Quinalizarin or 1,2,5,8-tetrahydroxyanthraquinone is an organic compound with formula C12H4(OH)4(CO)2.

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.

[1] It is also a potent catechol O-methyltransferase (COMT) inhibitor.