Efficient isolation of major procyanidin A-type dimers from peanut skins and B-type dimers from grape seeds

INRA, UMR SPO, 2 Place Viala, 34060 Montpellier, France
Food Chemistry (Impact Factor: 3.39). 12/2009; 117(4):713-720. DOI: 10.1016/j.foodchem.2009.04.047
Source: OAI


In order to fully explore the biofunctional potential of proanthocyanidins (PA), isolated and well-characterised PA dimers are of great importance. Current methods to obtain pure A- and B-type dimers are laborious, because they comprise multiple chromatographic steps, often yielding only one or two specific dimers. In the current study, an efficient isolation procedure is described, to isolate a large variety of A-type dimers from peanut skins and B-type dimers from grape seeds. Yields increased 20–400 times for A-type dimers and about 10 times for B-type dimers compared to other methods with a lesser number of chromatographic steps. Dimers isolated from peanut skins were identified as; epicatechin-(2-O-7, 4-8)-catechin (A1), epicatechin-(2-O-7, 4-8)-epicatechin (A2), epicatechin-(2-O-7, 4-6)-catechin, epicatechin-(2-O-7, 4-8)-entcatechin, isolated from peanut skins for the first time, and epicatechin-(4-6)-catechin (B7). Dimers from grape seeds were identified as; epicatechin-(4-8)-catechin (B1), epicatechin-(4-8)-epicatechin (B2), catechin-(4-8)-catechin (B3) and catechin-(4-8)-epicatechin (B4).

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Available from: Peter C H Hollman
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    • "[23] [24] [25] [26] Interestingly, ESI-MS/MS fragmentation allows discrimination of B-type and A-type procyanidin dimers. [27] Indeed, [M-H] À product ions at m/z 451 (HRF) and 425 (RDA) are specific to procyanidin B2 (Fig. 1, I), whereas [M- H] À product ions at m/z 449 (HRF) and 423 (RDA) are assigned to procyanidin A2 (Fig. 1, II). A considerable part of fruit produce is processed into derived products such as non fermented beverages (juices, concentrates, purees, jams. . "
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    ABSTRACT: Procyanidins (i.e. condensed tannins) are polyphenols commonly found in fruits. During juice and cider making, apple polyphenol oxidase catalyzes the oxidation of caffeoylquinic acid (CQA) into its corresponding o-quinone which further reacts with procyanidins and other polyphenols, leading to the formation of numerous oxidation products. However, the structure and the reaction pathways of these neoformed phenolic compounds are still largely unknown. Experiments were carried out on a model system to gain insights into the chemical processes occurring during the initial steps of fruit processing. Procyanidin B2 was oxidized by caffeoylquinic acid o-quinone (CQAoq) in an apple juice model solution. The reaction products were monitored using high performance liquid chromatography (HPLC) coupled to ultraviolet (UV)-visible and electrospray tandem mass spectrometry (ESI-MS/MS) in the negative mode. Oxidative conversion of procyanidin B2 ([M-H](-) at m/z 577) into procyanidin A2 at m/z 575 was unambiguously confirmed. In addition, several classes of products were characterized by their deprotonated molecules ([M-H](-)) and their MS/MS fragmentation patterns: hetero-dimers (m/z 929) and homo-dimers (m/z 1153 and 705) resulting from dimerization involving procyanidin and CQA molecules; intramolecular addition products at m/z 575, 573, 927, 1151 and 703. Interestingly, no extensive polymerization was observed. Analysis of a cider apple juice enabled comparison with the results obtained on a biosynthetic model solution. However, procyanidin A2 did not accumulate but seemed to be an intermediate in the formation of an end-product at m/z 573 for which two structural hypotheses are given. These structural modifications of native polyphenols as a consequence of oxidation probably have an impact on the organoleptic and nutritional properties of apple juices and other apple-derived foods.
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