BILIVERDIN FROM HEMOGLOBIN IN VITRO 471 



3. PHOTOCHEMICAL FORMATION OF BILE PIGMENTS 

 FROM PORPHYRIN METAL COMPLEXES 



While free porphyrins have never been converted into bile pigments, 

 Fischer and Bock (804,805) found a photochemical oxidation of the sodium 

 metal complex of etioporphyrin to bile pigments (etiobiliverdin and bili- 

 violinoid pigments) as well as to an a-formyl-a'-hydroxypyrromethene, if the 

 pyridine solution of the complex salt was exposed to strong light in the 

 presence of atmospheric oxygen. 



The mechanism of the reaction is not yet clear in all its phases, but can 

 be formulated as addition of oxygen to a double bond between one methene 

 group and a pyrrole nucleus, followed by the formation of a tetrapyrrotriene 

 with a formyl group at one end (Fig. 9). The latter ii. ultimately replaced 



II\0 



H H 



Fig. 9. Photochemicai formation of bile pigments (only the lower halves of the 

 molecules in which the alterations occur are shown). 



by a hydroxyl group, yielding the bilatriene etiobiliverdin. If the reaction 

 occurs on two opposite methene groups, dipyrrolic substances are formed and 

 the formyl group remains attached. 



An alternative explanation was first preferred, but was later {805) with- 

 drawn because it was based on an erroneous assumption of the nature of a 

 presumed intermediate. 



It is not impossible that chlorophyll may be converted into bile pigments 

 by such a photochemical oxidation. 



4. FORMATION OF BILIVERDIN FROM HEMOGLOBIN 

 m VITRO. CHOLEGLOBIN 



4.1. Introduction 



The formation of green pigments from hemoglobin has been fre- 

 quently observed. In 1901 Lewin (1726) obtained "hemoverdin" 

 from the btood of animals poisoned with phenylhydrazine. Schott- 



