Effect of Hydroxytyrosol Found in Extra Virgin Olive Oil on Oxidative DNA Damage and on Low-Density Lipoprotein Oxidation

Abstract

Hydroxytyrosol found in extra virgin olive oil strongly inhibited low-density lipoprotein oxidation stimulated by 2,2‘-azobis(2-amidinopropane) hydrochloride (AAPH), suggesting the ability to scavenge the AAPH-derived peroxyl radicals. Hydroxytyrosol inhibited iron-dependent phospholipid liposome peroxidation at low concentrations (IC50 = 50 ± 1.3 μM). In similar experiments, the calculated, IC50 values for other antioxidants compared are 1.5 ± 0.05 μM (carnosol), 2.25 ± 0.08 μM (carnosic acid), 65 ± 2.6 μM (Trolox C), and 250 ± 10 μM (vitamin E). Hydroxytyrosol and ascorbate reduced copper(II) ions to their copper(I) prooxidant form, but this was not reflected by their abilities to induce oxidative DNA damage in the complex copper−phenanthroline. Only high, nonphysiological, millimolar concentrations of pure hydroxytyrosol weakly stimulated copper-dependent chemical modification to DNA bases. The prooxidant (redox actions on metal ions) concentrations in vitro may never be achieved in vivo (following consumption of extra virgin olive oil). Thus, hydroxytyrosol may represent a useful diet-derived antioxidant depending on its bioavailability. Keywords: Extra virgin olive oil; hydroxytyrosol; low-density lipoprotein; rosemary; vitamin E; lipid peroxidation; plant antioxidants; DNA damage

Antioxidant activity of olive oil mill wastewater obtained from different thermal treatments

“…The OOMWW phenolic fraction is characterized by a great complexity, as demonstrated by Bianco et al (2003); one of the most abundant and very interesting compounds from a nutritional point of view is hydroxytyrosol, which has been widely studied, demonstrating its antioxidant and beneficial health properties as well as its good bioavailability. Hydroxytyrosol scavenges free radicals (Visioli et al, 1999) and inhibits human low-density lipoprotein (LDL) oxidation (Aruoma et al, 1998;Casalino et al, 2002;Deiana et al, 1999). For economic reasons, OOMWW is usually concentrated in evaporation ponds and left to dry throughout the summer season (Borja et al, 1992;Benitez et al, 1997).…”

The phenolic compounds of olive oil: structure, biological activity and beneficial effects on human health

“…This is due, in part, to the relatively low content of PUFA and also to the high concentration of polyphenolic antioxidants, particularly in extra-virgin olive oil. The antioxidant activity of olive oil phenolic compounds, and in particular of oleuropein and its byproduct hydroxytyrosol, has been studied in many experimental models: with the use of transition metals; the chemically induced oxidation of LDL; ROS formation, for example the radicals superoxide and trichlormethylperoxylic, and hypochlorous acid (Aeschbach et al 1994;Salami et al 1995;Visioli et al 1995aVisioli et al , 1998Aruoma et al 1998). By estimating the antioxidant activity of these polyphenolic compounds on the basis of their ability to inhibit the formation of peroxides, it has been shown that hydroxytyrosol and caffeic and protocatechuic acids have a higher protective activity (Papadopoulos & Boskou, 1991).…”

Two new c-glucosyl benzoic acids and flavonoids from Mallotus nanus and their antioxidant activity

“…The reducing abilities of isolated compounds were determined according to the method of Aruoma et al (1998). The forty micro-liters of different concentrations of the compounds in distilled water were mixed with 160 µL of the mixture containing 0.5 mM CuCl 2 and 0.75 mM neocuproine in 10 mM phosphate buffer, pH 7.4.…”