Abstract: β-Glucosidase modified with polyethylene glycol (PEG) was used as catalyst for the synthesis of salidroside from tyrosol and D-glucose, and its catalytic activity in three ionic liquids, [bmim]PF₆, [bmim]BF₄, and [bmim]Tf₂N, and two common organic solvents, 1,4-dioxane and n-hexane, was measured. Ionic liquid [bmim]PF₆ was the optimal reaction medium, and different reaction conditions were optimized in it. A yield of 88.5% (product content of 61.93 mmo1/L) was obtained under the conditions of H₂O content of 2%, temperature of 50 ^oC, tyrosol content of 70 mmo1/L, D-glucose/tyrosol molar ratio of 2, and reaction time of 24 h. The results suggest that both the modification with PEG and using ionic liquid [bmim]PF₆ as reaction medium have obvious promoting effects on the enzymatic synthesis of salidroside.

Key words: ionic liquid, β-glucosidase, salidroside, biocatalysis, tyrosol