Recent progress in the chemistry of polyacylated anthocyanins as flower color pigments

It is recognized that the bluing effect and stabilization of flower colors will remarkably depend on the number of aromatic acids presented in the polyacylated anthocyanins. Although polyacyl functions would be considered to contribute strongly in the bluing of the flower color at the early stage of the investigation of polyacylated anthocyanin chemistry, the stabilization of flower color is considered to be another important objective by the presence of these aromatic acids at the present time. Since aromatic acids in the polyacylated anthocyanins are obviously linked with the sugar residues through the ester bonds, the polyacylated anthocyanins are classified into seven types by the substitution pattern of acyl functions, and the effect of the stacking structures of polyacyl anthocyanins on the stabilization of the flower color depending on the substitution pattern of acyl groups will be discussed. The physicochemical properties (NMR, UV-VIS spectra) in relation to the stability of the anthocyanins will also be discussed.