1,3-Dihydroxyanthraquinone, also called purpuroxanthin or xanthopurpurin, is an organic compound with formula C14H8O4 that occurs in the plant Rubia cordifolia (Indian madder).

Its molecular structure can be viewed as being derived from anthraquinone by replacement of two hydrogen atoms (H) by hydroxyl groups (-OH).

Xanthopurpurin occurs in small amounts (as a glycoside) in the root of the common madder plant, Rubia tinctorum, together with alizarin, purpurin and other anthraquinone derivatives.

[2] Xanthopurpurin is insoluble in hexane but soluble in chloroform.

[1] Like many dihydroxy- and trihydroxyanthraquinones, it has a purgative action, although only 1/6 as effective as 1,2,7-trihidroxyanthraquinone (anthrapurpurin).