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Stereochemistry and glycosidic linkages of C3-glycosylations affected the reactivity of cyanidin derivatives

Farr, Jacob E., Sigurdson, Gregory T., Giusti, M. Mónica
Food chemistry 2019 v.278 pp. 443-451
anthocyanins, ascorbic acid, bisulfites, bleaching, cyanidin, disaccharides, glycosidic linkages, glycosylation, half life, high performance liquid chromatography, monosaccharides, pH, stereochemistry
The impact of glycosylation on anthocyanin stability has largely been associated with sugar type, site, and size, with glycosyl stereochemistry being under-explored. Seven cyanidin-3-glycosides were isolated by HPLC, diluted in pH 1–9, mixed with bisulfite or ascorbic acid at pH 3, and stored for 8 weeks (25 °C, dark). Spectral changes, half-lives, and bleaching rates were determined. Cyanidin-3-galactoside was more reactive (susceptible to hydration and bleaching) than cyanidin-3-glucoside. The 1 → 2 disaccharides exhibited greater λvis-max (≤16 nm), resistance to hydration, and bleaching compared to 1 → 6 disaccharides.The 1 → 6 disaccharides had similar λvis-max (∼2 nm) to the monosaccharides but slightly improved resistance to hydration and bleaching. The tri-glycosylated anthocyanin had the greatest stability and its spectral and bleaching characteristics was intermediate to 1 → 2 and 1 → 6 disaccharides. The 1 → 2 disaccharides generally exhibited lower half-lives compared to monosaccharides; whereas, 1 → 6 disaccharides exhibited higher stability. These findings highlight the role of glycosyl assembly on anthocyanin reactivity and stability.