Chromatographische Trennung und quantitative Bestimmung aller acht Stereoisomeren von α‐Tocopherol

Abstract

The results of the analysis of several derivatives of (all-mc)-&-tocopherol by HPLC on a chirdl stationary phase and by capillary GC on a acbiral stationary phase are reported. Consecutive application of both methods to the ethyl-ether derivative allows the separation and quantification of all eight possible stereoisomers of (all-rac)-atocopherol.Einleitung. -Der Begriff Vitamin E umfasst 8 nahe verwandte 6-Chromanole mit isoprenoider Seitenkette [ 11. Wichtigster Vertreter ist a -Tocopherol (1 a), das, soweit bekannt [2-5], in der Natur ausschliesslich (R,R,R)-konfiguriert vorkommt.Heutige technische Totalsynthesen von a -Tocopherol basieren auf der saurekatalysierten Kondensation von 2,3,6-Trimethylhydrochinon mit (all-rac)-Isophytol ( = 3,7,11,15-Tetramethylhexadec-l-en-3-ol) [6]. Das dabei erhaltene (all-rac)-a -Tocopherol ist ein aquimolares Gemisch der 8 moglichen Stereoisomeren. Zur Klarung der Frage, wie sich diese Stereoisomeren des (all-rac)-a -Tocopherols im Organismus von Mensch und Tier bei Aufnahme, Verteilung, Abbau und Ausscheidung verhalten, ist es erforderlich, nach Applikation von (all-rac)-a -Tocopherol, also der 8 Stereoisomeren in gleicher Menge, den Pegel der einzelnen Isomeren quantitativ zu verfolgen. Zu diesem Zweck kann nur eine chromatographische Methode eingesetzt werden, da die mittels NMR erzielbare Unterscheidung nicht ausreichend ist [7]. Die Trennung von 8 Stereoisomeren, die sich nur in der Konfiguration der 3 chiralen Me-substituierten C-Atome unterscheiden, war auf den ersten Blick ein hochgestecktes Ziel. Durch Kombination von HPLC und Kapillar-GC schien es jedoch erreichbar. 1980 ')

Identification of The Tocopherol‐Cyclase in the Blue‐Green Algae Anabaena variabilis KÜTZING (Cyanobacteria)

“…A control experiment revealed that no traces of 3 are produced from 22 in the absence of enzyme under otherwise identical conditions of incubation. Furthermore, it was shown by GLC [19] of [7-rnethyZ-3H,'4C]-23, the methyl ether of [7-rnet/~yl-~H,'~C1-3, that the y -tocopherol obtained from incubation had the natural (R, R, R)-configuration (Fig. ).…”

A Simple 13C NMR Method for the Discrimination of Complex Mixtures of Stereoisomers: All Eight Stereoisomers of α‐Tocopherol Resolved

“…E-mail: peter.lankhorst@dsm.com a GC method. In the first study, 15 a derivatization was performed to obtain the ethyl ether derivative of (all-rac)-α-tocopherol, followed by two chromatographic separations: first a chiral HPLC separation, which yielded two fractions. One fraction contained the four (2R) stereoisomers, the other fraction contained the four (2S) stereoisomers.…”

Synthesis of All Four Stereoisomers of (E)‐Vitamin KT (Phylloquinone), Analysis of Their Diastereoisomeric and Enantiomeric Purities and Determination of Their Biopotencies

“…In addition, the development of a HPLC method for distinguishing all four stereoisomers of (E)-vitamin K, (and three of the four stereoisomers of (2)-vitamin K,) represents a milestone in the analysis of chiral compounds containing chiral CH(CH,) centres and affords now a valuable analytical tool for vitamin-K, research. In this context, we refer also to our recent improvements of the analysis of a -tocopherol stereoisomers [25].…”

“…HPLC system for vitamin K, and derivatives: Lichrosorb S160 (5 pm, column 3 x 300 mm), 0.5 % of (i-Pr)20 and 0.1 % of octan-1-01 in hexane; benzyl benzoate as internal standard; see [25] for HPLC system for the separation of vitamin-K1 stereoisomers on (+)-poly(trity1 methacrylate). Specific rotations [ a ] g : at 589, 546, 436, 405, and 365 nm at 20°; Perkin-Elmer-241 polarimeter.…”

“…In the dose range of 9. [20][21][22][23][24][25][26][27][28].14 pg per animal, the frequencies of the positive (+) and negative (-) results achieved with each Table 4. Comparison of l c ( = (2'E,7'S,1 l'S)-l) with l a ( = (2'E,7'R,I I'R)-l) in the Curative Prothrombin (PT) Time Test.…”