Synthesis and application of molecularly imprinted polymers for preferential removal of emodin and physcion from Polygonum multiflorum stem extract

Abstract

Polygonum multiflorum Thunb. (PM) has been used since ancient times as Chinese traditional medicine. 2,3,5,4′-tetrahydroxystilbene-2-O-β-glucoside (THSG), a major active component in its extracts, has been reported to exhibit numerous bioactivities in cells and animals. Notably, anthraquinones, such as emodin and physcion, are of potential hazards when PM is sampled for composition analysis and application. Herein, molecularly imprinted polymers (MIPs) using emodin and physcion as templates were constructed to remove anthraquinones from PM extracts while fully reserved THSG. Through characterization analysis, MIPs were found to have looser scaffolds than non-molecularly imprinted polymers (NIPs). Static isothermal adsorption demonstrated that the absorption capacity best fitted to the Langmuir model and pseudo-first-order kinetics. The maximum absorption capacity for emodin and physcion was 48.87 and 32.00 μmol/g, respectively. Remarkably, highly selective absorption and removal towards merely targeted templates were noticed in the resulting MIPs, with no specific adsorption towards THSG. Tandemly connected emodin-MIPs and physcion-MIPs cartridges successfully removed emodin and physcion from PM extracts accompanied with > 90% recovery for THSG. Further, the MIPs cartridges displayed an excellent regeneration capacity in multiple cycles. This work pointed that MIPs can be introduced as an effective and accurate technique to obtain anthraquinones-free but THSG-rich crude PM extracts, thereby increasing the overall application of PM extracts.