School of Chinese Medicine
Folding fan mode counter-current chromatography offers fast blind screening for drug discovery. Case study: Finding anti-enterovirus 71 agents from Anemarrhena asphodeloides
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 (9.13g) 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±2.1μM) and a 40-fold higher selective index (SI=92.9) than the positive control (IC50=361.7±104.6μM, SI=2.4), ribavirin. The structure-activity relationship (SAR) of these compounds was also studied.
A. asphodeloides, Bioassay-guided counter-current chromatography, Enterovirus 71, Folding fan mode, Structure-activity relationship
Source Publication Title
Journal of Chromatography A
This work was supported by the National Natural Science Foun-dation of China (Grant No. 81303289), the Major ApplicationDevelopment Project of Chongqing (cstc2014yykfc10002), the Sci-ence Foundation for the Excellent Youth Scholars of Shanghai (No.ZZszy13059), and Hong Kong Baptist University (FRG2/13-14/026).We thank Dr. Long Song from the School of Pharmacy, ShanghaiUniversity of Traditional Chinese Medicine for identification of A.asphodeloides; and Professor Hanzhong Wang from the WuhanInstitute of Virology, Chinese Academy of Sciences, for providingthe BrCr strain of EV71.
Link to Publisher's Edition
Liu, Mengshun, Ling Tao, Siu Leung Chau, Rong Wu, Hong Zhang, Yifu Yang, Dajian Yang, Zhaoxiang Bian, Aiping Lu, Quanbin Han, and Hongxi Xu. "Folding fan mode counter-current chromatography offers fast blind screening for drug discovery. Case study: Finding anti-enterovirus 71 agents from Anemarrhena asphodeloides." Journal of Chromatography A 1368 (2014): 116-124.