Laccase-mediated oxidation of natural glycosides

Regioselective oxidations of the primary OHʹs of natural glycosides (thiocolchicoside, colchicoside, amygdalin, asiaticoside, ginsenoside RE) have been performed on a preparative scale by exploiting the laccase–2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) methodology. The influence of water-miscible organic cosolvents on the stability and activity of a laccase from Trametes pubescens has been investigated. The enzyme has been covalently linked to Eupergit C250L and its performances evaluated. The recovered immobilized enzyme catalyzed several oxidative cycles of thiocolchicoside, without showing significant loss of activity.