NATURAL WAXES 



343 



Cholesterol 



Dihydrocholesterol 



CuO 



Cholestanone 



(A /B : trans) 



Cholestenoiic 



Transformation of alio to normal series 



Coprostanone 

 (A/B: cia) 



c'. Dihydrocliolesterol. This substance closely resembles cholesterol, 

 with which it is frequently associated in nature. As noted earlier, most 

 preparations of cholesterol made from natural sources contain 1 to 2% of 

 this saturated sterol. '^'' '^^ It was discovered by von Boehm^'* in intestinal 

 contents and was later isolated from the feces by Windaus and Uibrig.^ii 

 Presumably, it is formed by hydrogenation of cholesterol in the body, and 

 is excreted through the intestinal wall, which explains its presence in feces. -^' 

 Dihydrocholesterol can readilj'^ be prepared in the laboratory by controlled 

 reduction of cholesterol. It also originates, along with equal amounts of 



218 R. Yon Borhm, Biochem. Z., 33, 474-479 (1911). 



"3 R. Sclunihi-imor and II. v. Behring, Z. phijsiol. Chem., 192, 102-111 (1930). 



