Journal of Lipid Research, Vol 20, 489-493, Copyright © 1979 by Lipid Research, Inc.
Metabolism of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol into cholic acid in normal human subjects
RF Hanson, AB Staples and GC Williams
Side chain oxidation and cleavage of precursors in cholic acid synthesis is
thought to involve initial hydroxylation at either position 25 or 26 of the
side chain. Therefore, the conversion of 5 beta-cholestane-3 alpha, 7
alpha, 12 alpha, 26-tetrol and 5 beta- cholestane-3 alpha, 7 alpha, 12
alpha, 25-tetrol into cholic acid was studied in normal subjects after
single intravenous injections of these labeled alcohols. Eighty-six percent
and 82% of 5 beta-cholestane, 3 alpha, 7 alpha, 12 alpha, 26-tetrol was
converted into cholic acid in two subjects, respectively. However, only 14
and 16% of the injected 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,
25-tetrol was converted into cholic acid in two subjects, respectively.
Thus, this study indicates that 5 beta-cholestane-3 alpha, 7 alpha, 12
alpha, 25-tetrol is an inefficient substrate for cholic acid biosynthesis
in man and that the major route of cholic acid synthesis probably involves
the 26- hydroxylated intermediate.
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