [12], where it may act as a quencher of ROS. It has been demonstrated that HT and its derivatives protect LDL particles from oxidative damage [3], [45], using much lower amounts than the dose used in our study.…”

“…HT was purified from an olive mill waste water extract using food grade solvents, preparative chromatography and further desiccation. The HT obtained was a white powder soluble in water with a purity of 99.5% (see reference 12 for details). The HT used for analytical determinations was synthesised by reducing 3,4-dihydroxyphenylacetic acid with LiAlH 4 in tetrahydrofuran under refluxing for 4 h. The reaction product was purified by chromatography on silica gel with CHCl 3 :MeOH (7:1) as the eluting solvent.…”

“…We also purified large amounts of HT from olive mill waste aimed to produce an almost pure (99.5%) water-soluble pharmacological formulation and characterised its absorption profile in humans [12]. So far, no chronic studies reporting effects of pure HT in human volunteers have been published.…”

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

“…Other phenolic compounds include hydroxytyrosol, 3,4-dihydroxyphenylacetic, 4-hydroxyphenylacetic, and 4-hydroxybenzoic acids as well as protocatechuic, vanillic, syringic, and p-coumaric acids (Cabrini et al, 2001). However, Owen et al (2000) reported that hydroxytyrosol is one of the main components of virgin olive oil and olive mill waste with a strong antioxidant potential (González-Santiago, Fonollá, & Lopez-Huertas, 2010). Amongst the phenolic compounds found in extra-virgin olive oils, o-dihydroxy-phenolics are very potent antioxidants (Boskou, Blekas, & Tsimidou, 2005).…”

Biological Properties of Hydroxytyrosol and Its Derivatives

“…It has been shown that hydroxytyrosol can inhibit LDL oxidation efficiently due to its capacity to scavenge peroxyl radicals (Arouma et al, 1998;Turner et al, 2005). Hydroxytyrosol reduces oxidation of the low-density lipoproteins carrying cholesterol (LDL-C), which is a critical step in the development of atherosclerosis and other cardiovascular diseases (Gonzalez-Santiago et al, 2010;Vázquez-Velasco et al, 2011); hydroxytyrosol has also a potential protective effect against oxidative stress induced by tertbutyl hydroperoxide (Goya et al, 2007).…”