title: Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method.
abstract: An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Hai Nan Normal University, Haikou, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Fu
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Cai
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Huaxia
authors.initials: H
authors.lastname: Xin
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Dai
authors.affiliation: Engineering Research Center of Pharmaceutical Process Chemistry, Ministry of Education, School of Pharmacy, East China University of Science and Technology, Shanghai, P. R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jin
mesh_terms: D002853:Chromatography, Liquid; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification*; D006035:Glycyrrhiza / Q000737:chemistry*; D052616:Solid Phase Extraction
chemical_list: D005419:Flavonoids
keywords: Flavonoids; Licorice; Preparative high-performance liquid chromatography; Two-dimensional separation