Immobilization of α-Glucosidase on Polyethylene Glycol Diglycidyl Ether-Modified NH2-MIL-53(Al) for Inhibitory Activity Assay of Traditional Chinese Medicine

Enzyme inhibition-based drug screening is a critical strategy in drug development. However, significant limitations arise from the instability, limited reusability, and narrow applicability of traditional enzyme assays when screening for inhibitors in complex matrices, such as extracts of traditional Chinese medicines (TCMs). A screening strategy was developed that combines capillary electrophoresis (CE) with an enzymatic assay utilizing covalently immobilized α-glucosidase (α-Glu). NH2-MIL-53(Al) was synthesized using a hydrothermal method, serving as a robust support for enzyme immobilization. By employing polyethylene glycol diglycidyl ether (PEGDGE) as a covalent linker, significant enhancements in the stability and reusability of α-Glu were achieved. The immobilized enzyme maintained 77.7% of its initial activity over 10 cycles and displayed a Michaelis–Menten constant of 1.25 mM. Moreover, the inhibition constant and IC50 values for acarbose were determined to be 17.41 μM and 0.46 μM, respectively. Utilizing this immobilized enzyme system, screening of 12 TCMs identified several potent α-Glu inhibitors, including Chebulae Fructus and Curcumae Longae Rhizoma. These results highlight the successful integration of NH2-MIL-53(Al) and PEGDGE in creating a stable and reusable screening platform for enzyme inhibitors. This approach not only advances the field of enzyme immobilization technology but also provides a promising pathway for discovering antidiabetic agents from natural sources.