<unk>  <unk>  is a red-orange compound that occurs in the normal catabolic pathway that<unk> eaks down heme in vertebrates. This catabolism is a necessary process in the body's clearance of waste products that arise from the destruction of aged or abnormal red blood cells. First the hemoglobin gets stripped of the heme molecule which thereafter passes through various processes of porphyrin catabolism, depending on the part of the body in which the<unk> eakdown occurs. For example, the molecules excreted in the urine differ from those in the feces. The production of<unk> verdin from heme is the first major step in the catabolic pathway, after which the enzyme<unk> verdin reductase performs the second step, producing<unk>  from<unk> verdin. Ultimately, the metabolites of<unk>  are excreted through<unk> e and urine, and elevated levels may indicate certain diseases. It is responsible for the yellow color of<unk> uises and the yellow discoloration in jaundice. Its<unk> eakdown products, such as stercobilin, cause the<unk> own color of feces. A different<unk> eakdown product, urobilin, is the main component of the straw-yellow color in urine. Although<unk>  is usually found in animals rather than plants, at least one species, Strelitzia nicolai, is known to contain the pigment.
Bilirubin
Lumirubin
Bile acid
Uric acid
Lipoprotein
Blood protein
Hemoglobin
Alanine transaminase