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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Cell Wall Biology and Utilization Research » Research » Publications at this Location » Publication #362054

Research Project: Removing Limitations to the Efficient Utilization of Alfalfa and Other Forages in Dairy Production, New Bio-Products, and Bioenergy to Enhance Sustainable Farming Systems and Food Security

Location: Cell Wall Biology and Utilization Research

Title: Elucidating composition and structure of purified condensed tannins: Corroboration of thiolysis and spectroscopic data

item Zeller, Wayne
item Reinhardt, Laurie
item HARDCASTLE, EMILY - University Of Wisconsin
item ROBE, JAMISON - University Of Wisconsin
item MUELLER-HARVEY, IRENE - University Of Reading
item RAMSAY, AINA - University Of Reading
item ROPIAK, HONORATA - University Of Reading
item FRYGANAS, CHRISTOS - University Of Reading
item BROWN, RONALD - University Of Reading
item DRAKE, CHRIS - University Of Reading
item SEPELA, REBECKA - Miami Dade University
item HAGERMAN, ANN - Miami Dade University

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/22/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Condensed tannins (CTs) consist of oligomers and polymers of flavan-3-ol subunits varying in hydroxylation patterns, cis- and trans-configuration of C-ring substituents, interflavan bond connections, mean degree of polymerization (mDP) and extent of depsidic linkage (esterification). Robust analytical methods to determine CT composition and structure are paramount to understanding the biological activity exerted by these secondary plant metabolites in human health, agriculture and environmental systems. Using wet chemistry (thiolytic degradation) and spectroscopic methods (two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy) in concert, progress in the structural elucidation of purified CTs has been made. We have previously shown that integration of the 2D NMR cross-peaks signals for procyanidin/prodelphinidin (PC/PD) and cis/trans flavan-3-ol subunit provides relative ratios that corroborated thiolytic data. Recent progress of CT structure elucidation using these methods include the identification and content estimations of the terminal flavan-3-ol subunits, the extent of galloylation, ratios of A-type to B-type interflavan linkages and mDP of purified CT samples. In addition, a second set of 2D NMR cross-peaks signals (H/C-2) can provide reliable determination of flavan-3-ol cis/trans ratios. Corroboration of the data from these methods provides a confirmation of CT structure and will assist in the accurate formulation of CT structure-biological activity relationships.