UV-Visible Spectroscopic Investigation of the 8,8-Methylmethine Catechin-malvidin 3-Glucoside Pigments in Aqueous Solution: Structural Transformations and Molecular Complexation with Chlorogenic Acid

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• 作者：Montserrat Dueñ ; as ; Erika Salas ; V&eacute ; ronique Cheynier ; Olivier Dangles ; and H&eacute ; l&egrave ; ne Fulcrand
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2006
• 出版时间：January 11, 2006
• 年：2006
• 卷：54
• 期：1
• 页码：189 - 196
• 全文大小：293K
• 年卷期：v.54,no.1(January 11, 2006)
• ISSN：1520-5118

文摘

The physicochemical properties of 8,8-methylmethine catechin-malvidin 3-O-glucoside isomers,commonly referred to as catechin-ethyl-malvidin 3-O-glucoside, have been studied in aqueoussolutions and compared with those of the parent anthocyanin (malvidin 3-O-glucoside). The hydrationand acidity constants (pK_h and pK_a) of the catechin-ethyl-malvidin 3-O-glucoside pigments and malvidin3-O-glucoside were determined by UV-visible spectroscopic measurements. The ethyl-linkedcatechin-malvidin 3-O-glucoside pigments present higher stability toward hydration than the parentanthocyanin. The high resistance of these ethyl-linked pigments toward the hydration is related tothe self-association that offers optimal protection from the nucleophilic attack of water. Moreover,the ethyl link may confer to the molecule enough flexibility to undergo intramolecular interaction,further protecting it from hydration and bisulfite discoloration. In the wine pH range (3.2-4.0), due tothe low pK_a and high pK_h values, the ethyl-linked pigments are present as colored forms (flavyliumcation and quinonoid bases).Keywords: Malvidin 3-O-glucoside; ethyl-linked pigments; hydration and transfer proton constants;intramolecular interaction and self-association