Lignin Nanoparticles Support Lipase-Tyrosinase Enzymatic Cascade in the Synthesis of Lipophilic Hydroxytyrosol Ester Derivatives

Abstract

Lipophilic esters of hydroxytyrosol have been synthesized in a one-pot procedure from tyrosol and long side-chain carboxylic acids by a lignin nanoparticles supported enzymatic cascade of lipase M and tyrosinase. The reaction involved the initial esterification of the aliphatic carboxylic group with the hydroxyl group of tyrosol followed by ortho-hydroxylation of the aromatic moiety. Lipase M and tyrosinase were immobilized on lignin nanoparticles by layer-by-layer procedure using chitosan as positive charged polyelectrolyte and Concanavalin A as molecular spacer to control the optimal distance between the active sites of the two enzymes. The occurrence of substrate channeling effect was hypothesized on the basis of FRET analysis. Lipophilic hydroxytyrosol esters were synthesized in high yield in 2-methyltetrahydrofuran and in the presence of a very low amount of buffer to generate the hydration sphere of the enzyme.