Screening of ß-secretase inhibitors from Dendrobii Caulis by covalently enzyme-immobilized magnetic beads coupled with ultra-high-performance liquid chromatography

Li-Hong Ye^a, Rui Zhang^b, Jun Cao^b

Department of Traditional Chinese Medicine, Hangzhou Red Cross Hospital, Hangzhou, 310003, China.

Abstract

In the present study, to effectively discover potential β-secretase inhibitors from Dendrobii Caulis, β-secretase was immobilized on magnetic beads via direct covalent connection and coupled with ultra-high-performance liquid chromatography. Mechanochemical-assisted extraction was used to extract active ingredients from Dendrobii Caulis. The main reaction conditions, including screening enzyme inhibitors, were evaluated, and the most important enzyme kinetic parameters were also investigated across the UV–vis spectrophotometer. Five compounds (rutin, scoparone, naringenin, dendrophenol, and erianin) with high binding affinity to magnetic beads were removed from the extract. The results indicated that β-secretase was successfully immobilized and screened out five potential inhibitor compounds by ligand fishing. The lowest IC50 values were noted for rutin (5.437 μM) and erianin (2.039 μM). This is the first report on immobilized β-secretase on magnetic beads for the identification of potential active compounds against Alzheimer's disease from complex biological mixtures.

Keywords: Ultra-high-performance liquid chromatography, Enzyme inhibitor screening, Enzyme immobilization, Mechanochemical-assisted extraction, Dendrobii Caulis.