Research Article| Volume 33, ISSUE 5, P635-646, May 1992

Solubility of calcium salts of unconjugated and conjugated natural bile acids.

Open AccessPublished:May 01, 1992DOI:
      This paper is only available as a PDF. To read, Please Download here.
      The approximate solubility products of the calcium salts of ten unconjugated bile acids and several taurine conjugated bile acids were determined. The formation of micelles, gels, and/or precipitates in relation to Ca2+,Na+, and bile salt concentration was summarized by “phase maps.” Because the ratio of Ca2+ to bile salt in the precipitates was ca. 1:2, and the activity of Ca2+ but not that of bile salt (BA-) could be measured, the ion product of aCa2+ [BA-]2 was calculated. The ion product (= Ksp) ranged over nine orders of magnitude and the solubility thus ranged over three orders of magnitude; its value depended on the number and orientation of the hydroxyl groups in the bile acid. Ion products (in units of 10(-9) mol/l)3 were as follows: cholic (3 alpha OH,7 alpha OH,12 alpha OH) 640; ursocholic (3 alpha OH,7 beta OH,12 alpha OH) 2300; hyocholic (3 alpha OH,6 alpha OH,7 alpha OH) 11; ursodeoxycholic (3 alpha OH,7 beta OH) 91; chenodeoxycholic (3 alpha OH,7 alpha OH) 10; deoxycholic (3 alpha OH,12 alpha OH) 1.5; 12-epideoxycholic (lagodeoxycholic, 3 alpha OH,12 beta OH) 2.2; hyodeoxycholic (3 alpha OH,6 alpha OH) 0.7; and lithocholic (3 alpha OH) 0.00005. The critical micellization temperature of the sodium salt of murideoxycholic acid (3 alpha OH,6 beta OH) was greater than 100 degrees C, and its Ca2+ salt was likely to be very insoluble. Taurine conjugates were much more soluble than their corresponding unconjugated derivatives: chenodeoxycholyltaurine, 384; deoxycholyltaurine, 117; and cholyltaurine, greater than 10,000. Calcium salts of unconjugated bile acids precipitated rapidly in contrast to those of glycine conjugates which were metastable for months. Thus, hepatic conjugation of bile acids with taurine or glycine not only enhances solubility at acidic pH, but also at Ca2+ ion concentrations present in bile and intestinal content.


        • Hofmann A.E.
        The enterohepatic circulation of bile acids.
        in: Schultz S.G. Handbook of physiology. The Gastrointestinal System. American Physiological Society, Bethesda, MD1989: 567-596
        • Carey M.C
        • Cahalane M.J.
        Enterohepatic circulation.
        in: Arias I.M. Jakoby W.B. Popper H. Schachter D. Shafritz D.A. The Liver. Biology and Pathobiology. Raven Press, New York, NY1988: 573-616
        • Setchell K.D.R.
        • Street J.M.
        • Sjovall J.
        Fecal bile acids.
        in: Setchell K.D.R. Kritch-evsky D. Nair P.P. The Bile Acids. Plenum Press, New York1988: 441-570
        • Fini A.
        • Roda A.
        Chemical properties of bile acids. IV. Acidity constants of glycine-conjugated bile acids.
        J. Lipid Res. 1987; 28: 755-759
        • Hofmann A.R
        • Mysels K.J.
        Bile salts as biological surfactants.
        Colloids Surf. 1988; 30: 145-173
        • Hofmann A.F
        • Mysels K.J.
        Bile acid solubility and precipitation in vitro and in vivo: the role of conjugation, pH, and Ca2+ ions.
        J. Lipid Res. 1992; 33: 617-626
        • Hofmann A.F
        • Roda A.
        Physicochemical properties of bile acids and their relationship to biological properties: an overview of the problem.
        J. Lipid Res. 1984; 25: 1477-1489
        • Jones C
        • Hofmann A.F.
        • Mysels K.J.
        • Roda A.
        The effect of calcium and sodium ion concentration on the properties of dilute aqueous solutions of glycine conjugated bile salts.
        J. Colloid Interface. Sci. 1986; 114: 452-470
        • Newmark H.L.
        • Wargovich M.J.
        • Bruce W.R.
        Colon cancer and dietary fat, phosphate and calcium: a hypothesis.
        J. Natl. Cancer Inst. 1984; 72: 1323-1325
        • Lipkin M.
        • Newmark H.
        Effect of added dietary calcium on colonic epithelial-cell proliferation in subjects at high risk for familial colonic cancer.
        N. Engl. J. Med. 1985; 313: 1381-1384
        • Tserng K-Y.
        • Hachey D.I.
        • Klein P.D.
        An improved procedure for the synthesis of glycine and taurine conjugates of bile acids.
        J. Lipid Res. 1977; 18: 404-407
        • Hofmann A.F.
        Thin-layer adsorption chromatography of free and conjugated bile acids on silicic acid..
        J. Lipid Res. 1962; 3: 127-128
        • Rossi S.S.
        • Converse J.L.
        • Hofmann A.F.
        High pressure liquid chromatographic analysis of conjugated bile acids in human bile: simultaneous resolution of sulfated and unsulfated lithocholyl amidates and the common conjugated bile acids.
        J. Lipid Res. 1987; 28: 589-595
        • Abu-Hamdiyyah M.
        • Mysels K.J.
        The dialysis of sodium dodecyl sulfate, its activity above the CMC, and the phase separation model of micelle formation.
        J. Phys. Chem. 1967; 71: 418-424
        • Roda A.
        • Fini A.
        Effect of nuclear hydroxy sub-stituents on aqueous solubility and acidic strength of bile acids.
        Hepatology. 1984; 4: 72S-76S
        • Ekwall P.
        • Rosendahl T.
        • Lofman N.
        Studies on bile acid salt solutions. I. The dissociation constants of the cholic and deoxycholic acids.
        Acta Chem. Scand. 1957; 11: 590-598
        • Cabral D.J.
        • Small D.M.
        Physical chemistry of bile.
        in: Schultz S.G. Forte J.G. Rauner B.B. Handbook of Physiology. Section 6: The Gastrointestinal System. American Physiological Society, Bethesda1989: 621-662
        • Turley S.D.
        • Dietschy J.M.
        Re-evaluation of the 3α-hydroxysteroid dehydrogenase assay for total bile acids in bile.
        J. Lipid Res. 1978; 19: 924-928
        • Schoelmerich J.
        • van Berge Henegouwen G.P.
        • Hofmann A.F.
        • DeLuca M.
        A bioluminescence assay for total 3α-hydroxy bile acids in serum using immobilized enzymes.
        Clin. Chim. Acta. 1984; 137: 21-32
        • Skoog D.A.
        • West D.M.
        Fundamentals of Analytical Chemistry. 2nd Edition. Rinehart and Winston, New York, NY1969
        • Roda A.
        • Hofmann A.F.
        • Mysels K.J.
        The influence of bile salt structure on self-association in aqueous solutions.
        J. Biol. Chem. 1983; 258: 6362-6370
        • Mukerjee P.
        • Cardinal J.R.
        Solubilization as a method for studying self-association: solubility of naphthalene in the bile salt sodium cholate and the complex pattern of its aggregation.
        J. Pharm. Sci. 1976; 65: 882-886
        • Mukerjee P.
        • Mysels K.J.
        Critical concentrations of aqueous surfactant systems. NSRDS-NBS 36, Government Printing Office, Washington, D.C.1971
        • Abramowitz M.
        • Syegum I.
        Handbook of Mathematical Functions. Dover Publications, New York1965
        • Moore E.W.
        • Celic L.
        • Ostrow J.D.
        Interactions between ionized calcium and sodium taurocholate: bile salts are important buffers for prevention of calcium-containing gallstones.
        Gastroenterology. 1982; 83: 1079-1089
        • Small D.M.
        • Admirand W.H.
        Solubility of bile salts.
        Nature. 1969; 221: 265-267
        • Hogan A.
        • Ealick S.E.
        • Bugg C.E.
        • Barnes S.
        Aggregation patterns of bile salts: crystal structure of calcium cholate chloride heptahydrate.
        J. Lipid Res. 1984; 25: 791-798
        • Lichtenberg D.
        • Younis N.
        • Bor A.
        • Kushnir T.
        • Shefi M.
        • Almog S.
        • Nir S.
        On the solubility of calcium deoxycholate: kinetics of precipitation and the effect of conjugated bile salts and lecithin.
        Chem. Phys. Lipids. 1988; 46: 279-291
        • Rich A.
        • Blow D.M.
        Formation of a helical steroid complex.
        Nature. 1958; 182: 423-426
        • DAlgni M.
        • Forcellese M.L.
        • Giglio E.
        Study of the interaction between an optical probe and micelles of sodium deoxycholate.
        Colloid Polymer. Sci. 1985; 263: 160-163
        • Campanelli A.R.
        • Candeloro De Sanctis S.
        • Giglio E.
        • Scaramuzza L.
        A model for micellar aggregates of a bile salt: crystal structure of sodium taurodeoxycholate monohydrate.
        J. Lipid Res. 1987; 28: 483-489
        • Lindley P.F
        • Mahmoud M.M.
        • Watson F.E.
        The structure of chenodeoxycholic acid, C24H40O4.
        Acta Crystallogr. 1980; B36: 1893-1897
        • Lindley P.F.
        • Carey M.C.
        Molecular packing of bile acids: structure of ursodeoxycholic acid.
        J. Crystallogr. Spectres. Res. 1987; 17: 231-249
        • Schmassmann A.
        • Angellotti M.A.
        • Clerici C.
        • Hofmann A.F.
        • Ton-Nu H-T.
        • Schteingart C.D.
        • Marcus S.N.
        • Hagey L.R.
        • Rossi S.S.
        • Aigner A.
        Transport, metabolism, and effect of chronic feeding of lagodeoxy-cholic acid, a new, natural bile acid. Studies in three rodent species.
        Gastroenterology. 1990; 99: 1092-1104