|RAMSAY, AINA - University Of Reading|
|ROPIAK, HONORATA - University Of Reading|
|FRYGANAS, CHRISTOS - University Of Reading|
|MUELLER-HARVEY, IRENE - University Of Reading|
|BROWN, RONALD - University Of Reading|
|DRAKE, CHRIS - University Of Reading|
Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/19/2014
Publication Date: 3/23/2015
Citation: Zeller, W.E., Ramsay, A., Ropiak, H.M., Fryganas, C., Mueller-Harvey, I., Brown, R.H., Drake, C., Grabber, J.H. 2015. Estimation of procyanidin/prodelphinidin and cis/trans flavanol ratios of condensed tannin fractions by 1H-13C HSQC NMR spectroscopy: Correlation with thiolysis [abstract]. 249th American Chemical Society Meeting, March 22-26, 2015, Denver, Colorado. Abstract No. AGFD 50.
Technical Abstract: Integration of cross-peak contours of H/C-2’,6’ signals from prodelphinidin (PD) and of H/C-6’ signals from procyanidin (PC) units in 1H-13C HSQC nuclear magnetic resonance (NMR) spectra of condensed tannins yielded nuclei-adjusted PC/PD estimates that were highly correlated with PC/PD ratios obtained by thiolysis (R2 = 0.99) with benzyl mercaptan. Cis/trans flavanol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by thiolysis (R2 = 0.89). The method was developed using a diverse array of 22 condensed tannin (CT) fractions from 9 plant species and fractions containing 44 to ~100 g CT/100 g fraction, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios from 58/42 to 95/5 as determined by thiolysis. Overall, 1H-13C HSQC NMR appears to be a viable alternative to thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.