Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is an organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles. It is an isomer of lawsone, which is the staining compound in the henna leaf.