Human biliary β‐glucuronidase: correlation of its activity with deconjugation of bilirubin in the bile

Abstract

Total and conjugated bilirubin contents of gall-bladder and hepatic biles before and after 24-h incubation at 37 degrees C and beta-glucuronidase activity of hepatic biles were determined in forty-eight patients divided equally into four groups: no stones or control (C), cholesterol stones (CS), black pigment stones (black PS), and brown pigment stones (brown PS). The percent conjugation of bilirubin is lower in gall-bladder biles and hepatic biles after incubation, particularly in black PS and brown PS, when compared with hepatic biles before incubation. Mean endogenous beta-glucuronidase activities at pH 5.2 were 12.0, 15.5, 44.5 and 147.7 nmol min-1 ml-1 for C, CS, black PS, and Brown PS, respectively, which correlated well with the degree of deconjugation of bilirubin in gall-bladder and hepatic biles and with the rate of deconjugation of hepatic bile incubated at 37 degrees C. Only four biles in brown PS exhibited bacterial enzyme activity. We concluded that though bacterial beta-glucuronidase might be responsible for deconjugation of bilirubin in some patients in brown PS, endogenous biliary beta-glucuronidase could play a key role in the pathogenesis of pigment cholelithiasis.

Identification of bilirubin reduction products formed by Clostridium perfringens isolated from human neonatal fecal flora

“…It is highly likely that hydrolysis bilirubin diglucuronide by ␤-glucuronidase of either bacterial [36] or human origin [37] precedes bilirubin reduction, compatible with the finding that natural unconjugated bile pigments, UCB and MB, are more efficiently reduced than conjugated pigments, and Clostridia secrete ␤-glucuronidase [36]. Thus, our studies did not detect conjugated urobilinoids as products of the microbial reduction of bilirubin conjugates.…”

Deconjugation of bilirubin accelerates coprecipitation of cholesterol, fatty acids, and mucin in human bile—In vitro study

“…This result was probably due to the non-enzymatic hydrolysis of conjugated bilirubin 24 and to nonbacterial 13-glucuronidase activity in bile. 25 The weight of free fatty acids in the precipitate increased during the incubation period; this we ascribed to a non-enzymatic reaction and nonbacterial phospholipase activity in bile, 26 The idea of the non-specific hydrolysis of lecithin 26 was supported by our finding of increased free fatty acid concentration in the supernatant during the incubation.…”

Hypotensive effect and enzyme inhibition activity of mapuche medicinal plant extracts

“…It has been demonstrated that the administration of hepatotoxic compounds produced an important increase of the serum p-gluc activity (Suzuki et al, 1975). Furthermore, it has been proposed that endogenous biliary p-gluc might be responsible for bilirubin deconjugation leading to gallstones (Ho et al, 1986). Some natural products have been reported to be p-gluc inhibitors, including flavonoids (Kawasaki et al, 1988) and a trihydroxy pipecolic acid (Cenci di Bello et a [ .…”