title: beta-Muricholic acid; potentiometric and cholesterol-dissolving properties.
abstract: Some physicochemical properties of beta-muricholic acid (3 alpha,6 beta,7 beta-trihydroxy-5 beta-cholanic acid), a major bile acid biosynthesized by rat liver, were determined and compared to those of ursodeoxycholic and chenodeoxycholic acids. From potentiometric studies, the following characteristics of beta-muricholic acid were shown: a low monomer solubility (13 microM), a high equilibrium precipitation pH (7.92 for 30 mM solution), an apparent critical micellar concentration of 4 mM, and a very low micellar capacity of the bile salt to dissolve the protonated bile acid. Sodium beta-muricholate solution (30 mM) poorly solubilized cholesterol, as indicated by a bile salt/cholesterol molar ratio of 1430, whereas saturation ratios obtained with chenodeoxycholate and ursoseoxycholate were 24 and 384, respectively. Sodium beta-muricholate (30 mM)/phosphatidylcholine/cholesterol mixtures contained non-micellar aggregates from very low cholesterol concentrations. At physiological phosphatidylcholine concentrations, sodium beta-muricholate (100 mM) dissolved cholesterol crystals via essentially lamellar liquid-crystal formation. These solubilizing properties might have important physiological relevance to the dissolution of cholesterol gallstones in man.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002635:Chenodeoxycholic Acid; D002784:Cholesterol; D002793:Cholic Acids; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008433:Mathematics; D008823:Micelles; D011199:Potentiometry; D051381:Rats; D012995:Solubility; D014580:Ursodeoxycholic Acid
chemical_list: D002793:Cholic Acids; D008823:Micelles; D002635:Chenodeoxycholic Acid; C004821:muricholic acid; D014580:Ursodeoxycholic Acid; D002784:Cholesterol