VITAMINS 343 



Human deficiency states cured with jxiiuotlienic acid are common 

 in certain areas in India. Sore tongue, anemia, toot irritations, and 

 fatal necrosis of the adrenal cortex are symptomatic. Some cases 

 occur in hospitals and result from special diets. Characteristic loss of 

 hair pigments in particular areas occurs in experimental rats, pigs, and 

 dogs. Dermatitis, growth failure, nose bleed, and failure of the adrenal 

 cortex are additional symptoms. 



BIOTIN 



This vitamin is also a member of the so-called B complex and is 

 assigned the following structvu^e: 



O 



HN NH 



H 



H2V 



H 



H— (CH2)4COOH 



biotin 



In many biological materials it occius as the amide of the e-amino 

 group of lysine. Biotin is synthesized commercially and included in 

 many vitamin supplements. 



Nothing definite is known of the metabolic functions of this vitamin, 

 which plays roles as yet unspecified in the carboxylation and de- 

 carboxylation of certain acids of physiological importance. Neverthe- 

 less, this substance deserves its inclusion with the other vitamins since 

 it is universally distributed and deficiencies can be induced. 



By extrapolation from studies with rats, the daily human require- 

 ment is about 10 mg., one of the lower allowances. Biotin is synthe- 

 sized in the rumen, making it unnecessary in the diets of ruminants. 

 Indeed, widespread synthesis by intestinal flora makes it difficult to 

 produce experimental biotin deficiencies. Chicks and turkey poults 

 are believed to require 45 to 70 mg. of biotin per lb. of ration. 



Biotin occurs particularly in egg yolks, yeast, meat, milk, vegetables, 

 and seeds. Although deficiencies are rare in nature, they can be 

 induced readily by feeding a diet containing raw egg white as the 

 sole or major source of protein. Egg white contains a particular 

 protein called avidin which inactivates biotin by removing it from 

 an otherwise complete diet. If the intestinal flora is then controlled 

 with a suitable antibiotic, deficiency symptoms develop. Dermatitis, 



