Fully-Naphthalenoid Hydrocarbons: Enumeration and Classification

Abstract

A fully-naphthalenoid system (or simply fully-naphthalenoid) is a benzenoid where all vertices can be covered by disjoint naphthalene units. Invariants of these systems are studied with special emphasis on the C_nH_s formulae. An extensive enumeration of fully-naphthalenoids by means of a computer program is reported. A detailed classification of the numbers includes the symmetry distribution and an enumeration of the C_nH_s isomers. The forms of the smallest fully-naphthalenoids are displayed together with their Kekulé structure counts.     

Role of the Bay- and L-Regions in the Metabolic Activation and Carcinogenicity of Picene and Dibenz[ a,h ]anthracene

Early carcinogenicity tests found no evidence of activity for picene but found considerable initiating and carcinogenic activity for DBA. More recent investigation suggests that both pentacyclics are complete carcinogens when administered as single s.c. injections in NMRI mice, despite findings that picene acts as neither an initiating nor promoting agent. To investigate this contradiction, the complete carcinogenicity of both isomers was compared by s.c. injection in female Sprague-Dawley rats. The results demonstrated that 1 w mol of DBA administered three times weekly for 20 doses, induced sarcomas in all test animals by 33 weeks (100%). Similar treatment with picene did not induce sarcoma in any test animals by 37 weeks (0%). These present results agree with the earlier studies. It follows then that the metabolic activation and carcinogenicity of DBA and picene are dependent on the presence of an L-region, but are independent of the presence of a bay-region.