Influence of cyanidin glycosylation patterns on carboxypyranoanthocyanin formation.

Anthocyanins can condense with compounds having enolizable groups to form pyranoanthocyanins. These pigments are less susceptible to degradation and color changes associated with nucleophilic addition common to anthocyanins. This study aimed to evaluate the impact of glycosylation patterns of anthocyanins on carboxypyranoanthocyanin formation. Nine cyanidin derivatives were isolated by semi-preparative HPLC. Pyruvic acid was added to induce pyranoanthocyanin formation. Composition (HPLC-MS/MS), spectra (absorbance 380-700 nm), and color (CIEL*c*h*) of solutions were monitored during 31 days storage at 25 °C. Cyanidin-3-glycosides with 1 → 6 disaccharides produced the highest pyranoanthocyanin yield (∼31%), followed by Cyanidin-3-monoglycosides (∼20%); 1 → 2 disaccharides produced the least proportions of pyranoanthocyanins (5-7%). Cyanidin-3-arabinoside converted to pyranoanthocyanins but degraded quickly (3% yield) under these conditions. No pyranoanthocyanins were formed from Cyanidin-3-sophoroside-5-glucoside. Glycosyl bonds were more critical than the size of the substitution alone, further supported by Cyanidin-3-(glucosyl)-(1 → 6)-(xylosyl-(1 → 2)-galactoside) yield (11%). Pyranoanthocyanins were hypsochromically shifted and had higher hue angles than their respective anthocyanins.