Analysis of synthetic isoleucine conjugates of cucurbic acid isomers by liquid chromatography
โ Scribed by Dr. Robert Kramell; Andrea Porzel; Otto Miersch; Gernot Schneider
- Book ID
- 101284483
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 91 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0958-0344
No coin nor oath required. For personal study only.
โฆ Synopsis
Conjugates of 3,7-trans cucurbic acid isomers with either (S)-or (R)-isoleucine were synthesised from the diastereomeric conjugate of (3R, 7R)-jasmonic acid and (3S, 7S)-jasmonic acid by sodium borohydride reduction. The resulting diastereomers were characterised by nuclear magnetic resonance spectra. The authentic substances were subjected to liquid chromatography using a reversed-phase C 18 matrix and the chiral stationary phase Chiralpak AS. For all (6RS)-hydroxy epimeric pairs, a baseline separation could be observed. The elution sequences obtained indicate that the 3,6-trans oriented epimers with (S)-isoleucine elute prior to the 3,6-cis configured individuals independent of the mode of chromatography. In contrast, the elution pattern of the conjugates containing (R)-isoleucine was reversed on the chiral stationary phase. The epimers with a 3,6-cis configured hydroxy group and the acid side chain eluted faster than those with the 3,6trans configuration. The chromatographic conditions described are suitable for resolving mixtures of isomeric N-(cucurbinoyl)-isoleucines in order to assign their stereochemistry and to obtain chiral reference materials on a preparative scale.
๐ SIMILAR VOLUMES
A commercial mixture of conjugated linoleic acid (CLA) isomers, reportedly consisting of six components, was recently resolved into 12 peaks attributed to CLA isomers using silver-ion high performance liquid chromatography (Ag + -HPLC). In this study, the coupling of two analytical silver-ion high p