Nitrogen-containing heterocyclic quinones: a class of potential selective antitumor agents.

The development of prodrugs that are enzymatically activated into anticancer agents is a promising perspective in cancer therapy. Many nitrogen-containing quinoid heterocycles have been reported to show antitumor effect. The principal interest in these compounds lies on their potential to produce tumor-selective toxicity. Selectivity occurs by difference in oxygen tension between normal and tumor tissue and by levels of the required activating enzymes.