New Phenolic Compounds Found in EVOO

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The Mediterranean diet is the world’s most stud­ied dietary pat­tern and has been shown to pro­vide valu­able health ben­e­fits and reduce the risk of numer­ous dis­eases.

Extra vir­gin olive oil (EVOO) is the major source of lipids in the Med Diet and is con­sumed on a daily basis. EVOO con­tains pow­er­ful phe­no­lic com­pounds that exert many of these known health ben­e­fits, namely hydrox­y­ty­rosol, tyrosol and their deriv­a­tives.

Understanding the chem­i­cal iden­tity of the var­i­ous phe­no­lic com­pounds is crit­i­cally impor­tant for fur­ther­ing research and for per­mit­ting spe­cific health claims in rela­tion to spe­cific phe­no­lic com­pounds. However, it has been noted that some lit­er­a­ture does not accu­rately define terms and can often be mis­lead­ing, in some cases caus­ing prob­lems in trans­lat­ing results and out­comes. Without a doubt, there are tech­ni­cal dif­fi­cul­ties; how­ever, there is no offi­cially defined method for the mea­sure­ment of phe­no­lic com­pounds, par­tic­u­larly in rela­tion to mak­ing health claims, some­thing that the European Union Legislation (EU 432/2012) has recently per­mit­ted.

According to research pub­lished in OLIVAE, key com­pounds in hydrox­y­ty­rosol and tyrosol ​“are found in olive oil mainly in the ester­i­fied forms of olea­cein (3,4‑DHPEA – EDA) and oleo­can­thal (p‑DHPEA – EDA) as well as oleu­ropein agly­con (3,4‑DHPEA-EA) and ligstro­side agly­con (p‑HPEA-EA), which all have sig­nif­i­cant bio­log­i­cal activ­i­ties.” However, the researchers also sug­gest that in par­tic­u­lar, ​“oleu­ropein agly­con and ligstro­side agly­con are terms that are not accu­rately defined and are often used in a mis­lead­ing way.” Most notably the con­fu­sion comes from report­ing the var­i­ous com­pli­cated and descrip­tive names, ​“hydrox­y­lated form, monoalde­hy­dic form, dialde­hy­dic form, hydrated form, open ring, closed ring, car­boxy­lated, decar­boxy­lated” and so forth.

During their research, Panagiotis Diamantakos1, Angeliki Velkou, Brian Killday, Thanasis Gimisis, Eleni Melliou1, and Prokopios Magiatis dis­cov­ered for the first time ever, new olive oil (OO) ingre­di­ents belong­ing to the oleu­ropein and ligstro­side agly­con fam­ily. The researchers sug­gest nam­ing the new com­pounds oleoko­ronal, oleomis­sional and ligstro­dial ​“to min­i­mize the con­fu­sion aris­ing from the use of com­pli­cated or abbre­vi­ated names.”

To dis­cover the com­pounds, the researchers con­ducted screen­ing of 2,000 vari­eties of OO using NMR analy­sis. To ensure the results were not an arti­fact of the extrac­tion and dilu­tion process, and to prove that they were real ingre­di­ents, the researchers used a EVOO sam­ple with­out any sol­vent and put it through an exci­ta­tion pulse exper­i­ment before com­par­ing it to a diluted form of the same EVOO. The exper­i­ment revealed ​“the enol form 14 of ligstro­side agly­con” for both EVOO sam­ples, indi­cat­ing that the ingre­di­ents were real.

According to the research, Koroneiki and Mission vari­eties were the first observ­able EVOO vari­eties dis­cov­ered to con­tain oleoko­ronal and oleomis­sional. The authors stated that ​“in most of the oils stud­ied the con­cen­tra­tion of oleoko­ronal and oleomis­sional and of the related dialde­hy­des was lower than that of oleo­can­thal and olea­cein and in many cases they were totally absent.”

At this stage, it appears that these newly noted phe­no­lics are only present in cer­tain vari­eties, or may be depen­dent on the pro­duc­tion para­me­ters of oils.

• OLIVAE