Structure elucidation of deoxylutein II isomers by on-line capillary high performance liquid chromatography-(1)H nuclear magnetic resonance spectroscopy.
Thermal and iodine-catalyzed photochemical (Z/E)-isomerization of deoxylutein II [(3R,6'R)-3-hydroxy-3',4'-didehydro-beta,gamma-carotene, anhydrolutein I] (2), the dehydration product of lutein [(3R,3'R,6'R)-beta,epsilon-carotene-3,3'-diol] (4), yielded multi-component mixtures of (Z)-isomers. By I(2)-catalyzed photoisomerization, (9Z)-2, (9'Z)-2, (13Z)-2, (13'Z)-2 and (15Z)-2 are generated as main products. In addition, this thermodynamic-equilibrium mixture contains traces of (9Z,9'Z)-2 and other (di-Z)-isomers in minor concentrations. Thirteen isomers are chromatographically separated and detected on-line by UV-vis and mass spectrometry. (all-E)-Deoxylutein II (2) and six of its (Z)-configured isomers are separated by capillary HPLC (acetone-d(6)/D(2)O = 85:15) and detected on-line by (1)H NMR spectroscopy in a microprobe. With the microprobe and the active detection volume of 1.5 microl, it is possible to perform structure elucidation with very small amounts available for various (Z)-isomers of deoxylutein II (2) in the isomerization mixture.
Hentschel
Petra
P
Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany.
Grynbaum
Marc David
MD
Molnár
Péter
P
Putzbach
Karsten
K
Rehbein
Jens
J
Deli
József
J
Albert
Klaus
K
D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D007536:Isomerism; D014975:Lutein / Q000031:analogs & derivatives* / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000295:instrumentation / Q000379:methods*; D009862:Online Systems; D010777:Photochemistry
C511285:deoxylutein II; D014975:Lutein