DIPYRROLIC AND RELATED PIGMENTS IN NATURE 



149 



serum albumin, while the nature of the protein in "indirect" bilirubin is not 

 yet established; some workers claim it to be globin {2623,1223,2162). 



8. DIPYRROLIC AND RELATED PIGMENTS 

 OCCURRING IN NATURE 



While these compounds are not bile pigments in the proper sense, they 

 are chemically and physiologically related to them and are therefore treated 

 in this section; some were previously considered to be bile pigments and have 

 only recently been recognized to contain two, not four, pyrroles. 



MEM? 



H H 



lead tetraacetate 



M E M P 



H O H 



neoxanthobilirubinio 

 acid 



"propentdyopent" 



Na amalgam 



M E M P 



HO 



H /\ H 

 H OH 



OH 



MEM 



HO 



(dipyrrylcarbinol) 



Fig. 27. Formation of mesobilifuscin (Siedel and Moller, 23r>8). 



8.1. "Bilifuscins" (a,Q:'-Dihydroxypyrromethenes) 



Bilifuscin is a brown alcohol-soluble pigment obtained as a by-product 

 of the preparation of bilirubin from gallstones {358,2607,3012,3182). Its 



