14581-78-3Relevant articles and documents
A 4 - hydroxy methyl phenyl - beta - D glucopyranoside synthesis method (by machine translation)
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Paragraph 0026, (2017/07/19)
A 4 - hydroxy methyl phenyl - beta - D glucopyranoside synthetic method, comprises the following steps, step 1. The glycosidation reaction: five acetyl glucose, cresol, montmorillonite, Lewis acid in an organic solvent in the glycosidation reaction, and getting the middle raw material 1, and then in order to methanol recrystallization; step 2. Oxidation reaction: step 1 obtained in the middle of the raw material 1 in an organic solvent is added, by nitric acid ammonium oxidation intermediate raw material 1 obtained after the aldehyde group of the intermediate raw material 2, and then the ethanol solution is recrystallized; step 3. Ester exchange and reduction reaction: the step 2 to obtain the intermediate raw material 2 with methanol catalyst under the action of the ester exchange reaction, to obtain the 4 - formyl phenyl - beta - D - glucopyranoside, adding the borohydride reduction, to obtain the final product; the invention effectively solves the current Gastrodin synthesis in present technology; with more economic, environmental protection, safe and convenient operation, industrialization with stronger adaptability characteristics. (by machine translation)
Improved synthesis of gastrodin, a bioactive component of a traditional chinese medicine
Li, Yu-Wen,Ma, Cui-Li
, p. 1205 - 1212 (2015/01/30)
Highly practical, four-step synthesis of gastrodin was developed using penta- O-acetyl-β-D-glucopyranose and p-cresol as glycosyl donor and glycosyl acceptor, respectively, in 58.1% overall yield. As the initial step, the penta-O-acetyl-β-D-glucopyranose was treated with p-cresol in the presence of BF3 ?Et2O as catalyst to generate 4-methylphenyl 2,3,4,6-tetra-O-acetyl-β-D- -glucopyranoside in 76.3% yield. Further, this product was subjected to radical bromination with N-bromosuccinimide (NBS) to provide 4-(bromomethyl)phenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside in 91% yield. Subsequently, reaction of 4-(bromomethyl)phenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside with a solution of acetone and saturated aqueous sodium bicarbonate led to 4-(hydroxymethyl)phenyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside in 93% yield. Finally, global deprotection of 4-(hydroxymethyl)phenyl 2,3,4,6-tetra-O- -acetyl-β- D-glucopyranoside under Zemplen conditions furnished gastrodin in 90% yield. Compared to the previously reported methods, this protocol has the advantages of operational simplicity, chromatography-free separation, high overall yield, inexpensive and common reagents as well as less waste pollutants, rendering it an alternative suitable for industrial production.
Mechanistic evaluation of MelA α-galactosidase from citrobacter freundii: A family 4 glycosyl hydrolase in which oxidation is rate-limiting
Chakladar, Saswati,Cheng, Lydia,Choi, Mary,Liu, James,Bennet, Andrew J.
experimental part, p. 4298 - 4308 (2012/03/22)
The MelA gene from Citrobacter freundii, which encodes a glycosyl hydrolase family 4 (GH4) α-galactosidase, has been cloned and expressed in Escherichia coli. The recombinant enzyme catalyzes the hydrolysis of phenyl α-galactosides via a redox elimination-addition mechanism involving oxidation of the hydroxyl group at C-3 and elimination of phenol across the C-1-C-2 bond to give an enzyme-bound glycal intermediate. For optimal activity, the MelA enzyme requires two cofactors, NAD+ and Mn2+, and the addition of a reducing agent, such as mercaptoethanol. To delineate the mechanism of action for this GH4 enzyme, we measured leaving group effects, and the derived βlg values on V and V/K are indistinguishable from zero (-0.01 ± 0.02 and 0.02 ± 0.04, respectively). Deuterium kinetic isotope effects (KIEs) were measured for the weakly activated substrate phenyl α-d-galactopyranoside in which isotopic substitution was incorporated at C-1, C-2, or C-3. KIEs of 1.06 ± 0.07, 0.91 ± 0.04, and 1.02 ± 0.06 were measured on V for the 1-2H, 2- 2H, and 3-2H isotopic substrates, respectively. The corresponding values on V/K were 1.13 ± 0.07, 1.74 ± 0.06, and 1.74 ± 0.05, respectively. To determine if the KIEs report on a single step or on a virtual transition state, we measured KIEs using doubly deuterated substrates. The measured DV/K KIEs for MelA-catalyzed hydrolysis of phenyl α-d-galactopyranoside on the dideuterated substrates, DV/K(3-D)/(2-D,3-D) and DV/K (2-D)/(2-D,3-D), are 1.71 ± 0.12 and 1.71 ± 0.13, respectively. In addition, the corresponding values on V, DV (3-D)/(2-D,3-D) and DV(2-D)/(2-D,3-D), are 0.91 ± 0.06 and 1.01 ± 0.06, respectively. These observations are consistent with oxidation at C-3, which occurs via the transfer of a hydride to the on-board NAD+, being concerted with proton removal at C-2 and the fact that this step is the first irreversible step for the MelA α-galactosidase-catalyzed reactions of aryl substrates. In addition, the rate-limiting step for Vmax must come after this irreversible step in the reaction mechanism.
