| 词条 | Taraxasterol |
| 释义 |
| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 464379673 | ImageFile = Taraxasterolformat.png | ImageSize = 200px | IUPACName = (3S,4aR,6aR,6bR,8aR,12S,12aR,12bR,14aR,14bR)-4,4,6a,6b,8a,12,14b-Heptamethyl-11-methylenedocosahydropicen-3-ol | OtherNames = Anthesterin |Section1={{Chembox Identifiers | Abbreviations = | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | ChemSpiderID = 103120 | SMILES = O[C@H]1CC[C@@]2(C)[C@](CC[C@]3(C)[C@]2([H])CC[C@@]4([H])[C@@]3(C)CC[C@](CC5)(C)[C@]4([H])[C@H](C)C5=C)([H])C1(C)C | InChI = InChI=1S/C30H50O/c1-19-11-14-27(5)17-18-29(7)21(25(27)20(19)2)9-10-23-28(6)15-13-24(31)26(3,4)22(28)12-16-30(23,29)8/h20-25,31H,1,9-18H2,2-8H3/t20-,21-,22+,23-,24+,25-,27-,28+,29-,30-/m1/s1 | InChIKey = XWMMEBCFHUKHEX-ZJJHUPNDSA-N | StdInChI_Ref = {{stdinchicite|changed|chemspider}} | StdInChI = 1S/C18H17ClO6/c1-9-6-15-14(25-15)5-3-2-4-10(20)7-11-16(18(23)24-9)12(21)8-13(22)17(11)19/h2-5,8-9,14-15,21-22H,6-7H2,1H3/b4-2+,5-3-/t9-,14-,15-/m1/s1 | StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} | StdInChIKey = WYZWZEOGROVVHK-GTMNPGAYSA-N | CASNo = 1059-14-9 | EINECS = | PubChem = 115250 | ChEMBL_Ref = {{ebicite|changed|EBI}} | ChEMBL = 453386 | RTECS = | MeSHName = | ChEBI_Ref = {{ebicite|changed|EBI}} | ChEBI = 9401 | KEGG = }} |Section2={{Chembox Properties | C=30 | H=50 | O=1 | Appearance = | Density = | MeltingPt = | MeltingPt_notes = | BoilingPt = | BoilingPt_notes = | Solubility = | SolubleOther = | Solvent = | pKa = | pKb = | IsoelectricPt = | SpecRotation = | RefractIndex = | Viscosity = | Dipole = |Section3={{Chembox Structure | CrystalStruct = | Coordination = | MolShape = | Dipole = |Section4={{Chembox Thermochemistry | DeltaHf = | DeltaHc = | Entropy = | HeatCapacity = |Section5={{Chembox Pharmacology | AdminRoutes = | Bioavail = | Metabolism = | HalfLife = | ProteinBound = | Excretion = | Legal_status = | Legal_US = | Legal_UK = | Legal_AU = | Legal_CA = | Pregnancy_category = | Pregnancy_AU = | Pregnancy_US = |Section6={{Chembox Explosive | ShockSens = | FrictionSens = | DetonationV = | REFactor = |Section7={{Chembox Hazards | ExternalSDS = | EUClass = | MainHazards = | NFPA-H = | NFPA-F = | NFPA-R = | NFPA-S = | RPhrases = | SPhrases = | RSPhrases = | FlashPt = | AutoignitionPt = | ExploLimits = | PEL = |Section8={{Chembox Related | OtherAnions = | OtherCations = | OtherFunction = | OtherFunction_label = | OtherCompounds = }}Taraxasterol (anthesterin) is a triterpene derived from the mevalonate pathway and is found in dandelions.[1] BiosynthesisThe precursor for the biosynthesis of taraxasterol is squalene. In the first step of this formation squalene is cyclized with molecular oxygen, FAD, and NADPH via the enzyme squalene epoxidase a flavoprotein to yield (2S)-2,3-oxidosqualene. In the second step if the oxidosqualene is folded in the chair conformation in the enzyme a cascade of cyclizations will occur that results in the formation of the dammarenyl cation.[1] The dammarenyl cation is then subjected to an alkyl shift to create a six-membered ring and relieving ring strain to form the baccharenyl cation. This allows the baccharenyl double bond to attack the secondary positive charge and forms a pentacyclic ring system to yield the tertiary lupanyl cation. A Wagner-Meerwein 1,2-alykl shift will occur to form the hexacyclic ring system and the secondary oleanyl cation. This is followed by a Wagner-Meerwein 1,2-methyl shift to create the tertiary taraxasteryl cation. This cation is the last intermediate in the taraxasterol pathway. An E2 reaction follows where deprotonation of a proton yields taraxasterol. The enzymes involved in this biosynthesis are oxidosesqualene: lupeopl cyclase and oxidosqualene: B-amyrin cyclase.[1] {{gallery|File:Dammarenyl cation.png |Dammarenyl cation |File:Taraxasterol synthesis.png |Taraxasterol synthesis }} References1. ^1 2 {{cite book | title = Medicinal Natural Products: A Biosynthetic Approach | date = 2011 | isbn = 978-0-470-74168-9 | pages =243–247}} {{biochemistry-stub}}{{chemistry-stub}} 1 : Triterpenes |
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