The scaffold structures of examples of sibling relationships between mutagenic scaffolds and non-mutagenic scaffolds.

<p>(A) Acridine, (B) Phenanthrene, (C) Quinoxaline, (D) Naphthalene, and (E) Quinoline groups. Below the labels of scaffold names were labelled by the mutagen rates and the numbers of mutagen compounds/the numbers of overall compounds in that scaffolds. In the structures of child scaffolds, the differences from the parent scaffold were colored as red.