Bilirubin: An Endogenous Product of Heme Degradation with Both Cytotoxic and Cytoprotective Properties: Fig. 1

Bilirubin is a linear tetrapyrrole that is formed during the process of heme degradation. Heme is released from a series of hemeproteins, including hemoglobin and cytochrome P450, and metabolized by heme oxygenase to form carbon monoxide, biliverdin, and free iron. Biliverdin is subsequently