title: Separation of polar betalain pigments from cacti fruits of Hylocereus polyrhizus by ion-pair high-speed countercurrent chromatography.
abstract: Polar betacyanin pigments together with betaxanthins from ripe cactus fruits of Hylocereus polyrhizus (Cactaceae) were fractionated by means of preparative ion-pair high-speed countercurrent chromatography (IP-HSCCC) also using the elution-extrusion (EE) approach for a complete pigment recovery. HSCCC separations were operated in the classical 'head-to-tail' mode with an aqueous mobile phase. Different CCC solvent systems were evaluated in respect of influence and effectiveness of fractionation capabilities to separate the occurring pigment profile of H. polyrhizus. For that reason, the additions of two different volatile ion-pair forming perfluorinated carboxylic acids (PFCA) were investigated. For a direct comparison, five samples of Hylocereus pigment extract were run on preparative scale (900 mg) in 1-butanol-acetonitrile-aqueous TFA 0.7% (5:1:6, v/v/v) and the modified systems tert.-butyl methyl ether-1-butanol-acetonitrile-aqueous PFCA (2:2:1:5, v/v/v/v) using 0.7% and 1.0% trifluoroacetic acid (TFA) or heptafluorobutyric acid (HFBA) in the aqueous phase, respectively. The chemical affinity to the organic stationary CCC solvent phases and in consequence the retention of these highly polar betalain pigments was significantly increased by the use of the more lipophilic fluorinated ion-pair reagent HFBA instead of TFA. The HFBA additions separated more effectively the typical cacti pigments phyllocactin and hylocerenin from betanin as well as their iso-forms. Unfortunately, similar K(D) ratios and selectivity factors alpha around 1.0-1.1 in all tested solvent systems proved that the corresponding diastereomers, 15S-type pigments cannot be resolved from the 15R-epimers (iso-forms). Surprisingly, additions of the stronger ion-pair reagent (HFBA) resulted in a partial separation of hylocerenin from phyllocactin which were not resolved in the other solvent systems. The pigments were detected by means of HPLC-DAD and HPLC-electrospray ionization-MS using also authentic reference materials.
authors.affiliation: Faculty of Analytical Chemistry, Institute C-1, Department of Chemical Engineering and Technology, Cracow University of Technology, ul. Warszawska 24, 31-155 Cracow, Poland. swybran@chemia.pk.edu.pl
authors.forename: Sławomir
authors.initials: S
authors.lastname: Wybraniec
authors.forename: Paweł
authors.initials: P
authors.lastname: Stalica
authors.forename: Gerold
authors.initials: G
authors.lastname: Jerz
authors.forename: Bettina
authors.initials: B
authors.lastname: Klose
authors.forename: Nadine
authors.initials: N
authors.lastname: Gebers
authors.forename: Peter
authors.initials: P
authors.lastname: Winterhalter
authors.forename: Aneta
authors.initials: A
authors.lastname: Spórna
authors.forename: Maciej
authors.initials: M
authors.lastname: Szaleniec
authors.forename: Yosef
authors.initials: Y
authors.lastname: Mizrahi
mesh_terms: D053000:Analytic Sample Preparation Methods; D016477:Artifacts; D050859:Betacyanins / Q000032:analysis / Q000302:isolation & purification; D050858:Betalains / Q000032:analysis / Q000302:isolation & purification*; D050860:Betaxanthins / Q000032:analysis / Q000302:isolation & purification; D029421:Cactaceae / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003377:Countercurrent Distribution / Q000379:methods*; D005466:Fluorocarbons; D005638:Fruit / Q000737:chemistry*; D008738:Methyl Ethers; D010936:Plant Extracts / Q000737:chemistry; D012997:Solvents; D021241:Spectrometry, Mass, Electrospray Ionization; D014269:Trifluoroacetic Acid
chemical_list: D050859:Betacyanins; D050860:Betaxanthins; D005466:Fluorocarbons; D008738:Methyl Ethers; D010936:Plant Extracts; D012997:Solvents; C508223:hylocerenin; C508222:phyllocactin; C043243:methyl tert-butyl ether; D050858:Betalains; C033094:perfluorobutyric acid; C020228:betanin; D014269:Trifluoroacetic Acid