bilirubin

Also known as 2,17-diethenyl-1,10,19,22,23,24-hexahydro-3,7,13,18-tetramethyl-1,19-dioxo-21H-biline-8,12-dipropanoic acid, 1,10,19,22,23,24-hexahydro-2,7,13,17-tetramethyl-1,19-dioxo-3,18-divinylbiline-8,12-dipropionic acid, bilirubin IXalpha, 8,12-bis(2-carboxyethyl)-2,7,13,17-tetramethyl-3,18-divinylbiladiene-ac-1,19(21H,24H)-dione, 2,7,13,17-tetramethyl-1,19-dioxo-3,18-divinyl-1,10,19,22,23,24-hexahydro-21H-biline-8,12-dipropanoic acid, 3-[2-[[3-(2-carboxyethyl)-4-methyl-5-[(Z)-(4-methyl-5-oxo-3-vinyl-pyrrol-2-ylidene)methyl]-1H-pyrrol-2-yl]methyl]-4-methyl-5-[(Z)-(3-methyl-5-oxo-4-vinyl-pyrrol-2-ylidene)methyl]-1H-pyrrol-3-yl]propanoic acid, 3-[2-[[3-(2-carboxyethyl)-5-[(Z)-(5-keto-4-methyl-3-vinyl-3-pyrrolin-2-ylidene)methyl]-4-methyl-1H-pyrrol-2-yl]methyl]-5-[(Z)-(5-keto-3-methyl-4-vinyl-3-pyrrolin-2-ylidene)methyl]-4-methyl-1H-pyrrol-3-yl]propionic acid, 3-[2-[[3-(2-carboxyethyl)-5-[(Z)-(3-ethenyl-4-methyl-5-oxopyrrol-2-ylidene)methyl]-4-methyl-1H-pyrrol-2-yl]methyl]-5-[(Z)-(4-ethenyl-3-methyl-5-oxopyrrol-2-ylidene)methyl]-4-methyl-1H-pyrrol-3-yl]propanoic acid

Bilirubin (BR) (adopted from German, originally bili, for bile, plus ruber, Latin for red) is a red-orange compound that occurs as the reduction product of biliverdin, a breakdown product of heme. It is further broken down in the colon to urobilinogen, most of which becomes stercobilin, causing the brown color of feces. Some unconverted urobilinogen, metabolised to urobilin, provides the straw-yellow color in urine.