25G IV. DIGESTION OF LIPIDS OTHER THAN FATS 



born), and also from the feces of bile-fistula dogs on a fat-free diet. Sterile 

 cysts in the small and large intestine also contained this alcohol. It is 

 believed that it is normally secreted into the lumen of the intestine, to be 

 excreted in the feres. It is suggested by Sohoenheimer and Hilgetag 14 

 that endogenous cetyl alcohol may act as a natural purgative, a fact 

 proved earlier by Macht 35 with exogenous cetyl alcohol. However, in 

 latter work, Stetten and Schoenheimer 36 failed to note any purgative 

 action on the part of cetyl or octadecyl alcohol in rats. 



Although the presence of cetyl alcohol in feces might be interpreted as 

 indicative of its failure to be absorbed, there is evidence that this alcohol 

 may be taken up by the intestinal mucosa. The metabolic fate may to 

 some extent resemble that of cholesterol, which can be absorbed by the 

 small intestine, and which is also known to be secreted by the mucosa, 

 particularly of the large intestine. As noted earlier, Munk and Rosen- 

 stein 25 were unable to detect cetyl palmitate or cetyl alcohol in the chyle 

 from a patient suffering from a chronic chyle fistula, after he had been 

 given cetyl palmitate in the form of spermaceti, although they did demon- 

 strate the presence of some of the palmitic acid, as tripalmitin, in the 

 chyle. This would indicate that the ester was hydrolyzed, and that at 

 least part of it was absorbed. The experiments of Mancke 37 are some- 

 what more indicative in proving the absorption of cetyl alcohol, since 

 he was able to account for only a fraction of ingested cetyl alcohol in the 

 feces. As much as 62% of the cetyl alcohol fed to a goose failed to be 

 recovered from the feces. However, no cetyl alcohol was found in the 

 deposit fat or in the chyle, so there is still a possibility that the alcohol 

 unaccounted for might have been destroyed in the gastrointestinal tract. 

 Thomas and Flaschentrager 38 have shown that the dog absorbs cetyl alcohol 

 rather poorly, but that its ester is more readily utilized. The authors 

 attribute this difference in assimilability to the lower melting point of the 

 ester. Others have demonstrated the same behavior in the rat. 36 - 39 - 40 



Channon and Collinson 40 considered that the finding of a markedly in- 

 creased unsaponifiable fraction in the liver of rats following the adminis- 

 tration of cetyl alcohol was indirect proof that the alcohol itself had been 

 absorbed. The quantities of unsaponifiable extract were too small to 

 afford a positive identification of the substance. However, the presence 



* D. I. Macht, Proc. Soc. Exptl. Biol. Med., 30, 1272-1273 (1932-19.33). 



36 De W. Stetten and R. Schoenheimer, J. Biol. Chem., 133, 347-357 (1940). 



87 R. Mancke, Z. phystol Chem., 162, 238-263 (1927). 



38 K. Thomas and B. Flaschentrager, Skand. Arch. Physiol, 43, 1-5 (1923). 



39 C. L. Carter and J. Malcolm, Biochem, J., 21, 484^93 (1927). 



40 H. J. Channon and G. A. Collinson, Biochem. J., 22, 391-401 (1928). 



