Identification of two novel Prodelphinidin A-type dimers from roasted hazelnut skins ( Corylus avellana L.).

Two new A-type dimeric prodelphinidins, EGC-(2β→O7, 4β→8)-C and EGC-(2β→O5, 4β→6)-C, were isolated from the skins of roasted hazelnut ( Corylus avellana L.) by low-speed rotary countercurrent chromatography (LSRCCC) and final purification by preparative HPLC. Their structures were determined by a combination of mass spectrometry (HPLC-ESI-MS(n) and HR-ESI-MS) and NMR spectroscopy that included the application of 2D methods ((1)H-(1)H COSY, HSQC, HMBC, and NOESY). Furthermore, circular dichroism (CD) and acid-catalyzed degradation (phloroglucinolysis) confirmed the proposed structures.