title: A novel varanic acid epimer--(24R,25S)-3α,7α,12α,24-tetrahydroxy-5β-cholestan-27-oic acid--is a major biliary bile acid in two varanid lizards and the Gila monster.
abstract: A key intermediate in the biosynthetic pathway by which C(24) bile acids are formed from cholesterol has long been considered to be varanic acid, (24ξ,25ξ)-3α,7α,12α-24-tetrahydroxy-5β-cholestan-27-oic acid. The (24R,25R)-epimer of this tetrahydroxy bile acid, in the form of its taurine N-acyl amidate, was thought to be the major biliary bile acid in lizards of the family Varanidae. We report here that a major biliary bile acid of three lizard species - the Komodo dragon (Varanus komodoensis), Gray's monitor (Varanus olivaceus), and the Gila monster (Heloderma suspectum) - is a novel epimer of varanic acid. The epimer was shown to be (24R,25S)-3α,7α,12α,24-tetrahydroxy-5β-cholestan-27-oic acid (present in bile as its taurine conjugate). The structure was established by mass spectroscopy and by (1)H and (13)C nuclear magnetic spectroscopy, as well as by synthesis of the compound.
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla, CA 92093-063, USA. LHagey@ucsd.edu
authors.forename: Lee R
authors.initials: LR
authors.lastname: Hagey
authors.forename: Shoujiro
authors.initials: S
authors.lastname: Ogawa
authors.forename: Narimi
authors.initials: N
authors.lastname: Kato
authors.forename: Rika
authors.initials: R
authors.lastname: Satoh née Okihara
authors.forename: Mizuho
authors.initials: M
authors.lastname: Une
authors.forename: Kuniko
authors.initials: K
authors.lastname: Mitamura
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ikegawa
authors.forename: Alan F
authors.initials: AF
authors.lastname: Hofmann
authors.forename: Takashi
authors.initials: T
authors.lastname: Iida
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001659:Biliary Tract / Q000378:metabolism*; D002777:Cholestanols / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008116:Lizards; D013237:Stereoisomerism
chemical_list: D001647:Bile Acids and Salts; D002777:Cholestanols; C024759:3,7,12,24-tetrahydroxycholestanoic acid