AI Article Synopsis
- The study examined how (-)-epicatechin reacts with caffeoylquinic acid o-quinones in a model of apple juice, focusing on its two phenolic parts (A- and B-rings).
- The findings showed that while both rings can form covalent bonds, only the B-ring participates in electron transfer, leading to different oxidation products for each ring.
- Ultimately, the variety of oxidation products in apple juice stems from not only the polymerization of phenolic compounds but also from numerous smaller molecules in various oxidation and isomer forms.
Article Abstract
The reactivity of the (-)-epicatechin structure towards caffeoylquinic acid o-quinones was studied in an apple juice model solution. The approach consisted in considering separately the reactivities of the two phenolic moieties of an (-)-epicatechin molecule: phloroglucinol and 4-methylcatechol were chosen to represent A- and B-rings, respectively. The oxidation products were characterised by RP-HPLC coupled with electrospray ionisation Mass spectrometry (MS). The reactivities of the A- and B-rings were clearly different on the basis of the oxidation products formed. Both A- and B-rings could be involved in covalent bond formation, but electron transfers only occurred with the B-ring. Most of the (-)-epicatechin oxidation products were linked by A/B-ring linkage ("head-to-tail" intermolecular coupling). After this first dimerisation step, intramolecular reactions seemed to be favoured. Therefore, the complexity of oxidation products in apple juice does not only result from an extensive polymerisation of native phenolic compounds, but also from a multiplicity of small molecules in different oxidation states and isomeric forms.
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| http://dx.doi.org/10.1016/j.chroma.2007.11.083 | DOI Listing |
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