UNIDENTIFIED VITAMINS 79 



to know whether the effectiveness of commercial liver preparations is 

 due to its content of pteroylglutamic acid. Numerous microbiological 

 assays have been made with L. casei for the content of pteroylglutamic 

 acid in liver preparations. For example, Clark reported that commercial 

 parenteral liver extracts contained only 0.02-3.67JU, of pteroylglutamic 

 acid per unit of liver extract. 



It was found that one U.S. P. unit of a certain liver extract when 

 administered daily for ten days was equivalent to only 3.8^0, of pteroyl- 

 glutamic acid. A dose of 20 mg. of pteroylglutamic acid daily for ten 

 days is 200,000^^. Alexander reported that only 0.035 ^S- ^^ ^ ^^"^^^ 

 fraction was required to show antipernicious anemia activity. 



Furthermore, Stokstad and Jukes have recently described the failure 

 of vitamin Be conjugase to liberate appreciable pteroylglutamic acid 

 from a parenteral liver extract. 



Thus it appears that the antipernicious anemia factor in liver is not 

 pteroylglutamic acid, although the latter has antipernicious anemia 

 activity (Table IX). 



TABLE IX 

 Treatment of Pernicious Anemia by Liver Therapy 



Liver therapy, Minot and Murphy (1926) 



Commercial parenteral liver extracts contain 0.02-3.67 /x/unit, Clark (1945) 

 I U.S. P. unit liver extract daily for ten days ^ 3.8 ix pteroylglutamic acid 

 20 mg. pteroylglutamic acid daily for ten days ^ 200,000 p., Moore and 



associates (1945) 

 0.035 n^g- Liver fraction active, Alexander 



"vitamin Be conjugase" 



Parenteral liver extract > no appreciable libera- 



dried chicken pancreas tion of pteroylglutamic 



acid, Stokstad and 

 Jukes (1946) 



Castle and his associates in 1944 studied the effect of the daily ad- 

 ministration of various substances together with neutralized normal 

 human gastric juice on several cases of pernicious anemia. The data on 

 two typical cases are summarized in Table X. In addition to an adequate 

 amount of "vitamin-free" casein and all the known B vitamins, xan- 

 thopterin and a folic acid concentrate were also administered. It was 

 concluded that folic acid had no effect upon the red blood cell count or 

 the reticulocyte peak. However, when beef muscle was used as a sup- 



