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Stilbenes
Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C2–C6 structure. In biochemical terms, they belong to the family of phenylpropanoids and share most of their biosynthesis pathway with chalcones. Most stilbenoids are produced by plants, and the only known exception is the antihelminthic and antimicrobial stilbenoid, 2-isopropyl-5- ''E'')-2-phenylvinylenzene-1,3-diol, biosynthesized by the Gram-negative bacterium '' Photorhabdus luminescens.'' Chemistry Stilbenoids are hydroxylated derivatives of stilbene and have a C6–C2–C6 structure. They belong to the family of phenylpropanoids and share most of their biosynthesis pathway with chalcones. Under UV irradiation, stilbene and its derivatives undergo intramolecular cyclization, called stilbene photocyclization to form dihydrophenanthrenes. Oligomeric forms are known as oligostilbenoids. Types ;Aglycones * Piceatannol in the roots of Norway spruces * Pinosylvin is a fungal toxin protecting woo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stilbene Photocyclization
In organic chemistry, the Mallory reaction is a photochemical-cyclization– elimination reaction of diaryl-ethylene structures to form phenanthrenes and other polycyclic form polycyclic aromatic hydrocarbons and heteroaromatics.Mallory, F. B.; Mallory, C. W. '' Org. React.'' 1984, ''30'', 1. This name reaction is named for Frank Mallory, who discovered it while a graduate student. Under UV irradiation, stilbene and its derivatives undergo intramolecular cyclization to form dihydrophenanthrenes. In the presence of an oxidant, the dihydrophenanthrenes aromatize to give polycyclic aromatics. Typically, the dihydrophenanthrenes themselves are relatively unstable, and revert to ''cis''-stilbenes in the absence of a hydrogen-trapping agent. Suitably substituted stilbenes may undergo irreversible, rearomatizing elimination or ,nshift processes in the absence of an oxidant. Aryl enynes, heteroatomic stilbene derivatives (e.g. amides), and substrates containing a single heteroatom in pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinosylvin
Pinosylvin is an organic compound with the formula C6H5CH=CHC6H3(OH)2. A white solid, it is related to trans-stilbene, but with two hydroxy groups on one of the phenyl substituents. It is very soluble in many organic solvents, such as acetone. Occurrence Pinosylvin is produced in plants in response to fungal infections, ozone-induced stress, and physical damage for example. It is a fungitoxin protecting the wood from fungal infection. It is present in the heartwood of '' Pinaceae'' and also found in ''Gnetum cleistostachyum''. Injected in rats, pinosylvin undergoes rapid glucuronidation and a poor bioavailability. Biosynthesis Pinosylvin synthase, an enzyme, catalyzes the biosynthesis of pinosylvin from malonyl-CoA and cinnamoyl-CoA Cinnamoyl-Coenzyme A is an intermediate in the phenylpropanoids metabolic pathway. Enzymes using Cinnamoyl-Coenzyme A * Cinnamoyl-CoA reductase, an enzyme that catalyzes the chemical reaction cinnamaldehyde + CoA + NADP+ → cinnamoyl-CoA + N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligostilbenoid
Oligostilbenoids (oligo- or polystilbenes) are oligomeric forms of stilbenoids. Some molecules are large enough to be considered polyphenols and constitute a class of tannins. Examples Dimers * Ampelopsin A * Epsilon-viniferin * Pallidol * Quadrangularin A Trimers * α-Viniferin * Ampelopsin E * ''trans''-Diptoindonesin B * Gnetin H Tetramers * cajyphenol A * cajyphenol B * Flexuosol A * Hemsleyanol D * Hopeaphenol * Vaticanol B * R2-Viniferin (syn. Vitisin A) Modified * Diptoindonesin C can be isolated from the bark of '' Shorea pinanga'' Other * Diptoindonesin F can be isolated from the bark of ''Shorea gibbosa'' Glycosides * Diptoindonesin A Diptoindonesin A is a C- glucoside of ε-viniferin isolated from the two Dipterocarpaceae '' Shorea seminis'' and ''Dryobalanops aromatica ''Dryobalanops aromatica'', commonly known as Borneo camphor, camphor tree, Malay camphor, or Sumatran c ... References External links * {{oligostilbenoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heartwood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or woodchips or fiber. Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper. More recently it emerged as a feedstock for the production ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grape
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ago, and the fruit has been used as human food over history. Eaten fresh or in dried form (as raisins, currants and sultanas), grapes also hold cultural significance in many parts of the world, particularly for their role in winemaking. Other grape-derived products include various types of jam, juice, vinegar and oil. History The Middle East is generally described as the homeland of grape and the cultivation of this plant began there 6,000–8,000 years ago. Yeast, one of the earliest domesticated microorganisms, occurs naturally on the skins of grapes, leading to the discovery of alcoholic drinks such as wine. The earliest archeological evidence for a dominant position of wine-making in human culture dates from 8,000 years ago in Georg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytoalexins
Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined, not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants that produce the compounds rapidly at sites of pathogen infection. In general phytoalexins are broad spectrum inhibitors; they are chemically diverse, and different chemical classes of compounds are characteristic of particular plant taxa. Phytoalexins tend to fall into several chemical classes, including terpenoids, glycosteroids and alkaloids, however the term applies to any phytochemicals that are induced by microbial infection. Function Phytoalexins are produced in plants to act as toxins to the attacking organism. They may puncture the cell wall, delay maturation, disrupt metabolism or prevent reproduction of the pathogen in question. Their importance in plant defense is indicated by an increase in susceptibility of plant tissue t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piceid
Piceid is a stilbenoid glucoside and is a major resveratrol derivative in grape juices. It can be found in the bark of ''Picea sitchensis''. It can also be isolated from ''Reynoutria japonica'' ( syn. ''Fallopia japonica''), the Japanese knotweed (syn. ''Polygonum cuspidatum''). Resveratrol can be produced from piceid via the mold ''Aspergillus oryzae''. as the fungus produces a potent beta-glucosidase. ''trans''-Piceid is the glucoside formed with ''trans''-resveratrol, while ''cis''-piceid is formed with ''cis''-resveratrol. ''trans''-Resveratrol-3-''O''-glucuronide is one of the two metabolites of ''trans''-piceid in rat. Resveratrol glucoside from transgenic alfalfa prevents aberrant crypt foci in mice.R See also * Resveratroloside Resveratroloside is a stilbenoid glucoside. It can be found in ''Paeonia lactiflora ''Paeonia lactiflora'' (Chinese peony, Chinese herbaceous peony, or common garden peony) is a species of herbaceous perennial flowering plant in the fami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterostilbene
Pterostilbene () (trans-3,5-dimethoxy-4-hydroxystilbene) is a stilbenoid chemically related to resveratrol. In plants, it serves a defensive phytoalexin role. Natural occurrence Pterostilbene is found in almonds, various ''Vaccinium'' berries (including blueberries), grape leaves and vines, and ''Pterocarpus marsupium'' heartwood. Safety and regulation Pterostilbene is considered to be a corrosive substance, is dangerous upon exposure to the eyes, and is an environmental toxin, especially to aquatic life. A randomized, double-blind, placebo-controlled of healthy human subjects given pterostilbene for 6–8 weeks, showed pterostilbene to be safe for human use at dosages up to 250 mg per day. Its chemical relative, resveratrol, received FDA GRAS status in 2007, and approval of synthetic resveratrol as a safe compound by the European Food Safety Authority (EFSA) in 2016. Pterostilbene differs from resveratrol by exhibiting increased bioavailability (80% compared to 20% in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampelopsin B
Ampelopsin B is a stilbenoid dimer found in ''Ampelopsis glandulosa ''Ampelopsis glandulosa'' is a species of plant native to China, Japan, India, Nepal, Myanmar, Vietnam, and the Philippines. Varieties Several varieties are distinguished: * var. ''hancei'' * var. ''kulingensis'' * var. ''glandulosa'' * var ...'' var. ''hancei'' (formerly ''Ampelopsis brevipedunculata'' var. ''hancei'').Chemical determination of the absolute structures of resveratrol dimers, ampelopsins A, B, D and F. Yoshiaki Takaya, Ke-Xu Yan, Kenji Terashima, Junko Ito and Masatake Niwa, Tetrahedron, 2002, 58, pages 7259–7265, References Stilbenoid dimers Ampelopsis {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piceatannol
Piceatannol is the organic compound with the formula . Classified as a stilbenoid and a phenol, it is a white solid, although samples often are yellow owing to impurities. Natural occurrences Piceatannol and its glucoside, astringin, are found in mycorrhizal and non-mycorrhizal roots of Norway spruces (''Picea abies''). It can also be found in the seeds of the palm ''Aiphanes horrida'' and in ''Gnetum cleistostachyum''. The chemical structure of piceatannol was established by Cunningham et al. as being an analog of resveratrol. In food Piceatannol is a metabolite of resveratrol found in red wine, grapes, passion fruit, white tea, and Japanese knotweed. Astringin, a piceatannol glucoside, is also found in red wine. The formation of piceatannol from resveratrol is catalyzed by cytochrome P450. Biochemical study A 1989 ''in vitro'' study found that piceatannol blocked LMP2A, a viral protein-tyrosine kinase implicated in leukemia, non-Hodgkin's lymphoma and other diseases ass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampelopsin A
Ampelopsin A is a resveratrol dimer found in ''Ampelopsis glandulosa ''Ampelopsis glandulosa'' is a species of plant native to China, Japan, India, Nepal, Myanmar, Vietnam, and the Philippines. Varieties Several varieties are distinguished: * var. ''hancei'' * var. ''kulingensis'' * var. ''glandulosa'' * var ...'' var. ''hancei'' (formerly ''A. brevipedunculata'' var. ''hancei'').Chemical determination of the absolute structures of resveratrol dimers, ampelopsins A, B, D and F. Yoshiaki Takaya, Ke-Xu Yan†, Kenji Terashima, Junko Ito and Masatake Niwa, Tetrahedron, Volume 58, Issue 36, 2 September 2002, Pages 7259–7265, References External links kanaya.naist.jp/knapsack_jsp Resveratrol oligomers Stilbenoid dimers Ampelopsis {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenylpropanoid
The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. Their name is derived from the six-carbon, aromatic phenyl group and the three-carbon propene tail of coumaric acid, which is the central intermediate in phenylpropanoid biosynthesis. From 4-coumaroyl-CoA emanates the biosynthesis of myriad natural products including lignols (precursors to lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. The coumaroyl component is produced from cinnamic acid. Phenylpropanoids are found throughout the plant kingdom, where they serve as essential components of a number of structural polymers, provide protection from ultraviolet light, defend against herbivores and pathogens, and also mediate plant-pollinator interactions as floral pigments and scent compounds. Hydroxycinnamic acids Phenylalanine is first converted to cinnamic aci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
