Abstract
The formation of the bilirubin oxidation products (BOXes), BOX A ([4-methyl-5-oxo-3-vinyl-(1,5-dihydropyrrol-2-ylidene)acetamide]) and BOX B (3-methyl-5-oxo-4-vinyl-(1,5-dihydropyrrol-2-ylidene)acetamide), as well as MVM (4-methyl-3-vinylmaleimide) were synthesized by oxidation of bilirubin with H(2)O(2) without and with FeCl(3), respectively. Compound identity was confirmed with NMR and mass spectrometry (MS; less than 1 ppm, tandem MS up to MS(4)). UV absorption profiles, including λ(max), and extinction coefficient (ε; estimated using NMR) for BOX A, BOX B, and MVM in H(2)O, 15% CH(3)CN plus 10 mM CF(3)CO(2)H, CH(3)CN, CHCl(3), CH(2)Cl(2), and 0.9% NaCl were determined. At longer wavelengths, λ(max)'s for 1) BOX A were little affected by the solvent, ranging from 295-297 nm; 2) BOX B, less polar solvent yielded λ(max)'s of lower wavelength, with values ranging from 308-313 nm, and 3) MVM, less polar solvent yielded λ(max)'s of higher wavelength, with values ranging from 318-327 nm. Estimated ε's for BOX A and BOX B were approximately 5- to 10-fold greater than for MVM.