Über die Konstitution des Bilirubins und über bilirubinoide Farbstoffe

Abstract

To obtain information concerning the structure of the unsaturated side chains of ring I and IV of bilirubin, 0.3 g. bilirubin dimethyl ester was fused with 8-10 g. resorcinol, and vinylneoxanthobilirubinic acid ester, m. 186[degree], obtained. Since this compound was derived from the first half of the bilirubin. molecule, the structure of that half of the molecule was proved. Bilirubin was esterified with diazo-methane, and monomethoxy and dimethoxybilirubinic dimethyl ester isolated. However, the hydroxy groups may not have been present in bilirubin originally. Similar com-pounds were formed by the action of diazomethane on meso-bilirubin and koprobilirubin. The azo dye hydrochlorides of methoxyneoxanthobilirubinic acid methyl ester and of the iso compound were prepared and from their properties it was concluded that the constitution of bilirubin may be unsymmetrical. A "nitrite compound," shown to be methyl-yinylmaleamide, was prepared from bilirubin and biliverdin in 1.5% yield, and from vinylneoxanthobilirubinic acid in 6.6% yield. From the above results, it was concluded that the formula for bilirubin can not contain a hydrofuran ring. It was concluded that 2 vinyl groups were present in bilirubin and biliverdin. Methods of prep. and the properties of many compounds which are considered in reference to the structure of bilirubin are given.