ORGN 533 |
| Bilirubin IXα is the lipophilic, water insoluble, yellow-orange pigment of jaundice. It is produced in the body as the end product of heme metabolism. Bilirubin IXα is composed of two dipyrrinone units conjoined together through a -CH2- group, and each dipyrrinone contains a propionic acid side chain. Each dipyrrinone unit can rotate independently around the -CH2- in order to reach the lowest energy conformation. The most stable conformation is one with six intramolecular hydrogen bonds, from each dipyrrinone to a CO2H, causing the pigment to adopt a ridge-tile conformation. The shape of bilirubin IXα plays a major role in its physicochemical properties and metabolism, making it very important to study. Major perturbations at the center of the pigment (at the C(10) -CH2-) and the alkanoic acid group can exert a large influence on the intramolecular hydrogen bonding and hence on its conformation and properties in solution. The C(10) -CH2- group has now been homologated to -CH2-CH2- with expected folding up of the ridge-tile, and the propionic acid chain has been replaced with butanoic acid to better favor intramolecular hydrogen bonding. In the closed-up pigment conformation the stereochemical consequences of these alterations are studied by 1H NMR, NOE experiments, VPO measurements and UV-Vis spectroscopy. |
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Heterocycles, Aromatics, Metal-Mediated Reactions and Syntheses, Materials, Devices, and Switches
8:00 PM-10:00 PM, Wednesday, 29 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster
Division of Organic Chemistry |