Peak 37: A-type procyanidin dimer (PC2*). This peak had a UV
spectra maximum at 278 nm and MS signals at m/z 575.1 and
449.1, corresponding to an A-type procyanidin dimer and its HRF
fragment ion, respectively (Li and Deinzer, 2007). Nevertheless, the
mass spectra also contained a second (by mean of intensity)
unknown molecular ion at m/z 649.2. A-type procyanidins should
be present naturally in grape seeds, or they can appear as an
artefact of the oxidation of B-type procyanidins if reactive oxygen
species are introduced in the solvent medium (Kondo et al., 2000)
during extraction or post-extraction treatments