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Structure Determination of Novel Oxidation Products from Epicatechin: Thearubigin-Like Molecules
Kazuhiro Uchida1, Kazuki Ogawa2, Emiko Yanase3
1Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. u8121006@edu.gifu-u.ac.jp.
Abstract:
Following the oxidation of epicatechin (EC), three novel compounds and two known compounds were isolated. The chemical structures of these oxidation products were determined by mass spectrometry (MS) and various nuclear magnetic resonance (NMR) experiments, and the A-ring-B-ring linkage that is characteristic of catechin was found in each molecule. Three compounds showed similar ultraviolet-visible (UV-Vis) spectra to EC, whereas two compounds showed different spectral absorption in the region between 300 and 500 nm. A similar spectrum was obtained for the thearubigin fraction prepared from a black tea infusion. This result suggests that the condensation reaction between the A-ring and B-ring is more important than reaction between B-rings for thearubigin formation.
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