Oleuropein

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Oleuropein
Oleuropein structure.svg
Names
IUPAC name
Methyl (2S,3E,4S)-4-{2-[2-(3,4-Dihydroxyphenyl)ethoxy]-2-oxoethyl}-3-ethylidene-2-(β-D-glucopyranosyloxy)-2H-pyran-5-carboxylate
Systematic IUPAC name
Methyl (2S,3E,4S)-4-{2-[2-(3,4-Dihydroxyphenyl)ethoxy]-2-oxoethyl}-3-ethylidene-2-{[(2S,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}-2H-pyran-5-carboxylate
Other names
2-(3,4-Dihydroxyphenyl)ethyl [(2S,3E,4S)-3-ethylidene-2-(β-D-glucopyranosyloxy)-5-(methoxycarbonyl)-3,4-dihydro-2H-pyran-4-yl]acetate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.046.466 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C25H32O13/c1-3-13-14(9-19(29)35-7-6-12-4-5-16(27)17(28)8-12)15(23(33)34-2)11-36-24(13)38-25-22(32)21(31)20(30)18(10-26)37-25/h3-5,8,11,14,18,20-22,24-28,30-32H,6-7,9-10H2,1-2H3/b13-3+/t14-,18+,20+,21-,22+,24-,25-/m0/s1 Yes check.svgY
    Key: RFWGABANNQMHMZ-ZCHJGGQASA-N Yes check.svgY
  • InChI=1/C25H32O13/c1-3-13-14(9-19(29)35-7-6-12-4-5-16(27)17(28)8-12)15(23(33)34-2)11-36-24(13)38-25-22(32)21(31)20(30)18(10-26)37-25/h3-5,8,11,14,18,20-22,24-28,30-32H,6-7,9-10H2,1-2H3/b13-3+/t14-,18+,20+,21-,22+,24-,25-/m0/s1
    Key: RFWGABANNQMHMZ-ZCHJGGQABE
  • O=C(OCCc1ccc(O)c(O)c1)C[C@H]2C(=C/C)\[C@@H](O\C=C2\C(=O)OC)O[C@@H]3O[C@@H]([C@@H](O)[C@H](O)[C@H]3O)CO
Properties
C25H32O13
Molar mass 540.518 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Oleuropein is a glycosylated seco-iridoid, a type of phenolic bitter compound found in green olive skin, flesh, seeds, and leaves. [1] The term oleuropein is derived from the botanical name of the olive tree, Olea europaea.

Contents

Because of its bitter taste, oleuropein must be completely removed or decomposed to make olives edible. During processing of bitter and inedible green olives for consumption as table olives, oleuropein is removed from olives via a number of methods, including by immersion in lye. [2] [3]

Chemical treatment

Oleuropein is a derivative of elenolic acid linked to the orthodiphenol hydroxytyrosol by an ester bond and to a molecule of glucose by a glycosidic bond. [4] When olives are immersed in a lye solution, the alkaline conditions lead to hydrolysis of the ester bond. The basic conditions also significantly increases the solubility of these derivatives, facilitating their release into the lye solution. [5] [6]

The high pH accelerates the oxidation of the phenolics, leading to blackness, as during their normal ripening, if the solution is oxygenated by air injection (alkaline oxidation of olives is also called the California process). [7] [8]

The lye solution is replaced several times until the bitter taste has dissipated. An alternative process uses amberlite macroporous resins to trap the oleuropein directly from the solution, reducing waste water while capturing the extracted molecules. [9] [10]

Enzymatic hydrolysis during the maturation of olives is also an important process for the decomposition of oleuropein and elimination of its bitter taste. [6] [11]

Green olive blackening

Green olives may be treated industrially with ferrous gluconate (0.4 wt. %) [7] to change their color to black. [12] Gluconate, an edible oxidation product of glucose, is used as non-toxic reactant to maintain Fe2+ in solution. When in contact with polyphenols, the ferrous ions form a black complex, giving the final color of the treated olives. [9] [10] [7] Black olives treated with iron(II) gluconate are also depleted in hydroxytyrosol, as iron salts are catalysts for its oxidation. [13]

Research

Oleuropein has been proposed as a proteasome activator. [14] [15]

See also

Related Research Articles

<span class="mw-page-title-main">Glucose</span> Naturally produced monosaccharide

Glucose is a sugar with the molecular formula C6H12O6. Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. Glucose is used by plants to make cellulose—the most abundant carbohydrate in the world—for use in cell walls, and by all living organisms to make adenosine triphosphate (ATP), which is used by the cell as energy.

<span class="mw-page-title-main">Olive</span> Flowering plant in the family Oleaceae

The olive, botanical name Olea europaea, meaning 'European olive', is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin, with wild subspecies found further afield in Africa and western Asia. When in shrub form, it is known as Olea europaea'Montra', dwarf olive, or little olive. The species is cultivated in all the countries of the Mediterranean, as well as in Australia, New Zealand, North and South America and South Africa. It is the type species for its genus, Olea. The tree and its fruit give their name to the Oleaceae plant family, which also includes species such as lilac, jasmine, forsythia, and the true ash tree.

<span class="mw-page-title-main">Starch</span> Glucose polymer used as energy store in plants

Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc).

<span class="mw-page-title-main">Gallic acid</span> 3,4,5-Trihydroxybenzoic acid

Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6H2(OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It is a white solid, although samples are typically brown owing to partial oxidation. Salts and esters of gallic acid are termed "gallates".

<span class="mw-page-title-main">Polyphenol</span> Class of chemical compounds

Polyphenols are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.

<span class="mw-page-title-main">Glucose oxidase</span> Class of enzymes

The glucose oxidase enzyme also known as notatin is an oxidoreductase that catalyses the oxidation of glucose to hydrogen peroxide and D-glucono-δ-lactone. This enzyme is produced by certain species of fungi and insects and displays antibacterial activity when oxygen and glucose are present.

<span class="mw-page-title-main">Reducing sugar</span> Sugars that contain free OH group at the anomeric carbon atom

A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reaction, the sugar becomes a carboxylic acid.

<span class="mw-page-title-main">Gluconic acid</span> Chemical compound

Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4CO2H. A white solid, it forms the gluconate anion in neutral aqueous solution. The salts of gluconic acid are known as "gluconates". Gluconic acid, gluconate salts, and gluconate esters occur widely in nature because such species arise from the oxidation of glucose. Some drugs are injected in the form of gluconates.

<span class="mw-page-title-main">Sulfonic acid</span> Organic compounds with the structure R−S(=O)2−OH

In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

<span class="mw-page-title-main">Kuding</span> Bitter infusion used in traditional Chinese medicine

Kuding is a particularly bitter-tasting Chinese infusion, which due to their similarities in appearance is derived from several plant species. The two most common plants used to make kuding are the wax tree species Ligustrum robustum and the holly species Ilex kaushue, the former being more commonly grown in Sichuan and Japan while the latter is most commonly grown and used in the rest of China. Tea produced from Ligustrum or many species of Ilex is caffeine-free, although not Ilex paraguariensis, the source of mate drank in South America.

<span class="mw-page-title-main">Hydroxytyrosol</span> Chemical compound

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, although samples often turn beige during storage. It is a derivative, formally speaking, of catechol.

<span class="mw-page-title-main">Tyrosol</span> Chemical compound

Tyrosol is an organic compound with the formula HOC6H4CH2CH2OH. Classified as a phenylethanoid, i.e. a derivative of phenethyl alcohol, It is found in a variety of natural sources. The compound is colorless solid. The principal source in the human diet is olive oil.

<span class="mw-page-title-main">Olive leaf</span> Herbal medicinal product

Olive leaf is the leaf of the olive tree. Although olive oil is well known for its flavor and possible health benefits, the leaf and its extracts remain under preliminary research with unknown effects on human health.

<span class="mw-page-title-main">Anthocyanin</span> Class of plant-based pigments

Anthocyanins, also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compound that gives flowers a blue color, Anthokyan, in his treatise "Die Farben der Blüthen". Food plants rich in anthocyanins include the blueberry, raspberry, black rice, and black soybean, among many others that are red, blue, purple, or black. Some of the colors of autumn leaves are derived from anthocyanins.

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<span class="mw-page-title-main">Wine color</span> Wine characteristic

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<span class="mw-page-title-main">Elenolic acid</span> Chemical compound

Elenolic acid is a component of olive oil, olive infusion and olive leaf extract. It can be considered as a marker for maturation of olives.

<span class="mw-page-title-main">Blue bottle experiment</span> Color-changing redox chemical reaction

The blue bottle experiment is a color-changing redox chemical reaction. An aqueous solution containing glucose, sodium hydroxide, methylene blue is prepared in a closed bottle containing some air. Upon standing, it spontaneously turns from blue to colorless due to reduction of methylene blue by the alkaline glucose solution. However, shaking the bottle oxidizes methylene blue back into its blue form. With further shaking, this color-change cycle can be repeated many times. This experiment is a classic chemistry demonstration that can be used in laboratory courses as a general chemistry experiment to study chemical kinetics and reaction mechanism. The reaction also works with other reducing agents besides glucose and other redox indicator dyes besides methylene blue.

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<span class="mw-page-title-main">Manzanilla olive</span> Type of olive

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References

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  2. "How olives are made". California Olive Committee. 2017. Archived from the original on 5 August 2017. Retrieved 5 August 2017.
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  4. Panizzi, L.; Scarpati, M.L.; Oriente, E.G. (1960). "Structure of the bitter glucoside oleuropein. Note II". Gazzetta Chimica Italiana. 90: 1449–1485.
  5. Yuan, Jiao-Jiao; Wang, Cheng-Zhang; Ye, Jian-Zhong; Tao, Ran; Zhang, Yu-Si (2015). "Enzymatic hydrolysis of oleuropein from Olea Europea (olive) leaf extract and antioxidant activities". Molecules. 20 (2): 2903–2921. doi: 10.3390/molecules20022903 . ISSN   1420-3049. PMC   6272143 . PMID   25679050.
  6. 1 2 Ramírez, Eva; Brenes, Manuel; García, Pedro; Medina, Eduardo; Romero, Concepción (2016). "Oleuropein hydrolysis in natural green olives: Importance of the endogenous enzymes" (PDF). Food Chemistry. 206: 204–209. doi:10.1016/j.foodchem.2016.03.061. hdl: 10261/151764 . ISSN   0308-8146. PMID   27041317. Archived (PDF) from the original on 2018-07-23. Retrieved 2019-09-27.
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