13405-60-2Relevant articles and documents
Two UGT84 family glycosyltransferases catalyze a critical reaction of hydrolyzable tannin biosynthesis in pomegranate (Punica granatum)
Ono, Nadia N.,Qin, Xiaoqiong,Wilson, Alexander E.,Li, Gang,Tian, Li
, (2016)
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.
Gallotannins and Tannic Acid: First Chemical Syntheses and in Vitro Inhibitory Activity on Alzheimer's Amyloid β-Peptide Aggregation
Sylla, Tahiri,Pouységu, Laurent,Dacosta, Grégory,Deffieux, Denis,Monti, Jean-Pierre,Quideau, Stéphane
, p. 8217 - 8221 (2015/07/07)
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.
Identification of UGT84A13 as a candidate enzyme for the first committed step of gallotannin biosynthesis in pedunculate oak (Quercus robur)
Mittasch, Juliane,B?ttcher, Christoph,Frolova, Nadezhda,B?nn, Markus,Milkowski, Carsten
, p. 44 - 51 (2014/03/21)
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.