Anthraquinone is the class-defining compound for a number of naturally-occurring plant pigments. Anthraquinone itself has been associated with causing liver, bladder and kidney cancers, and other non-neoplastic disorders.. It also, however, has been a starting point for developing antineoplastic agents, especially the anthracycline agents, of which doxorubricin (Adriamycin) is best known. 
Anthraquinone derivatives called sennosides are used as cathartics; they are the active principle in senna extract.
- TR-494 Anthraquinone, National Toxicology Program, U.S. Department of Health and Human Services
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