title: Isolation and characterization of a cyanidin-catechin pigment from adzuki bean (Vigna angularis).
abstract: Adzuki bean is used to prepare many kinds of foods in east Asia, and the seed coat contains water-soluble anthocyanins, catechins, and flavonols. In the present study, ethyl acetate-soluble purplish pigments were isolated from adzuki bean. Pigments of soaked adzuki bean were extracted with 1% HCl in methanol. Ethyl acetate-soluble purple pigments were obtained from the methanol soluble components. Purple pigments 1 and 2 were purified from the ethyl acetate-soluble pigments by Sephadex LH-20 column chromatography and preparative reversed-phase HPLC. NMR and mass spectra suggested that pigment 1 was a condensation product of cyanidin and (+)-catechin, in which 5-hydroxy and C-4 positions of the cyanidin moiety were substituted by the addition of 5-hydroxy and C-6 positions of the (+)-catechin moiety, respectively. Pigment 2 was an isomer of pigment 1. It is suggested that pigments 1 and 2 contribute to the purplish-red colour of foods prepared using adzuki bean.
authors.affiliation: Department of Bioscience, Kyushu Dental University, Kitakyushu 803-8580, Japan. takahama@kyu-dent.ac.jp
authors.forename: Umeo
authors.initials: U
authors.lastname: Takahama
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamauchi
authors.forename: Sachiko
authors.initials: S
authors.lastname: Hirota
mesh_terms: D000872:Anthocyanins / Q000737:chemistry* / Q000302:isolation & purification*; D002392:Catechin / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D007887:Fabaceae / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification*; D012639:Seeds / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D010936:Plant Extracts; C017154:cyanidin; D002392:Catechin