Flavones in Green Tea

Abstract

Pigments IIIa and IIIb, the major components of flavones in green tea, were isolated in a pure state and identified as 6, 8-di-C-d-glucopyranosyl apigenin, from results of UV, IR, NMR spectra and other analytical data. They were also interconvertible by boiling with mineral acids. One of them, IIIb, gave an equilibrium mixture, which consisted of IIIb₁, HIb₂, and IIIb₃, when its aqueous solution was heated for extended periods of time. These pigments were distinguished by their interconvertibility and degradation pattern with acid, from another known 6, 8-di-C-glycosyl apigenin, vicenin-2.