The production of cancer by pure hydrocarbons. VI

Abstract

A series of eight 5-alkyl derivatives of 1:2-benzanthracene (methyl, ethyl, propyl, iso -propyl, butyl, amyl, hexyl, heptyl) was tested for cancer-producing activity. The higher members of the series showed progressive diminution of carcinogenic power upon the skin, and those having more than three carbon atoms in the side chain did not produce sarcoma. Tests upon several 10-substituted benzanthracenes are recorded. The results given by several new derivatives of 3:4-benzphenanthrene confirm earlier findings in showing (1) that sub­stitution in position 2, and to a less degree in position 1, promotes carcinogenic action, and (2) that most of these compounds are deficient in sarcoma-producing power. 1:2:3:4-Tetramethylphenanthrene, which has a weak but quite distinct property of producing tumours of the skin, is one of the simplest carcinogenic compounds known. In its molecular structure it forms a connecting link between the carcinogenic hydrocarbons of the 1:2-benzanthracene and 3:4-benzphenanthrene groups, and is also related to 1:2-dimethylchrysene which is one of the two homologues of chrysene known to be carcinogenic. 3 :4 :5 :6-Dibenzfluorene differs from the 1:2:3:4-, 1:2:5:6- and 1:2:7: 8-compounds in showing no action upon the skin. Further tests were made of the carcinogenic power of 1:2:5:6-dibenzcarbazole in view of its considerable growth-inhibitory power. The relation between two azonaphthalenes and the diaminodinaphthyls and dibenzcarbazoles which may be obtained from them is discussed in regard to the production of tumours of the liver. Some data are given of the occurrence of multiple and remote tumours, especially in mice receiving certain classes of compounds (2:3:4-substituted phenanthrenes, 1:2:5:6-dibenzcarbazole and 1:2:5: 6-dibenzacridine).