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World J Gastroenterol. Jun 15, 2002; 8(3): 413-417
Published online Jun 15, 2002. doi: 10.3748/wjg.v8.i3.413
Relationship between bilirubin free radical and formation of pigment gallstone
Xiang-Tao Liu, Jian Hu
Xiang-Tao Liu, Jian Hu, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing 100083, China
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, No. 3880768 and No. 39170719
Correspondence to: Xiang-Tao Liu, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing 100083, China.
Telephone: +86-10-62091539 Fax: +86-10-62015584
Received: July 19, 2001
Revised: July 28, 2001
Accepted: September 4, 2001
Published online: June 15, 2002

In this paper, we summarize the main progresses made in our group in the field of the mechanism of pigment gallstone formation. It was found that after treatment with free radicals, bilirubin (BR) was changed into free radical itself, and a semiquinone free radical and a superoxide free radical bound with metal were recognized, which was detected by ESR (electron spin resonance). By the means of NMR (nuclear magnetic resonance) and IR (Infra-red spectra), it was postulated that bilirubin polymerized through the reaction between the vinyl group and the hydroxyl group under the attack of free radicals. It was also found that bilirubin free radical were liable to calcify in a kinetic study. Because of its chemical properties, bilirubin free radical was shown to be cytotoxic to hepatocyte, which was demonstrated based on the following facts: induction of phospholipid peroxidation (LPO), leakage of lactate dehydrogenase (LDH) and decrease of glutathione. As to the mechanism of bilirubin-induced cytotoxicity, it was postulated that the main target of bilirubin free radical was the cell membrane, including phospholipid and membrane bound proteins, especially spectrin, a content of cytoskeleton. Based on the results mentioned above, it was deduced that bilirubin free radical is the key factor that initiates and promotes the formation of pigment gallstone, which is consistent with other researches in recent years.

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