- An Efficient Strategy for the Chemo-Enzymatic Synthesis of Bufalin Glycosides with Improved Water Solubility and Inhibition against Na+, K+-ATPase
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In this study, bufalin was glycosylated by an efficient chemo-enzymatic strategy. Firstly, 2-chloro-4-nitrophenyl-1-O-β-D-glucoside (sugar donors) was obtained by chemical synthesis. Then, the glycosylation of the bufalin was achieved with the synthesized sugar donor under the catalysis of two glycosyltransferases (Loki and ASP). Finally, two glycosides, i. e., bufalin-3-O-β-D-glucopyranoside and bufalin-3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside)], were obtained by preparative HPLC. Compared to our previously reported sole chemical (total yield 10 % in four steps) or enzymatic methods (30 %), our combined chemo-enzymatic strategy in this article greatly improves the yields of monoglycoside (68 %) and diglycoside (21 %) and decreased the experimental cost (90 %). Furthermore, we tested the water solubility of these glycosides and found that the water solubilities of the two glycosides were 13.1 and 53.7 times of bufalin, respectively. In addition, the inhibitory activity of these glycosides against Na+, K+-ATPase were evaluated. The mono-glycosylated compound showed more potent activity than bufalin, while the diglycosylated compound was less potent.
- Liu, Yan,Xu, Wei,Huang, Zhao-He,Guo, Jun,Jiang, Ren-Wang
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- Facile and Versatile Chemoenzymatic Synthesis of Enterobactin Analogues and Applications in Bacterial Detection
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Siderophores, such as enterobactin (Ent), are small molecules that can be selectively imported into bacteria along with iron by cognate transporters. Siderophore conjugates are thus a promising strategy for delivering functional reagents into bacteria. In this work, we present an easy-to-perform, one-pot chemoenzymatic synthesis of functionalized monoglucosylated enterobactin (MGE). When functionalized MGE is conjugated to a rhodamine fluorophore, which affords RhB-Glc-Ent, it can selectively label Gram-negative bacteria that utilize Ent, including some E. coli strains and P. aeruginosa. V. cholerae, a bacterium that utilizes linearized Ent, can also be weakly targeted. Moreover, the targeting is effective under iron-limiting but not iron-rich conditions. Our results suggest that the RhB-Glc-Ent probe is sensitive not only to the bacterial strain but also to the iron condition in the environment.
- Lee, Albert A.,Chen, Yi -Chen S.,Ekalestari, Elisa,Ho, Sheng -Yang,Hsu, Nai -Shu,Kuo, Tang -Feng,Wang, Tsung -Shing Andrew
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p. 12338 - 12342
(2016/10/13)
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- Binuclear copper(II) complexes discriminating epimeric glycosides and α- And β-glycosidic bonds in aqueous solution
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Two chiral binuclear copper(II) complexes were synthesized and characterized for the first time as efficient chemoselective catalysts for the hydrolysis of aryl glycosides and disaccharides in aqueous solution at near neutral pH. Under these conditions, discrimination of epimeric aryl α-glycopyranosides was observed by both 29-fold different reaction rates and 3-fold different proficiency of the catalyst. Additionally, large differentiation of the nature of α- and β-glycosidic bond in aryl glycosides as model compounds is apparent, but also noted in selected disaccharides. The influence of the chirality of the complexes and the role of the configuration of the carbohydrate upon interaction with the catalyst is discussed in detail. Lastly, a putative mechanism for the metal complex-catalyzed hydrolysis is derived from the experimental evidence pointing at deprotonation of the hydroxyl group at C-2 as a pre-requisite for glycoside hydrolysis.
- Striegler, Susanne,Fan, Qiu-Hua,Rath, Nigam P.
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p. 349 - 364
(2016/05/24)
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- Natural product disaccharide engineering through tandem glycosyltransferase catalysis reversibility and neoglycosylation
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A two-step strategy for disaccharide modulation using vancomycin as a model is reported. The strategy relies upon a glycosyltransferase-catalyzed 'reverse' reaction to enable the facile attachment of an alkoxyamine-bearing sugar to the vancomycin core. Ne
- Peltier-Pain, Pauline,Marchillo, Karen,Zhou, Maoquan,Andes, David R.,Thorson, Jon S.
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p. 5086 - 5089
(2013/01/15)
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- Examination of the active sites of human salivary α-amylase (HSA)
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The action pattern of human salivary amylase (HSA) was examined by utilising as model substrates 2-chloro-4-nitrophenyl (CNP) β-glycosides of maltooligosaccharides of dp 4-8 and some 4-nitrophenyl (NP) derivatives modified at the nonreducing end with a 4,6-O-benzylidene (Bnl) group. The product pattern and cleavage frequency were investigated by product analysis using HPLC. The results revealed that the binding region in HSA is longer than five subsites usually considered in the literature and suggested the presence of at least six subsites; four glycone binding sites (-4, -3, -2, -1) and two aglycone binding sites (+1, +2). In the ideal arrangement, the six subsites are filled by a glucosyl unit and the release of maltotetraose (G4) from the nonreducing end is dominant. The benzylidene group was also recognisable by subsites (-3) and (-4). The binding modes of the benzylidene derivatives indicated a favourable interaction between the Bnl group and subsite (-3) and an unfavourable one with subsite (-4). Thus, subsite (-4) must be more hydrophylic than hydrophobic. As compared with the action of porcine pancreatic α-amylase (PPA) on the same substrates, the results showed differences in the three-dimensional structure of active sites of HSA and PPA. (C) 2000 Elsevier Science Ltd.
- Kandra, Lili,Gyemant, Gyoengyi
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p. 579 - 585
(2007/10/03)
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