Hydroxytyrosol

image:Oleuropein structure.svg, bitter compound, an ester of hydroxytyrosol found in green olive skin]]

The olives, leaves, and olive pulp contain large amounts of hydroxytyrosol derivative oleuropein, more so than olive oil. Unprocessed, green (unripe) olives contain between 4.3 and 116 mg of hydroxytyrosol per 100 g of olives, while unprocessed, black (ripe) olives contain up to 413.3 mg per 100 g.{{Cite web|title=Showing all foods in which the polyphenol Hydroxytyrosol is found - Phenol-Explorer|url=http://phenol-explorer.eu/contents/polyphenol/674|access-date=2021-07-02|website=phenol-explorer.eu}} The ripening of an olive substantially increases the amount of hydroxytyrosol.{{cite journal | vauthors = Rocha J, Borges N, Pinho O | title = Table olives and health: a review | journal = Journal of Nutritional Science | volume = 9 | pages = e57 | year = 2020 | pmid = 33354328 | pmc = 7737178 | doi = 10.1017/jns.2020.50 }} Processed olives, such as the common canned variety containing iron(II) gluconate, contain little hydroxytyrosol, as iron salts are catalysts for its oxidation.{{cite journal |doi=10.1016/S0308-8146(00)00338-1 |title=Phenolic compounds change during California-style ripe olive processing | vauthors = Marsilio V, Campestre C, Lanza B |journal=Food Chemistry |volume =74 | issue =1 |date= July 2001 |pages= 55–60}}

Hydroxytyrosol is considered safe as a novel food for human consumption, with a no-observed-adverse-effect level of 50 mg/kg body weight per day, as evaluated by the European Food Safety Authority (EFSA).{{cite journal | vauthors = Turck D, Bresson JL, Burlingame B, Dean T, Fairweather-Tait S, Heinonen M, Hirsch-Ernst KI, Mangelsdorf I, McArdle HJ, Naska A, Neuhäuser-Berthold M, Nowicka G, Pentieva K, Sanz Y, Siani A, Sjödin A, Stern M, Tomé D, Vinceti M, Willatts P, Engel KH, Marchelli R, Pöting A, Poulsen M, Schlatter J, Turla E, van Loveren H | display-authors = 6 | title = Safety of hydroxytyrosol as a novel food pursuant to Regulation (EC) No 258/97 | journal = EFSA Journal | volume = 15 | issue = 3 | pages = e04728 | date = March 2017 | pmid = 32625437 | pmc = 7010075 | doi = 10.2903/j.efsa.2017.4728 }}

In the United States, hydroxytyrosol is considered to be a safe ingredient (GRAS) in processed foods at levels of 5 mg per serving.{{Cite web|access-date=2 July 2021|title=GRAS notice for hydroxytyrosol|date=13 May 2016|url=https://www.cfsanappsexternal.fda.gov/scripts/fdcc/?set=GRASNotices&id=600&sort=GRN_No&order=DESC&startrow=1&type=basic&search=hydroxytyrosol|publisher=US Food and Drug Administration}}

File:Synthesis of Hydroxytyrosol.jpg

In nature, hydroxytyrosol is generated by the hydrolysis of oleuropein that occurs during olive ripening. Oleuropein accumulates in olive leaves and fruit as a defense mechanism against pathogens and herbivores. During olive ripening or when the olive tissue is damaged by pathogens, herbivores, or mechanical damage, the enzyme β-glucosidase catalyzes hydroxytyrosol synthesis via hydrolysis from oleuropein.{{cite journal | vauthors = Charoenprasert S, Mitchell A | title = Factors influencing phenolic compounds in table olives (Olea europaea) | journal = Journal of Agricultural and Food Chemistry | volume = 60 | issue = 29 | pages = 7081–7095 | date = July 2012 | pmid = 22720792 | doi = 10.1021/jf3017699 }}

Shortly after olive oil consumption, 98% of hydroxytyrosol in plasma and urine appears in conjugated forms (65% glucuronoconjugates), suggesting extensive first-past metabolism and a half-life of 2.43 hours.{{cite journal | vauthors = Miro-Casas E, Covas MI, Farre M, Fito M, Ortuño J, Weinbrenner T, Roset P, de la Torre R | display-authors = 6 | title = Hydroxytyrosol disposition in humans | journal = Clinical Chemistry | volume = 49 | issue = 6 Pt 1 | pages = 945–952 | date = June 2003 | pmid = 12765992 | doi = 10.1373/49.6.945 | doi-access = free }}

Mediterranean diets, characterized by regular intake of olive oil, have been shown to positively affect human health, including reduced rates of cardiovascular diseases.{{cite journal | vauthors = Hu T, He XW, Jiang JG, Xu XL | title = Hydroxytyrosol and its potential therapeutic effects | journal = Journal of Agricultural and Food Chemistry | volume = 62 | issue = 7 | pages = 1449–1455 | date = February 2014 | pmid = 24479643 | doi = 10.1021/jf405820v }}{{cite journal | vauthors = Martínez-González MA, Gea A, Ruiz-Canela M | title = The Mediterranean Diet and Cardiovascular Health | journal = Circulation Research | volume = 124 | issue = 5 | pages = 779–798 | date = March 2019 | pmid = 30817261 | doi = 10.1161/CIRCRESAHA.118.313348 | doi-access = free }} Research on consumption of olive oil and its components includes hydroxytyrosol and oleuropein, which may inhibit oxidation of LDL cholesterol {{ndash}} a risk factor for atherosclerosis, heart attack or stroke.{{cite journal | vauthors = Marcelino G, Hiane PA, Freitas KC, Santana LF, Pott A, Donadon JR, Guimarães RC | title = Effects of Olive Oil and Its Minor Components on Cardiovascular Diseases, Inflammation, and Gut Microbiota | journal = Nutrients | volume = 11 | issue = 8 | page = 1826 | date = August 2019 | pmid = 31394805 | pmc = 6722810 | doi = 10.3390/nu11081826 | doi-access = free }} The daily intake of hydroxytyrosol within the Mediterranean diet is estimated to be between 0.15 and 30 mg.{{cite journal | vauthors = de Pablos RM, Espinosa-Oliva AM, Hornedo-Ortega R, Cano M, Arguelles S | title = Hydroxytyrosol protects from aging process via AMPK and autophagy; a review of its effects on cancer, metabolic syndrome, osteoporosis, immune-mediated and neurodegenerative diseases | journal = Pharmacological Research | volume = 143 | pages = 58–72 | date = May 2019 | pmid = 30853597 | doi = 10.1016/j.phrs.2019.03.005 | s2cid = 73726654 }}

The EFSA has issued a scientific opinion on health claims in relation to dietary consumption of hydroxytyrosol and related polyphenol compounds from olive fruit and oil, and protection of blood lipids from potential oxidative damage.{{Cite web|title=Scientific Opinion on the substantiation of health claims related to polyphenols in olive and protection of LDL particles | quote = From oxidative damage (ID 1333, 1638, 1639, 1696, 2865), maintenance of normal blood HDL cholesterol concentrations (ID 1639), maintenance of normal blood pressure (ID 3781), “anti-inflammatory properties” (ID 1882), “contributes to the upper respiratory tract health” (ID 3468), “can help to maintain a normal function of gastrointestinal tract” (3779), and “contributes to body defences against external agents” (ID 3467) pursuant to Article 13(1) of Regulation (EC) No 1924/2006|url=https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2011.2033|access-date=2021-04-13|publisher=European Food Safety Authority| date = 8 April 2011|language=en}}

EFSA concluded that a cause-and-effect relationship existed between the consumption of hydroxytyrosol and related compounds from olives and olive oil and protection of blood lipids from oxidative damage, providing a health claim for consumption of olive oil polyphenols containing at least 5 mg of hydroxytyrosol and its derivatives (oleuropein complex and tyrosol) per 20 g of olive oil.

• Echinacoside, a hydroxytyrosol-containing glycoside
• Tyrosol
• Verbascoside, another hydroxytyrosol-containing glycoside
• Resveratrol

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Category:Monoamine oxidase inhibitors

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