PMID: 39865Aug 1, 1979

The origins of unconjugated bilirubin in bile

Gastroenterologia Japonica
H Masuda, K P Heirwegh


In order to investigate the origin of unconjugated bilirubin in bile, beta-glucuronidase activity in rat and human bile was determined at various pH. beta-Glucuronidase in rat and human bile had their optimum pH at 5.5 when phenolphthalein glucuronide and delta 1-azopigment were used as substrate, and at 6.0 when bile itself was incubated. In human and rat bile the hydrolysis was suppressed to a minimum at each physiologic pH. However, human bile shows remarkable hydrolysis in alkaline pH (7.5--8.0). On the other hand, when delta 1-azopigment was incubated in various buffers, several per cent of delta 1-azopigment were hydrolyzed non-enzymatically in neutral to alkaline pH. Thus, it was suggested that enzymatic and nonenzymatic hydrolysis contributes to the existence of unconjugated bilirubin in bile.


Sep 18, 2004·American Journal of Physiology. Gastrointestinal and Liver Physiology·Aldo D MottinoMary Vore

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Phenolphthalein glucuronide

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