title: Preparative separation of six rhynchophylla alkaloids from Uncaria macrophylla wall by pH-zone refining counter-current chromatography.
abstract: pH-Zone refining counter-current chromatography was successfully applied to the preparative isolation and purification of six alkaloids from the ethanol extracts of Uncaria macrophylla Wall. Because of the low content of alkaloids (about 0.2%, w/w) in U. macrophylla Wall, the target compounds were enriched by pH-zone refining counter-current chromatography using a two-phase solvent system composed of petroleum ether-ethyl acetate-isopropanol-water (2:6:3:9, v/v), adding 10 mM triethylamine in organic stationary phase and 5 mM hydrochloric acid in aqueous mobile phase. Then pH-zone refining counter-current chromatography using the other two-phase solvent system was used for final purification. Six target compounds were finally isolated and purified by following two-phase solvent system composed of methyl tert-butyl ether (MTBE)-acetonitrile-water (4:0.5:5, v/v), adding triethylamine (TEA) (10 mM) to the organic phase and HCl (5 mM) to aqueous mobile phase. The separation of 2.8 g enriched total alkaloids yielded 36 mg hirsutine, 48 mg hirsuteine, 82 mg uncarine C, 73 mg uncarine E, 163 mg rhynchophylline, and 149 mg corynoxeine, all with purities above 96% as verified by HPLC Their structures were identified by electrospray ionization-mass spectrometry (ESI-MS) and 1H-NMR spectroscopy.
authors.forename: Qinghai
authors.initials: Q
authors.lastname: Zhang
authors.forename: Changhu
authors.initials: C
authors.lastname: Lin
authors.affiliation: Department of Biochemical Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, China. duanwj@sdatc.com.cn.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Duan
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Biochemical Engineering, School of Life Science, Beijing Institute of Technology, Beijing 100081, China. bitluo@bit.edu.cn.
authors.forename: Aiqin
authors.initials: A
authors.lastname: Luo
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D003377:Countercurrent Distribution / Q000379:methods*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D032070:Uncaria / Q000737:chemistry
chemical_list: D000470:Alkaloids; D010936:Plant Extracts; D012997:Solvents