Abstract
In this study, xanthine oxidase immobilized silica coated Fe3O4 nanoparticles (Fe3O4@SiO2-XO) were successfully prepared and characterized by transmission electron microscope, X-ray powder diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The average diameter of the Fe3O4 nanoparticles was about 300 nm to 350 nm with a shell thickness of 60 nm. The maximum saturation magnetization of the Fe3O4@SiO2-XO nanoparticles was 44.9 emu/g, which ensured the separation from the medium within one minute by using an ordinary magnet. A xanthine oxidase (XO) inhibitor screening method using Fe3O4@SiO2-XO nanoparticles was established and utilized in the extract of Clerodendranthus spicatus. Under the optimized conditions, two compounds were screened out and identified as gardenin B and eupatorin. The half maximal inhibitory concentration (IC50) values of these two compounds were 1.488 μg/mL and 11.197 μg/mL, respectively. The interactions between these two compounds and XO were investigated by the fluorescence spectroscopic method. The results suggested that the quenching effects of gardenin B and eupatorin were due to a static quenching mechanism. Furthermore, gardenin B showed stronger binding capacity than that of eupatorin. In conclusion, this screening method exhibited efficiency and reusability in screening, identification and analysis of enzyme inhibitors from complex mixtures.
Highlights
Natural products were fruitful sources of bioactive compounds for drug discovery [1]
Enzyme modified magnetic nanoparticles could be used as agents in the screening of active and bioactive compounds from natural products
It could be seen that a light grey coating layer existed on the surface of the Fe3 O4 nanoparticles and that the shell thickness of the silica layer was about 60 nm
Summary
Natural products were fruitful sources of bioactive compounds for drug discovery [1]. Unclear function mechanisms, complex composition, and tiring separation and purification procedures often hinder the research of natural products [2]. The research on active compounds in natural products would benefit from more efficient and novel screening technologies. Many kinds of magnetic nanoparticles were applied as the catalysts, the carriers, the supports and so on [6,7]. High stability and high surface area made magnetic nanoparticles become ideal solid supports for enzyme immobilization [9]. Enzyme modified magnetic nanoparticles could be used as agents in the screening of active and bioactive compounds from natural products.
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