Studies on the Conversion of Mevalonate into Bile Acids and Bile Alcohols in Toad and the Stereospecific Hydroxylation at Carbon Atom 26 during Bile Alcohol Biogenesis
1. When mevalonate-2-14C was injected intraperitoneally into toad, radioactive cholic acid* and 5β-bufol were isolated from the gall-bladder bile, while the main bile acids of this Anura, 3α, 7α, 12alpha;-trihydroxy-5β-cholest-22-ene-24-carboxylic acid, and 3α, 7α, 12α-trihydroxy-5β-cholest-23-enoic acid were found to be unlabeled. 2. The radioactive 5β-bufol was oxidized with lead tetraacetate to cholyl methyl ketone with the liberation of formaldehyde. The cholyl methyl ketone had the same specific radioactivity as the 5β-bufol. The cholyl methyl ketone was degraded into homocholic acid with decreased (16.7%) specific activity. It was concluded that the 26-hydroxylation in the biosynthesis of 53-bufol occurs in a stereospecific manner.