beta-Muricholic acid; potentiometric and cholesterol-dissolving properties

Area of Science:

• Biochemistry
• Physical Chemistry
• Hepatology

Background:

• Beta-muricholic acid is a primary bile acid synthesized in rat liver.
• Understanding its physicochemical properties is crucial for its biological role.
• Comparison with other bile acids like ursodeoxycholic and chenodeoxycholic acids provides context.

Purpose of the Study:

• To determine and compare the physicochemical properties of beta-muricholic acid with other bile acids.
• To investigate the cholesterol-solubilizing capacity of beta-muricholic acid.
• To explore the potential physiological relevance of these properties, particularly for gallstone dissolution.

Main Methods:

• Potentiometric studies were employed to determine key properties.
• Solubility and aggregation behavior of beta-muricholic acid were assessed.
• Cholesterol solubilization by sodium beta-muricholate was quantified using molar ratios.

Main Results:

• Beta-muricholic acid demonstrated low monomer solubility (13 microM) and a high precipitation pH (7.92).
• Its critical micellar concentration was found to be 4 mM, with limited capacity to dissolve protonated bile acid.
• Sodium beta-muricholate showed poor cholesterol solubilization (molar ratio 1430) compared to chenodeoxycholate and ursodeoxycholate.

Conclusions:

• Beta-muricholic acid possesses distinct physicochemical characteristics compared to other bile acids.
• While exhibiting low cholesterol solubilization in simple solutions, it can dissolve cholesterol crystals via lamellar liquid-crystal formation at physiological concentrations.
• These unique properties suggest a potential role in the physiological dissolution of cholesterol gallstones.