Tumorigenic Activity of Hydrogenated Derivatives of Dibenz[a,h]anthracene

Eight partially hydrogenated derivatives of dibenz[a,h]-anthracene (DBA) were tested by application to the skin of Swiss female mice as 0.2 percent solutions in acetone, administered twice weekly for 50 weeks. The tested compounds were 5,6-dihydro-; 1,2,3,4-tetrahydro-; 5,6,12,13-tetrahydro-; 1,2,3,4,12,13-hexahydro-; 1,2,3,4,8,9,10,11-octahydro-(two isomers of mp 196–197° C and 176.5–177.5° C); 1,2,3,4,1a,-4a,5,6,8,9,10,11-dodecahydro-; and 1,2,3,4,1a,4a,5,6,8a,11a,12,13,8,9,10,11-hexadecahydro-DBA. Of these, 1,2,3,4-tetrahydro-DBA showed strong carcinogenic activity, comparable with that of DBA itself; 5,6-dihydro-DBA and 1,2,3,4,12,13-hexahydro-DBA were also carcinogenic, although weaker. No carcinogenic activity was demonstrated by the remaining 5 compounds tested. The relationship between chemical structure and carcinogenic activity for these compounds is discussed. The hexahydro compound does not have a K-region and yet shows definite carcinogenic activity.