ADENINE AND GUANINE IN COW’S MILK. 
By CARL VOEGTLIN anp CARL P. SHERWIN. 
(From the Division of Pharmacology, Hygienic Laboratory, Washington.) 
(Received for publication, November 19, 1917.) 
In the course of some work on the isolation of the antineuritic 
substance present in cow’s milk, we incidentally discovered that 
this food contains fair amounts of adenine and guanine. Inas- 
much as we were unable to locate any reference in the litera- 
ture to such findings, we present this brief note, which may be of 
interest in connection with the biochemistry of milk for the fol- 
lowing reasons: (1) milk is usuaJly considered to be practically 
purine-free and has been widely used in metabolism experi- 
ments as a purine-free diet; (2) milk was used as a diet in ex- 
periments to determine whether or not the animal body can syn- 
thesize purines and nucleic acid from purine-free food; (8) the 
mammary glands may act under certain conditions as an excretory 
organ for metabolism products, drugs, and poisons. 
Concerning the occurrence of purines in cow’s milk, Schmidt- 
Miilheim (18838) claims that he detected free hypoxanthine. 
Buridn and Schur (1897) state that they did not succeed in iso- 
lating uric acid from cow’s milk; however, the presence of xan- 
thine bases was established by means of the silver precipitate 
method. The following figures are given: 1 liter of cow’s milk 
yielded approximately 0.005 gm. of purine nitrogen in the silver 
purine precipitate. , 
One grave objection can be raised to the method employed by 
these investigators; namely, the use of AgNO3;, a reagent which is 
known to deaminize amino-purine unless it is used carefully. 
It is possible that the hypoxanthine which was isolated was in 
reality due to the deamination of adenine primarily contained 
in the milk. 
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