3,4-Dihydroxyphenylglycol (DHPG): An Important Phenolic Compound Present in Natural Table Olives

Abstract

The presence of 3,4-dihydroxyphenylglycol (DHPG) was studied in 32 samples and 10 different cultivars of natural table olives, using an accurate method to avoid wrong quantification. Hydroxytyrosol (HT), tyrosol, and verbascoside were also quantified, as these four compounds comprise the majority of the chromatographic profile. Analyses were carried out by HPLC-DAD-UV after extraction of all phenolics, and hydroxytyrosol was the major component in nearly all samples. High levels of DHPG (up to 368 mg/kg of dry weight) were found in the pulp of natural black olives independent of cultivar and processing method, similar to its concentration in the brine in almost all of the samples. The presented data for this antioxidant indicate that natural table olives are a rich source of DHPG and hydroxytyrosol, compounds with interesting nutritional and antioxidant properties.

A Straightforward Access to New Families of Lipophilic Polyphenols by Using Lipolytic Bacteria

“…DHPG is a simple phenol structurally similar to HT, but with an additional hydroxyl group at the benzylic position. The reason to use this poorly studied polyphenol relies on its antioxidant efficiency in water, which is 2–3 times higher than that of ascorbic acid or HT, whereas in lipid medium it is comparable to that of vitamin E despite its high polarity [31]. Interestingly, this compound could be obtained from olive-mill wastes (alperujo) using a simple method [32].…”

Determination of 3,4-dihydroxyphenylglycol, hydroxytyrosol and tyrosol purified from olive oil by-products with HPLC in animal plasma and tissues

“…The first eluent was chosen to recover DHPG, avoiding potential degradation of this phenol in a consequent concentration step. We recently observed that using high concentrations of ethanol or methanol produces split peaks for DHPG during HPLC analysis (Rodríguez et al, 2009a(Rodríguez et al, , 2009b. Tissue extractions were carried out using two concentrations of ethanol (50% and 100%), and both gave similar recoveries for all three phenols (data not shown).…”

“…We chose 100% ethanol to extract DHPG, hydroxytyrosol and tyrosol from the tissues as it gave a cleaner extract with less interfering peaks close to the DHPG peak. We observed previously that DHPG is not stable in alkaline conditions, or when adding acid such as ascorbic acid to prevent the oxidation of phenols, as it degrades during the concentration process when the pH is out with the range of 6.0-6.5 (Rodríguez et al, 2009a(Rodríguez et al, , 2009b. Therefore, our method to extract phenols from plasma and tissues avoids the addition of any acid to the final solution, oxidation being prevented by use of a vacuum manifold and nitrogen during sample concentration.…”

“…Tyrosol was purified from the fraction that was eluted with water obtained from the first chromatographic column by an additional column of polystyrene based resins (Amberchrom Ò CG161). DHPG was also purified by a novel chromatographic system under patent in which water was the only eluent (Rodríguez, Lama, Trujillo, Espartero, & Fernández-Bolaños, 2009a, 2009b. In this case, three chromatographic steps were necessary to get the pure compound.…”

MnSOD activity regulates hydroxytyrosol-induced extension of chronological lifespan

“…Hydroxytyrosol (2-(3,4-dihydroxyphenyl) ethanol) is a hydrophilic polyphenol commonly found in olives; olive oil is a common ingredient of the Mediterranean diet (Rodriguez et al 2009). The use of olive oil in the diet is believed to be associated with a lower incidence of cancer and cardiovascular diseases in the Mediterranean population (Fabiani et al 2008;Visioli et al 1998).…”