PUOPEUTIKS OF CEREBROSIDES 485 



ency to undergo myelin formation.^'-*''"* Further description of myeliniza- 

 tion is given by Lehmann/-^ Plirenosine is dextro-rotatory, but the data 

 obtained by various investigators differ greatly. In a 3:1 chloroform- 

 methyl alcohol solution, the values for the specific rotation are as follows: 

 +8.1 (50°C.)^^«; +8.03, 6.3, 8.4 (50°C.)^'-'"; +7.40 (40°C.), +10.4 

 (45°C.)•*^^• +9.5 (3.6% solution), +10.7 (6.7% solution ).''3i In 1:1 

 chloroform-methyl alcohol solution, Levene and Taylor^''^ report values at 

 20°C. of +11.2° and +9.7°. The rotation in pyridine was found to be 

 considerably lower. Rosenheim^*- reports values of +3.70 (18°C.), +3.70 

 (20°C.), +3.78 (20°C.), and +4.30 (30°C.), while Levene and Taylor^^^^ 

 give the value at 20°C. as +5.0°C. Thierfelder and Klenk'* criticize the 

 data of Levene on the hypothesis that sufficient proof is not given to estab- 

 lish the purity of their preparations. An iodine number of 30.7 has been 

 reported.* 



Phrenosine is not acted on by pancreatic lipase or by commercial emulsin. 

 It has been suggested by Jungmann and Kimmelstiel*'** that galactose is 

 split from the cerebroside molecule after death, although the degree of 

 hydrolysis may be quite small. '*^'' 



Phrenosine forms relatively few derivatives. Those that are known 

 include the dibromo compound, ^^^•'*^^ which is soluble in benzene and 

 slightly soluble in ether and alcohol. Other compounds include those listed 

 below. 



Hexaacetylphrenosive (m.p., 40-41°C.) is insoluble in water, and soluble 

 in most organic solvents; [afj = —3°.*'^^ 



Tribe nzoylphrenosine separates as an oil or as crystals when a methyl 

 alcohol solution is cooled, depending upon the concentration. It dissolves 

 readily in acetone, benzene, petroleum ether, chloroform, acetic acid, and 

 pyridine. It melts at 65-66°C., and has a specific rotation (7% solution) 

 of +21.1°. 



Methylphrerwsine, which contains 5 to 6 methyl groups, is formed when 

 phrenosine is treated with methyl iodide and silver oxide. It is a white 

 amorphous powder, melting at 35-40°C., which has a specific rotation at 

 16°C. of 7.5°. ■*^'' Phrenosine is precipitated quantitatively from an alco- 

 holic solution on the addition of ammoniacal lead acetate. *^^ 



"8 J. L. Smith and W. Mair, /. Path. Bad., 15, 122-12:3 (1910). 

 «9 O. Lehmann, Biochem. Z., 63, 74-86 (1914). 

 '^ H. Thierfelder, Z. physiol. Chem., 85, :35-58 (1913). 

 "' P. A. Levene, J. Biol Chem., 15, 359-:364 (1913). 

 "2 P. A. Levene and F. A. Taylor, ./. Biol. Chem., 52, 227-240 (1922). 

 *" P. A. Levene and F. A. Taylor, ./. Biol. Chem., 80, 227-230 (1928). 

 "* H. Jungmann and P. Kimmelstiel, Biochem. Z., 212, 347-358 (1929). 

 "^ P. Kimmelstiel, Biochem. Z., 212, 359-362 (1929). 

 "« P. A. Levene and W. A. Jacobs, ./. Biol. Chem., 12, 381-388 (1912). 

 ^" J. Pryde and R. W. Humphreys, Biochem. J., 18, 661-664 (1924); 20, 825-828 

 (1926). 



