Characterisation of oligomeric and polymeric procyanidins from grape seeds by liquid secondary ion mass spectrometry

Abstract

Several fractions of oligomeric and polymeric procyanidins have been obtained from grape seeds by gel chromatography on Fractogel TSK. Their molecular weights (Mw) were directly determined by Liquid Secondary Ion Mass Spectrometry (LSIMS). We observed that tannins were molecules with a wide range of Mw: from 290 to 3100 (decamers). Catechins (Mw 290), procyanidin dimers (Mw 578), (−)-epicatechin gallate (Mw 442), procyanidin dimer gallates (Mw 730), procyanidin dimer digallates (Mw 882), procyanidin trimers (Mw 866) and procyanidin trimer gallates (Mw 1018), were identified as (M−H) − quasimolecular ions by negative LSIMS. Some structures were elucidated by partial thiolysis and enzymatic hydrolysis.