Obtaining hesperetin 7-O-glucosyl 6''-O-laurate, a high lipophilic flavonoid ester, from Citrus waste

A biotechnological process that combines the treatment of Citrus processing waste to extract a high-valuable biomolecule, neohesperidin (NEO), and its further modification by biocatalysis to enhance the lipophilicity of its flavonoic moiety is presented. NEO was extracted from immature fruits of Citrus aurantium and hydrolyzed by a commercial alpha-rhamnosidase to obtain hesperetin 7-glucoside (HG). NEO and HG were mono-acylated with vinyl laurate by using Novozym 435 in their primary OH-groups, but the esterification reaction was substantially faster for HG than NEO. Furthermore, the activation energy of the reaction lowers as solvents' log-P decreases linearly. Under best conditions, HGL was obtained at gram scale with a simple downstream process. The solubility in n-octanol increased with each biocatalytic step (NEO < HG < HGL), reaching a difference of 2 orders when comparing HGL with its parent molecules. This dramatic change in hydrophobic/ hydrophilic balance opens many possibilities to use the product in lipophilic media as an active agent in functional foods, therapeutic and cosmetic industries.