Toxophor-Auxotox Theory

Toxophor-Auxotox Theory. The theory of toxophors and auxotoxes, first elaborated by Ehrlich for toxic substances and later applied by Nekrassov to the war gases, attributes the physiopathological properties of these substances to special atoms or radicles in a similar manner to Witt s theory regarding the colour of organic substances. 

There also exist other groups capable of communicating the characteristic toxic functions of the toxophoric group, that is, of 

With the aid of this theory it is explained that just as in coloured substances the introduction of some auxochromic groups changes the colour of the substances, so in the war gases the presence of certain autotoxes can alter the type of biological action. Thus, for example, halogen introduced into the hydrocyanic acid molecule reduces the toxicity of the toxophor, —CN, and confers on the product lachrymatory properties. 

However, Nekrassov s theory cannot be applied so generally to the war gases as Witt s to coloured substances. 

In some cases there are actually strongly marked differences. Thus in the coloured substances the auxochrome group brings out the latent colour-potentiality of the chromophore group and so makes colouration possible, while in the war gases the auxotox group merely develops the characteristic property of the toxophor 

---

General theories concerning the relation between chemical structure and physiopathological action have been elaborated with especial reference to the war gases. From among the many published, an account is given here of two Meyer s Theory and the Toxophor-Auxotox Theory. 

Experimental work carried out in these laboratories during recent years has been based on the theory that insecticides owe their activity to a toxic nucleus—the toxophore—the properties of which may be modified by auxiliary radicals—the auxotoxes. This nomenclature is suggested by the names of analogous functions in dyestuffs, the chromophore and auxochrome groups. 

A striking illustration of the effect of chemical structure on insecticidal properties is provided by the data given in this paper on compounds related to piperonyl butoxide. According to the above theory, the methylenedioxyphenyl nucleus present in this substance is the toxophore. The materials selected for comparison show the reduction in toxicity produced, first, by modifying the toxophore, and, second, by substituting different groups for the auxotox radical. 

---