- Identification and quantification of astaxanthin esters in shrimp (Pandalus, borealis) and in a microalga (Haematococcus pluvialis) by liquid chromatography-mass spectrometry using negative ion atmospheric pressure chemical ionization
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Negative ion liquid chromatography-atmospheric pressure chemical ionization mass spectrometry [negative ion LC-(APCI)MS] was used for the identification of astaxanthin esters in extracts of commercial shrimp (Pandalus borealis) and dried microalga (Haematococcus pluvialis) samples. A cleanup step using a normal phase solid phase extraction (SPE) cartridge was applied prior to analysis. Recovery experiments with astaxanthin oleate as model compound proved the applicability of this step (98.5 ± 7.6%; n = 4). The assignment of astaxanthin esters in negative ion LC-(APCI)MS was based on the detection of the molecular ion (M.-) and the formation of characteristic fragment ions, resulting from the loss of one or two fatty acids. Quantification of individual astaxanthin esters was performed using an astaxanthin calibration curve, which was found to be linear over the required range (1-51 μmol/L; r2 = 0.9996). Detection limits, based on the intensity of M.-, a signal-to-noise ratio of 3:1, and an injection volume of 20 μL, were estimated to be 0.05 μg/mL (free astaxanthin), 0.28 μg/mL (astaxanthin-C16:0), and 0.78 μg/mL (astaxanthin-C16:0/C16:0), respectively. This LC-(APCI)MS method allows for the first time the characterization of native astaxanthin esters in P. borealis and H. pluvialis without using time-consuming isolation steps with subsequent gas chromatographic analyses of fatty acid methyl esters. The results suggest that the pattern of astaxanthin-bound polyunsaturated fatty acids of P. borealis does not reflect the respective fatty acid pattern found in triacylglycerides. Application of the presented LC-(APCI)MS technique in common astaxanthin ester analysis will forestall erroneous xanthophyll ester assignment in natural sources.
- Breithaupt, Dietmar E.
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- ASTAXANTHIN MEDIUM-CHAIN FATTY ACID ESTER, PROCESS FOR PRODUCING THE SAME AND COMPOSITION CONTAINING THE ESTER
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The present invention provides an astaxanthin medium-chain fatty acid ester, which is expected to be applied in the fields of food, cosmetics and pharmaceuticals, and has higher digestibility and tissue penetration than long chain fatty acid ester form astaxanthins. When the synthesis of an astaxanthin medium-chain fatty acid ester is attempted using the catalytic action of lipase by conventional methods, ester cannot be formed. However, according to the present invention, a composition comprising an astaxanthin medium-chain fatty acid monoester and/or diester is produced by adding a certain amount of water into a reaction system and reacting an astaxanthin or a long chain fatty acid ester thereof with a medium-chain fatty acid, a triglyceride thereof or a suitable ester. Moreover, these monoesters and/or diesters are isolated, as necessary. The present invention further provides food or cosmetics comprising the composition of the present invention.
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