THE NICOTINIC ACID GROUP 609 



sterile condition with defibrinated human blood. However, these results 

 do not necessarily contradict the reported activity of these compounds 

 in treatment of pellagra, since a change of the "V" factor content of the 

 blood is not a reliable method of determining utilization of analogues 

 of nicotinic acid. This is particularly true in view of the fact that oral 

 administration of nicotinamide to human subjects does not cause a 

 change in the "V" factor concentration of the blood; but oral administra- 

 tion of nicotinic acid is followed by a prompt elevation of the concentra- 

 tion of this factor, as determined by Hemophilus influenzae. 59 ' 60 The 

 increase in concentration of the factor is paralleled by changes in the 

 rate at which erythrocytes oxidize lactate and malate. 



The activity of the esters of nicotinic acid for chicks increases with 

 increasing chain length from ethyl to n-butyl. 33 n-Butyl nicotinate is 

 almost as active as nicotinic acid. For bacteria, however, the activity 

 appears to decrease with increasing chain length. Animals appear in most 

 instances to utilize both the esters and N-substituted amides more effec- 

 tively than most bacteria. The search for utilizable but water-insoluble 

 forms of nicotinic acid has largely been centered around the esters and 

 N-substituted amides. 29, 52, G1 - 62 These forms of the vitamin are needed 

 for enrichment of certain foods, such as corn grits and white rice, which 

 are customarily subject to rinsing before cooking. 



Methyl nicotinate has been reported to be the most active form of the 

 vitamin for certain organisms. For example, with glucose as a substrate, 

 the respiration of dysentery bacilli grown on a medium deficient in nico- 

 tinamide can be stimulated by coenzyme I, coenzyme II, nicotinamide, 

 nicotinic acid, methyl nicotinate or other derivatives. 63 Methyl nicotinate 

 is reported to be more active than nicotinamide, which in turn is more 

 active than coenzyme I or II or nicotinic acid. It was suggested that, 

 since these variations cannot be explained by differences in rate of diffu- 

 sion, the results are incompatible with the theory that nicotinamide 

 serves simply as a precursor of coenzyme I or II or both. 03 



A similar high activity of methyl nicotinate has been reported 38 for 

 Proteus vulgaris 3056. The activity of nicotinamide and methyl nicotinate 

 varies with the pH of the medium. At pH 7.2, these activities are 78 

 and 92 per cent, respectively, of nicotinic acid; however, at pH 7.8-8.1, 

 the activities are 215 and 636 per cent, respectively. Thus, methyl nico- 

 tinate is significantly more active than either nicotinic acid or nicotin- 

 amide under these conditions. For other strains of Proteus, nicotinic acid, 

 nicotinamide, and coenzyme I have been reported 41 to be equally ef- 

 fective. 



The growth requirements of 189 strains of Proteus were investi- 

 gated, and strains of P. vulgaris, P. anindolo genes, P. par a-americ anus. 



