Photonics of Bilirubin: A Biologically Important Molecule (Review)

Bilirubin (BR), a bile pigment with photochemical activity, plays an important role in the body. The photonics (photophysics and photochemistry) of BR continues to attract scientific and practical interest from researchers to this day. This is due to the fact that its molecule is capable of ultrafast photoisomerization processes and also contains two interacting dipyrromethenone chromophores. Furthermore, the photochemical reactions of BR are used in the widespread phototherapy method of neonatal jaundice (neonatal hyperbilirubinemia (NHB)), carried out to reduce the level of BR in the body. This review briefly discusses the photonics of BR and its main photochemical reactions in the phototherapy of NHB.