Screening of cathepsin B inhibitors in traditional Chinese medicine by capillary electrophoresis with immobilized enzyme microreactor

Publication date: Available online 13 August 2019Source: Journal of Pharmaceutical and Biomedical AnalysisAuthor(s): Baofang Zhang, Zilin ChenAbstractA simple and valid method for rapid screening of cathepsin B inhibitors from traditional Chinese medicines (TCMs) was established by the combination of immobilized enzyme microreactor (IMER) and capillary electrophoresis. Cathepsin B was immobilized on the inner surface of the capillary by glutaraldehyde method. The separation of substrate and product could be finished by baseline within 3 min. The activity of the immobilized cathepsin B remained approximately 90% after 50 runs. The quantification and statistical analysis of the product peak area was used to evaluate the catalytic activity of cathepsin B. The value of Michaelis-Menten constant of cathepsin B was 0.85 mM. The half-maximal inhibitory concentration (IC50) of L-trans-Epoxysuccinyl-leucylamido(4-guanidino)butane (E-64) was measured as 36.08 nM, which indicated that the cathepsin B reactor was successfully developed and was feasible for inhibitor screening. The raised method was then applied to discover the inhibitory potential of 17 standard compounds from traditional Chinese medicines. Five natural products, including kaempferol, rutaecarpine, evodiamine, theophylline, lycobetaine showed potential inhibition for cathepsin B. Additionally, molecular docking study was investigated for supporting the interaction between enzyme and inhibitors.Graphical abstract
Source: Journal of Pharmaceutical and Biomedical Analysis - Category: Drugs & Pharmacology Source Type: research