- Biotransformation of umbelliferone by Panax ginseng root cultures
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Panax ginseng root cultures biotransformed umbelliferone (1) to its 7-O-β-D-glucopyranoside (2), 7-O-β-D-glucopyranosyl (1→6) β-D-glucopyranoside (3), 7-O-β-D-xylopyranosyl (1→6) β-D-glucopyranoside (4) and 7-O-α-L-rhamnopyranosyl (1→2) β-D-glucopyranosid
- Li, Wei,Koike, Kazuo,Asada, Yoshihisa,Yoshikawa, Takafumi,Nikaido, Tamotsu
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- Molecular cloning and biochemical characterization of a new coumarin glycosyltransferase CtUGT1 from Cistanche tubulosa
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UDP-glycosyltransferases (UGTs) are an important and functionally diverse family of enzymes involved in secondary metabolite biosynthesis. Coumarin is one of the most common skeletons of natural products with candidate pharmacological activities. However, to date, many reported GTs from plants mainly recognized flavonoids as sugar acceptors. Only limited GTs could catalyze the glycosylation of coumarins. In this study, a new UGT was cloned from Cistanche tubulosa, a valuable traditional tonic Chinese herb, which is abundant with diverse glycosides such as phenylethanoid glycosides, lignan glycosides, and iridoid glycosides. Sequence alignment and phylogenetic analysis showed that CtUGT1 is phylogenetically distant from most of the reported flavonoid UGTs and adjacent to phenylpropanoid UGTs. Extensive in vitro enzyme assays found that although CtUGT1 was not involved in the biosynthesis of bioactive glycosides in C. tubulosa, it could catalyze the glucosylation of coumarins umbelliferone 1, esculetine 2, and hymecromone 3 in considerable yield. The glycosylated products were identified by comparison with the reference standards or NMR spectroscopy, and the results indicated that CtUGT1 can regiospecifically catalyze the glucosylation of hydroxyl coumarins at the C7-OH position. The key residues that determined CtUGT1's activity were further discussed based on homology modeling and molecular docking analyses. Combined with site-directed mutagenesis results, it was found that H19 played an irreplaceable role as the crucial catalysis basis. CtUGT1 could be used in the enzymatic preparation of bioactive coumarin glycosides.
- Xu, Xiping,Yan, Yaru,Huang, Wenqian,Mo, Ting,Wang, Xiaohui,Wang, Juan,Li, Jun,Shi, Shepo,Liu, Xiao,Tu, Pengfei
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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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- Two trifunctional leloir glycosyltransferases as biocatalysts for natural products glycodiversification
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Two promiscuous Bacillus licheniformis glycosyltransferases, YdhE and YojK, exhibited prominent stereospecific but nonregiospecific glycosylation activity of 20 different classes of 59 structurally different natural and non-natural products. Both enzymes transferred various sugars at three nucleophilic groups (OH, NH2, SH) of diverse compounds to produce O-, N-, and S-glycosides. The enzymes also displayed a catalytic reversibility potential for a one-pot transglycosylation, thus bestowing a cost-effective application in biosynthesis of glycodiversified natural products in drug discovery.
- Pandey, Ramesh Prasad,Bashyal, Puspalata,Parajuli, Prakash,Yamaguchi, Tokutaro,Sohng, Jae Kyung
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supporting information
p. 8058 - 8064
(2019/10/14)
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- Exploring the catalytic promiscuity of a new glycosyltransferase from Carthamus tinctorius
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The catalytic promiscuity of a new glycosyltransferase (UGT73AE1) from Carthamus tinctorius was explored. UGT73AE1 showed the capability to glucosylate a total of 19 structurally diverse types of acceptors and to generate O-, S-, and N-glycosides, making it the first reported trifunctional plant glycosyltransferase. The catalytic reversibility and regioselectivity were observed and modeled in a one-pot reaction transferring a glucose moiety from icariin to emodin. These findings demonstrate the potential versatility of UGT73AE1 in the glycosylation of bioactive natural products.
- Xie, Kebo,Ridao, Chen,Li, Jianhua,Wang, Ruishan,Chen, Dawei,Dou, Xiaoxiang,Dai, Jungui
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supporting information
p. 4874 - 4877
(2015/04/27)
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- Hydrolysis of toxic natural glucosides catalyzed by cyclodextrin dicyanohydrins
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The hydrolysis of toxic 7-hydroxycoumarin glucosides and other aryl and alkyl glucosides, catalyzed by modified α- and β-cyclodextrin dicyanohydrins, was investigated using different UV, redox, or HPAEC detection assays. The catalyzed reactions all followed Michaelis-Menten kinetics, and an impressive rate increase of up to 7569 (kcat/kuncat) was found for the hydroxycoumarin glucoside substrate 4-MUGP. Good and moderate degrees of catalysis (kcat/kuncat) of up to 1259 were found for the natural glucosides phloridzin and skimmin. By using a newly developed catechol detection UV-assay, a weak degree of catalysis was also found for the toxic hydroxycoumarin esculin. A novel synthesized diaminomethyl β-cyclodextrin showed a weak catalysis of p-nitrophenyl β-D-glucopyranoside hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Bjerre, Jeannette,Nielsen, Erik Holm,Bols, Mikael
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p. 745 - 752
(2008/09/17)
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- STRUCTURES AND ACCUMULATION PATTERNS OF SOLUBLE AND INSOLUBLE PHENOLICS FROM NORWAY SPRUCE NEEDLES
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Key Word Index - Picea abies; Pinaceae; Norway spruce; phenolics; identification; seasonal accumulation pattern; turnover; translocation; cell wall localization; flavonol glucosyltransferase. - Abstract - Twenty-two soluble phenolics have been isolated from Norway spruce needles and their structures elucidated on the basis of chromatographic (TLC, HPLC), chemical (hydrolysis), enzymic and spectroscopic (UV, NMR, MS) techniques.These phenolics have been quantified by HPLC during the first year of needle development from a forest near Bad Muenstereifel (F.R.G.) and showed a differential accumulation pattern.Kaempferol 3-O-glucoside showed an interesting metabolism, indicating rapid turnover and/or translocation from a soluble to an insoluble (cell wall bound) pool.The enzyme involved in the formation of this flavonoid, UDP-glucose:flavonol glucosyltransferase, showed a marked transient increase in activity that correlated with the possible kaempferol 3-O-glucoside translocation.
- Strack, Dieter,Heilemann, Juergen,Wray, Victor,Dirks, Herbert
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p. 2071 - 2078
(2007/10/02)
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- AN APIOSE-CONTAINING COUMARIN GLYCOSIDE FROM GMELINA ARBOREA ROOT
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Umbelliferone 7-apiosylglucoside has been characterized from the root of Gmelina arborea. Key Word Index - Gmelina arborea; Verbenaceae; root; coumarin; β-apiofuranosyl-(1->6)-β-D-glucopyranosyl-umbelliferone.
- Satyanarayana, P.,Subrahmanyam, P.,Kasai, R.,Tanaka, O.
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p. 1862 - 1863
(2007/10/02)
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