Covalent immobilization of tyrosinase on magnetic multi‐walled carbon nanotubes for inhibitor screening

Abstract

The inhibition of tyrosinase is considered to be a common therapeutic strategy for some hyperpigmentation disorders. Screening of tyrosinase inhibitors is of great significance to the treatment of pigmentation diseases. In this study, tyrosinase was covalently immobilized on magnetic multi-walled carbon nanotubes for the first time, and the immobilized tyrosinase was applied for ligand fishing of tyrosinase inhibitors from complex medicinal plants. The immobilized tyrosinase was characterized by transmission electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and thermo-gravimetric analyzer, which indicated that tyrosinase was immobilized onto magnetic multi-walled carbon nanotubes. The immobilized tyrosinase showed better thermal stability and reusability than the free one. The ligand was fished out from Radix Paeoniae Alba and identified as 1,2,3,4,6pentagalloylglucose by ultra-performance liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry. 1,2,3,4,6-pentagalloylglucose was found to be a tyrosinase inhibitor with similar half maximal inhibitory concentration values of 57.13 ± 0.91 μM compared to kojic acid (41.96 ± 0.78 μM).

Fast screening of α‐glucosidase inhibitors from Ginkgo biloba leaf by using α‐glucosidase immobilized on magnetic metal‐organic framework

“…The amount of protein in the supernatant was quantified by the Coomassie Brilliant Blue method using the BSA analysis curve [34,35]. The amount of α-glucosidase immobilized on the Fe 3 O 4 -NH 2 @MIL-101(Cr)-NH 2 was defined as the protein quantity (µg, calculated by subtracting the protein content in the supernatant from the total amount added during the immobilization procedure) per milligram of Fe 3 O 4 -NH 2 @MIL-101(Cr)-NH 2 .…”