An overview of recent progress in multiple dual-mode counter-current chromatography

Comparison of two different multiple dual-mode counter-current chromatograph for separation of ketoconazole enantiomers

In this work, two different multiple dual-mode (MDM) counter-current chromatography methods, conventional MDM and modified MDM elution modes, were compared for the chiral separation of the ketoconazole enantiomers. The biphasic solvent system which consisted of n-hexane: isobutyl acetate: 0.1 mol/L phosphate buffer (2:4:6, v/v) (pH = 8.5) was employed as stationary phase and mobile phase. And the hydroxypropyl-β-cyclodextrin (HP-β-CD) with a concentration of 100 mmol/L was dissolved in the phosphate buffer, as the chiral selector. Under two different methods, dual-mode (DM) elution was performed to determine the time of the transformed phase roles and multiple cycles were performed to isolate ketoconazole, respectively. The result indicated that the modified MDM elution had a significant improvement on the separation, increasing the resolution from 0.51 to 1.19, while the resolution was increased from 0.40 to 0.79 by the conventional MDM elution. Ultimately, baseline separation of ketoconazole enantiomers was essentially achieved by high-speed counter-current chromatography under optimized modified MDM separation conditions. The final recoveries of the two enantiomers, R-(K) and S-(K), were 92.5 % and 83.3 %, respectively, corresponding to enantiomeric excess values of 99.0 % and 97.0 %, as determined by HPLC.

Efficient discovery of active isolates from Dioscorea spongiosa by the combination of bioassay-guided macroporous resin column chromatography and high-speed counter-current chromatography

In the present study, twelve compounds from Dioscorea spongiosa were successfully purified by an efficient technique combined bioassay-guided fractionation macroporous resin column chromatography (MRCC) pretreatment and high-speed counter-current chromatography (HSCCC) separation for the first time. Then, D101 MRCC was used to fractionate the crude extract into five parts, which further applied the bioassay-guided fractionation strategy to screen the active fractions of 2 and 4. As for the separation, 200 mg Fr.2 was purified by HSCCC using EtOAc/n-BuOH/H2 O (2:2:3, v/v), leading to annulatomarin (1), dioscoresides C (2), diosniponol C (3), methyl protodioscin (4), pseudoprotodioscin (5), protogracillin (6), as well as 200 mg Fr.4 yielding montroumarin (7), dioscorone A (8), diosniponol D (9), protodioscin (10), gracillin (11), and dioscin (12) using CH2 Cl2 /MeOH/H2 O (3:3:2, v/v) with the purities over 95.0%. Finally, the isolates were assayed for their anti-inflammatory, urico-lowering, and anti-diabetic activities in vitro, which indicated that the steroidal saponins of 5, 6, and 11 showed all these three activities.

Separation of polysaccharides from Lycium barbarum L. by high-speed countercurrent chromatography with aqueous two-phase system

The traditional method for isolation and purification of polysaccharides is time-consuming. It often involves toxic solvents that destroy the function and structure of the polysaccharides, thus limiting in-depth research on the essential active ingredient of Lycium barbarum L. Therefore, in this study, high-speed countercurrent chromatography (HSCCC) and aqueous two-phase system (ATPS) were combined for the separation of crude polysaccharides of Lycium barbarum L. (LBPs). Under the optimized HSCCC conditions of PEG1000-K2HPO4-KH2PO4-H2O (12:10:10:68, w/w), 1.0 g of LBPs-ILs was successfully divided into three fractions (126.0 mg of LBPs-ILs-1, 109.9 mg of LBPs-ILs-2, and 65.4 mg of LBPs-ILs-3). Moreover, ATPS was confirmed as an efficient alternative method of pigment removal for LBPs purification, with significantly better decolorization (97.1 %) than the traditional H2O2 method (88.5 %). Then, the different partitioning behavior of LBPs-ILs in the two-phase system of HSCCC was preliminarily explored, which may be related to the difference in monosaccharide composition of polysaccharides. LBPs-ILs-1 exhibited better hypoglycemic activities than LBPs-ILs-2 and LBPs-ILs-3 in vitro. Therefore, HSCCC, combined with aqueous two-phase system, was an efficient separation and purification method with great potential for separating and purifying active polysaccharides in biological samples.