[An observation on nucleating activity of monoconjugated bilirubin (MCB) in model bile system]

Recently, the increasing data suggest that the pathogenesis of cholesterol gallstones may be related to the imbalance between pro- and anti-mucleating factors in bile. Our previous results have shown that monoconjugated bilirubin (MCB) possessed certain pro-nucleating activity and might play an important role in the formation of gallstones. The present study was made to observe the effect of MCB on nucleating activity by using our previous established methods of purification and preparation of MCB in model system of supersaturated bile according to Kibe's method with cholesterol saturation index of 1.2, total lipid concentration of 10g/dl, and bile salt phospholipid ratio of 2.3. Nucleation time (NT) was observed in 3 experimental groups with six samples each and 2 different contents of lyophilized MCB was added to above model bile rendered a final MCB concentration of (1) 173 microM; (MCB 1 group) (2) 340 microM; (MCB-2 group) and (3) no MCB in the as control group. The results were NT 3.33 +/- 0.52, 2.17 +/- 0.41 and 5.83 +/- 0.75 days in groups. 1, 2 and 3 respectively with the P value < 0.05 when compared between the 2 groups. The nucleating activity (NA) value was 0.5712 and 0.3722 in groups 1 and 2, which revealed that the NA elevated in parallele with the dose of MCB added in model bile. Our findings suggust that MCB has a strong pro-nucleating activity in model supersaturated biles, and MCB may participate in the formation of cholesterol gallstones throngh its special pro-nucleating activity.