Phytosterols in Normal and Tumor-bearing Rats¹

The typical phytosterols, 24-methyl- and 24-ethylcholesterol, were isolated from a Morris rat hepatoma as well as from normal rat liver. They represented 1% of the total sterol in both normal and cancerous cases. When rats bearing the hepatoma were given injections of 22,23-³H₂-24-ethylcholesterol, 15% of the labeled sterol was subsequently found distributed between the normal liver, the hepatoma, and the remaining carcass. The deposition of injected cholesterol-4-¹⁴C was also demonstrated, and greater incorporation of label (85%) indicated a slower turnover rate than for the phytosterol. The radioactive 24-ethylcholesterol did not lead to incorporation of label into cholesterol or into any other observable sterol. Since the phytosterols found in the liver and hepatoma corresponded to the most common of the plant sterols, and since one of them (the 24-ethyl derivative) was experimentally depositable, they are presumably of dietary origin.