32S TV. WAXES, HIGHER AT.COHOT.S, ETC. 



terol, cholestanol, has been isolated from certain sponges.'"^ Chalinasterol 

 has also been found."- Panzer"^ has demonstrated the presence of choles- 

 terol in one protozoon, namely, Goussia gadi, which he isolated from the air 

 bladders of the pollack. It is possible that cholesterol may haxe origi- 

 nated from the host rather than from the parasitic coccidia. Although 

 cholesterol is found in many bivalves, the oyster contains a modified form 

 referred to as ostreasterol."^ Gastropods (snails) have been found to con- 

 tain cholesterol regardless of feeding habits. "^ 



(2') Physical Properties of Cholesterol: Cholesterol occurs in two 

 types of crystals. When it is prepared from solutions of anhydrous sol- 

 vents, it forms needle-like crystals. On the other hand, when the solvent 

 contains water, for example, 95% alcohol, the cholesterol separates as shiny 

 monoclinic platelets resembling mother of pearl, having one molecule of 

 water of crystallization. The water of crystallization is lost when these 

 platelets are heated at 100 °C., or when the product is dried over concen- 

 trated sulfuric acid. The crystals readily disintegrate on standing. 



Like other lipids, cholesterol is soluble in organic solvents, such as 

 alcohol, ether, chloroform, benzene, and petroleum ether, as well as in fats 

 and oils. It readily dissolves in cold ethyl acetate, which fact enables it to 

 be easily separated from other lipoids. It is soluble with difficulty in cold 

 alcohol, but it readily dissolves in hot 95% (5.5 parts) and 85% (9 parts) 

 alcohol. Colloidal solutions of cholesterol, which remain remarkably 

 stable over long periods, can be prepared by the addition of an acetone solu- 

 tion to water. "^ Cholesterol melts sharply at 148.5 °C. It can be dis- 

 tilled under a high vacuum and can also be sublimed. 



Because of the presence of several asymmetric carbon atoms, cholesterol 

 exhibits optical rotation, [afj" is given as —31.1"^ and —29.9^^* in 4% 

 ethereal solution. Apparently, the specific rotation is independent of con- 

 centration. After a prolonged exposure to air, oxidation occurs, with a 

 yellowing of the crystals and a resultant lowering of the melting point and 

 a change in solubility. 



Another interesting property exhibited by cholesterol deposits in the 

 tissues is that of birefringence. Such double refraction is of considerable 

 assistance in the qualitative identification of this lipid in tissues, as it is not 

 exhibited by other lipids. 



Considerable data are available on the turbidity points, melting points, 

 and optical rotation of the cholesteryl esters (see Table 4). Cholesteryl 



'" W. Bergmann, D. H. Gould, and E. M. Low, J. Org. Chem., 10, 570-579 (1945). 



1" W. Bergmann, H. P. Schedl, and E. M. Low, J. Org. Chem., 10, 587-593 (1945). 



1" T. Panzer, Z. physiol. Chem., 73, 109-127 (1911). 



17* W. Bergmann, J. Biol. Chem., 104, 317-328, 553-557 (1934). 



175 W. Bergmann and E. M. Low, J. Org. Chem., 12, G7-75 (1947). 



i'« L. S. Moyer, Biochem. Z., 273, 122-131 (1934). 



i" O. Hessej Ann., 192, 175-179 (1878). 



