Stereospecific formation of (24E)-3.ALPHA.,7.ALPHA.,12.ALPHA.-trihydroxy-5.BETA.-cholest-24-en-26-oic acid and (24R,25S)-3.ALPHA.,7.ALPHA.,12.ALPHA.,24-tetrahydroxy-5.BETA.-cholestan-26-oic acid from either (25R)- or (25S)-3.ALPHA.,7.ALPHA.,12.ALPHA.-trihydroxy-5.BETA.-cholestan-26-oic acid by rat liver homogenate.

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  • UNE Mizuho
    Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine
  • MORIGAMI Izumi
    Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine
  • KIHIRA Kenji
    Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine
  • HOSHITA Takahiko
    Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine

Description

Studies of the stereochemistry of the intermediates, 3α, 7α, 12α-trihydroxy-5β-cholest-24-en-26-oic acid and 3α, 7α, 12α, 24-tetrahydroxy-5β-cholestan-26-oic acid, in the bio-synthetic sequence between 3α, 7α, 12α-trihydroxy-5β-cholestan-26-oic acid and cholic acid have been undertaken. (25 R)- or (25 S)-3α, 7α, 12α-Trihydroxy-5β-cholestan-26-oic acid was incubated with rat liver homogenates. The reaction products were converted to p-bromophenacyl ester derivatives and the esters were analyzed by high-performance liquid chromatography. By comparison with authentic samples of two (24 E)- and (24 Z)-isomers of the α, β-unsaturated acid and of four isomers at C-24 and C-25 of the β-hydroxy acid, (24 E)-3α, 7α, 12α-trihydroxy-5β-cholestan-26-oic acid and (24 R, 25 S)-3α, 7α, 12α, 24-tetrahydroxy-5β-cholestan-26-oic acid were found to be formed from either (25 R)- or (25 S)-3α, 7α, 12α-trihydroxy-5β-cholestan-26-oic acid. No formation of the (24 Z)-isomer of the trihydroxycholestenoic acid or the other three isomers of the tetrahydroxycholestanoic acid was detected. The findings are discussed in relation to the assumed pathway for side chain cleavage in cholic acid biosynthesis.

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