Effect of Acylation of Anthocyanins with Acetic Acid on the Retention of Glycosides in Reverse Phase Chromatography

Abstract

The effect of acylation of anthocyanins with acetic acid on the chromatographic retention is evaluated. It is shown that the absence of correlations between the experimental data on the retention of substances and the CLOGP data is explained, in some cases of structural changes, by the specificity of the float mechanism of the retention of anthocyanins. In this case, the conformational analysis of anthocyanins (in the Chem3D software package) can explain a number of features peculiar to the effect of acylation on the retention in accordance with the Horvath–Melander model used for glycoside substituents. It is shown that the contribution of the acetyl group to the total retention value of anthocyanins depends on the composition of the mobile phase, the structures of glycosidic substituents and aglycone for a given stationary phase, and the temperature of separation. In general, acetylation leads to a substantial increase in the retention of anthocyanins, namely, to an increase by a factor of about 10 for 3-(6-acetylglucosides), and this increase is about 1.5 times lower in the case of similar acetylation of 3,5-diglucosides.