Phenolic compounds, including novel c-glycosylflavone, from the flowers of the tall bearded iris cultivar 'victoria falls'

Abstract

A new C-glycosylflavone, luteolin 7-methyl ether 6-C-[β- arabinopyranosyl-(1→2)-β-glucopyranoside] (swertiajaponin 2'-O-arabinoside) (1) was isolated and identified from the violet blue colored flowers of the tall bearded iris (Iris hybrid) cultivar "Victoria Falls", together with five known flavonoids, swertisin 2'-O-arabinoside (2), schaftoside (3), isoschaftoside (4), swertiajaponin (5), swertisin 2'-O-glucoside (6) and a C-glycosylxanthone, mangiferin (7). Of these compounds, 1 and 2 were elucidated from NMR spectroscopic data, which revealed the rotameric pairs. C-Glycosylflavone O-arabinosides were isolated from the genus Iris for the first time.