Direct enzymatic glucosylation of naringin in grapefruit juice by α‐ D ‐glucosidase from the marine mollusc Aplysia fasciata

The enzymatic glucosylations of naringin, performed using α‐ D ‐glucosidase, identified in the Mediterranean mollusc Aplysia fasciata is reported. The enzyme actively operates on maltose and has an interesting transglycosylation potential using this donor. We also investigated the use of this marine α‐glucosidase for a food‐compatible glucosylation of naringin to produce new enzymatically modified carbohydrate possessing naringin derivatives. The regioselective formations of the β‐gluco‐C6 α‐glucosyl derivative and of the corresponding isomaltosyl diglucoside of naringin were obtained in high yield and efficiency of reaction. Suspensions of naringin can be used up to ∼90 mg/mL initial acceptor concentration. In different experiments it was demonstrated that the enzyme was still active after 48 h in presence of this high amount of acceptor and that one of the diasteromers of the naringin is preferred by the enzyme from A. fasciata during glucosylation/deglucosylation enzymatic steps. Finally, the feasibility of efficient naringin glucosylation in grapefruit juice was also demonstrated at optimal pH of the enzyme and low maltose concentrations.