SYNTHESIS AND CONFORMATION OF A BILIRUBIN ANALOG WITH PROPIONIC ACID SIDE CHAINS EXTENDED TO UNDECANOIC ACID

Article abstract of DOI:10.1016/S0040-4020(01)89846-X

A lipophilic analog of bilirubin with propionic acid groups replaced by undecanoic acid groups (1), was synthesized from 11-bromo-undecanoic acid.UV-visible and NMR spectroscopic analyses suggest reduced intramolecular H-bonding and a preference for a helical conformation.Molecular dynamics computations predict a global energy minimum for a helical porphyrin-like conformation with unusual distorted structures when H-bonding is invoked.Circular dichroism of the pigment complex with human serum albumin gives a bilirubin-like bisignate Cotton effect: Δε^max₄₄₉ = + 33, Δε^max₃₉₆ = 47.