THE NICOTINIC ACID GROUP 605 



strated by Elvehjem and co-workers. 16 These reports, particularly with 

 the extension of the biological role of nicotinic acid to treatment of human 

 pellagra, 17 - 1S stimulated an intense search among analogues of nicotinic 

 acid for those which possessed biological activity. 



The specificity of the nicotinic acid group for various organisms is 

 indicated in Table 23. It is interesting to note that nicotinic acid cannot 

 replace nicotinamide in the nutrition of certain strains of Pasteurella, 

 and that nicotinamide is essentially inactive in replacing nicotinic acid for 

 Leuconostoc mesenteroides 9135 and 8293 and Leuconostoc dextranicum 

 8086. Quantitative variations in ability to utilize these compounds are 

 common among various organisms. For example, nicotinamide is approxi- 

 mately ten times as active as nicotinic acid for certain dysentery bacilli, 

 but nicotinic acid is ten times as effective as nicotinamide in stimulating 

 the growth of Cory meb acterium diphtheriae. 15 Most organisms, however, 

 use nicotinic acid and its amide with about the same efficiency. The 

 Hemophilus group which requires the "V" factor cannot utilize either 

 nicotinic acid or its amide. For Hemophilus parainfluenzae and Hemo- 

 philus influenzae, the "V" factor requirement is satisfied most effectively 

 by coenzyme I or by the equally active dihydrocoenzyme I. 50, 51 Desamino- 

 coenzyme I is only 60 per cent as active as coenzyme I. As indicated in 

 Table 23, nicotinamide riboside replaces the coenzyme, but is considerably 

 less active on a molar basis. Growth response of the organism to increas- 

 ing concentrations of the riboside is not proportional to that obtained 

 with corresponding concentrations of coenzyme I. Coenzyme II is also 

 less active than nicotinamide riboside, but the growth response closely 

 parallels that of the riboside, indicating the possibility that it is utilized 

 by prior conversion to the riboside before coenzyme I synthesis. 50, 51 The 

 amount of nicotinamide riboside just necessary for detectable growth of 

 Hemophilus influenzae or Hemophilus parainfluenzae is less than that of 

 coenzyme I for the same, response. However, for appreciable growth con- 

 siderably more of the riboside than of coenzyme I is essential. 50 - 51 



As indicated in Table 23, organisms which require nicotinic acid or 

 nicotinamide for growth can usually utilize the coenzymes. However, 

 Leuconostoc mesenteroides 8293 and Leuconostoc dextranicum 8086 can- 

 not utilize effectively either coenzyme I or II. 39a Furthermore, coenzyme 

 I injected intravenously is reported to have no therapeutic effect on 

 canine blacktongue, 25 but administered orally in rats, it is reported to be 

 more active than nicotinamide. 54 In many instances, coenzymes I and II 

 are less effective as microbial growth factors than either nicotinic acid 

 or nicotinamide. 38, 46 Although neither Leuconostoc mesenteroides 8293 

 nor Leuconostoc dextranicum 8086 can utilize exogenous coenzyme I or 

 II, both organisms synthesize from nicotinic acid a factor which replaces 



