Juglone

Juglone is an aromatic organic compound with the molecular formula C10H6O3.

Juglone is found naturally in the leaves, roots and bark of plants in the Juglandaceae family, particularly the black walnut. Juglone is an allelopathic compound, meaning it is synthesized by one type of plant and affects the growth of another. In the case of juglone, it is toxic or growth stunting to many types of plants. Landscapers have long known that gardening underneath or near black walnut trees can be difficult. Juglone exerts its affect by inhibiting certain enzymes needed for metabolic function. It is occasionally used as an herbicide.

Because of its tendency to create dark orange-brown stains, juglone has also found use as a coloring agent for foods and cosmetics, such as hair dyes. It is known in the food industry as C.I. Natural Brown 7 or C.I. 75500. Traditionally, juglone has been used as a natural dye for clothing and fabrics, particularly wool, and as ink. Its other names are Iuglon, Juglane, Nucin, Regianin, Walnut extract, Yuglon, NCI 2323, Oil Red BS and 1,4-naphthoquinone. It is an isomer of Lawsone.