title: A novel 9 × 9 map-based solvent selection strategy for targeted counter-current chromatography isolation of natural products.
abstract: Counter-current chromatography (CCC) is an efficient liquid-liquid chromatography technique for separation and purification of complex mixtures like natural products extracts and synthetic chemicals. However, CCC is still a challenging process requiring some special technical knowledge especially in the selection of appropriated solvent systems. In this work, we introduced a new 9 × 9 map-based solvent selection strategy for CCC isolation of targets, which permit more than 60 hexane-ethyl acetate-methanol-water (HEMWat) solvent systems as the start candidates for the selection of solvent systems. Among these solvent systems, there are clear linear correlations between partition coefficient (K) and the system numbers. Thus, an appropriate CCC solvent system (i.e., sweet spot for K = 1) may be hit by measurement of k values of the target only in two random solvent systems. Besides this, surprisingly, we found that through two sweet spots, we could get a line ("Sweet line") where there are infinite sweet solvent systems being suitable for CCC separation. In these sweet solvent systems, the target has the same partition coefficient (K) but different solubilities. Thus, the better sweet solvent system with higher sample solubility can be obtained for high capacity CCC preparation. Furthermore, we found that there is a zone ("Sweet zone") where all solvent systems have their own sweet partition coefficients values for the target in range of 0.4 < K< 2.5 or extended range of 0.25 < K < 16. All results were validated by using 14 pure GUESSmix mimic natural products as standards and further confirmed by isolation of several targets including honokiol and magnolol from the extracts of Magnolia officinalis Rehd. Et Wils and tanshinone IIA from Salvia miltiorrhiza Bunge. In practice, it is much easier to get a suitable solvent system only by making a simple screening two to four HEMWat two-phase solvent systems to obtain the sweet line or sweet zone without special knowledge or comprehensive standards as references. This is an important advancement for solvent system selection and also will be very useful for isolation of current natural products including Traditional Chinese Medicines.
authors.affiliation: Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China; Research and Development Center of Natural Medicine, Zhejiang Agriculture and Forest University, Lin'an, Zhejiang Province 311300, China.
authors.forename: Junling
authors.initials: J
authors.lastname: Liang
authors.affiliation: Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Meng
authors.affiliation: Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China; Rui'an Food Inspection and Testing Center, Rui'an 325204, Zhejiang Province, China.
authors.forename: Dingfang
authors.initials: D
authors.lastname: Wu
authors.affiliation: Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, Xuzhou, Jiangsu 221004, China.
authors.forename: Mengzhe
authors.initials: M
authors.lastname: Guo
authors.affiliation: Research Center of Siyuan Natural Pharmacy and Biotoxicology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: drwushihua@zju.edu.cn.
authors.forename: Shihua
authors.initials: S
authors.lastname: Wu
mesh_terms: D045784:Abietanes / Q000737:chemistry; D001688:Biological Products / Q000302:isolation & purification*; D001713:Biphenyl Compounds / Q000302:isolation & purification; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D003377:Countercurrent Distribution; D006586:Hexanes / Q000737:chemistry; D017705:Lignans / Q000302:isolation & purification; D031566:Magnolia / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D015203:Reproducibility of Results; D027561:Salvia miltiorrhiza / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D045784:Abietanes; D001688:Biological Products; D001713:Biphenyl Compounds; D006586:Hexanes; D017705:Lignans; D000432:Methanol; D012997:Solvents; D014867:Water; C005498:magnolol; C021751:tanshinone; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols; C026385:n-hexane
keywords: HEMWat 9×9 map; Magnolia officinalis Rehd. Et Wils; Natural products isolation; Salvia miltiorrhiza Bunge; Selection of solvent system; Targeted counter-current chromatography