DIGESTION, ETC. OF STEROLS IN THE G.I. TRACT 2G9 



no increase in liver sterols could be detected after the feeding of stig- 

 masterol or brassicasterol to mice. The latter sterol belongs to the C28- 

 series, and was first isolated from the oil of turnip. 



Phytosterols possess the property of forming soluble compounds with 

 bile salts. Thus, Kuthy 121 demonstrated that phytosterols are as readily 

 diffusible through parchment paper, in the presence of bile acids, as is 

 cholesterol. In spite of this finding, and also in spite of the fact that 

 phytosterols occur to a large extent in the human diet, there is no valid 

 evidence that they can be converted to cholesterol or that they can be 

 absorbed as such. 



Ostreasterol, which is a Cog-sterol obtained from oysters and other mol- 

 luscs, and which occupies a position intermediate between cholesterol and 

 the phytosterols, resembles cholesterol in that it is capable of being ab- 

 sorbed. Thus, Sperry and Bergmann 120 found that an appreciable in- 

 crease in liver sterols occurred after ostreasterol was fed to mice. 



In addition to the phytosterols, there is considerable evidence that 

 sterols more closely related to cholesterol cannot be absorbed. Tests 

 have been made on several of the C 2 rgroup of sterols, such as /3-cholestanol, 

 coprostanol, and coprostenol (allocholesterol). According to Schon- 

 heimer and co-workers, 113 as well as to Burger and Winterseel, 122 /3-chole- 

 stanol (dihydrocholesterol), which is present in most cholesterol prepara- 

 tions to the extent of 1 to 2%, is not absorbed by man or by animals. 

 Coprostanol, also, is non-absorbable. 122 The same is true of copro- 

 stenol, 118 - 122 which is isomeric with cholesterol 113 ' 117 ' 123 - 124 ; this sterol can- 

 not be absorbed by mice or dogs. Evans 125 reported that coprostenol 

 could not be demonstrated in eggs after it had been fed to hens. Pre- 

 sumably, this sterol is not absorbed by the hen. Finally, Schon- 

 heimer 112 ' 113,126 reported that all four isomers of cholestanol are non- 

 absorbable. Thus, in the group of C27-steroids, only cholesterol can be 

 absorbed from the gastrointestinal tract. 



Ergosterol is the sole common representative of the C 2 8-sterols to be 

 investigated. Although Schonheimer et al. 127 were unable to demonstrate 



121 A. v. Kuthy; cited by F. Verzar and E. J. McDougall, Absorption jrom the Intes- 

 tine, Longmans, Green, London-New York, 1936, p. 213. 



122 M. Burger and W. Winterseel, Z. physiol. Chem., 202, 237-245 (1931). 



123 R. Schoenheimer, Science, 74, 579-584 (1931). 



124 R. Schoenheimer, D. Dam, and K. von Gottberg, /. Biol. Chem., 110, 667-671 

 (1935). 



128 E. A. Evans, Jr., J. Biol. Chem., 115, 449-451 (1936). 



126 R. Schonheimer and H. v. Behring, Z. physiol. Chem., 192, 102-111 (1930). 



127 R. Schonheimer, H. v. Behring, and K. v. Gottberg, Z. physiol. Chem., 208, 77-85 

 (1932). 



