Bile acids. LI. Formation of 12alpha-hydroxyl derivatives and companions from 5 alpha-sterols by rabbit liver microsomes.

A comparison of the activity of rabbit liver microsomes fortified with 0.1 mM NADPH to promote 12alpha-hydroxylation over 60 minutes with appropriate sterols provided the following relative order of activities: kalpha-cholestane-3alpha, 7alpha-diol, 100; 7alpha-hydroxy-5alpha-cholestane-3one, 76; 7alpha-hydroxycholest-4-en-3-one, 64; 5alpha-cholestane-3-3beta, 7alpha-diol, 26; allochendoexycholate, 22. If the more polar products formation. Investigation by gas-liquid chromatography-mass spectrometry of the nature of these more polar products derived form 5alpha-cholestane-3alpha, 7alpha-diol showed that a series of tetrols was dormed; i.e., 5alpha-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol as the major product and lesser amounts of 5alpha-cholestane-3alpha, 7alpha, 12alpha, 24- and 3alpha, 7alpha, 12alpha, 23tetrols. No significant amount of 26-hydroxylated product was formed.