Immobilized snailase in hollow silica nanospheres to highly efficient biotransformation of icariin to icaritin in deep eutectic solvents

Abstract Icaritin (ICT), a biologically active isoprenylated flavonoid, which has been shown to delay liver fibrosis, inhibit cancer cell proliferation and other therapeutic effects in the treatment of hepatocellular carcinoma. However, traditional methods for icaritin preparation suffer from significant drawbacks such as high environmental pollution, energy consumption, and low yield. In this study, snailase (SNA) was immobilized for the first time in hollow silica nanospheres (HSN) through facile and novel in situ immobilization and soft template removal method to construct highly active biocatalysts (SNA@HSN) where enzymes in the cavity exhibit “immobilized but not rigid state”. The resultant SNA@HSN showed excellent activity (78% activity recovery) and stability suffered from extreme pH, temperature, and organic solvents. Meanwhile, the reusability and storage stability of SNA@HSN were satisfactory. After 5 cycles, SNA@HSN still maintained 79% original activity. Especially, SNA@HSN exhibited highly efficient biotransformation of icariin (ICA) to ICT in deep eutectic solvents (DESs) system. ICT yield in choline chloride–propylene glycol (ChCl:P, 25% v/v) system was 111% higher than that of aqueous system, reached 374 mg/L. Thus, this study developed an efficient methodology for icaritin preparation through the integration of enzymatic catalysis and environmentally friendly catalytic medium.