Identification of 9 new Bisacetylenic oxylpins (polyacetylenes) in Daucus Carota (carrots)
26 Nov 2009
A recent study (last week) published in the Journal of Agricultural and Food Chemistry reported the identification of the chemical structure of polyactelyenes (more correctly bisacetylenic oxylipins) in carrots (Daucus Carota L.). Besides the falcarinol, falcarindiol and falcarindiol 3-acetate, nine compounds additional compounds were identified, six of them were reported for the first time in literature and three of them were not previously identified in carrots. The results of this study have a extraordinary impact in the knowledge of bisacetylenic compounds from carrots, which are an important source of these biologically active compounds in human diet and one of Ireland's largest crop.
The identification of the complete chemical structure of bioactive compounds is usually of extreme importance in order to determine the mechanism of its biological activity. Very often in a mixture of very similar compounds (even diasteroisomers) only one is biologically active.
The study was conducted in collaboration between the Chair of Food Chemistry and Molecular Sensory Science, from Munich Technical University in Germany and the Laboratory of Molecular and Thio-Organic Chemstry in Caen in France. The work was composed of two parts, one the isolation of bisacetylenic compounds from carrots and the other one the chemcial synthesis of standards to use in the identification of the carrot extracted compounds.
Bisacetylenic oxylipins were screened from an extract made from carrots (Daucus carota L.). Then they were isolated and their structures were determined by means of LC-MS and 1D/2D NMR spectroscopy. The determination the absolute stereochemistry of falcarindiol in carrots was performed by comparison with the (3R,8R)-, (3R,8S)-, (3S,8R)-, and (3S,8S)-stereoisomers of falcarindiol that were synthesized according to a novel 10-step total synthesis (involving a Cadiot-Chodkiewicz cross-coupling reaction of (S)- and (R)-trimethylsilanyl-4-dodecen-1-yn-3-ol and (R)- and (S)-5-bromo-1-penten-4-yn-3-ol, respectively).
Comparative chiral HPLC analysis of the synthetic stereoisomers with the isolated phytochemical led to the unequivocal assignment of the (Z)-(3R,8S)-configuration for falcarindiol in carrot extracts from Daucus carota L.
For further information on this interesting article please check the following link:
http://pubs.acs.org/doi/abs/10.1021/jf9031475
Enjoy the reading!
