Biotransformation of phloretin by amylosucrase yields three novel dihydrochalcone glucosides.

Glycosylation is one of the most important tailoring reactions for natural products. It typically exerts profound direct or indirect effects on their biological activity. The dihydrochalcone phloretin and its known sugar derivatives, particularly phlori(d)zin, have been shown to influence various cellular processes. We found that a non-Leloir glycosyltransferase, amylosucrase from Neisseria polysaccharea, is an excellent catalyst for the stereospecific glucosylation of phloretin at the 4' position. Three novel phloretin derivatives were obtained, the first ones in which the sugar-aglycone bond possesses the configuration. A first biological characterization in a cell viability assay showed that each sugar attachment reduced the compound toxicity approximately two-fold.