Preparation of 10-(hexylcarbamoyl)pyranomalvidin-3-glucoside from 10-carboxypyranomalvidin-3-glucoside using carbodiimide chemistry.

Anthocyanins and pyranoanthocyanins are appealing natural pigments for replacement of synthetic ones. However, due to instability and solubility issues, lipophilization process of anthocyanins has raised as a valuable and efficient strategy to extend their stability and affinity into liposoluble formulations and enhance their unique physicochemical and biological properties. In this work, 10-carboxypyranomalvidin-3-glucoside was functionalized with hexylamine via carbodiimide chemistry compatible with the absence of hydroxyl protecting groups. A new amide conjugate attached to an alkyl chain with better hydrophobic features was obtained and isolated from its precursor. Mass spectrometry, FTIR, and NMR spectroscopy confirmed that the lipophilization site took place at the carboxyl group and the octanol-water partition coefficient determined by UV-Vis revealed its superior affinity for non-polar media. Overall, we reported a new pyranoanthocyanin lipophilic derivative for the first time which encourage further investigation for this novel class of compounds towards their incorporation into lipid-based foods and cosmetic formulations.