Reversed-phase and size-exclusion chromatography as useful tools in the resolution of peroxidase-mediated (+)-catechin oxidation products

The peroxidase-catalysed oxidation of plant phenolics involves one-electron oxidation reactions, and yields unstable mono-radical species, which coupl e to generate heterogeneous product mixtures of different degrees of polyme risation. One such phenolic susceptible to oxidation by peroxidase is (+)-c atechin. Low-pressure chromatography on Sephadex LH-20, using methanol as m obile phase, resolves the main peroxidase-mediated (+)-catechin oxidation p roducts into a dimeric compound (dehydrodicatechin A) and an oligomeric fra ction with a polymerisation degree equal or greater than 5. These pure frac tions were used to develop rapid high-performance liquid chromatographic me thods, both reversed-phase and size-exclusion chromatography for the direct analysis of the peroxidase-mediated (+)-catechin oxidation products. The j oint use of both chromatographic systems permitted the qualitative and quan titative identification of the peroxidase-mediated (+)-catechin oxidation p roducts, and can thus be considered as a useful tool for analysing the comp lex mixtures of natural bioactive plant products synthesized in reactions c atalyzed by plant peroxidases. (C) 2001 Elsevier Science BN. All rights res erved.