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29-440: The name of the catechin chemical family derives from catechu , which is the tannic juice or boiled extract of Mimosa catechu ( Acacia catechu L.f). Catechin possesses two benzene rings (called the A and B rings) and a dihydropyran heterocycle (the C ring) with a hydroxyl group on carbon 3. The A ring is similar to a resorcinol moiety while the B ring is similar to a catechol moiety. There are two chiral centers on

58-517: A polypyrenous drupe . The shriveled remains of the sepals , style and stamens can sometimes be seen at the end of a pome opposite the stem, and the ovary is therefore often described as inferior in these flowers. The best-known example of a pome is the apple . Other examples of plants that produce fruit classified as a pome are Cotoneaster , Crataegus (hawthorn and mayhaw), medlar , pear , Pyracantha , quince , rowan , loquat , toyon , and whitebeam . Some pomes may have

87-439: A copper mordant. Black catechu has recently also been used by Blavod Drinks Ltd. to dye their vodka black. White cutch , also known as gambier, gambeer, or gambir, which is extracted from Uncaria gambir has the same uses. Palm-catechu is extracted from the seeds of Areca catechu . The catechu extract gave its name to the catechin and catechol chemical families first derived from it. Pome In botany,

116-422: A pome is a type of fruit produced by flowering plants in the subtribe Malinae of the family Rosaceae . Pome fruits consist of a central "core" containing multiple small seeds, which is enveloped by a tough membrane and surrounded by an edible layer of flesh. Pome fruit trees are deciduous, and undergo a dormant winter period that requires cold temperatures to break dormancy in spring. Well-known pomes include

145-558: A (2 S )-phenyl group resisted the biooxidation. Leucoanthocyanidin reductase (LAR) uses (2 R ,3 S )-catechin, NADP and H 2 O to produce 2,3- trans -3,4- cis - leucocyanidin , NADPH, and H. Its gene expression has been studied in developing grape berries and grapevine leaves. Only limited evidence from dietary studies indicates that catechins may affect endothelium -dependent vasodilation which could contribute to normal blood flow regulation in humans. Green tea catechins may improve blood pressure, especially when systolic blood pressure

174-403: A two-step oxidation can be achieved by Burkholderia sp. (+)-Catechin and (−)-epicatechin are transformed by the endophytic filamentous fungus Diaporthe sp. into the 3,4-cis-dihydroxyflavan derivatives, (+)-(2 R ,3 S ,4 S )-3,4,5,7,3′,4′-hexahydroxyflavan (leucocyanidin) and (−)-(2 R ,3 R ,4 R )-3,4,5,7,3′,4′-hexahydroxyflavan , respectively, whereas (−)-catechin and (+)-epicatechin with

203-409: Is above 130 mmHg. Due to extensive metabolism during digestion, the fate and activity of catechin metabolites responsible for this effect on blood vessels, as well as the actual mode of action, are unknown. Catechin and its metabolites can bind tightly to red blood cells and thereby induce the development of autoantibodies , resulting in haemolytic anaemia and renal failure . This resulted in

232-472: Is an accessory fruit composed of one or more carpels surrounded by accessory tissue. The accessory tissue is interpreted by some specialists as an extension of the receptacle and is then referred to as "fruit cortex", and by others as a fused hypanthium (floral cup). It is the most edible part of this fruit. The carpels of a pome are fused within the "core". Although the epicarp , mesocarp , and endocarp of some other fruit types look very much like

261-514: Is an extract of acacia trees used variously as a food additive , astringent , tannin , and dye . It is extracted from several species of Acacia , but especially Senegalia catechu (previously called Acacia catechu ), by boiling the wood in water and evaporating the resulting brew. The Malay name kachu is the basis of the Latinized catechu chosen as the Linnaean taxonomy name of

290-515: Is biosynthesized from L -phenylalanine through the Shikimate pathway. L -Phenylalanine is first deaminated by phenylalanine ammonia lyase (PAL) forming cinnamic acid which is then oxidized to 4-hydroxycinnamic acid by cinnamate 4-hydroxylase. Chalcone synthase then catalyzes the condensation of 4-hydroxycinnamoyl CoA and three molecules of malonyl-CoA to form chalcone . Chalcone is then isomerized to naringenin by chalcone isomerase which

319-408: Is low. The ability to quench singlet oxygen seems to be in relation with the chemical structure of catechin, with the presence of the catechol moiety on ring B and the presence of a hydroxyl group activating the double bond on ring C. Electrochemical experiments show that (+)-catechin oxidation mechanism proceeds in sequential steps, related with the catechol and resorcinol groups and the oxidation

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348-653: Is metabolized to protocatechuic acid (PCA) and phloroglucinol carboxylic acid (PGCA). It is also degraded by Bradyrhizobium japonicum . Phloroglucinol carboxylic acid is further decarboxylated to phloroglucinol , which is dehydroxylated to resorcinol . Resorcinol is hydroxylated to hydroxyquinol . Protocatechuic acid and hydroxyquinol undergo intradiol cleavage through protocatechuate 3,4-dioxygenase and hydroxyquinol 1,2-dioxygenase to form β-carboxy- cis , cis -muconic acid and maleyl acetate . Among fungi, degradation of catechin can be achieved by Chaetomium cupreum . Catechins are metabolised upon uptake from

377-403: Is oxidized to eriodictyol by flavonoid 3′-hydroxylase and further oxidized to taxifolin by flavanone 3-hydroxylase. Taxifolin is then reduced by dihydroflavanol 4-reductase and leucoanthocyanidin reductase to yield catechin. The biosynthesis of catechin is shown below Leucocyanidin reductase (LCR) uses 2,3- trans -3,4- cis - leucocyanidin to produce (+)-catechin and is the first enzyme in

406-1493: Is pH-dependent. The oxidation of the catechol 3′,4′-dihydroxyl electron-donating groups occurs first, at very low positive potentials, and is a reversible reaction. The hydroxyl groups of the resorcinol moiety oxidised afterwards were shown to undergo an irreversible oxidation reaction. The laccase / ABTS system oxidizes (+)-catechin to oligomeric products of which proanthocyanidin A2 is a dimer. (500 MHz, CD3OD): Reference d : doublet, dd : doublet of doublets, m : multiplet, s : singlet 2.49 (1H, dd, J = 16.0, 8.6 Hz, H-4a), 2.82 (1H, dd, J = 16.0, 1.6 Hz, H-4b), 3.97 (1H, m, H-3), 4.56 (1H, d, J = 7.8 Hz, H-2), 5.86 (1H, d, J = 2.1 Hz, H-6), 5.92 (1H, d, J = 2.1 Hz, H-8), 6.70 (1H, dd, J = 8.1, 1.8 Hz, H-6'), 6.75 (1H, d, J = 8.1 Hz, H-5'), 6.83 (1H, d, J = 1.8 Hz, H-2') 273 water loss 139 retro Diels–Alder 123 165 147 (+)-Catechin and (−)-epicatechin as well as their gallic acid conjugates are ubiquitous constituents of vascular plants , and frequent components of traditional herbal remedies , such as Uncaria rhynchophylla . The two isomers are mostly found as cacao and tea constituents, as well as in Vitis vinifera grapes. The main dietary sources of catechins in Europe and

435-532: The apple , pear , and quince . The word pome entered English in the late 14th century, and referred to an apple or an apple-shaped object. It derived from the Old French word for "apple": pome (12th century; modern French is pomme ), which in turn derived from the Late Latin or Vulgar Latin word poma "apple", originally the plural of Latin pomum "fruit", later "apple". A pome

464-404: The colonic microbiome to gamma-valerolactones and hippuric acids which undergo further biotransformation , glucuronidation , sulfation and methylation in the liver . The stereochemical configuration of catechins has a strong impact on their uptake and metabolism as uptake is highest for (−)-epicatechin and lowest for (−)-catechin. Biotransformation of (+)-catechin into taxifolin by

493-410: The gastrointestinal tract , in particular the jejunum , and in the liver , resulting in so-called structurally related epicatechin metabolites (SREM). The main metabolic pathways for SREMs are glucuronidation , sulfation and methylation of the catechol group by catechol-O-methyl transferase , with only small amounts detected in plasma. The majority of dietary catechins are however metabolised by

522-528: The proanthocyanidin (PA) specific pathway. Its activity has been measured in leaves, flowers, and seeds of the legumes Medicago sativa , Lotus japonicus , Lotus uliginosus , Hedysarum sulfurescens , and Robinia pseudoacacia . The enzyme is also present in Vitis vinifera (grape). [REDACTED] Catechin oxygenase, a key enzyme in the degradation of catechin, is present in fungi and bacteria. Among bacteria, degradation of (+)-catechin can be achieved by Acinetobacter calcoaceticus . Catechin

551-443: The tanning of animal hides. Early research by Humphry Davy in the early 19th century first demonstrated the use of catechu in tanning over more expensive and traditional oak extracts. Under the name cutch , it is a brown dye used for tanning and dyeing and for preserving fishing nets and sails . Cutch will dye wool , silk , and cotton a yellowish-brown. Cutch gives gray-browns with an iron mordant and olive-browns with

580-613: The European ecosystem have defenses against catechin, but few plants are protected against it in the North American ecosystem where Centaurea maculosa is an invasive, uncontrolled weed. Catechin acts as an infection-inhibiting factor in strawberry leaves. Epicatechin and catechin may prevent coffee berry disease by inhibiting appressorial melanization of Colletotrichum kahawae . Catechu Catechu ( / ˈ k æ t ɪ ʃ uː / or / ˈ k æ t ɪ tʃ uː / )

609-627: The United States are tea and pome fruits. Catechins and epicatechins are found in cocoa , which, according to one database, has the highest content (108 mg/100 g) of catechins among foods analyzed, followed by prune juice (25 mg/100 ml) and broad bean pod (16 mg/100 g). Açaí oil , obtained from the fruit of the açaí palm ( Euterpe oleracea ), contains (+)-catechins (67 mg/kg). Catechins are diverse among foods, from peaches to green tea and vinegar . Catechins are found in barley grain, where they are

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638-699: The building blocks of the proanthocyanidins , a type of condensed tannin. Moreover, the flexibility of the C-ring allows for two conformation isomers , putting the B-ring either in a pseudoequatorial position (E conformer) or in a pseudoaxial position (A conformer). Studies confirmed that (+)-catechin adopts a mixture of A- and E-conformers in aqueous solution and their conformational equilibrium has been evaluated to be 33:67. As flavonoids, catechins can act as antioxidants when in high concentration in vitro , but compared with other flavonoids, their antioxidant potential

667-443: The ground by some plants may hinder the growth of their neighbors, a form of allelopathy . Centaurea maculosa , the spotted knapweed often studied for this behavior, releases catechin isomers into the ground through its roots, potentially having effects as an antibiotic or herbicide . One hypothesis is that it causes a reactive oxygen species wave through the target plant's root to kill root cells by apoptosis . Most plants in

696-412: The main phenolic compound responsible for dough discoloration. The taste associated with monomeric (+)-catechin or (−)-epicatechin is described as slightly astringent , but not bitter. [REDACTED] The biosynthesis of catechin begins with ma 4-hydroxycinnamoyl CoA starter unit which undergoes chain extension by the addition of three malonyl-CoAs through a PKSIII pathway. 4-Hydroxycinnamoyl CoA

725-411: The molecule on carbons 2 and 3. Therefore, it has four diastereoisomers . Two of the isomers are in trans configuration and are called catechin and the other two are in cis configuration and are called epicatechin . The most common catechin isomer is (+)-catechin. The other stereoisomer is (−)-catechin or ent -catechin. The most common epicatechin isomer is (−)-epicatechin (also known under

754-487: The names L -epicatechin, epicatechol, (−)-epicatechol, L -acacatechin, L -epicatechol, epicatechin, 2,3- cis -epicatechin or (2 R ,3 R )-(−)-epicatechin). The different epimers can be separated using chiral column chromatography . Making reference to no particular isomer, the molecule can just be called catechin. Mixtures of the different enantiomers can be called (±)-catechin or DL -catechin and (±)-epicatechin or DL -epicatechin. Catechin and epicatechin are

783-664: The plant species which provides the extract. As an astringent it has been used since ancient times in Ayurvedic medicine as well as in breath-freshening spice mixtures—for example in France and Italy it is used in some licorice pastilles . It is also an important ingredient in South Asian cooking paan mixtures, such as ready-made paan masala and gutka . The catechu mixture is high in natural vegetable tannins (which accounts for its astringent effect), and may be used for

812-429: The skin, flesh, and core respectively of a pome, they are parts of the carpel (see above diagram). The epicarp and mesocarp of a pome may be fleshy and difficult to distinguish from one another and from the hypanthial tissue. The endocarp forms a leathery or stony case around the seed , and corresponds to what is commonly called the core. A pome-type fruit with a stony rather than a leathery endocarp may be called

841-627: The withdrawal of the catechin-containing drug Catergen, used to treat viral hepatitis , from market in 1985. Catechins from green tea can be hepatotoxic and the European Food Safety Authority has recommended not to exceed 800 mg per day. One limited meta-analysis showed that increasing consumption of green tea and its catechins to seven cups per day provided a small reduction in prostate cancer . Nanoparticle methods are under preliminary research as potential delivery systems of catechins. Catechins released into

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