A trihydroxyanthraquinone derived from anthracene by substitution with oxo groups at C-9 and C-10 and with hydroxy groups at C-1, C-2 and C-4. ChEBI: Purpurin is a trihydroxyanthraquinone derived from anthracene by substitution with oxo groups at C-9 and C-10 and with hydroxy groups at C-1, C-2 and C-4. It has a role as a biological pigment, a histological dye and a plant metabolite.