Hydroxytyrosol is an
organic compound with the formula (HO)2C6H3CH2CH2OH. It is a
phenylethanoid, i.e. a relative of
phenethyl alcohol. Its derivatives are found in a variety of natural sources, notably olive oils and wines. Hydroxytyrosol is a colorless solid,[3][4] although samples often turn
beige during storage. It is a derivative, formally speaking, of
catechol.
It or its derivatives occurs in olives and in wines[5][6]
Occurrence
Olives
The olives, leaves, and olive pulp contain large amounts of hydroxytyrosol derivative
Oleuropein, more so than
olive oil.[1] Unprocessed, green (unripe) olives, contain between 4.3 and 116 mg of hydroxytyrosol per 100g of olives, while unprocessed, black (ripe) olives contain up to 413.3 mg per 100g.[7] The ripening of an olive substantially increases the amount of hydroxytyrosol.[8] Processed olives, such as the common canned variety containing
iron(II) gluconate, contained little hydroxytyrosol, as iron salts are catalysts for its oxidation.[9]
In the United States, hydroxytyrosol is considered to be a safe ingredient (
GRAS) in processed foods at levels of 5 mg per serving.[11]
Function and production
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.[12]
Metabolism
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.[13]
Mediterranean diet
Mediterranean diets, characterized by regular intake of olive oil, have been shown to positively affect human health, including reduced rates of
cardiovascular diseases.[5][14][15] Research on consumption of olive oil and its components includes hydroxytyrosol and oleuropein, which may inhibit oxidation of LDL cholesterol – a
risk factor for atherosclerosis, heart attack or stroke.[16] The daily intake of hydroxytyrosol within the Mediterranean diet is estimated to be between 0.15 and 30 mg.[17]
Regulation
Europe
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.[18]
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,[18] 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.[19]
See also
Echinacoside, a hydroxytyrosol-containing glycoside
^
abBaldioli M, Servili M, Perretti G, Montedoro GF (1996). "Antioxidant activity of tocopherols and phenolic compounds of virgin olive oil". Journal of the American Oil Chemists' Society. 73 (11): 1589–1593.
doi:
10.1007/BF02523530.
S2CID84749200.
^de Pablos RM, Espinosa-Oliva AM, Hornedo-Ortega R, Cano M, Arguelles S (May 2019). "Hydroxytyrosol protects from aging process via AMPK and autophagy; a review of its effects on cancer, metabolic syndrome, osteoporosis, immune-mediated and neurodegenerative diseases". Pharmacological Research. 143: 58–72.
doi:
10.1016/j.phrs.2019.03.005.
PMID30853597.
S2CID73726654.
^
ab"Scientific Opinion on the substantiation of health claims related to polyphenols in olive and protection of LDL particles". European Food Safety Authority. 8 April 2011. Retrieved 2021-04-13. 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