NICOTINIC ACID (nIACIN) 



misleading. As will be seen later (page 296), the so-called " pellagra- 

 like " dermatitis of rats is produced by yet another factor called by 

 P. Gyorgy/ vitamin Bg. 



An attempt to find an animal the response of which to the PP- 

 factor was more specific than that of the rat was made by C. A. 

 Elvehjem and C. J. Koehn,^ who found that chicks, when fed on a 

 pellagra-producing diet, also developed a form of dermatitis ; for a 

 time, protection against chick " pellagra " and the production of 

 normal growth were taken to be a measure of PP-factor activity. 

 Liver and a commercial extract of liver were found to be highly active, 

 whereas riboflavine was inactive. By fractionation of the liver 

 extract a much richer concentrate of the chick dermatitis factor was 

 obtained which also cured blacktongue in dogs,^ and it seemed as 

 though the production of dermatitis in chickens was in fact a valid 

 test of PP-factor deficiency. Subsequently, however, it was found 

 that the factor responsible for chick dermatitis (the so-called filtrate 

 factor) was not the PP-factor at all but the substance now known as 

 pantothenic acid (see page 348). 



In the ultimate, therefore, experiments with rats and chicks were 

 unsuccessful, and progress in the elucidation of the nature of the 

 pellagra-preventative factor came to depend on clinical tests supple- 

 mented by experiments with dogs. In a series of papers published 

 between 1926 and 1934, Goldberger and his colleagues ^ reported the 

 examination of a large number of foodstuffs by the addition of known 

 quantities of the food to a pellagra-producing diet and noting the 

 incidence of pellagra in a group of patients. 



Goldberger and his colleagues also carried out parallel tests with 

 dogs,^ and this work eventually demonstrated that the foodstuffs 

 that cured pellagra in human beings also cured blacktongue in dogs, 

 whence it was concluded that the same dietary factor was responsible 

 for both conditions. 



Yeast was introduced in the treatment of pellagra by J. Goldberger 

 and W. F. Tanner,^ but large amounts had to be administered to make 

 this form of treatment successful. Liver extracts gave better results, 

 and in 1937 Elvehjem et al.}^ by fractionating a liver extract having 

 marked anti-blacktongue activity and subjecting the active fraction 

 to high vacuum distillation, isolated nicotinamide and showed that it 

 and nicotinic acid were highly effective in curing canine blacktongue. 

 H. R. Street and G. R. Cowgill ^^ also obtained good results with 

 nicotinic acid in blacktongue, and Chick et al}"^ in a corresponding 

 condition in pigs (see page 238). 



The beneficial effects of nicotinic acid on pellagrins was reported 

 by Spies et al.}^ by L. J. Harris,^* and by Smith et al}^ 



Actually nicotinic acid had been isolated in 1912 from yeast by 



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