title: Chiral ligand exchange high-speed countercurrent chromatography: mechanism and application in enantioseparation of aromatic α-hydroxyl acids.
abstract: This work concentrates on the separation mechanism and application of chiral ligand exchange high-speed countercurrent chromatography in enantioseparation of ten racemic aromatic α-hydroxyl acids, including mandelic acid, 2-chloromandelic acid, 4-methoxymandelic acid, 4-hydroxymandelic acid, α-methylmandelic acid, 4-hydroxy-3-methoxy-mandelic acid, 3-chloromandelic acid, 4-bromomandelic acid, α-cyclopentylmandelic acid and α-cyclohexylmandelic acid, in which five of the racemates were successfully enantioseparated by analytical apparatus with an optimized solvent system. The two-phase solvent system was composed of butanol-water (1:1, v/v) or hexane-n-butanol-water (0.5:0.5:1, v/v), to which N-n-dodecyl-l-proline was added in the organic phase as chiral ligand and cupric acetate was added in the aqueous phase as a transition metal ion. Various influence factors in high-speed countercurrent chromatography were optimized by enantioselective liquid-liquid extraction. The separation mechanism for chiral ligand exchange high-speed countercurrent chromatography was proposed based on the results of present studies. Successful enantioseparations of 72mg of mandelic acid, 76mg of 2-chloromandelic acid and 74mg of 4-methoxymandelic acid were achieved individually with high resolution by preparative high-speed countercurrent chromatography. The HPLC purity of all enantiomers was over 96% with the recovery in the range of 82-90% from the collected fractions.
authors.affiliation: College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, China; Laboratory of Bioseparation Technologies, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Shengqiang
authors.initials: S
authors.lastname: Tong
authors.affiliation: College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Mangmang
authors.initials: M
authors.lastname: Shen
authors.affiliation: College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Dongping
authors.initials: D
authors.lastname: Cheng
authors.affiliation: College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Yamei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Laboratory of Bioseparation Technologies, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: itoy@nhlbi.nih.gov.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Ito
authors.affiliation: College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: zyx@zjut.edu.cn.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Yan
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003377:Countercurrent Distribution / Q000379:methods; D059625:Liquid-Liquid Extraction; D008333:Mandelic Acids / Q000737:chemistry / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D008333:Mandelic Acids; D012997:Solvents; C037938:mandelic acid
keywords: Aromatic α-hydroxyl acids; Chiral ligand exchange; Enantioseparation; High-speed countercurrent chromatography; Separation mechanism
references.citation: J Chromatogr A. 2011 Aug 19;1218(33):5602-8
references.pmid: 21752382
references.citation: J Chromatogr. 1987 Jul 29;400:65-75
references.pmid: 3667760
references.citation: J Sep Sci. 2006 Jul;29(10):1440-6
references.pmid: 16894789
references.citation: J Pharm Biomed Anal. 1997 Jun;15(9-10):1509-14
references.pmid: 9226583
references.citation: J Chromatogr. 1971 Aug 26;60(2):280-3
references.pmid: 5096112
references.citation: J Chromatogr A. 2001 Jan 12;906(1-2):365-78
references.pmid: 11215897
references.citation: J Chromatogr. 1987 Sep 11;404(2):391-3
references.pmid: 3667768
references.citation: Science. 1979 Jun 15;204(4398):1226-8
references.pmid: 36662