530 THE BIOCHEMISTRY OF B VITAMINS 



also counteracted by p-aminobenzoic acid. 427 The question of specificity 

 of p-aminobenzoic acid in eliciting some of these responses has not been 

 adequately determined. 



The toxicity of salvarsan, neosalvarsan, or neostibosan for Streptobac- 

 terium plantarum is prevented by p-aminobenzoic acid. 129 



Similarly, the toxic manifestations caused by administration of sodium 

 ??i-chloro-p-acetylaminobenzenestibonate to rats are counteracted by 

 p-aminobenzoic acid, which does not appreciably affect the therapeutic 

 activity of the drug against Trypanosoma equiperdum* 28 



Phosphanilic acid inhibits the growth of Streptobacterium plantarum, 

 and p-aminobenzoic acid prevents the inhibition. The inhibition index for 

 half-maximum growth is approximately 12,000. 26 Both phosphanilic acid 

 and phosphanilamide are reported to inhibit with varying degrees of 

 activity the growth of Escherichia coli, Staphylococcus aureus and Sal- 

 monella typhimurium.* 29 Phosphanilic acid also inhibits the growth of 

 Mycobacterium tuberculosis in vitro. 430, 431 Administered three times 

 daily in doses of 15 mg, it is not toxic to mice, but only low concentra- 

 tions in the blood are attained. 431 



p-Aminobenzenephosphorous acid is slightly less inhibitory than sulfa- 

 nilamide to the growth of Escherichia coli. p-Aminobenzoic acid prevents 

 the inhibitory effect of the analogue. 432 



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