Two-Step Enzymatic Modification of Solid-Supported Bergenin in Aqueous and Organic Media.

The natural flavonoid bergenin was directly immobilized onto carboxylic acid functionalized controlled pore glass (carboxy-CPG) at 95% yield. Immobilized bergenin was brominated via chloroperoxidase in aqueous solution and then transesterified with vinyl butyrate in diisopropyl ether by subtilisin carslberg (SC) extracted into the organic solvent via ion pairing. Enzymatic cleavage of 7-bromo-4-butyrylbergenin from carboxy-CPG (9.6% final yield) was accomplished using lipase B (LipB) in an aqueous/organic mixture (90/10 v/v of water/acetonitrile), demonstrating the feasibility of solid phase biocatalysis of a natural product in aqueous and non-aqueous media.