UV light absorption parameters of the pathobiologically implicated bilirubin oxidation products, MVM, BOX A, and BOX B

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.