THE NICOTINIC ACID GROUP 613 



Methyl 3-Pyridyl Ketone (3-Acetylpyridine). For Streptobacterium 

 plantarum, 3-acetylpyridine is toxic only at high concentrations, and the 



-COCH3 



methyl 3-pyridyl ketone (3-acetylpyridine) 



inhibition is not reversed by nicotinic acid. 72 However, the analogue is 

 toxic for nicotinic acid-deficient dogs but not for normal dogs. 24 This 

 suggested the possibility that it might be used to produce symptoms of 

 nicotinic acid deficiency in mice. 73 With doses of 2 to 4 mg per day, the 

 animals began to breathe rapidly very soon after administration of the 

 analogue. In a few hours, difficulties in control of the hind legs developed. 

 Within two days, complete paralysis of the hind legs resulted. The mice 

 appeared emaciated, extremely wet and unkempt. The skin became very 

 red and inflamed, and, after four to seven days, fiery red tongues devel- 

 oped in about half the animals. Supplementing the ration with nicotinic 

 acid for three or four days prior to administration of the analogue pre- 

 vented the disease; however, only partial success was reported for at- 

 tempts to cure animals ill with the deficiency disease. 



Tryptophan also prevents the toxicity of 3-acetylpyridine, which causes 

 the pellagra-like manifestations. 74 The amino acid in amounts as little as 

 0.1 per cent of the diet was sufficient to protect the animals, and was as 

 active as nicotinic acid in exerting the protective action. 



3-Acetylpyridine injected into the yolk-sac is toxic for a 4-day old 

 developing chick embryo. 75 Sublethal concentrations cause certain mal- 

 developments of the chick, such as undersized, deformed legs and a general 

 edema-like condition over the body. However, approximately 600 y of 

 3-acetylpyridine per egg was lethal within 24 hours. The toxicity of the 

 analogue was prevented entirely when sufficient nicotinamide was injected 

 simultaneously. The inhibition index required for the lethal effect in all 

 the eggs was 15.4-16.7. The lowest ratio of analogue to metabolite just 

 necessary not to exert any lethal effects was 13.6-14.5. However, in order 

 to prevent maldevelopment of the chick, a still lower ratio of analogue 

 to metabolite was essential. As compared with nicotinamide, nicotinic acid 

 and tryptophan exerted much weaker effects in preventing the toxicity 

 of the analogue for the chick embryo, but there appears to be some slight 

 ability of the embryo to utilize nicotinic acid and tryptophan in place of 

 nicotinamide at this stage of development. 



Marked electrocardiographic abnormalities of an isolated rabbit's heart 

 occurred on perfusion with 3-acetylpyridine. 76 Administration of nicotin- 



