Flavonols
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Flavonols
Flavonols are a class of flavonoids that have the 3-hydroxyflavone backbone (IUPAC name : 3-hydroxy-2-phenylchromen-4-one). Their diversity stems from the different positions of the phenols, phenolic hydroxyl, -OH groups. They are distinct from flavanols (with "a") such as catechin, another class of flavonoids. Flavonols are present in a wide variety of fruits and vegetables. In Western populations, estimated daily intake is in the range of 20–50 mg per day for flavonols. Individual intake varies depending on the type of diet consumed. The phenomenon of dual fluorescence (due to excited state intramolecular proton transfer or ESIPT) is induced by tautomerism of flavonols (and glucosides) and could contribute to plant UV protection and flower colour. Besides being a subclass of flavonoids, flavonols are suggested by a study of cranberry juice to play a role along with proanthocyanidins, in the juice's ability to block bacterial adhesion, demonstrated by the compressing the ...
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Flavonol Num
Flavonols are a class of flavonoids that have the 3-hydroxyflavone backbone (IUPAC name : 3-hydroxy-2-phenylchromen-4-one). Their diversity stems from the different positions of the phenols, phenolic hydroxyl, -OH groups. They are distinct from flavanols (with "a") such as catechin, another class of flavonoids. Flavonols are present in a wide variety of fruits and vegetables. In Western populations, estimated daily intake is in the range of 20–50 mg per day for flavonols. Individual intake varies depending on the type of diet consumed. The phenomenon of dual fluorescence (due to excited state intramolecular proton transfer or ESIPT) is induced by tautomerism of flavonols (and glucosides) and could contribute to plant UV protection and flower colour. Besides being a subclass of flavonoids, flavonols are suggested by a study of cranberry juice to play a role along with proanthocyanidins, in the juice's ability to block bacterial adhesion, demonstrated by the compressing the ...
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Myricetin
Myricetin is a member of the flavonoid class of polyphenolic compounds, with antioxidant properties. Common dietary sources include vegetables (including tomatoes), fruits (including oranges), nuts, berries, tea, and red wine. Myricetin is structurally similar to fisetin, luteolin, and quercetin and is reported to have many of the same functions as these other members of the flavonol class of flavonoids. Reported average intake of myricetin per day varies depending on diet, but has been shown in the Netherlands to average 23 mg/day. Myricetin is produced from the parent compound taxifolin through the (+)-dihydromyricetin intermediate and can be further processed to form laricitrin and then syringetin, both members of the flavonol class of flavonoids. Dihydromyricetin is frequently sold as a supplement and has controversial function as a partial GABAA receptor potentiator and treatment in Alcohol Use Disorder (AUD). Myricetin can alternatively be produced directly from kae ...
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Kaempferol
Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a natural flavonol, a type of flavonoid, found in a variety of plants and plant-derived foods including kale, beans, tea, spinach, and broccoli. Kaempferol is a yellow crystalline solid with a melting point of . It is slightly soluble in water and highly soluble in hot ethanol, ethers, and DMSO. Kaempferol is named for 17th-century German naturalist Engelbert Kaempfer.Kaempferol
at Merriam-Webster.com; retrieved October 20, 2017


Natural occurrence

Kaempferol is a secondary metabolite found in many plants, plant-derived foods, and traditional medicines. Its flavor is considered bitter.


In plants and food

Kaempferol is common in

Isorhamnetin
Isorhamnetin is an O-methylated flavon-ol from the class of flavonoids. A common food source of this 3'-methoxylated derivative of quercetin and its glucoside conjugates are pungent yellow or red onions, in which it is a minor pigment, quercetin-3,4'-diglucoside and quercetin-4'-glucoside and the aglycone quercetin being the major pigments. Pears, olive oil, wine and tomato sauce are rich in isorhamnetin. Others sources include the spice, herbal medicinal and psychoactive Mexican tarragon ''(Tagetes lucida)'', which is described as accumulating isorhamnetin and its 7-O-glucoside derivate. Nopal (Opuntia ficus-indica (L.)) is also a good source of isorhamnetin, which can be extracted by supercritical fluid extraction assisted by enzymes. Metabolism The enzyme quercetin 3-O-methyltransferase uses S-adenosyl methionine and quercetin to produce S-adenosylhomocysteine and isorhamnetin. The enzyme 3-methylquercetin 7-O-methyltransferase uses S-adenosyl methionine and 5,7,3',4'-tet ...
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Fisetin
Fisetin (7,3′,4′- flavon-3-ol) is a plant flavonol from the flavonoid group of polyphenols. It can be found in many plants, where it serves as a yellow/ochre colouring agent. It is also found in many fruits and vegetables, such as strawberries, apples, persimmons, onions and cucumbers. Its chemical formula was first described by Austrian chemist Josef Herzig in 1891. The biological activity of fisetin has been studied in many laboratory assays; like other polyphenols it has many activities. Biological sources Fisetin can be found in a wide variety of plants. It is found in Eudicotyledons, such as trees and shrubs in the family Fabaceae, such as the acacias ''Acacia greggii'' and ''Acacia berlandieri'', the parrot tree ('' Butea frondosa''), the honey locust (''Gleditsia triacanthos''), members of the family Anacardiaceae such as the ''Quebracho colorado'' and species of the genus '' Rhus'', which contains the sumacs. Along with myricetin, fisetin provides the color of the tra ...
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Flavonoids
Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and a heterocyclic ring (C, the ring containing the embedded oxygen). This carbon structure can be abbreviated C6-C3-C6. According to the IUPAC nomenclature, they can be classified into: *flavonoids or bioflavonoids *isoflavonoids, derived from 3-phenyl chromen-4-one (3-phenyl-1,4-benzopyrone) structure *neoflavonoids, derived from 4-phenylcoumarine (4-phenyl-1,2-benzopyrone) structure The three flavonoid classes above are all ketone-containing compounds and as such, anthoxanthins ( flavones and flavonols). This class was the first to be termed bioflavonoids. The terms flavonoid and bioflavonoid have also been more loosely used to describe non- ...
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Kaempferide
Kaempferide is an ''O''-methylated flavonol, a type of chemical compound. It can be found in ''Kaempferia galanga'' (aromatic ginger). It has been noted to inhibit pancreatic cancer growth by blockading an EGFR-related pathway. Metabolism The enzyme kaempferol 4'-''O''-methyltransferase uses ''S''-adenosyl-L-methionine and kaempferol to produce ''S''-adenosyl-L-homocysteine and kaempferide. Glycosides Icariin is the tert-amyl alcohol ''tert''-Amyl alcohol (TAA) or 2-methylbutan-2-ol (2M2B), is a branched pentanol. Historically TAA has been used an anesthetic and more recently used as a recreational drug. TAA is mostly a positive allosteric modulator for GABAA receptors in t ... derivative of kaempferide 3,7-''O''-diglycoside. References External links Kaempferide at the HMDB O-methylated flavonols {{Aromatic-stub ...
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Flavonoid
Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and a heterocyclic ring (C, the ring containing the embedded oxygen). This carbon structure can be abbreviated C6-C3-C6. According to the IUPAC nomenclature, they can be classified into: *flavonoids or bioflavonoids *isoflavonoids, derived from 3-phenyl chromen-4-one (3-phenyl-1,4-benzopyrone) structure *neoflavonoids, derived from 4-phenylcoumarine (4-phenyl-1,2-benzopyrone) structure The three flavonoid classes above are all ketone-containing compounds and as such, anthoxanthins ( flavones and flavonols). This class was the first to be termed bioflavonoids. The terms flavonoid and bioflavonoid have also been more loosely used to describe non ...
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Azaleatin
Azaleatin is a chemical compound. It is an O-methylated flavonol, a type of flavonoid. It was first isolated from the flowers of ''Rhododendron mucronatum'' in 1956 and has since been recorded in forty-four other Rhododendron species, in ''Plumbago capensis'', in ''Ceratostigma willmottiana'' and in ''Carya pecan''. It has been also been found in the leaves of ''Eucryphia''. Glycosides Azalein is the 3-''O''-α-L-rhamnoside Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. Rhamnose predominantly occurs in nature in its L-form, L-form as L-rhamnose (6-deoxy-L-mannose). This is unusual, since ... of azaleatin. References O-methylated flavonols Catechols {{Aromatic-stub ...
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Natsudaidain
Natsudaidain is an O-methylated flavonol, a type of chemical compound. It can be isolated from Citrus plants (Rutaceae). The name of the molecule comes from ''Citrus natsudaidai'' (Natsumikan, lit. "summer tangerine"), a fruit of Japan developed in 1740 with a particularly tart/sour taste. References O-methylated flavonols Flavonoids found in Rutaceae {{Aromatic-stub ...
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Pachypodol
Pachypodol is an O-methylated flavonol, a type of chemical compound. It can be isolated from '' Pachypodanthium confine'', from leaves of ''Agastache rugosa, (Korean mint)'', Latin denomination of part of plant : Agastache folium ''Agastache'' () is a genus of aromatic flowering herbaceous perennial plants in the family Lamiaceae. It contains 22 species, mainly native to North America, one species native to eastern Asia. The common names of the species are a variety of f ... . References O-methylated flavonols {{Aromatic-stub ...
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Rhamnazin
Rhamnazin is an ''O''-methylated flavonol, a type of chemical compound. It can be found in ''Rhamnus petiolaris'', a buckthorn plant endemic to Sri Lanka. Metabolism The enzyme 3-methylquercetin 7-''O''-methyltransferase uses ''S''-adenosyl methionine and isorhamnetin to produce ''S''-adenosyl homocysteine and rhamnazin. The enzyme 3,7-dimethylquercetin 4'-''O''-methyltransferase uses ''S''-adenosyl methionine and rhamnazin to produce ''S''-adenosyl homocysteine and ayanin Ayanin is an ''O''-methylated flavonol, a type of flavonoid. It is the 3,7,4'-tri-''O''-methylated derivative of quercetin. It can be found in ''Croton schiedeanus''. It can also be synthetized. Biosynthesis The enzyme 3,7-dimethylquercetin 4 .... References External links Rhamnazin on the Extrasynthese catalogue O-methylated flavonols {{Aromatic-stub ...
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