596 



BIOTIN 



up to 7.5 g., brain, spleen, and thymus up to 2.0 g., and rice polish up to 

 0.6 g. Cow's milk was not so potent in winter as in summer. Breast milk 

 had only very slight therapeutic potency in egg white injury; as much as 

 25 ml. daily had no constant effect. 



Most analytical data on the distribution of biotin in food products were 

 obtained by microljiological tests. In general, the agreement between the 

 findings of various workers is only fair, owing probably to differences in 

 the methods of extraction and to the particular test organisms used. The 

 liberation of free biotin from its bound form was attempted by autoclaving 

 with water or by acid hydrolysis- or by enzymatic treatment. ^'^ 



The microbiological tests confirmed in general the findings obtained in 

 animal assays.^ Biotin concentrations were found to be appreciably lower 

 in human milk than in cow's milk. The biotin content of milk from animals 

 of different species is given in Table X. 



TABLE X 

 Biotin Content of Milk from Mammals of Different Species, y/ml. 



In other series^ the biotin content of cow's milk, determined microbio- 

 logically, was found to vary between 0.011 to 0.037 7 per milliliter, the 

 value rising to a maximum after the first few days and then falling. 



In later European studies^ the biotin content of human milk was found 

 to range from a trace to 0.033 7 per milliliter with an a\-erage ^•alue of 

 0.0016, in good accord with the figures given in Table X. Intramuscular 

 injection of 5 mg. caused a marked rise in the biotin content of breast 

 milk, up to 0.768 7 per milliliter in one subject. The level fell after a few 

 hours, and the effect of the large dose disappeared within 3 days. 



2 J. O. Lampen, G. P. Bahler, and W. H. Peterson, ./. XutriiioN 23, 11 (1942). 



3 V. H. Cheldelin, M. A. Eppwright, E. E. Snell, and B. M. Ciuirani, Univ. Texas 

 Pitbl. 4237, 15 (1942). 



' R. J. Williams, V. H. Cheldelin, and 11. K. Mitchell, T/z/r. Tcx<n Puhl. 4237, 97 



(1942). 

 ^ V. H. Cheldelin and U. J. Williams, Vniv. Texas Publ. 4237, 105 (1942). 

 6 P. Gyorgy, D. B. Melville, I). Burk, and V. du Vigneaud, Science 91, 243 (1940). 

 ^ J. M. Lawrence, B. L. Hei'rington, and L. A. Maynard, ,/. Nutrition 32, 73 (1946). 

 8 W. Neuweiler and W. Rittcr, Intern. Z. Viiaminforsch. 21, 239 (1949). 



