VOL. 4 (1950) 



ABNORMALITIES IN CELL DIVISION 



297 



trons) in such positions that they increase the electron density of the phenanthrene 

 double bond. This double bond in the more potent carcinogenic hydrocarbons such as 

 9 : lo-dimethylbenzanthracene has a chemical reactivity for some addition reactions 

 approaching that of an aliphatic ethylenic bond and even greater than that of the ethyl- 

 ene bond of some stilbenes. This theory which is now substantiated by experimental 

 evidence, suggests that the more active carcinogens in any particular series of aromatic 

 compounds are those which are on the whole the more chemically reactive. 



Phenanthrene itself reacts readily with osmic acid (Criegee, Marchand, and 

 Wannowius") and the carcinogenic hydrocarbons react even more rapidly (Badger^^). 

 Osmic acid adds on to the double bond of the K region to form an adduct, which can be 

 easily hydrolysed to give cjs-dihydroxydihydro-derivatives. . 



Perbenzoic acid is another reagent which appears to react with carcinogenic hydro- 

 carbons at rates varying with the carcinogenic activity. This reagent was shown to 

 react with 20-methylcholanthrene and 3.4-benzpyrene more rapidly than with anthra- 

 cene and phenanthrene (Eckhardt^^) before the theory of the K region of carcinogens 

 had been developed. In looking for a means of measuring the relative reactivity of the 

 K region, the reaction of perbenzoic acid with a series of carcinogens has been deter- 

 mined. Some of the data obtained are shown in Table IL The figures show that the 

 carcinogenic hydrocarbons react at about the same rate as the carcinogenic aminostil- 

 benes. This suggests that the bond of the K region of the hydrocarbons is as reactive as 

 the ethylenic bond of the stilbene molecule and as the azo group of the carcinogenic 

 dimethylaminoazobenzene. 



The fact that dimethylaminoazobenzene dosed to animals in which it induces 

 hepatoma is found in a combined form in the protein of the liver (Miller and Miller^"), 



TABLE II 



REACTION OF CARCINOGENS AND RELATED SUBSTANCES WITH PERBENZOIC ACID 



M/50 solutions of substances dissolved in carbon tetrachloride with M/50 perbenzoic acid at 25° C. 



The remaining perbenzoic acid was estimated iodometrically and the results are expressed as millimols 



of perbenzoic acid used per mol substrate. 



References p. 300. 



