640 THE BIOCHEMISTRY OF B VITAMINS 



result of differences in cellular interactions. The structures of the enzymes 

 utilizing pantothenic acid may be slightly different, the analogues may 

 prevent different reactions in the utilization of pantothenic acid, or dif- 

 ferences in the ability of the organisms to convert the analogues to other 

 forms may exist. 



As indicated in Table 30, alteration of the structure of pantothenyl 

 alcohol tends to lower the inhibitory activity of the analogue. D-p-Tolyl- 

 pantothenol is more active than the corresponding methylpantothenol, 

 but is only 0.1 as active as the corresponding pantothenone for Lacto- 

 bacillus casei. However, in chicks with blood-induced infections of 

 Plasmodium gallinaceum, both p-tolylpantothenol and p-tolylpanto- 

 thenone possess approximately the same activity as quinine. 61 



N-Pantoylalkylamines and Related Compounds. A series of N-pantoyl 

 amines 19, 82 have been found to be relatively effective competitive 

 antagonists of pantothenic acid for Leuconostoc mesenteroides P-60, but 

 somewhat less effective as antimetabolites for Lactobacillus casei and 

 Lactobacillus arabinosus 17-5, as indicated in Table 31. 



For Leuconostoc mesenteroides, the effectiveness of the different pantoyl 

 alkyl amines as inhibitory analogues of pantothenic acid increases con- 

 siderably as the length of the alkyl chain is increased to four carbons, 

 and then slowly decreases with increasing chain length. The derivatives 

 containing a branched alkyl are less active than the corresponding n-alkyl 

 derivatives. For Lactobacillus arabinosus 17-5 and Lactobacillus casei, 

 no definite trend in effectiveness with increasing chain length was 

 apparent; both the n-propyl- and the w-heptylamides were more effective 

 than the intervening members of the series. 



D-N-Pantoyl-/?-phenylethylamine 80 also has a very slight activity 

 (quinine equivalent, 0.03) against blood-induced Plasmodium gallinaceum 

 infections in chicks. 61 



N-Pantoyl-n-butylamine and, less effectively, pantoyltaurine are re- 

 ported to inhibit competitively the utilization of pantothenic acid as a 

 carbon source for a strain of Pseudomonas. 83 



Miscellaneous Pantoyl Derivatives. DL-Pantamide and DL-panthy- 

 drazide have been synthesized and found to be antagonists of pantothenic 

 acid functioning in Lactobacillus casei.® 2 At concentrations of 0.025 and 

 2.5 y per cc of pantothenic acid, 1,250 and 10,000 y per cc, respectively, 

 of pantamide, and 6 and 5,000 y per cc, respectively, of panthydrazide 

 inhibited growth of the organism. 62 



For Leuconostoc mesenteroides P-60, DL-pantothenonitrile, DL-panto- 

 thenyl amine, and DL-N-pantoyl-/?-methoxyethylamine prevent com- 

 petitively the functioning of pantothenic acid. 82 The inhibition indices 

 are 10,000, 40,000 and 15,000, respectively. It is interesting to note 



