Synthesis of new bile acid analogues and their metabolism in the hamster: 3 alpha, 6 alpha-dihydroxy-6 beta-methyl-5 beta-cholanoic acid and 3 alpha, 6 beta-dihydroxy-6 alpha-methyl-5 beta-cholanoic acid.

N Matoba,E H Mosbach,B I Cohen,M Une,C K Mcsherry

doi:10.1016/s0022-2275(20)38288-2

Abstract

This paper reports the chemical synthesis of two new bile acid analogues, namely, 3 alpha, 6 beta-dihydroxy-6 alpha-methyl-5 beta-cholanoic acid from 3 alpha-hydroxy-6-oxo-5 beta-cholanoic acid and describes their metabolism in the hamster. A Grignard reaction of the oxo acid with methyl magnesium iodide in tetrahydrofuran gave two epimeric dihydroxy-6-methyl-cholanoic acids which were separated as the methyl esters by silica gel column chromatography. The configuration of the 6-methyl groups was assigned by proton nuclear magnetic resonance spectroscopy and was supported by the chromatographic properties of the new compounds. The metabolism of the two new bile acid analogues was studied in the hamster. After intraduodenal administration of the 14C-labeled analogues into bile fistula hamsters, both compounds were absorbed rapidly from the intestine and secreted into bile. Intravenous infusion studies revealed that these compounds were efficiently extracted by the liver; the administered analogues became major biliary bile acids, present as either the glycine or taurine conjugates. These compounds are useful to study the effect of methyl-substituted bile acids on cholesterol and bile acid metabolism and may possibly possess cholelitholytic properties.

Highlights

O UDCA give rise to the potentially hepatotoxic lithocholic acid (LCA) in the large intestine and may not acid with methyl magnesium iodide in tetrahydrofuran gave two be ideal for extended medical therapy of cholesterol choleepimeric dihydroxy-6-methyl-cholanoic acids which were lithiasis [6]
The methyl esters of the two isomers were separable by Thin-layer chromatography (TLC) (50 isomer, Rf 0.36, 5 a isomer, Rj 0.40, solvent system: benzene-acetone 7:3)
A similar observation was made in the protons at C-19 of 6a-Me-murideoxycholic acid (MDCA) (1.32 ppm) shifted to a case of 7-methyl-ursocholic acid [30]

Summary

MATERIALS AND METHODS

Melting points were determined on a Thermolyne melting point apparatus and are not corrected. Animal experiments prepared diazomethane gave an oily residue of bile acid methyl esters (about 2 g) which was chromatographed on. (lH, m, 30-H); 3 a , Ga-dihydroxy-6~-methyl-5~-chola-mm OD, Clay-Adams, Parsippany, NJ) was inserted into noic acid (111, 60-Me-HDCA), white crystals from ethyl the left femoral vein and 0.9 % NaCl solution was infused acetate, 490 mg, mp 186.5-188.OoC, P M R 0.65 Each labeled compound was Matoba et al Synthesis and metabolism of 6-methyl bile acids 1007 infused for 20 min at a dose of 50 pg/min (total amount administered, 1 mg) [25]; saline was again infused until the end of the experiment. Bile samples were collected every 20 min for 2.5 h

Analytical techniques

RESULTS AND DISCUSSION

Fragment A

No of Animals

GIT Ratio