Blue Light and Bilirubin Excretion

Abstract

Blue light converts bilirubin in the skin of jaundiced rats to metastable geometric isomers that are transported in blood and excreted in bile. The same reaction probably occurs in jaundiced babies exposed to light, particularly during treatment with phototherapy. Excretion of unisomerized bilirubin is prevented by intramolecular hydrogen bonding, and the pigment has to be metabolized to more polar derivatives to be excreted efficiently.

Effect of Position Changing on Bilirubin Levels During Phototherapy

“…11 During phototherapy, photons react with bilirubin in the extravascular space, producing water-soluble isomers that diffuse back into the circulation and are subsequently excreted in the bile. 11 However, bilirubin can also undergo photoisomerisation when bound to albumin in the blood.…”

“…11 During phototherapy, photons react with bilirubin in the extravascular space, producing water-soluble isomers that diffuse back into the circulation and are subsequently excreted in the bile. 11 However, bilirubin can also undergo photoisomerisation when bound to albumin in the blood. 12,13 When phototherapy is begun, bilirubin molecules in the extravascular space act as a filter that absorbs the photons and prevents their reaction with bilirubin in the vascular space.…”

“…The time required for diffusion of bilirubin into and out of the extravascular space has been estimated as 3.5 hours. 11 Thus, it is reasonable to assume that, by saving the diffusion time, intravascular photoisomerisation may in fact be more efficient.…”

Photolysis of bilirubin in serum specimens exposed to room lighting

“…Bilirubin is a substance absorbing light within the visible spectrum, and it is well recognized to undergo both isomerization and oxidation in serum exposed to visible light, resulting in decreased measured bilirubin values [10][11][12][13][14]. Monitoring of the photodegradation is complicated somewhat by variable rates of degradation of different molecular forms of bilirubin and variable reactivity of photodegradation products with different methods for analysis of bilirubin.…”

Structures of (Z)-3,4-diethyl-5-(phenylmethylene)-3-pyrrolin-2-one, C15H17NO (I), and (Z)(syn)-3,4-dimethyl-5-(2-pyridylmethylene)-3-pyrrolin-2-one, C12H12N2O (II)

“…It is now known that 'photobilirubin' is formed in this process (McDonagh, Palma & Lightner, 1980). The methylidynedipyrrole groups in bilirubin are normally in the (Z,Z) configuration with a synperiplanar conformation at the * Permanent address: Saha Institute of Nuclear Physics, 92 APC Road, Calcutta-700 009, India.…”