An effective β-cyclodextrin polyurethane spherical adsorbent for the chromatographic enrichment of corilagin from Phyllanthus niruri L. extract

A novel β-cyclodextrin polyurethane (β-CD-PU) spherical adsorbent was prepared by the reversed-phase suspension crosslinking technique for the chromatographic enrichment of a polyphenolic compound corilagin. β-Cyclodextrin (β-CD) and PEG1000 were co-crosslinked with hexamethylene diisocyanate, and the polyurethane skeleton was formed and confirmed by FTIR, TGA and 13C CP/MAS NMR analysis. A chromatographic operation was carried out with the raw Phyllanthus niruri L. extract directly loaded onto the adsorbent, and one-step capture of corilagin had been realized. The ethanol aqueous solution of 20%(w/w) was favorable for corilagin elution with recovery and purity of 49.4% and 64.8%, respectively. The adsorption kinetic experiments showed that the pseudo-second order model provided a good fit with the data, but the values of equilibrium adsorption capacity deviated notably, revealing the complexity of the adsorption mechanism. It was considered that the formation of inclusion complex corilagin/β-CD played a significant role on corilagin adsorption and recovery, which was illustrated by the inclusion property investigation. The inclusion complex preferred 1:1 stoichiometry and the association constant was determined as 1.69 × 103 L mol− 1 at 298 K, indicating the β-CD cavity showed excellent affinity to corilagin. Moreover, there was evidence that the crystal pattern of β-CD-PU changed when it adsorbed corilagin by XRD analysis, which indirectly revealed the mechanism of adsorption. These results suggested that β-CD-PU adsorbent was a promising candidate for the recovery and enrichment of corilagin or other polyphenolic natural products from plant materials.