Conversion of Cholesterol to Trihydroxycoprostanic Acid and Cholic Acid in Man*

Some lower vertebrates, such as certain fishes, amphibia, and reptiles, do not shorten the cholesterol side chain in the formation of bile acids but simply oxidize the terminal methyl groups to "primitive" 27-carbon bile alcohols or acids. Haslewood has proposed that some of these C-27 compounds may be intermediates in the biochemical pathway by which more recently evolved animals transform cholesterol to "modern" C-24 bile acids (1).