PABAXANTHIN. 403 



whereas heteroxanthin on similar treatment gives a dense pulveru- 

 lent precipitate. This reaction is not given by theophyllin. 



Like the other xanthin derivatives on treatment with methyl 

 iodid it yields caffein. 



The physiological action of paraxanthin has been studied by Salomon 

 and by Schmiedeberg, Injections into the muscles of 1—2 mg. pro- 

 duced almost at once a rigor mor-fe-like condition of the muscles af- 

 fected, with diminished reflex excitability without previous increase; 

 6-8 mg. introduced into the lymph sac bring on a gradual loss of volun- 

 tary motion as well as of reflex excitability ; the rigor is more marked 

 in the anterior extremities, which have a wooden or waxy consistency. 

 Dyspncea is likewise an early symptom, but as soon as rigor sets in 

 the respirations drop far below the normal and may be absent for 

 several minutes. At times the lungs are enormously dilated, same 

 as with theobromin. The heart's action is intact till the very last. 

 In mice the reflexes are increased almost to a tetanus. An injection 

 of 0.2 g. in a 600 g. guinea-pig produced convulsions and death in 

 half an hour. The same dose introduced into the vein of a rabbit 

 had no efiect. The lethal dose for frogs, subcutaneously, was found 

 to be 0.15—0.2 per cent, of the body-weight — somewhat lower than 

 that of theobromin and xanthin. The action of these three bases is 

 very similar. They produce in common the slow creeping move- 

 ments, followed by cessation of spontaneous muscle action, complete 

 loss of reflex excitability without a previous rise. The heart's action 

 is not afiected till in the latest stages. 



Kriiger and Schmidt^ found that paraxanthin when fed to rabbits 

 was excreted in part as such and in part as 1-methyl xanthin. 

 From this and similar experiments with theobromin and caffein it 

 would seem that at least in the bodies of rabbits the methyl group in 

 position 3 is most easily split off, the 7-methyl group next and lastly 

 that in position 1. When, however, 3-methyl xanthin is fed to 

 rabbits it is in part excreted as such but this may be due to the 

 rather large doses administered. For the studies of Schmiedeberg 

 see page 345. 



According to Kachford ' the xanthin bodies are important factors 

 in the causation of migraine. From the urine passed immediately 

 after an attack of this disease he obtained an extract which he 

 believed to contain relatively large quantities of paraxanthin, and he 

 ascribed the marked toxicity of such extracts to this base. Pfaff, 

 however, failed to find any increase of paraxanthin and interpreted 

 the toxicity of the extracts as due to the presence of ammonium salts 

 resulting from the method employed. Our present knowledge regard- 

 ing the origin of this base may be considered as definitely elimiting 

 paraxanthin as a possible etiological factor. 



'BericMe, 32,2677. 



' J)ram. Assoc. Amer. Physicians, 10, 11, 14, 224 (1899). 



