PANTOTHENIC ACID 637 



was stimulated appreciably in its growth in the presence of the vitamin. 

 Usually organisms which synthesize pantothenic acid are not affected 

 by most of the analogues of that vitamin. 



The activity of pantoyltauramide as an antimalarial led to the testing 

 of other analogues of pantothenic acid including phenyl pantothenone, 

 which was found to be effective as a suppressive agent in blood-induced 

 infections of Plasmodium gallinaceum in chicks. 61 As a result of this 

 activity, other analogues related to phenyl pantothenone were prepared. 80 

 The activities of these ketones are indicated in Table 29. Whereas p-tolyl 

 D-pantothenone is the most effective inhibitor against Lactobacillus 

 casei, p-chlorophenyl D-pantothenone is the most effective antimalarial 

 agent. 



An impure preparation of methyl pantothenone was found to inhibit 

 the growth of Saccharomyces cerevisiae and Lactobacillus casei. 79 This 

 inhibitory effect was not reversed by pantothenic acid, and the prepara- 

 tion was at lower concentrations 1 per cent as active as the vitamin in 

 stimulating growth of these two organisms. The possibility of contamina- 

 tion of the analogue with pantothenic acid appears possible. 



The toxicity of phenyl pantothenone for Saccharomyces cerevisiae is 

 not reversed by pantothenic acid, but certain amino acids at relatively 

 high concentrations prevent the toxicity of the inhibitor. 81 L-Histidine 

 (0.26 mg per cc) is the most effective amino acid in preventing the 

 toxicity of 160 y per cc of the inhibitor. L-Glutamic acid is somewhat 

 less effective, and L-proline, L-aspartic acid, L-asparagine and glycine 

 were about half as effective as L-glutamic acid, which also has a slight 

 effect on the toxicity of phenyl pantothenone for Lactobacillus casei. 

 Very slight effects were noted with serine, threonine, alanine and lysine, 

 but other amino acids were inactive. 



Pantothenyl Alcohol and Related Compounds. As previously indicated, 

 pantothenyl alcohol is converted by warm-blooded animals into panto- 

 thenic acid and serves as an available source of that vitamin for these 

 organisms; however, as indicated in Table 30, the alcohol analogue not 

 only is not utilized in place of the vitamin by lactic acid bacteria, but 

 on the contrary it prevents competitively the utilization of pantothenic 

 acid by these organisms. 19 Pantothenyl alcohol prevents the utiliza- 

 tion of pantothenic acid in Leuconostoc mesenteroides P-60 at an in- 

 hibition index of 300, whereas pantoyltaurine is inactive at a ratio of 

 200,000. On the other hand, pantoyltaurine is approximately 5 times as 

 active as pantothenyl alcohol in preventing the functioning of pantothenic 

 acid in Lactobacillus arabinosus 17-5. Such variations in sensitivity to 

 pantothenic acid analogues may result solely from differences in perme- 

 ability of various microbial cells, but more likely the variations are the 



