Isolation and structural elucidation of some procyanidins from apple by low-temperature nuclear magnetic resonance.
Procyanidin fractions from apple were separated according to the degree of polymerization using normal phase chromatography. Evaluation of physiological functionalities of procyanidins requires individual structural determination. However, it is difficult to elucidate the structure of procyanidins, in particular those with (+)-epicatechin (1) or (-)-catechin (2) units, and determine whether the interflavanoid bonds are 4beta-->8 or 4beta-->6 without cleavage and acetylation. Structural determination used LC-MS and low-temperature NMR. Nine procyanidins were separated by preparative HPLC consisting of three well-known procyanidins [procyanidin B1 (3), procyanidin B2 (4), and procyanidin C1 (5)] and six new procyanidins [epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-catechin (6); epicatechin-(4beta-->6)-epicatechin-(4beta-->8)-catechin (7); epicatechin-(4beta-->6)-epicatechin-(4beta-->8)-epicatechin (8); epicatechin-(4beta-->8)-epicatechin-(4beta-->6)-catechin (9); epicatechin-(4beta-->8)-epicatechin-(4beta-->6)-epicatechin (10); and epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-epicatechin (11)]. Compounds 6-11 were detected for the first time as apple constituents.
Shoji
Toshihiko
T
Fundamental Research Laboratory, Asahi Breweries, Ltd., 1-21 Midori 1-chome, Moriya, Ibaraki 302-0106, Japan. toshihiko.shoji@asahibeer.co.jp
Mutsuga
Motoh
M
Nakamura
Takatoshi
T
Kanda
Tomomasa
T
Akiyama
Hiroshi
H
Goda
Yukihiro
Y
D044946:Biflavonoids; D002392:Catechin / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D005638:Fruit / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D027845:Malus / Q000737:chemistry*; D044945:Proanthocyanidins; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature
D044946:Biflavonoids; D044945:Proanthocyanidins; C479579:procyanidin B1; C479580:procyanidin B2; C017674:procyanidin; D002392:Catechin