## 3 Results
### Identification and Characterization of OPCs in Purified Subfractions via Fragment Spectra  
Depending on the MS\({}^{2}\) data and the exact mass of the OPCs, it was possible to forecast the structures of six new OPCs in _Aronia \(\times\) prunifolia_ 'Nero', which are shown in Figure 3. The structures were determined by fragmentation mechanisms, which are described for OPCs in the literature. These mechanisms are the retro-Diels-Alder reaction (RDA), quinone methide (QM) cleavage and heterocyclic ring fission (HRF). The \(m/z\) 1167 ion (suggested molecular formula of C\({}_{60}\)H\({}_{47}\)O\({}_{25}\) [M-H]\({}^{-}\)) is allocated to an A-type procyanidin tetramer with one (epi)galactechin subunit (Figure 3 (1)). The main fragment ion \(m/z\) 591, which is formed by QM fission between the F-ring and G-ring, presents a (epi)catechin and a (epi)gallocatechin subunit which likely has an A-type linkage. This could be confirmed with the fragment ion \(m/z\) 465 ([M-126-H]\({}^{-}\)), which is generated by HRF at the I-ring of the fragment ion \(m/z\) 591. Another indication of the proposed structure is the fragment ion \(m/z\) 1015 ([M-152-H]\({}^{-}\)), which is the result of the RDA cleavage at the F-ring of the second (epi)catechin subunit and/or the C-ring of the first (epi)catechin subunit. The fragment ion of \(m/z\) 997 ([M-152-18-H]\({}^{-}\)) results from the RDA cleavage in combination with a loss of H\({}_{2}\)O. Another loss of H\({}_{2}\)O from the main ion \(m/z\) 1167 results in \(m/z\) 1149 ([M-18-H]\({}^{-}\)). The product ion of \(m/z\) 879 ([M-288-H]\({}^{-}\)) arises from a QM cleavage at the C-ring of the (epi)catechin subunit and leads to the loss of this complete subunit. Further fragmentation of this fragment ion by HRF of the F-ring leads to \(m/z\) of 753 ([M-288-126-H]\({}^{-}\)), and the loss of H\({}_{2}\)O is indicated due to the presence of \(m/z\) 861 ([M-288-18-H]\({}^{-}\)). This consolidates the assumption of the tetrameric structure of \(m/z\) 1167. Further fragmentations can be described by an HRF at the C-ring which leads to m/z 1041 ([M-126-H]\({}^{-}\)) as well as two consecutive QM fissions of the parent ion resulting in \(m/z\) 863 and \(m/z\) 573. Based on these data, it is postulated that the \(m/z\) 1167 ion is a tetramer which consists of (epi)catechin subunits with a terminal A-type linkage of a terminal (epi)gallocatechin subunit. The six isomers of the OPC hexamer (1730 Da; Figure 3 (2)) are detected as double-charged quasi-molecular ions with \(m/z\) 864 ([M-2H]\({}^{2-}\)), which could be confirmed by a mass difference of 0.5 Da between the signals of the isotopic pattern (Supporting Information Figure S15). The \(m/z\) 864 ion is probably a B-type procyanidin hexamer consisting of (epi)catechin units. The QM cleavage of the terminal (epi)catechin subunit results in the fragment ion \(m/z\) 1439 ([M-290-H]\({}^{-}\)), which is followed by an HRF fragmentation which  
Figure 3: Predictive structures of the new characterized OPCs in _Aronia \(\times\) prunifolia_ 'Nero’. leads to \(m/z\) 989 or \(m/z\) 449. Another QM fission between the L-ring and the M-ring of two (epi)catechin units results in the main fragment ions \(m/z\) 1151 ([M-290-H]\({}^{-}\)) or between the F-ring and the G-ring the fragment with m/z 1153 ([M-288-H]\({}^{-}\)). In combination with a further QM cleavage of these two fragmentations, the fragments with \(m/z\) 575 or \(m/z\) 577 are formed. The \(m/z\) 407 ion arises by RDA in combination with loss of H\({}_{2}\)O ([M-170-H]\({}^{-}\)) from the parent ion. The fragment ion of m/z 287 is also formed by a QM cleavage of the parent ion and represents the cleavage of a (epi)catechin subunit. Another fragmentation way from the parent ion \(m/z\) 1729 results in the fragment ion of \(m/z\) 1315, which is created by HRF of the F-ring. If the HRF takes place in the L-ring, it results in \(m/z\) 739. The substance with \(m/z\) 1027 is a phenylpropanol-conjugated OPC trimer, a so-called cinchanain.