466 



X. BILE PIGMENT FORMATION, ETC. 



in Figure 6. Cyanide prevents this reduction, perhaps by replacing 

 the hydroxy] group in A. 



O O 



C D 



Fig. 6. Conversion of verdohemochrome into yellow compounds. 



As by-products of the formation of verdohemochrome pecuHar 

 brown iron-containing substances are obtained which do not appear 

 to form hemochromes. One would expect ring IV in formula A, 

 Figure 5, to be labile, and its hydrolysis may lead to the brown 

 compounds. 



It is still uncertain whether the compounds isolated by Libowitzky {1731) 

 actually were verdoheme compounds or compounds with a ring closed by a 

 carbonyl group, in spite of the fact that the absorption spectrum in pyridine 

 was that of verdohemochrome. These compounds were obtained by the 

 autoxidation, not the coupled oxidation, of oxycoproporphyrin hem /chrome, 

 and appear to be more stable to acid than verdohemoclirome. Thus Libo- 

 witzky isolated a crystalline green hemin containing two atoms of chlorine 

 by methods which would split verdohemin. 



