New compounds obtained by evolution and oxidation of malvidin 3-O-glucoside in ethanolic medium.
Two new colorless phenolic compounds were formed from malvidin 3- O-glucoside incubated in an ethanolic solution. Their structures were characterized by means of one- and two-dimensional NMR analysis and through electrospray ionization-mass spectrometry. As compared to the structure of the initial anthocyanin skeleton, the first new compound showed the presence of two fused five-membered rings replacing the pyran ring and of a carbonyl function on the 2-position. The first five-membered ring was shown to result from the formation of a new linkage between the B ring 6'-position and the C ring 4-position, while the second was a dihydro furan ring with an oxygenated ether linkage between the 8a-position and the 3-position. The second isolated compound was shown to have similar structure with an ethyl ether moiety in the 3-position instead of the glucose moiety. A mechanism explaining the formation of the isolated compounds involving the passage through the chalcone form of the anthocyanin and an oxidation process is proposed.
Es-Safi
Nour-Eddine
NE
INRA-UMR Sciences pour l'CEnologie, 2 Place Viala, 34060 Montpellier, France. nouressafi@yahoo.fr
Meudec
Emmanuelle
E
Bouchut
Claire
C
Fulcrand
Helene
H
Ducrot
Paul-Henri
PH
Herbette
Gaëtan
G
Cheynier
Veronique
V
D000872:Anthocyanins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol; D005960:Glucosides; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization
D000872:Anthocyanins; D005960:Glucosides; D012996:Solutions; D000431:Ethanol; C458419:malvidin-3-glucoside