5G0 



BIOTIN 



biologically active. For L. arabinosus and L, pentosus 124-2 oxybiotin and 

 biotin are equally active. For other organisms oxybiotin is often less 

 effective in obtaining the maximum response. 



The activity of oxybiotin appears to be dependent upon the pH of the 

 medium. For Streptococcus faecalis it is essentially inactive at pH 6.6 and 

 shows some, although weak, activity at pH 7.3.^^^ The growth of Lacto- 

 hacillus arabinosus at pH 6.5 is not more than one-fifth of the maximum, 

 regardless of the level of oxybiotin. When the initial pH is 7.0 or more, 

 excellent growth results and oxybiotin is about 30 % as active as biotin.^^'' 



TABLE II 

 The Biological Activity of dZ-OxYBioTiN'" 



" Biotin deficiency induced by feeding raw egg white with biotin-deficient diet; iZ-oxybiotin injected 

 intramuscularly or subcutaneously. 



The dose-response curve differs in shape for (-l-)-biotin and oxybiotin. The relative activity of oxy- 

 biotin tends to decrease with increases in concentrations. 



' Animals on biotin deficient diet only. 



In rats and chicks the specific signs of biotin deficiency may be completely 

 cured by oxybiotin. ^^^^ ^^^ However, in the rat the general shape of the dose- 



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