Biliverdine

Biliverdin is a green tetrapyrrolic bile pigment, and is a product of heme catabolism. It is the pigment responsible for a greenish color sometimes seen in bruises. Biliverdin is a green tetrapyrrolic bile pigment, and is a product of heme catabolism. It is the pigment responsible for a greenish color sometimes seen in bruises. Biliverdin results from the breakdown of the heme moiety of hemoglobin in erythrocytes. Macrophages break down senescent erythrocytes and break the heme down into biliverdin along with hemosiderin, in which biliverdin normally rapidly reduces to free bilirubin. Biliverdin is seen briefly in some bruises as a green color. In bruises, its breakdown into bilirubin leads to a yellowish color. Biliverdin has been found in excess in the blood of humans suffering from hepatic diseases. Jaundice is caused by the accumulation of biliverdin or bilirubin (or both) in the circulatory system and tissues. Jaundiced skin and sclera (whites of the eyes) are characteristic of liver failure. While typically regarded as a mere waste product of heme breakdown, evidence that suggests that biliverdin — and other bile pigments — has a physiological role in humans has been mounting. Bile pigments such as biliverdin possess significant anti-mutagenic and antioxidant properties and therefore may fulfil a useful physiological function. Biliverdin and bilirubin have been shown to be potent scavengers of peroxyl radicals. They have also been shown to inhibit the effects of polycyclic aromatic hydrocarbons, heterocyclic amines, and oxidants — all of which are mutagens. Some studies have found that people with higher concentration levels of bilirubin and biliverdin in their bodies have a lower frequency of cancer and cardiovascular disease. It has been suggested that biliverdin — as well as many other tetrapyrrolic pigments — may function as an HIV-1 protease inhibitor as well as having beneficial effects in asthma though further research is needed to confirm these results. There are currently no practical implications for using biliverdin in the treatment of any disease. Biliverdin is an important pigment component in avian egg shells, especially blue and green shells. Blue egg shells have a significantly higher concentration of biliverdin than brown egg shells. Research has shown that the biliverdin of egg shells is produced from the shell gland, rather than from the breakdown of erythrocytes in the blood stream, although there is no evidence that the sources of the material are neither tetrapyrroles nor free haem from the blood plasma. Along with its presence in avian egg shells, other studies have also shown that biliverdin is present in the blue-green blood of many marine fish, the blood of tobacco hornworm, the wings of moth and butterfly, the serum and eggs of frogs, and the placenta of dogs. With dogs this can lead, in extremely rare cases, to the birth of puppies with green fur; however, the green colour fades out soon after birth. In the garfish (Belone belone) and related species, the bones are bright green because of biliverdin.