Oxidation reactions of bilirubin by peroxyl radicals in aqueous solutions

Halogenated peroxyl radicals were observed to oxidize bilirubin to its radical cation. The absolute rate constant for the oxidation of bilirubin has been measured by the pulse radiolysis technique. The oxidative power is observed to depend roughly on Taft's inductive parameter (σ*) of the halogenated peroxyl radical. The G(-bilirubin), determined on steady state γ-radiolysis, is also observed to depend on the rate constant value for the oxidation of bilirubin by halogenated peroxyl radicals. Steady state γ-radiolysis showed the formation of a strong absorption band in the region of 300-340 nm and a slight increase in absorption in the region of 520-560 nm. Violinoid may probably be one of the stable end products formed on γ-radiolysis. (author)