Catalytic hydrolysis of ginsenosides by pectinase immobilized on a covalent organic framework material

Covalent organic frameworks (COFs) have potential applications in immobilized enzyme fields due to their unique chemical and mechanical properties. First, a novel COF material for immobilizing enzyme for preparing ginsenosides was obtained using 1,3,5-tricarbaldehyde and 3,3′-dihydroxybenzidine （BTDH）as organic monomers. Then the morphology, stability, pore size and the loading capacity of COF-BTDH were investigated using transmission electron microscopy, Fourier transform infrared (FT-IR), and loading capacity experiments. At last effect of reaction time on ginsenoside extraction efficiency and the maximum usage amount of material were explored. Results showed that pectinase was effectively immobilized on COF-BTDH. In addition the optimized reaction time of catalytic hydrolysis for extracting ginsenosides Rb1 and Rd was 2 h, and the mass ratio of material to enzyme was 31.25:1. Additionally, the immobilized enzyme remained more than 85% active according to the amount ratio of ginsenoside Rd after five consecutive cycles.