Juglone
Encyclopedia
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, 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. It is sometimes used as a herbicide
, as a dye
for cloth and ink
s, and as a coloring agent for foods and cosmetics
.
atom by a hydroxyl
(OH) group. It is an isomer
of lawsone
. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles that melt at 162–163 °C.
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).
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 enzyme
s 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.
.
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.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
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, and bark of plants in the Juglandaceae
Juglandaceae
The Juglandaceae, also known as the Walnut Family, is a family of trees, or sometimes shrubs, in the order Fagales. Various members of this family are native to the Americas, Eurasia, and Southeast Asia....
family, particularly the black walnut (Juglans nigra), and is toxic or growth-stunting to many types of plants. It is sometimes used as a herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
, as a dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
for cloth and ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
s, and as a coloring agent for foods and cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
.
Chemistry and synthesis
Juglone is an aromatic compound, formally derived from 1,4-naphthoquinone through the replacement of one hydrogenHydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
atom by a hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
(OH) group. It is an isomer
Isomer
In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
of lawsone
Lawsone
Lawsone , also known as hennotannic acid, is a red-orange dye present in the leaves of the henna plant as well as jewelweed . Humans have used henna extracts containing lawsone as hair and skin pigments for more than 5000 years...
. It is insoluble in benzene but soluble in dioxane, from which it crystallizes as yellow needles that melt at 162–163 °C.
Juglone can be obtained from oxidation of 5,8-dihydroxy-1-tetralone with silver oxide
Silver(I) oxide
Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.-Preparation:...
(Ag2O), manganese dioxide (MnO2), or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone is the chemical reagent with formula C8Cl2N2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols and steroid ketones in organic chemistry. DDQ decomposes in water, but is stable in aqueous mineral acid.-Preparation:Synthesis of DDQ...
(DDQ).
Biological effects
Juglone is an example of allelopathicAllelopathy
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial or detrimental effects on the target organisms...
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
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
certain enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s 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)
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
.
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.
Uses
Juglone is occasionally used as a herbicideHerbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
.
Traditionally, juglone has been used as a natural dye for clothing and fabrics, particularly wool
Wool
Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....
, 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.