In Silico Screening of Comprehensive Two-Dimensional Centrifugal Partition Chromatography × Liquid Chromatography for Multiple Compound Isolation

Retention correlation and orthogonality between reversed phase countercurrent chromatography and liquid chromatography based on solvent strength

Correlation of elution performance between reversed phase countercurrent chromatography and liquid chromatography was investigated using five selected natural components. Theoretical guidance for orthogonality of two-dimensional countercurrent chromatography and liquid chromatography was proposed. The difference in retention behavior between countercurrent chromatography and liquid chromatography was studied when the mobile phase was composed of methanol and water by measuring the partition behavior of five selected compounds in two typical biphasic solvent systems composed of n-hexane-ethyl acetate-methanol-water and chloroform-methanol-water. An orthogonal diagram between countercurrent chromatography and liquid chromatography was obtained by normalized treatment of the measured partition coefficients and capacity factors. The experimental results showed that each biphasic solvent system used for countercurrent chromatography had a high orthogonality with liquid chromatography when a specific volume ratio was used.

Methodology for dyes purification by preparative bidimensional offline reversed-phase high-performance liquid chromatography separation based on mobile phase pH change: Case study of Justicia spicigera

The extensive characterization of the natural dyes involves the purification of their colored compounds for their structural analysis and stability studies. As most natural compounds being ionizable, herein is presented the optimization of an easy and affordable preparative bidimensional offline reversed-phase high-performance liquid chromatography purification based on mobile phase pH change. At the analytical scale, several combinations of stationary phases and mobile phases at different pH values were investigated first. The orthogonality between the dimensions was quantitatively evaluated using the nearest-neighbor distance approach. The optimized separation method was transferred to the preparative scale for the successful isolation of two colored compounds from Justicia spicigera, a traditional dye plant from Central America. They were identified as perisbivalvine B (2-amino-8-hydroxy-7-methoxy-3H-phenoxazin-3-one) and one of its derivatives, also found in another tinctorial plant species, Peristrophe bivalvis growing in Asia.

A Strategy for Pinpointing Natural Bioactive Components Using Two-Dimensional Bioassay Profilings Combined with Comprehensive Two-Dimensional Countercurrent Chromatography × High-Performance Liquid Chromatography

Inspired by the interpretation of two-dimensional (2D) nuclear magnetic resonance spectra, an efficient strategy was proposed for pinpointing bioactive components from complex natural products. An off-line comprehensive countercurrent chromatography (CCC) × high-performance liquid chromatography (HPLC) was employed to achieve a 2D chemical chromatogram, and 2D bioassay profilings were obtained from bioassays of the eluent of the first dimension (¹D) CCC and the eluent of the second dimension (²D) HPLC. Then 2D chemical chromatograms and 2D bioassay profilings were matched for pinpointing bioactive natural components from complex matrices. Thus, bioactive components in a complex matrix could be efficiently analyzed, separated, and bioactivity-determined. This experimental scheme was successfully demonstrated with a traditional medicinal herb Polygonum cuspidatum Sieb. et Zucc. The feasibility of this 2D strategy was verified with tyrosinase inhibition assay, α-glucosidase inhibition assay, DPPH radical scavenging assay, and ABTS^•+ decolorization assay. Eight natural inhibitors were successfully pinpointed and identified from P. cuspidatum. Both pieceid-2″-O-gallate (10) and vanicoside B (20) were screened and identified as natural tyrosinase inhibitors for the first time. Meanwhile, vanicoside B (20) was also found as the strongest α-glucosidase inhibitor among all the isolated components. Most of the compounds exhibited much higher radical scavenging activities. Compared with traditional methodology based on one-dimensional chromatographic separation, the present 2D strategy would be more precise, efficient, and convenient to screen and separate bioactive compounds from complex matrices.

In Silico Screening of Off-line Comprehensive Two-Dimensional Counter-current Chromatography with Liquid Chromatography for Four Saponins Isolation

Be restrained by the limited peak capacity, one dimension chromatography usually leads to an unsatisfactory separation with low purity of compounds in a complex mixture. To obtain more highly pure targets for standard reference and to discover new substances for structural elucidation, two-dimensional chromatography is more and more prevalent in many fields. As few metrics on assessment of preparative capability of two-dimensional chromatographic separations is reported, a methodology of in silico screening of various two-dimensional chromatographic separations with a minimal number of experiments was demonstrated in this work, which was based on three descriptors including the occupation rate of peaks and system homogeneity of a two-dimensional separation space, and the minimal distance of all nearest-neighbor distances of peaks. Combining the advantages of counter-current chromatography and liquid chromatography, we elaborated the methodology by employing off-line comprehensive two-dimensional counter-current chromatography with liquid chromatography to be in silico screened for separation of four saponins from Panax notoginseng at analytical scale to simulate the case of preparative scale transfer. The predictive results were presented by two-dimensional contour plots and verified by experiments. The result showed that the experimental results were in general accord with the predictive results. This article is protected by copyright. All rights reserved.

Orthogonality in the selection of biphasic solvent systems for off-line two-dimensional countercurrent chromatography from Polygonum cuspidatum Sieb. et Zucc

Off-line two-dimensional countercurrent chromatography has been widely applied to the isolation of complex samples, but little research on the investigation of orthogonality in the selection of biphasic solvent systems is available. In the present work, the orthogonality in the selection of a biphasic solvent system for liquid-liquid chromatographic separation of aqueous extract and ether extract from the traditional Chinese medicinal plant Polygonum cuspidatum Sieb. et Zucc was evaluated by the correlation coefficient and space occupancy rate. In total, 25 different biphasic solvent systems were tested, and 313 system combinations were analysed. A convex hull methodology was used to determine the separation space and to optimize separation conditions. The correlation coefficient matrix was transformed into dendrograms and a colour map to visualize the dissimilarity between, and orthogonality for, all solvent systems. The aqueous extracts from Polygonum cuspidatum were separated using selected biphasic solvent systems with high orthogonality: ethyl acetate-ethanol-water (70:1:70, v/v) and petroleum ether-ethyl acetate-water (1:5:5, v/v). The ether extracts from Polygonum cuspidatum were also separated using selected biphasic solvent systems with high orthogonality: petroleum-ethyl acetate-methanol-aqueous 0.25 M NH₃•H₂O (5:5:5:5, v/v) and petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v). Thirteen compounds were successfully obtained. The experimental results demonstrated that the evaluation of orthogonality provided an alternative strategy to select an applicable solvent system for the separation of complex samples using off-line two-dimensional countercurrent chromatography.