1. Isolation and structural elucidation of the predominant geometrical isomers of alpha-carotene.
- Author
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Emenhiser C, Englert G, Sander LC, Ludwig B, and Schwartz SJ
- Subjects
- Isomerism, Magnetic Resonance Spectroscopy, Carotenoids chemistry, Carotenoids isolation & purification, Chromatography, Liquid methods
- Abstract
The recent development and application of a polymeric C30 stationary phase have given unique separations of cis-trans carotenoid isomers in reversed-phase (RP) liquid chromatography (LC) owing to the exceptional shape selectivity of this stationary phase. In the present research, several geometrical isomers of alpha-carotene were at least partially resolved from a photo-isomerized mixture when chromatographed on a 3-microns polymeric C30 column. Double bond configurations of the five predominant alpha-carotene peaks, as isolated on a semi-preparative C30 column, were unambiguously assigned using 1H nuclear magnetic resonance (NMR) spectroscopy, giving the following order of elution: 13-cis, 13'-cis, all-trans, 9-cis, and 9'-cis geometrical forms. Electronic absorption spectra for these isomers were in agreement with the identification of peaks. The alpha-carotene isomers separated and identified herein had not been previously resolved in RPLC. Confirmation of the structures of geometrical alpha-carotene isomers will aid further studies on the possible physiological roles of these compounds in biological tissues. more...
- Published
- 1996
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