Identification of two novel proanthocyanidins in green tea
1999
Lakenbrink, C. | Engelhardt, U.H. | Wray, V.
The isolation and structural elucidation of epiafzelechingallate-(4beta leads to 8)-epicatechingallate (EAG-4beta leads to 8-ECG) and epiafzelechingallate-(4beta leads to 6)-epicatechingallate (EAG-4beta leads to 6-ECG) in green tea samples are described. The combination of various 2D NMR techniques allowed a full structural determination of the underivatized proanthocyanidins even though broadening of the signals did not allow observation of some key correlations that characterize the location of the interflavonoid linkage. The differences in the NMR spectra of the new compounds allowed formulation of criteria for the discrimination between the 4 leads to 6 and 4 leads to 8 isomers in this type of compound.
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