Structure Determination of Novel Oxidation Products from Epicatechin: Thearubigin-Like Molecules

Kazuhiro Uchida; Kazuki Ogawa; Emiko Yanase

doi:10.3390/molecules21030273

Structure Determination of Novel Oxidation Products from Epicatechin: Thearubigin-Like Molecules

Molecules. 2016 Feb 26;21(3):273. doi: 10.3390/molecules21030273.

Authors

Kazuhiro Uchida¹, Kazuki Ogawa², Emiko Yanase³

Affiliations

¹ Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. u8121006@edu.gifu-u.ac.jp.
² Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. t8121010@edu.gifu-u.ac.jp.
³ Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. e-yanase@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.

Keywords: black tea; epicatechin; oxidation; polymeric polyphenol; theaflavine; thearubigin.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Catechin / analogs & derivatives*
Catechin / chemistry*
Magnetic Resonance Spectroscopy
Mass Spectrometry
Molecular Structure
Oxidation-Reduction
Polyphenols / chemistry
Polyphenols / isolation & purification*
Tea / chemistry

Substances

Polyphenols
Tea
thearubigin
Catechin