Development and evaluation of a hydrogenated rosin (β-acryloxyl ethyl) ester–bonded silica stationary phase for high-performance liquid chromatography separation of paclitaxel from yew bark

Abstract

Paclitaxel (PTX) is a complex diterpenoid anticancer drug whose separation from yew biomass poses a significant challenge. In this study, a new stationary phase comprising hydrogenated rosin (β-acryloxyl ethyl) ester (HRE)–bonded silica (HRE@SiO2) is developed to separate and purify PTX from crude yew-bark extract using high-performance liquid chromatography. In HRE@SiO2, HRE molecules, which are functional ligands, are bonded to the surface of a silica gel matrix using a coupling agent, (3-mercaptopropyl)trimethoxysilane. The proposed HRE@SiO2 stationary phase was characterized by Fourier-transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, scanning electron microscopy, laser diffraction granulometry, and nitrogen gas adsorption. The HRE@SiO2 column exhibited excellent chromatographic performance, satisfactory performance reproducibility, and typical reversed-phase chromatographic behavior. An HRE@SiO2 column was used to separate PTX and its analogs, achieving resolutions exceeding 7.43 for consecutively eluted species. Stoichiometric displacement theory for retention (SDT-R), the van Deemter equation, and van 't Hoff plots were used to analyze the separation mechanism and properties of the HRE@SiO2 column. The results showed that hydrophobic interactions determine the analyte retention and the separation of PTX and its analogs on an HRE@SiO2 column is an exothermic process driven by enthalpy. Furthermore, an HRE@SiO2 column was employed to separate and purify PTX from crude yew-bark extract, increasing PTX purity from 6% to 82%. The findings of this study provide insights for developing rosin-based stationary phases for the separation of natural products.