612 THE BIOCHEMISTRY OF B VITAMINS 



3-Pyridinesulfonic Acid. The growth of Proteus vulgaris has been re- 

 ported to be effectively inhibited by 3-pyridinesulfonic acid (M/100). 64 



S0 2 OH 



3-pyridinesulfonic acid 



Although the toxicity of the inhibitor was not competitively prevented, 

 increased concentrations of nicotinic acid reversed the inhibition after 

 three to four days. When growth of the organism was promoted by an 

 equivalent concentration of nicotinamide, 3-pyridinesulfonic acid did not 

 inhibit it. Growth promoted by a preparation of coenzyme I was more 

 strongly inhibited than that obtained with nicotinic acid as a growth 

 stimulant. These indications that nicotinamide may not be used by 

 Proteus vulgaris solely for the synthesis of coenzyme I have been pointed 

 out by Mcllwain. 64 



With Staphylococcus aureus, the inhibition of growth by 3-pyridinesul- 

 fonic acid was prevented to some extent by nicotinic acid in a somewhat 

 competitive manner. 64 The inhibition index was 10,000 and 250,000 for 

 incubation periods of 23 hours and 5-6 days, respectively. 



The toxicity of pyridine-3-sulfonic acid (4xlO" 3 M) for Proteus vul- 

 garis is reported 67 to be prevented by either nicotinic acid (lXl0 _3 M) 

 or by thiazole-5-carboxamide (lxlO _3 M). The thiazole-5-carboxamide 

 without the inhibitor shows slight inhibition of growth of the organism. 

 The possibility that thiazole-5-carboxamide may actually function in the 

 organism in place of nicotinic acid was suggested. 



For Lactobacillus acidophilus (Hadley), 3-pyridinesulfonic acid caused 

 half-maximum inhibition of growth at an index of 1700. 68 However, no 

 data indicating reversal of the inhibition were indicated. 



Some inhibition of growth of rats was obtained by administration of 

 3-pyridinesulfonic acid in a diet containing a low amount of protein. 69 

 The inhibition of growth was prevented by either nicotinic acid or higher 

 amounts of protein in the diet. However, 3-pyridinesulfonic acid did not 

 appreciably affect the onset and reversibility of the effects of nicotinic 

 acid deficiency in dogs. 70 The sulfonic acid does not produce symptoms of 

 nicotinic acid deficiency in mice. 71 



Another interesting effect is stimulation of growth of Staphylococcus 

 aureus by low concentrations of 3-pyridinesulfonic acid (M/5000 to 

 M/1000) , which has been reported to occur in the presence of suboptimal 

 concentrations of nicotinic acid; however, no stimulation was obtained 

 even at high concentrations (M/100) in the absence of nicotinic acid. 53 



