An integrated strategy for combining three-phase liquid-liquid extraction with continuous high-speed countercurrent chromatography: Highly efficient in isolating and purifying zeaxanthin from the industrial crop Lycium barbarum L

Zeaxanthin, a carotenoid, has been widely concerned for its high medicinal and nutritional value. In this work, the crude zeaxanthin was firstly extracted from saponified Lycium barbarum L. fruits by three-phase mixture solvent system consisting of n-hexane-methyl acetate-acetonitrile-water (4:4:3:4, v/v). This extraction process can effectively enrich the trace zeaxanthin in Lycium barbarum. Furthermore, the crude zeaxanthin was purified by high-speed countercurrent chromatography (HSCCC) based on continuous injection mode. The key purification parameters including flow rate, revolution and sample concentration, were systematically and carefully studied. Using a two-phase solvent mixture consisting of n-hexane-ethyl acetate-ethanol-water (8:2:7:3, v/v) in the elution-extrusion mode, a sample of zeaxanthin with a purity of 82.94% was obtained from 500 mg of crude extract under optimum conditions. This is the first report on the efficient separation and purification of zeaxanthin from Lycium barbarum L. fruit by three-phase solvent extraction combined with continuous HSCCC.