45 



perimentation, owing to its insolubility in water. Pyrrolazotc (Fig. 

 9a) is more soluble. The phosphorescence of rhodamin, acridine, 

 and riboflavine phosphate was found completely quenched by this 

 substance in 3 X 10"* M concentration, while the fluorescence of 

 the unfrozen solutions remained unchanged. 



That this activity of Pyrrolazote is actually due to the combina- 

 tion of the S, C, and N present can be shown by testing 2-amino- 

 benzothiazole, which contains the same atoms but in a different 



^O^N-J^^ 



NH, 



,^*^N^^Y 



I 



CH2 



I 



CH2 



I 



N 



a 



(a) (6) 



Fig. 9. a: Pyrrolazotc. b: 2-Aminoben20tiiiazole. 



cycle and separated only by one C (Fig. 9b). This substance 

 quenches the phosphorescence of acridine in 0.005 Af and that of 

 riboflavine in 10~^ Af concentration. 



Pyrrolazote is not known to have any specific pharmacological 

 activity, which indicates that it lacks a specific affinity for tissues 

 or cell constituents. Naturally, if it interferes with E* and £* is 

 important for life, then it should kill the animal if it reaches the 

 concentrations in which it interferes with £*, and vke versa, if it 

 kills the animal by interfering with £*, then it should quench 

 also in vitro in the concentrations which are established in the ani- 

 mal by a lethal dose. The experiment showed that 100 mg injected 

 in mice per kilogram of body weight produced no symptoms, while 

 200 mg killed the animals; 200 mg per kilogram corresponds to 

 a random concentration of 6.10"* Af. The phosphorescence of 

 rhodamin and acridine were quenched by 3.10"* Af. 



It would be interesting to know how far the pharmacological 



