Photochemistry of Biliverdin IXδ as a Model for the Study of the Photoproducts from Natural Biliverdin IXγ (Pterobilin)

Article abstract of DOI:10.1002/hlca.19800630437

The configurations of biliverdin-IXγ and -IXδ dimethyl esters 1 and 2 in solutions, have been studied using Nuclear-Overhauser-Effect (NOE) experiments.Irradiation (500-700 nm) of biliverdin IXδ gave syn-Z -> anti-E isomerization of the central methine bridge and in aerated polar solutions, four new cyclized pigments were isolated for which structures 3, 4, 5 and 6 are proposed.Neobiliverdin IXδ is also formed in degassed solution (Φ = 4E-5) but pigments 4, 5 and 6 arise from photo-oxidation with O2.Biliverdin IXδ appears to be a good model for the study of photo-reactions occurring on the vinyl groups of the natural biliverdin IXγ (pterobilin).