title: Folding fan mode counter-current chromatography offers fast blind screening for drug discovery. Case study: finding anti-enterovirus 71 agents from Anemarrhena asphodeloides.
abstract: A new application of counter-current chromatography (CCC) in drug discovery, called folding fan mode (FFM), is designed to eliminate the extensive and time-consuming calculation of the partition coefficients of some preset compounds in conventional CCC separation. Careful reading of reports in the literature reveals that, when two-phase solvent systems are listed in a polarity-increasing sequence, the isolates also show a similar trend in polarity. The relationship between the two-phase solvent system and the isolates is like that between the folds and the picture of a folding fan. We can directly select a two-phase solvent system to separate fractions having similar polarity, just as opening a fan reveals a picture. The solvent ratio of two-phase solvent systems can be adjusted according to the polarity and weight ratio of active fractions rather than the partition coefficients. Without preset compounds, FFM-CCC not only requires no measurement of partition coefficients, but also achieves true blind screening. This paper reports the method's first success in drug discovery: six anti-EV71 saponins were found from the mixture (9.13 g) of ethanol extract and water extract of Anemarrhena asphodeloides after a total of four CCC separations, using hexan/ethyl acetate/methanol/butanol/water as the model solvent system. Among these saponins, timosaponin B-II displayed a comparable IC50 (4.3 ± 2.1 μM) and a 40-fold higher selective index (SI=92.9) than the positive control (IC50=361.7 ± 104.6 μM, SI=2.4), ribavirin. The structure-activity relationship (SAR) of these compounds was also studied.
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China; Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Cai Lun Lu 1200, Shanghai 201203, PR China; School of Chinese Medicine, Hong Kong Baptist University, Kowloon Town 999077, Hong Kong Special Administrative Region.
authors.forename: Mengshun
authors.initials: M
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China; Chongqing Academy of Chinese Materia Medica, Chongqing 400065, PR China.
authors.forename: Ling
authors.initials: L
authors.lastname: Tao
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Kowloon Town 999077, Hong Kong Special Administrative Region.
authors.forename: Siu Leung
authors.initials: SL
authors.lastname: Chau
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China; Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Cai Lun Lu 1200, Shanghai 201203, PR China.
authors.forename: Rong
authors.initials: R
authors.lastname: Wu
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China; Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Cai Lun Lu 1200, Shanghai 201203, PR China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Experimental Center of Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China.
authors.forename: Yifu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Chongqing Academy of Chinese Materia Medica, Chongqing 400065, PR China.
authors.forename: Dajian
authors.initials: D
authors.lastname: Yang
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Kowloon Town 999077, Hong Kong Special Administrative Region.
authors.forename: Zhaoxiang
authors.initials: Z
authors.lastname: Bian
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Kowloon Town 999077, Hong Kong Special Administrative Region.
authors.forename: Aiping
authors.initials: A
authors.lastname: Lu
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, Kowloon Town 999077, Hong Kong Special Administrative Region. Electronic address: simonhan@hkbu.edu.hk.
authors.forename: Quanbin
authors.initials: Q
authors.lastname: Han
authors.affiliation: School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, PR China; Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Cai Lun Lu 1200, Shanghai 201203, PR China. Electronic address: xuhongxi88@gmail.com.
authors.forename: Hongxi
authors.initials: H
authors.lastname: Xu
mesh_terms: D031403:Anemarrhena / Q000737:chemistry*; D000818:Animals; D000998:Antiviral Agents / Q000302:isolation & purification* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D055808:Drug Discovery; D004770:Enterovirus / Q000187:drug effects*; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology; D014709:Vero Cells
chemical_list: D000998:Antiviral Agents; D010936:Plant Extracts
keywords: A. asphodeloides; Bioassay-guided counter-current chromatography; Enterovirus 71; Folding fan mode; Structure–activity relationship