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Skeletal formula
Ball-and-stick model
CAS number 481-39-0 YesY
PubChem 3806
ChemSpider 3674 N
RTECS number QJ5775000
Jmol-3D images Image 1
Molecular formula C10H6O3
Molar mass 174.15 g mol−1
Appearance Yellow solid
Melting point 162 to 163 °C (324 to 325 °F; 435 to 436 K)
Solubility in water Slightly sol.
R-phrases R25
S-phrases S28 S45
Related compounds
Related compounds quinone
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) or 5-hydroxynaphthoquinone, 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. Other names in industry are Nucin, Regianin, NCI 2323, and Oil Red BS.

Juglone occurs naturally in the leaves, roots, husks, fruit (the epicarp), and bark of plants in the Juglandaceae family, particularly the black walnut (Juglans nigra), and is toxic or growth-stunting to many types of plants.[1] It is sometimes used as a herbicide, as a dye for cloth and inks, and as a coloring agent for foods and cosmetics.

Chemistry and synthesis[edit]

Juglone is an aromatic compound, formally derived from 1,4-naphthoquinone through the replacement of one hydrogen atom by a hydroxyl (OH) group. It is an isomer of lawsone, which is the staining compound in the henna leaf. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles that melt at 162–163 °C.[2]

Juglone can be obtained from oxidation of 5,8-dihydroxy-1-tetralone with silver oxide (Ag2O), manganese dioxide (MnO2), or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).[2]

Biological effects[edit]

Juglone is an example of allelopathic compound, a substance that is synthesized by one type of plant and affects the growth of another. Landscapers have long known that gardening underneath or near black walnut trees can be difficult. Juglone exerts its effect by inhibiting certain enzymes needed for metabolic function. A number of plants and trees are resistant to juglone including some species of maple (Acer), birch (Betula), and beech (Fagus).

It is highly toxic to many insect herbivores. Some of them, however, are capable of detoxification of juglone (and related naphthoquinones) to non-toxic 1,4,5-trihydroxynaphthalene. It has also shown anthelmintic (expelling parasitic worms) activity on mature and immature Hymenolepis nana in mice.[3] Antimicrobial activity of Napthoquinonic compounds.[4][5][6]


Juglone is occasionally used as a herbicide.

Traditionally, juglone has been used as a natural dye for clothing and fabrics, particularly wool, and as ink.

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.


  1. ^ Juglone toxicity
  2. ^ a b J. Khalafy and J.M. Bruce (2002). "Oxidative dehydrogenation of 1-tetralones: Synthesis of juglone, naphthazarin, and α-hydroxyanthraquinones". Journal of Sciences, Islamic Republic of Iran 13 (2): 131–139. 
  3. ^ Dama L.B. and Jadhav B.V. (1997). "Anthelmintic effect of Juglone on mature and Immature Hymenolepis nana in mice". Riv. Di Parassitol. 2: 301–302. 
  4. ^ Dama L.B., Poul B.N. and Jadhav B.V. (1998). "Antimicrobial activity of Napthoquinonic compounds". J. Ecotoxicol.Environ. Monit. 8: 213–215. 
  5. ^ Dama L.B., Poul B.N., Jadhav B.V and Hafeez MD. (1999). "Effect of "Juglone" on Development of the plant parasitic nematode (Meloidogyne Spp.) on Arachis hypogaea L.". J. Ecotoxicol. Environ. Monit. 9: 73–75. 
  6. ^ Dama L.B. (2002). "Effect of naturally occurring napthoquinones on root- knot nematode Meloidogyne spp.". Indian Phytopathology 55 (1): 67–69.