- A new non-enzymatic route to chenodeoxycholic acid
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A novel route for the production of the chenodeoxycholic acid is described, based on the selective non-enzymatic reduction of dehydrocholic acid. The relative reactivity scale was established to be in the order: 12-keto (1), 7-keto (2), 3-keto (17.5).
- Bortolini, Olga,Cova, Umberto,Fantin, Giancarlo,Medici, Alessandro
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- Biotransformations of Bile Acids with Bacteria from Cayambe Slaughterhouse (Ecuador): Synthesis of Bendigoles
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The biotransformations of cholic acid (1a), deoxycholic acid (1b), and hyodeoxycholic acid (1c) to bendigoles and other metabolites with bacteria isolated from the rural slaughterhouse of Cayambe (Pichincha Province, Ecuador) were reported. The more active strains were characterized, and belong to the genera Pseudomonas and Rhodococcus. Various biotransformation products were obtained depending on bacteria and substrates. Cholic acid (1a) afforded the 3-oxo and 3-oxo-4-ene derivatives 2a and 3a (45% and 45%, resp.) with P.?mendocina ECS10, 3,12-dioxo-4-ene derivative 4a (60%) with Rh.?erythropolis ECS25, and 9,10-secosteroid 6 (15%) with Rh.?erythropolis ECS12. Bendigole F (5a) was obtained in 20% with P.?fragi ECS22. Deoxycholic acid (1b) gave 3-oxo derivative 2b with P.?prosekii ECS1 and Rh.?erythropolis ECS25 (20% and 61%, resp.), while 3-oxo-4-ene derivative 3b was obtained with P.?prosekii ECS1 and P.?mendocina ECS10 (22% and 95%, resp.). Moreover, P.?fragi ECS9 afforded bendigole A (8b; 80%). Finally, P.?mendocina ECS10 biotransformed hyodeoxycholic acid (1c) to 3-oxo derivative 2c (50%) and Rh.?erythropolis ECS12 to 6α-hydroxy-3-oxo-23,24-dinor-5β-cholan-22-oic acid (9c, 66%). Bendigole G (5c; 13%) with P.?prosekii ECS1 and bendigole H?(8c) with P.?prosekii ECS1 and Rh.?erythropolis ECS12 (20% and 16%, resp.) were obtained.
- Costa, Stefania,Maldonado Rodriguez, Maria Elena,Rugiero, Irene,De Bastiani, Morena,Medici, Alessandro,Tamburini, Elena,Pedrini, Paola
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p. 969 - 975
(2016/09/09)
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- Radical-mediated dehydrogenation of bile acids by means of hydrogen atom transfer to triplet carbonyls
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The aim of the present paper is to explore the potential of radical-mediated dehydrogenation of bile salts (BSs), which is reminiscent of the enzymatic action of hydroxysteroid dehydrogenase enzymes (HSDH). The concept has been demonstrated using triplet carbonyls that can be efficiently generated upon selective UVA-excitation. Hydrogen atom transfer (HAT) from BSs to triplet benzophenone (BP) derivatives gave rise to radicals, ultimately leading to reduction of the BP chromophore with concomitant formation of the oxo-analogs of the corresponding BSs. The direct reactivity of triplet BP with BSs in the initial step was evaluated by determining the kinetic rate constants using laser flash photolysis (LFP). The BP triplet decay was monitored (λmax = 520 nm) upon addition of increasing BS concentrations, and the obtained rate constant values indicated a reactivity of the methine hydrogen atoms in the order of C-3 2 than under O2, also supporting the role of the oxygen-quenchable triplet in the dehydrogenation process. Furthermore, irradiation of deaerated aqueous solutions of sodium cholate in the presence of KPMe provided the oxo-analogs, 3[O],7[O]-CA, 3[O]-CA and 7[O]-CA, arising from the HAT process.
- Miro,Marin,Miranda
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p. 2679 - 2683
(2016/03/05)
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- Regio- and stereoselective reductions of dehydrocholic acid
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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 3α-hydroxy-7,12-diketo-5β-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. 1H and 13C resonances were assigned in details thanks to a series of 1D and 2D NMR runs including DEPT, NOESY, H-H COSY, gHSQC and gHMBC.
- Cravotto, Giancarlo,Binello, Arianna,Boffa, Luisa,Rosati, Ornelio,Boccalini, Marco,Chimichi, Stefano
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p. 469 - 475
(2007/10/03)
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