title: Regio- and stereoselective reductions of dehydrocholic acid.
abstract: Dehydrocholic acid (DHCA), an unnatural bile acid, is manufactured by oxidation of cholic acid. Its biotransformation by two basidiomycetes (Trametes hirsuta and Collybia velutipes) is reported. These mycelia showed different affinities for the substrate and selectivities of attack: T. hirsuta in particular regio- and stereoselectively reduced the 3-keto group to yield 3 alpha-hydroxy-7,12-diketo-5 beta-cholan-24-oic acid (7,12-diketolithocolic acid) as the main product. A number of different chemical reductions were carried out on DHCA; among them hydrogenation with Raney Nickel in water under high-intensity ultrasound proved highly regio- and stereoselective, yielding 7,12-diketolithocolic acid exclusively. (1)H and (13)C resonances were assigned in details thanks to a series of 1D and 2D NMR runs including DEPT, NOESY, H-H COSY, gHSQC and gHMBC.
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, via P. Giuria 9, 10125 Torino, Italy. giancarlo.cravotto@unito.it
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cravotto
authors.forename: Arianna
authors.initials: A
authors.lastname: Binello
authors.forename: Luisa
authors.initials: L
authors.lastname: Boffa
authors.forename: Ornelio
authors.initials: O
authors.lastname: Rosati
authors.forename: Marco
authors.initials: M
authors.lastname: Boccalini
authors.forename: Stefano
authors.initials: S
authors.lastname: Chimichi
mesh_terms: D001487:Basidiomycota / Q000378:metabolism*; D001711:Biotransformation; D003685:Dehydrocholic Acid / Q000378:metabolism*; D006865:Hydrogenation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D013045:Species Specificity; D013379:Substrate Specificity; D014465:Ultrasonics; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D003685:Dehydrocholic Acid