Wiktionary
indolequinone
n. (context chemistry English) Any of a class of molecules based upon an indole but with two additional ketone groups (quinone) attached to the ring structure.
Wikipedia
Indolequinone
Indolequinones are molecules which are based upon an indole but have two additional ketone groups ( quinone) attached to the ring structure.
This simple indolequinone indole-5,6-quinone is produced during the ripening of some fruit.
Other examples of indolequinones and the related mitosenes include natural compound mitomycin and the related chemotherapeutic agent apaziquone.