Evidence for the possible involvement of the superoxide radicals in the photodegradation of bilirubin
Ravi Kaul Hari K Kaul Prakash C Bajpai C R Krishna Murti
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The photodecomposition of bilirubin follows first order kinetics with akB value of 12.5 × 10-3 min-1. In the presence of a model system generating superoxide anions, such as xanthine-xanthine oxidase, thekB value was 103 × 10-3 min-1 This ten-fold enhancement ofkB value by xanthine-xanthine oxidase was abolished when the reaction mixture was supplemented with a superoxide ion scavenger— superoxide dismustase. Further, known singlet oxygen quenchers like Β-carotene and bistidine did not prevent the enhancement of bilirubin oxidation by xanthine-xanthine oxidase, thereby ruling out the obligatory conversion of Superoxide anion to singlet oxygen. It is concluded that radical oxygen mediated bilirubin degradation might be a natural catabolic route for the bile pigment degradation during oxygen stress.
Ravi Kaul1 Hari K Kaul1 Prakash C Bajpai1 C R Krishna Murti2
Volume 48, 2023
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