Physicochemical and physiological properties of 5 -cyprinol sulfate, the toxic bile salt of cyprinid fish

5 -Cyprinol sulfate was isolated from bile of the Asiatic carp, Cyprinus carpio . 5 -Cyprinol sulfate was surface active and formed micelles; its critical micellization concentration (CMC) in 0.15 M Na using the maximum bubble pressure device was 1.5 mM; by dye solubilization, its CMC was 4 mM. At concentrations 1 mM, 5 -cyprinol sulfate solubilized monooleylglycerol efficiently (2.1 molecules per mol micellar bile salt). When infused intravenously into the anesthetized rat, 5 -cyprinol sulfate was hemolytic, cholestatic, and toxic. In the isolated rat liver, it underwent little biotransformation and was poorly transported (T max 0.5 mol/min/kg) as compared with taurocholate. 5 -Cyprinol, its bile alcohol moiety, was oxidized to its corresponding C 27 bile acid and to allocholic acid (the latter was then conjugated with taurine); these metabolites were efficiently transported. 5 -Cyprinol sulfate inhibited taurocholate uptake in COS-7 cells transfected with rat asbt , the apical bile salt transporter of the ileal enterocyte. 5 -Cyprinol had limited aqueous solubility (0.3 mM) and was poorly absorbed from the perfused rat jejunum or ileum. Sampling of carp intestinal content indicated that 5 -cyprinol sulfate was present at micellar concentrations, and that it did not undergo hydrolysis during intestinal transit. These studies indicate that 5 -cyprinol sulfate is an excellent digestive detergent and suggest that a micellar phase is present during digestion in cyprinid fish. —Goto, T., F. Holzinger, L. R. Hagey, C. Cerrè, H-T. Ton-Nu, C. D. Schteingart, J. H. Steinbach, B. L. Shneider, and A. F. Hofmann. Physicochemical and physiological properties of 5 -cyprinol sulfate, the toxic bile salt of cyprinid fish. J. Lipid Res. 2003. 44: 1643–1651. Supplementary key words Cyprinus carpio • bile acids • micelles • bacterial deconjugation • fat digestion • fat absorption • hepatic transport • cholestasis • intestinal absorption • solubilization In vertebrates, cholesterol is eliminated by conversion to water-soluble amphipathic, functional molecules called bile salts. Bile salts can be divided into three classes based on side-chain structure: C 27 bile alcohols, C 27 bile acids, and C 24 bile acids (1). After their biosynthesis from cholesterol, bile alcohols and bile acids undergo “conjugation,” a biotransformation step that renders them water soluble and membrane impermeable at physiological pH. Bile alcohols are conjugated by esterification of the terminal C-27 hydroxy group with sulfate, whereas bile acids are usually conjugated by N-acyl amidation of the terminal C-27 or C-24 carboxyl group with taurine or glycine (2, 3). The occurrence of C 27 bile alcohol sulfates is widespread in nature. They are the dominant bile salts of ancient mammalian species (elephant, manatee, hyrax, and rhinoceros) (4). They are also the major biliary surfactants present in cartilaginous fish (sharks, rays, and skates), herbivorous bony fish (carp, arapima, and angelfish), and in some amphibians (salamanders and frogs) (3, 5). One of the common bile alcohols is 5 -cyprinol, a molecule with five hydroxy groups that was originally isolated from the bile of Cyprinus carpio, the Asiatic carp. Cyprinol was shown to have hydroxy groups at C-3, C-7, C-12, C-26, and C-27, based on the work of Hoshita, Magayoshi, and Kazuno (6) and Anderson, Briggs, and Haslewood (7). Confirmation of the structure of the sulfate ester of 5 -cyprinol by proton and 13 C-NMR as well as mass spectrometry (MS) has been reported by Asakawa et al. (8) 7 . The A/B ring juncture of cyprinol is 5 (A/B trans ), whereas the structure of most C 27 and C 24 bile acids is 5 (A/B cis ). It has become customary to add a 5 prefix to cyprinol to indicate clearly its 5 -A/B trans juncture, and thus distinguish it from 5 -cyprinol (A/B cis ), which is present in other fish, such as the sturgeon (9). The structure of 5 -cyprinol sulfate is shown in Fig. 1 . 1 Present address for T. Goto: Department of Chemistry and Biochemistry, Numazu College of Technology, Numazu, Shizuoka 410-8501, Japan. 2 Present address for F. Holzinger: Department of Surgery, Inselsspital, University of Bern, Switzerland. 3 Present address for C. Cerrè: Bioikos Farma s.r.l, 40122 Bologna, Italy. 4 Present address for H-T. Ton-Nu: La Jolla Pharmaceutical Company, San Diego, CA 92121. 5 Present address for C. D. Schteingart: Ferring Research Institute, San Diego, CA 92121. 6 To whom correspondence should be addressed. e-mail: [email protected] 7 Chemical Abstracts has assigned the registry number 15066-41-8 to 5 -cyprinol sulfate. Its index name is Cholestane-3,7,12,26,27-pentol, hydrogen sulfate, (3 ,5 ,7 ,12 ) . The assignment of the sulfate to C-27 versus C-26 is arbitrary. Manuscript received 14 April 2003 and in revised form 4 June 2003. Published, JLR Papers in Press, June 16, 2003. DOI 10.1194/jlr.M300155-JLR200 by gest, on A uust 8, 2017 w w w .j.org D ow nladed fom