Olive leaf is the leaf of the olive tree (Olea europaea). 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.
Olive leaf is the leaf of the olive tree (Olea europaea). 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.
The silvery green leaves are oblong, measuring 4–10 centimetres (1.6–3.9 inches) long and 1–3 centimetres (0.39–1.18 inches) wide. When consumed, leaves have an astringent bitter taste.[ citation needed ]
Olive phenolics are much more concentrated in the leaves compared with olive oil or olive fruit: 1450 mg total phenolics/100 g fresh leaf vs. 110 mg/100 g fruit and 23 mg/100 ml extra virgin olive oil. [1] [2] Chemical compounds in unprocessed olive leaf are oleuropein and hydroxytyrosol, as well as polyphenols and flavonoids, including luteolin, rutin, caffeic acid, catechin and apigenin. [3] Elenolic acid is a component of olive oil and olive leaf extract. It can be considered as a marker for maturation of olives. [4] Oleuropein, together with other closely related compounds such as 10-hydroxyoleuropein, ligstroside and 10-hydroxyligstroside, are tyrosol esters of elenolic acid. [2] The phenolic composition of olive leaf extract varies according to plant variety, harvesting season and method, leaf maturity, storage conditions and extraction method.[ citation needed ]
Olive leaves are sometimes used in deluxe Chinese cuisine. Olive leaves have been used by Gina Keatley in the creation of Matche, powdered olive leaves used on desserts and in tea. [5]
Scientific evidence for the supposed health effect of using olive leaf extract to manage blood glucose levels has been deemed insufficient by the European Food Safety Authority to have any cause-and-effect relationship. [6]
Olive oil is a liquid fat obtained by pressing whole olives, the fruit of Olea europaea, a traditional tree crop of the Mediterranean Basin, and extracting the oil.
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.
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".
Flavonoids are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.
Flavan-3-ols are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2H-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compounds, such as catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, proanthocyanidins, theaflavins, thearubigins. They play a part in plant defense and are present in the majority of plants.
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.
Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids.
Rutin is the glycoside combining the flavonol quercetin and the disaccharide rutinose. It is a flavonoid glycoside found in a wide variety of plants, including citrus.
A polyphenol antioxidant is a hypothetized type of antioxidant, in which each instance would contain a polyphenolic substructure; such instances which have been studied in vitro. Numbering over 4,000 distinct chemical structures, such polyphenols may have antioxidant activity {{{1}}} in vitro (although they are unlikely to be antioxidants in vivo). Hypothetically, they may affect cell-to-cell signaling, receptor sensitivity, inflammatory enzyme activity or gene regulation, although high-quality clinical research has not confirmed any of these possible effects in humans as of 2020.
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.
Olea europaea subsp. cuspidata is a subspecies of the well-known olive tree, which until recently was considered a separate species and is still mentioned as such in many sources. Native to mostly dry areas across sub-saharan Africa, West Asia, the Himalayan region and southern China, it has various common names, including wild olive, African olive, brown olive and Indian olive.
Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin.
Oleuropein is a glycosylated seco-iridoid, a type of phenolic bitter compound found in green olive skin, flesh, seeds, and leaves. The term oleuropein is derived from the botanical name of the olive tree, Olea europaea.
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.
Phenolic compounds—natural phenol and polyphenols—occur naturally in wine. These include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include phenolic acids, stilbenoids, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). This large group of natural phenols can be broadly separated into two categories, flavonoids and non-flavonoids. Flavonoids include the anthocyanins and tannins which contribute to the color and mouthfeel of the wine. The non-flavonoids include the stilbenoids such as resveratrol and phenolic acids such as benzoic, caffeic and cinnamic acids.
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.
A hydrolysable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids.
The phenolic content in tea refers to the phenols and polyphenols, natural plant compounds which are found in tea. These chemical compounds affect the flavor and mouthfeel of tea. Polyphenols in tea include catechins, theaflavins, tannins, and flavonoids.
The pomegranate ellagitannins, which include punicalagin isomers, are ellagitannins found in the sarcotestas, rind (peel), bark or heartwood of the pomegranate fruit.
Elenolic acid glucoside and hydroxytyrosol can be considered indicators of maturation for olives
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