Journal of Lipid Research, Vol 24, 781-783, Copyright © 1983 by Lipid Research, Inc.
[24,25-3H]Cholesterol: presence of tritium at additional sites in the side chain
RS Rosenfeld, I Paul and B Zumoff
In order to measure the distribution of radioactivity present in the side
chain of [24,25-3H]cholesterol prepared by a sequence involving catalytic
tritiation of 3 alpha, 5 alpha-cyclocholest-24-en-6 beta-ol 6- methyl
ether, the cholesterol was oxidized to 4-cholesten-3-one, which was then
cleaved between C-24 and C-25 to afford the C24 alcohol. Oxidation to the
corresponding cholenoic acid, followed by alkali equilibration and
esterification completed the sequence. It was found that about 20% of the
tritium in the labeled cholesterol is not lost when this tracer is
physiologically converted to bile acids. Consequently, measurements of bile
acid formation using this tracer must be corrected upward by this amount.