title: Chiral separation of two diastereomeric pairs of enantiomers of novel alkaloid-lignan hybrids from Lobelia chinensis and determination of the tentative absolute configuration.
abstract: Four novel alkaloid-lignan hybrids, lobechinenoids A-D (1-4), were isolated as a mixture of two diastereomeric pairs of enantiomers from the aerial parts of Lobelia chinensis. These compounds are constituted of the union of a tetrahydroisoquinoline alkaloid and a dihydrobenzofuran neolignan moiety. The structures were determined by detailed analyses of IR, MS and NMR data. These four compounds were characterized as two pairs of enantiomers by on-line chiral high performance liquid chromatography (HPLC)-circular dichroism (CD) analysis. The chiral HPLC separation was accomplished in the normal-phase mode using Chiralpak AD-H, a polysaccharide-derived chiral stationary phase (CSP) and a hexane-ethanol mobile phase. In order to study the chiroptical properties, all of the four single stereoisomers were successfully prepared on an analytical Chiralpak AD-H column and their stereochemical features were determined tentatively based on their CD spectra.
authors.affiliation: Department of Natural Products Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Shandong University, 44 Wenhuaxi Road, Jinan 250012, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Yang
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.forename: Shuqi
authors.initials: S
authors.lastname: Wang
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhao
authors.forename: Zhun
authors.initials: Z
authors.lastname: Hou
authors.forename: Hongxiang
authors.initials: H
authors.lastname: Lou
authors.forename: Dongmei
authors.initials: D
authors.lastname: Ren
mesh_terms: D000470:Alkaloids / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002942:Circular Dichroism / Q000379:methods; D017705:Lignans / Q000737:chemistry* / Q000302:isolation & purification; D029746:Lobelia / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D017705:Lignans
keywords: Absolute configuration; Lobechinenoids; Lobelia chinensis; On-line HPLC–CD