Static and dynamic studies of adsorption by four macroporous resins to enrich oridonin from Rabdosia rubescens

Oridonin, one of the active ingredients in Rabdosia rubescens (R. rubescens), has been reported to induce cell apoptosis and cell cycle arrest in many cancers. Conventional extraction methods tend to result in unsatisfied enrichment and poor quality of oridonin present in a given biomass. This paper aims to eval-uate the performance and separation characteristics of four different macroporous resins to arrive at the most suitable methodology for the isolation and purification of high-quality oridonin. Static absorption kinetics, thermodynamic and dynamic adsorption were evaluated. HP-20 was selected for further study due to its high adsorption capacity of 32 mg·g-1 and desorption ratio with 98.5％. The pseudo-second-order model was considered to be the most suitable for kinetic results, and Langmuir model was chosen to better describe the absorption thermodynamics. Under optimum conditions (flow rate of 4 ml·min-1, bed depth with 6 cm and initial concentration of 2.15 mg·ml-1), the effective content of oridonin increased from 33.9％ to 79.1％ in the dry extract with a recovery of 81％ and the purity of oridonin improved from 76％to 93％. The results confirm that HP-20 provides an efficient method to purify most oridonin from R. rubescens.