title: Production of oridonin-rich extracts from Rabdosia rubescens using hyphenated ultrasound-assisted supercritical carbon dioxide extraction.
abstract: BACKGROUND
  Among active components in Rabdosia rubescens, oridonin has been considered a key component and the most valuable compound because it has a wide range of activities beneficial to human health. To produce a high-quality oridonin extract, an alternative hyphenated procedure involving an ultrasound-assisted and supercritical carbon dioxide (HSC-CO2) extraction method to extract oridonin from R. rubescens was developed in this study. Fictitious solubilities of oridonin in supercritical CO2(SC-CO2) with ultrasound assistance were measured by using the dynamic method at temperatures ranging from 305.15 K to 342.15 K over a pressure range of 11.5 to 33.5 MPa.
  
  
  RESULTS
  Fictitious solubilities of oridonin at different temperatures and pressures were over the range of 2.13 × 10-6to 10.09 × 10-6(mole fraction) and correlated well with the density-based models, including the Bartle model, the Chrastil model, the Kumar and Johnston model and the Mendez-Santiago and Teja model, with overall average absolute relative deviations (AARDs) of 6.29%, 4.39%, 3.12% and 5.07%, respectively.
  
  
  CONCLUSIONS
  Oridonin exhibits retrograde solubility behaviour in the supercritical state. Fictitious solubility data were further determined and obtained a good fit with four semi-empirical models. Simultaneously, the values of the total heat of solution, vaporisation and solvation of oridonin were estimated. © 2016 Society of Chemical Industry.
authors.affiliation: Department and Graduate Institute of Pharmacology, Kaohsiung Medical University, Kaohsiung, Taiwan.|Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Yu-Chiao
authors.initials: YC
authors.lastname: Yang
authors.affiliation: Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
authors.forename: Pei-Hui
authors.initials: PH
authors.lastname: Lin
authors.affiliation: Department of Applied Geoinformatics, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Ming-Chi
authors.initials: MC
authors.lastname: Wei
mesh_terms: D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D045786:Diterpenes, Kaurane / Q000032:analysis* / Q000302:isolation & purification*; D037602:Isodon / Q000737:chemistry*; D010936:Plant Extracts / Q000032:analysis* / Q000302:isolation & purification*; D012995:Solubility; D014465:Ultrasonics / Q000379:methods*
chemical_list: D045786:Diterpenes, Kaurane; D010936:Plant Extracts; C011959:oridonin
keywords: Chrastil model; Rabdosia rubescens; fictitious solubility; oridonin; supercritical CO2 extraction