Quinalizarin or 1,2,5,8-tetrahydroxyanthraquinone is an organic compound with formula . It is one of many tetrahydroxyanthraquinone isomers, formally derived from anthraquinone by replacement of four hydrogen atoms by hydroxyl (OH) groups at the 1, 2, 5, and 8 positions.
Quinalizarin is an inhibitor of the enzyme protein kinase CK2. It is more potent and selective than emodin. It is also a potent catechol O-methyltransferase (COMT) inhibitor.