acridines mancude organic heterotricyclic parent acridine 2,3-benzoquinoline benzo[b]quinoline 2,3,5,6-dibenzopyridine dibenzo[b,e]pyridine acridine A polycyclic heteroarene that is anthracene in which one of the central CH groups is replaced by a nitrogen atom. 9-azaanthracene acridine Akridin 10-azaanthracene acrydine polycyclic heteroarene genotoxin