Bilirubin in coronary artery disease: Cytotoxic or protective?

Figure 1 Bilirubin metabolism (from heme to bilirubin). Hemoglobin is cleaved to yield globin and heme (red). Heme is enzymatically converted to biliverdin (green) by liberating iron, via oxidation with loss of a carbon atom (CO). This, in turn, yields bilirubin (orange) after enzymatic reduction of biliverdin. In the liver, bilirubin is conjugated to enable excretion, requiring the enzyme UGT1A1[4].