Nonenzymatic C-glycosylation of flavan-3-ols by oligo- and polysaccharides.
Model reactions between the polysaccharide amylose and the polyphenol (-)-epicatechin followed by partial enzymatic hydrolysis of the reaction products formed led to the detection of mono- and oligo-C-glucosylated flavan-3-ols by means of LC-MS/MS experiments. To confirm the structure of these putative flavan-3-ol/oligosaccharide conjugates, (-)-epicatechin was reacted with maltose and maltotriose, respectively, giving rise to a series of previously unreported flavan-3-ol/maltose and flavan-3-ol/maltotriose conjugates, namely, (-)-epicatechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-6- C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, (-)-catechin-6-C-beta-D-glucopyranosyl-(4-->1)- O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside, and (-)-epicatechin-6/8-C-beta-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranosyl-(4-->1)-O-alpha-D-glucopyranoside. Furthermore, quantitative analysis of flavan-3-ol-C-glucosides in an enzymatic total hydrolysate using a newly developed stable isotope dilution assay (SIDA) enabled a first insight into the yield of the formation of polyphenol/polysaccharide cross-links, for example, an amount of 14.0, 9.0, and 0.15 micromol of flavan-3-ol-6-C-beta-D-glucopyranoside, flavan-3-ol-8-C-beta-D-glucopyranoside, and flavan-3-ol-6- C,8-C-beta-D-glucopyranoside were per mmol (-)-epicatechin when reacted with amylose.
Stark
Timo
T
Institut für Lebensmittelchemie, Universität Münster, Corrensstrasse 45 D-48149 Münster, Germany.
Keller
Daniela
D
Wenker
Kerstin
K
Hillmann
Hedda
H
Hofmann
Thomas
T
D000688:Amylose / Q000737:chemistry; D002392:Catechin / Q000737:chemistry; D003432:Cross-Linking Reagents; D005419:Flavonoids / Q000737:chemistry*; D005960:Glucosides / Q000032:analysis; D006031:Glycosylation; D007201:Indicator Dilution Techniques; D009844:Oligosaccharides / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*
D003432:Cross-Linking Reagents; D005419:Flavonoids; D005960:Glucosides; D009844:Oligosaccharides; D011134:Polysaccharides; C404987:flavan-3-ol; D002392:Catechin; D000688:Amylose