Highly galloylated and A-type prodelphinidins and procyanidins in persimmon (Diospyros kaki L.) peel

The structure of persimmon peel proanthocyanidins (PPPAs) was characterized. After acid catalysis of PPPAs in the presence of phloroglucinol, five reaction products such as (epi)gallocatechin-phloroglucinol ((E)GC-ph) etc. were identified by HPLC-DAD-ESI/MS. FT-IR analysis confirmed that all of the compounds exhibited a 2, 3-cis configuration. Therefore, the extension units in PPPAs were EGC, epigallocatechin gallate (EGCG), epicatechin, and epicatechin gallate and only EGCG was detected as the terminal unit. PPPAs contained 25.21% of procyanidins and 74.79% of prodelphindins and had a high degree of 3-O-galloylation (>74.79%). The mean degree of polymerization of PPPAs was calculated to be 10.18. MALDI-TOF MS analysis showed that A-type linkage and galloylation existed commonly in PPPAs.