COPPER BILIRUBINATE AND BLACK PIGMENT GALLSTONE

A series of copper bilirubinate complexes (CuBR) was synthesized in so lution and in solid state to mimic the black color of the black-pigmen t gallstone and to explore the formation mechanism of the gallstone in vitro. The variation of the copper contents of these samples indicate d that CuBR also exhibits nonstoichiometric characteristics from the F TIR study, i.e., both the so-called acid and neutral copper complex mo ieties exist in CuBR. The NH groups in pyrrole and lactam groups of bi lirubin (H(2)BR) are binding to the copper ions. An EPR study demonstr ates the generation of free radicals and the variation of its electron ic structure and conjugation system in the skeleton of H(2)BR molecule during complex formation. A polymer of CuBR may form through the reac tion of H(2)BR with copper ions. (C) 1995 John Wiley & Sons, Inc.