title: Combinative application of pH-zone-refining and conventional high-speed counter-current chromatography for preparative separation of caged polyprenylated xanthones from gamboge.
abstract: An efficient method for the preparative separation of four structurally similar caged xanthones from the crude extracts of gamboge was established, which involves the combination of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography for the first time. pH-zone-refining counter-current chromatography was performed with the solvent system composed of n-hexane/ethyl acetate/methanol/water (7:3:8:2, v/v/v/v), where 0.1% trifluoroacetic acid was added to the upper organic stationary phase as a retainer and 0.03% triethylamine was added to the aqueous mobile phase as an eluter. From 3.157 g of the crude extract, 1.134 g of gambogic acid, 180.5 mg of gambogenic acid and 572.9 mg of a mixture of two other caged polyprenylated xanthones were obtained. The mixture was further separated by conventional high-speed counter-current chromatography with a solvent system composed of n-hexane/ethyl acetate/methanol/water (5:5:10:5, v/v/v/v) and n-hexane/methyl tert-butyl ether/acetonitrile/water (8:2:6:4,v/v/v/v), yielding 11.6 mg of isogambogenic acid and 10.4 mg of β-morellic acid from 218.0 mg of the mixture, respectively. The purities of all four of the compounds were over 95%, as determined by high-performance liquid chromatography, and the chemical structures of the four compounds were confirmed by electrospray ionization mass spectrometry and NMR spectroscopy. The combinative application of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography shows great advantages in isolating and enriching the caged polyprenylated xanthones.
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.|Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.|Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, People's Republic of China.
authors.forename: Wenwei
authors.initials: W
authors.lastname: Fu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.|Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, People's Republic of China.
authors.forename: Baojun
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.|Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, People's Republic of China.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Tan
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Xiu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.|Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai, People's Republic of China.
authors.forename: Hongxi
authors.initials: H
authors.lastname: Xu
mesh_terms: D003377:Countercurrent Distribution / Q000379:methods*; D029760:Garcinia / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010936:Plant Extracts / Q000737:chemistry; D044004:Xanthones / Q000302:isolation & purification*
chemical_list: D010936:Plant Extracts; D044004:Xanthones
keywords: Beta-morellic acid; Counter-current chromatography; Gambogenic acid; Gambogic acid; Isogambogenic acid