Little J M, Zimniak P, Shattuck K E, Lester R, Radominska A
Department of Medicine, University of Arkansas for Medical Science, Little Rock 72205.
J Lipid Res. 1990 Apr;31(4):615-22.
Milligram amounts of [3 beta-3H]lithocholic (3 alpha-hydroxy-5 beta-cholanoic) acid were administered by intravenous infusion to rats prepared with a biliary fistula. Analysis of sequential bile samples by thin-layer chromatography (TLC) demonstrated that lithocholic acid glucuronide was present in bile throughout the course of the experiments and that its secretion rate paralleled that of total isotope secretion. Initial confirmation of the identity of this metabolite was obtained by the recovery of labeled lithocholic acid after beta-glucuronidase hydrolysis of bile samples. For detailed analysis of biliary metabolites of [3H]lithocholic acid, pooled bile samples from infused rats were subjected to reversed-phase chromatography and four major labeled peaks were isolated. After complete deconjugation, the two major compounds in the combined first two peaks were identified as murideoxycholic (3 alpha, 6 beta-dihydroxy-5 beta-cholanoic) and beta-muricholic (3 alpha, 6 beta, 7 beta-trihydroxy-5 beta-cholanoic) acids and the third peak was identified as taurolithocholic acid. The major component of the fourth peak, after isolation, derivatization (to the methyl ester acetate), and purification by high pressure liquid chromatography (HPLC), was positively identified by proton nuclear magnetic resonance as lithocholic acid 3 alpha-O-(beta-D-glucuronide). These studies have shown, for the first time, that lithocholic acid glucuronide is a product of in vivo hepatic metabolism of lithocholic acid in the rat.
将毫克量的[3β-³H]石胆酸（3α-羟基-5β-胆烷酸）通过静脉输注给予制备有胆瘘的大鼠。通过薄层色谱法（TLC）对连续胆汁样本进行分析表明，在整个实验过程中胆汁中均存在石胆酸葡萄糖醛酸苷，其分泌速率与总同位素分泌速率平行。通过对胆汁样本进行β-葡萄糖醛酸酶水解后回收标记的石胆酸，初步证实了该代谢产物的身份。为了详细分析[³H]石胆酸的胆汁代谢产物，将来自输注大鼠的合并胆汁样本进行反相色谱分析，并分离出四个主要的标记峰。完全去结合后，合并的前两个峰中的两种主要化合物被鉴定为murideoxycholic（3α，6β-二羟基-5β-胆烷酸）和β-鼠胆酸（3α，6β，7β-三羟基-5β-胆烷酸），第三个峰被鉴定为牛磺石胆酸。通过高压液相色谱法（HPLC）对第四个峰的主要成分进行分离、衍生化（生成甲酯乙酸酯）和纯化后，通过质子核磁共振确定其为石胆酸3α-O-（β-D-葡萄糖醛酸苷）。这些研究首次表明，石胆酸葡萄糖醛酸苷是大鼠体内石胆酸肝脏代谢的产物。
