Purification of thonningianins A and B and four further derivatives from Thonningia sanguinea by one‐ and two‐dimensional centrifugal partition chromatography

Luca Pompermaier,Hermann Stuppner,Monizi Mawunu,Karine Faure,Thea Lautenschlaeger,Stefan Schwaiger

doi:10.1002/jssc.201900811

Abstract

Thonningia sanguinea is a parasitic herb widely used in traditional African medicine. Dihydrochalcone glucosides (unsubstituted, substituted with hexahydroxydiphenoyl or galloyl moieties) are the main constituents in the subaerial parts of this plant. In the present study, purification of the six major compounds from a methanol extract of the plant's subaerial parts was achieved by centrifugal partition chromatography. A first dimension centrifugal partition chromatography separation with the solvent system methyl tert‐butyl ether/1,2‐dimethoxyethane/water (1:2:1) in the ascending mode enabled the isolation of the two major bioactive compounds thonningianin A and B from 350 mg of methanol extract within only 16 min with respectable yields (25.7 and 21.1 mg), purities (87.1 and 85%), and recoveries (71.2 and 70.4%). Using a multiple heart‐cutting strategy, the remaining four major dihydrochalcone glucosides of the extract were further separated in a second dimension centrifugal partition chromatography with the solvent system ethyl acetate/1,2‐dimethoxyethane/water (2:1:1) in the descending mode with high purities (88.9–98.8%).

Highlights

Thonningia sanguinea is a widely used medicinal plant throughout tropical Africa [1,2,3]
The crude methanol (MeOH) extract of the plant batch investigated in the present study contained six dihydrochalcone glucosides as major compounds, which were identified as thonningianin A, thonningianin B, 3hydroxyphloridzin (1), 2′-O-(6-O-galloyl-β-D-glucopyranosyl)-3-hydroxyphloretin (2), 2′-O(4,6-O-Sa-hexahydroxydiphenoyl-β-D-glucopyranosyl)-3-hydroxyphloretin (3), and 2′-O-(3galloyl-4,6-O-Sa-hexahydroxydiphenoyl-β-D-glucopyranosyl)-3-hydroxyphloretin (4) [5,7]
The first step of Counter-current chromatography (CCC) method development consists in the selection of a suitable solvent system, in which target compounds have distribution coefficients (K) in an acceptable range that would allow to elute them in one step, i.e K between 0.1 to 8 [15], along with separation factors a (a = K2/K1) > 1.5 in order to guarantee a successful separation

Summary

Introduction

Thonningia sanguinea is a widely used medicinal plant throughout tropical Africa [1,2,3]. Further benefits of CCC are the possibility to recover all components injected into the system thanks to extrusion and the absence of irreversible adsorption or sample contamination through interaction with a solid stationary phase. It is suited for the separation of complex samples such as plant extracts and plays an important role in natural products chemistry [9]. CCC has been used for the separation and purification of common hydrolysable tannins [10,11,12] as well as for the isolation of dihydrochalcone glucosides from Sweet Tea (Lithocarpus polystachyus) [13]. CPC devices generally can be operated with almost any two-phase system, are resistant to stationary phase loss and allow high flow rates and short separation times [14]

Objectives

Methods

Results

Conclusion