- Two UGT84 family glycosyltransferases catalyze a critical reaction of hydrolyzable tannin biosynthesis in pomegranate (Punica granatum)
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Hydrolyzable tannins (HTs) play important roles in plant herbivore deterrence and promotion of human health. A critical step in HT production is the formation of 1-O-galloyl-β-D-glucopyranoside (β-glucogallin, ester-linked gallic acid and glucose) by a UDP-glucosyltransferase (UGT) activity. We cloned and biochemically characterized four candidate UGTs from pomegranate (Punica granatum), of which only UGT84A23 and UGT84A24 exhibited β-glucogallin forming activities in enzyme assays. Although overexpression and single RNAi knockdown pomegranate hairy root lines of UGT84A23 or UGT84A24 did not lead to obvious alterations in punicalagin (the prevalent HT in pomegranate) accumulation, double knockdown lines of the two UGTs resulted in largely reduced levels of punicalagins and bis-hexahydroxydiphenyl glucose isomers. An unexpected accumulation of galloyl glucosides (ether-linked gallic acid and glucose) was also detected in the double knockdown lines, suggesting that gallic acid was utilized by an unidentified UGT activity for glucoside formation. Transient expression in Nicotiana benthamiana leaves and immunogold labeling in roots of pomegranate seedlings collectively indicated cytosolic localization of UGT84A23 and UGT84A24. Overall, functional characterization and localization of UGT84A23 and UGT84A24 open up opportunities for further understanding the regulatory control of HT metabolism in plants and its coordination with other biochemical pathways in the metabolic network.
- Ono, Nadia N.,Qin, Xiaoqiong,Wilson, Alexander E.,Li, Gang,Tian, Li
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- Solvent-Dependent Mechanism and Stereochemistry of Mitsunobu Glycosylation with Unprotected Pyranoses
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An SN2 mechanism was proposed for highly stereoselective glycosylation of benzoic acid with unprotected α-d-glucose under Mitsunobu conditions in dioxane, while an SN1 mechanism was indicated for nonstereoselective glycosylation in DMF. The SN2-type stereoselective Mitsunobu glycosylation is generally applicable to various unprotected pyranoses as glycosyl donors in combination with a wide range of acidic glycosyl acceptors such as carboxylic acids, phenols, and imides, retaining its high stereoselectivity (33 examples). Glycosylation of a carboxylic acid with unprotected α-d-mannose proceeded also in an SN2 manner to directly afford a usually less accessible 1,2-cis-mannoside. One-or two-step total syntheses of five simple natural glycosides were performed using the glycosylation strategy presented here using unprotected α-d-glucose.
- Fujimori, Yusuke,Furuta, Takumi,Kawabata, Takeo,Nagaishi, Masaru,Sasamori, Takahiro,Shibayama, Hiromitsu,Takeuchi, Hironori,Tokitoh, Norihiro,Ueda, Yoshihiro,Yoshimura, Tomoyuki
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supporting information
(2020/06/29)
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- Gallotannins and Tannic Acid: First Chemical Syntheses and in Vitro Inhibitory Activity on Alzheimer's Amyloid β-Peptide Aggregation
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The screening of natural products in the search for new lead compounds against Alzheimer's disease has unveiled several plant polyphenols that are capable of inhibiting the formation of toxic β-amyloid fibrils. Gallic acid based gallotannins are among these polyphenols, but their antifibrillogenic activity has thus far been examined using "tannic acid", a commercial mixture of gallotannins and other galloylated glucopyranoses. The first total syntheses of two true gallotannins, a hexagalloylglucopyranose and a decagalloylated compound whose structure is commonly used to depict "tannic acid", are now described. These depsidic gallotannins and simpler galloylated glucose derivatives all inhibit amyloid β-peptide (Aβ) aggregation invitro, and monogalloylated α-glucogallin and a natural β-hexagalloylglucose are shown to be the strongest inhibitors.
- Sylla, Tahiri,Pouységu, Laurent,Dacosta, Grégory,Deffieux, Denis,Monti, Jean-Pierre,Quideau, Stéphane
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p. 8217 - 8221
(2015/07/07)
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- NOVEL GLYCOSYLTRANSFERASE, NOVEL GLYCOSYLTRANSFERASE GENE, AND NOVEL GLYCOSYL DONOR COMPOUND
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An object of the present invention is to provide a sugar donating reagent comprising a sugar donor compound other than a sugar nucleotide and an enzyme capable of catalyzing a glycosyl transfer reaction using a sugar donor compound other than a sugar nucleotide. The present invention provides the following: a sugar donating reagent containing a compound of formula (A): wherein R 1 is independently selected from hydrogen, or C 1-6 alkyl, C 2-6 alkenyl, and C 2-6 alkynyl in which each of the groups is unsubstituted or substituted with one or more groups selected from OH, F, Cl, Br, I, CN, NO 2 , and SO 2 , n is 0, 1, 2, 3, 4 or 5, m is 0 or 1, and X represents a monosaccharide bound via a 2 bond on its anomeric carbon; a glycosyltransferase capable of catalyzing a glycosyl transfer reaction using the sugar donor; and a glycosyltransferase gene comprising DNA encoding the glycosyltransferase.
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Paragraph 0112
(2015/09/22)
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- COMPOUNDS REDUCING THE PRODUCTION OF SORBITOL IN THE EYE AND METHODS OF USING THE SAME
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Methods of inhibiting the progression of or treating secondary complications of diabetes, especially a diabetic eye disease, in a mammal by inhibiting the production of sorbitol in the mammal. Small molecule inhibitors of sorbitol production in the eye useful in the methods of the invention and pharmaceutical compositions containing the compounds, and methods of using the same.
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- Identification of UGT84A13 as a candidate enzyme for the first committed step of gallotannin biosynthesis in pedunculate oak (Quercus robur)
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A cDNA encoding the ester-forming hydroxybenzoic acid glucosyltransferase UGT84A13 was isolated from a cDNA library of Quercus robur swelling buds and young leaves. The enzyme displayed high sequence identity to resveratrol/hydroxycinnamate and hydroxybenzoate/hydroxycinnamate glucosyltransferases from Vitis species and clustered to the phylogenetic group L of plant glucosyltransferases, mainly involved in the formation of 1-O-β-d-glucose esters. In silico transcriptome analysis confirmed expression of UGT84A13 in Quercus tissues which were previously shown to exhibit UDP-glucose:gallic acid glucosyltransferase activity. UGT84A13 was functionally expressed in Escherichia coli as N-terminal His-tagged protein. In vitro kinetic measurements with the purified recombinant enzyme revealed a clear preference for hydroxybenzoic acids as glucosyl acceptor in comparison to hydroxycinnamic acids. Of the preferred in vitro substrates, protocatechuic, vanillic and gallic acid, only the latter and its corresponding 1-O-?-D-glucose ester were found to be accumulated in young oak leaves. This indicates that in planta UGT84A13 catalyzes the formation of, 1-O-galloyl-?-D-glucose, the first committed step of gallotannin biosynthesis.
- Mittasch, Juliane,B?ttcher, Christoph,Frolova, Nadezhda,B?nn, Markus,Milkowski, Carsten
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- Design of an amide N-glycoside derivative of β-glucogallin: A stable, potent, and specific inhibitor of aldose reductase
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β-Glucogallin (BGG), a major component of the Emblica officinalis medicinal plant, is a potent and selective inhibitor of aldose reductase (AKR1B1). New linkages (ether/triazole/amide) were introduced via high yielding, efficient syntheses to replace the labile ester, and an original two-step (90%) preparation of BGG was developed. Inhibition of AKR1B1was assessed in vitro and using transgenic lens organ cultures, which identified the amide linked glucoside (BGA) as a stable, potent, and selective therapeutic lead toward the treatment of diabetic eye disease.
- Li, Linfeng,Chang, Kun-Che,Zhou, Yaming,Shieh, Biehuoy,Ponder, Jessica,Abraham, Adedoyin D.,Ali, Hadi,Snow, Anson,Petrash, J. Mark,Labarbera, Daniel V.
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- GLUCOSYLATION OF PHENOLICS BY HAIRY ROOT CULTURES OF LOBELIA SESSILIFOLIA
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Two new glucosides, (-)-epiafzelechin 7-O-β-D-glucopyranoside and photocatechuic acid 3-O-β-D-glucopyranoside were isolated from hairy roots of Lobelia sessilifolia after cultivation with (-)-epicatechin or protocatechuic acid, respectively. - Keywords: L
- Yamanaka, Michiko,Shimomura, Koichiro,Sasaki, Kazuo,Yoshihira, Kunitoshi,Ishimaru, Kanji
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p. 1149 - 1150
(2007/10/02)
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- REACTION OF DEHYDROELLAGITANNINS WITH L-CYSTEINE METHYL ESTER
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Reaction of dehydroellagitannins (e.g. 1) with L-cysteine methyl ester (5) at room temperature yielded the condensation products (e.g. 3 and 4), together with a partial hydrolysate (e.g. 2), while heating the mixture at 80 deg C afforded 4 and the hydrolysate (2) in fairly good yields.In addition, reduction of a dehydrohexahydroxydiphenoyl ester group to a hexahydroxy-diphenoyl group with thiols is also described.
- Tanaka, Takashi,Fujisaki, Hiroshi,Nonaka, Gen-ichiro,Nishioka, Itsuo
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p. 375 - 383
(2007/10/02)
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