Glycosylation of polyphenols may increase their aqueous solubility, stability, bioavailability and pharmacological activity. Herein, we used a mutant of sucrose phosphorylase from Thermoanaerobacterium thermosaccharolyticum engineered to accept large polyphenols (variant TtSPP_R134A) to produce phloretin glucosides. The selective formation of a monoglucoside or a diglucoside can be kinetically controlled. MS and 2D-NMR determined that the monoglucoside was phloretin 4’-O-α-D-glucopyranoside and the diglucoside phloretin-4’-O-[α-D-glucopyranosyl-(1→3)-O-α-D-glucopyranoside], a novel compound. The molecular features that determine the specificity of this enzyme for 4’-OH phenolic group were analysed by induced-fit docking analysis of each putative derivative, using the crystal structure of TtSPP and changing the mutated residue. The mono- and diglucoside were, respectively, 71- and 1200-fold more soluble in water than phloretin at room temperature. Since phloretin attracts a great interest in dermocosmetic applications, we analyzed the percutaneous absorption of glucosides and the aglycon employing a pig skin model. Although the three compounds were detected in all skin layers (except the fluid receptor), the diglucoside was present mainly on superficial layers.
Ref: "Enzymatic Synthesis of Phloretin α‐Glucosides using a Sucrose Phosphorylase Mutant and its Effect on Solubility, Antioxidant Properties and Skin Absorption. Advanced Synthesis & Catalysis". J.L. Gonzalez-Alfonso, Z. Ubiparip, E. Jimenez-Ortega, A. Poveda, C. Alonso, L. Coderch, J. Jimenez-Barbero, J. Sanz-Aparicio, A. Ballesteros, T. Desmet, F.J. Plou. (2021). Volume363, Issue12, Pages 3079-3089 https://doi.org/10.1002/adsc.202100201