Synthesis of Bioactive Hydroxytyrosol Esters via Multienzyme Cascade on Electroactive Melanin Lignin Nanoparticles: A One-Pot Approach without Extra Reducing Agents

A one-pot strategy for the synthesis of bioactive hydroxytyrosol esters from tyrosol and lipophilic carboxylic acids has been developed via multienzyme cascade immobilized on electroactive melanin lignin nanoparticles. The novel catalyst involved the co-immobilization of lipase and tyrosinase on the polyphenolic support and was operative in the presence of sustainable 2-methyltetrahydrofuran as organic reaction solvent. The system did not require the use of extra reducing agents for the selective synthesis of catechols. Optoelectronic and electrochemical studies suggested the role played by melanin lignin nanoparticles in the regeneration of the active site of tyrosinase from unproductive met-form to reversible deoxy/oxy-form. This effect improved the overall activity of tyrosinase in the multienzyme cascade favouring the reduction of undesired quinones to corresponding catechols.