Enzyme‐mediated transglycosylation of rutinose (6‐O‐α‐l‐rhamnosyl‐d‐glucose) to phenolic compounds by a diglycosidase from Acremonium sp. DSM 24697

The structure of the carbohydrate moiety of a natural phenolic glycoside can have a significant effect on the molecular interactions and physicochemical and pharmacokinetic properties of the entire compound, which may include anti‐inflammatory and anticancer activities. The enzyme 6‐ O ‐α‐rhamnosyl‐β‐glucosidase (EC 3.2.1.168) has the capacity to transfer the rutinosyl moiety (6‐ O ‐α‐ l ‐rhamnopyranosyl‐β‐ d ‐glucopyranose) from 7‐ O ‐rutinosylated flavonoids to hydroxylated organic compounds. This transglycosylation reaction was optimized using hydroquinone (HQ) and hesperidin as rutinose acceptor and donor, respectively. Since HQ undergoes oxidation in a neutral to alkaline aqueous environment, the transglycosylation process was carried out at pH values ≤6.0. The structure of 4‐hydroxyphenyl‐β‐rutinoside was confirmed by NMR, that is, a single glycosylated product with a free hydroxyl group was formed. The highest yield of 4‐hydroxyphenyl‐β‐rutinoside (38%, regarding hesperidin) was achieved in a 2‐h process at pH 5.0 and 30 °C, with 36 mM OH‐acceptor and 5% (v/v) cosolvent. Under the same conditions, the enzyme synthesized glycoconjugates of various phenolic compounds (phloroglucinol, resorcinol, pyrogallol, catechol), with yields between 12% and 28% and an apparent direct linear relationship between the yield and the p K a value of the aglycon. This work is a contribution to the development of convenient and sustainable processes for the glycosylation of small phenolic compounds.