Two-Step Lipase-Catalyzed Acylation of Non-Glycosylated Flavonoids: Application to Phloretin.

We describe an efficient method for acylating non-glycosylated polyphenols, which involves an initial α-glucosylation step catalyzed by sucrose phosphorylase, followed by acylation using an immobilized lipase. This method is applied to phloretin. It is first glucosylated at the 4'-OH position, followed by quantitative acylation at the 6-OH of glucose with C8, C12, and C16 acyl chains using the lipase from Thermomyces lanuginosus. The aqueous solubility of the acyl glucosides is similar to that of the aglycone. The radical scavenging capacity of the new phloretin derivatives measured with ABTS·+ shows a slight decrease. This methodology offers a means to adjust the physicochemical and biological properties of polyphenols by varying the length and nature of the acyl donor.