Wikipedia

Juglone

Juglone,also called5-hydroxy-1,4-naphthalenedione(IUPAC) is aphenolicorganic compoundwith themolecular formulaC10H6O3.In the food industry, juglone is also known asC.I. Natural Brown 7andC.I. 75500.It is insoluble inbenzenebut soluble indioxane,from which it crystallizes as yellow needles. It is anisomeroflawsone,which is the active dye compound in thehennaleaf.

Juglone
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
5-Hydroxynaphthalene-1,4-dione
Other names
  • 5-Hydroxy-1,4-naphthoquinone
  • 5-Hydroxy-p-naphthoquinone
  • Regianin
  • 5-Hydroxynaphthoquinone
  • Nucin
  • NCI 2323
  • Oil Red BS
  • C.I. Natural Brown 7
Identifiers
3D model (JSmol)
1909764
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.006.880Edit this at Wikidata
EC Number
  • 207-567-5
RTECS number
  • QJ5775000
UNII
  • InChI=1S/C10H6O3/c11-7-4-5-9(13)10-6(7)2-1-3-8(10)12/h1-5,12H☒N
    Key: KQPYUDDGWXQXHS-UHFFFAOYSA-N☒N
  • InChI=1/C10H6O3/c11-7-4-5-9(13)10-6(7)2-1-3-8(10)12/h1-5,12H
    Key: KQPYUDDGWXQXHS-UHFFFAOYAH
  • O=C\2c1c(c(O)ccc1)C(=O)/C=C/2
Properties
C10H6O3
Molar mass 174.155g·mol−1
Appearance Yellow solid
Melting point 162 to 163 °C (324 to 325 °F; 435 to 436 K)
Slightly sol.
Related compounds
Related compounds
 quinone
Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).

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

History

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The allelopathic effects ofwalnuttrees on other plants were observed as far back as the 1st century CE.[2]Juglone itself was first isolated fromblack walnutin 1856, and was identified as the compound responsible for its allelopathic effects in 1881.[2]

In 1921, a study observed thattomato plantsnear black walnut trees exhibited wilted leaves, suggesting an adverse interaction.[3]In 1926, instances ofapple treedamage caused by bothJuglans nigraandJuglans cinerea(butternut) trees were reported in northern Virginia.[4]Certain apple tree varieties displayed varying levels of resistance to walnuttoxicity.

In 1926, it was observed that walnut trees inalfalfafields resulted in crop death, while grass remained unaffected.[5]Subsequent experiments indicated that the toxic compound within walnut trees exhibited limited solubility in water, implying that the compound underwent chemical changes upon leaving the tree. It was only in 1928 that thephytotoxicnature of the compound was identified for other plant species.[6]

The scientific community faced controversy when the harmful effects of walnut trees on certain crops and trees were initially reported, following claims that the trees damagingappletrees in northern Virginia were not walnut trees at all.[7]

In 1942 it was demonstrated that tomato and alfalfa germination and seedling growth were inhibited by contact with pieces of walnut roots, providing additional scientific evidence of juglone's phytotoxicity.[8]

Juglone was usedmedicinallyin America during the early 1900s, prescribed for the treatment of variousskin diseases.[9]

Chemistry

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Synthesis

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Juglone is derived by oxidation of hydrojuglone,1,5-dihydroxynaphthalene,after enzymatic hydrolysis.[10]It can also be obtained by oxidations of 5,8-dihydroxy-1-tetralone withsilver oxide(Ag2O),manganese dioxide(MnO2), or2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).[11]

Extraction

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Juglone has been extracted from the husk of walnut fruit of which it contains 2–4% by fresh weight.[12][13]

Degradation

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Before oxidization, juglone exists in plants such as walnuts in the form of colorless hydroxyjuglone, thehydroquinoneanalog. This is rapidly oxidized to juglone once exposed to air. The evidence that hydroxyjuglone is readily degraded is most apparent in the color change of walnut hulls from yellow to black after being freshly cut.[14]

Indigenous bacteria found in the soil of black walnut roots, most notablyPseudomonas putidaJ1, are able to metabolize juglone and use it as their primary source of energy and carbon.[15]Because of this, juglone is not so active as a cytotoxin in well-aerated soils.[16]

Spectral data

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TheIR spectrumfor juglone shows bands at 3400, 1662, and 1641 cm−1,which are characteristic respectively of thehydroxyland two carbonyl groups.[17]The13C-NMRspectrum shows 10 signals, including at 160.6, 183.2, and 189.3 ppm for the hydroxyl and two carbonyl carbons.[17][11]

Biological effects

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Juglone is anallelopathiccompound, a substance produced by a plant to stunt the growth of another plant. Juglone affectsgerminationof plants less than it affects growth of the root and stem systems. In below average concentrations, it has increased the rate of germination in someconiferousseeds.[18]

Juglone exerts its effect byinhibitingcertainenzymesneeded for metabolic function. This in turn inhibits the effects of respiration ofmitochondriaand inhibitsphotosynthesisfound in common crops such asmaizeandsoyat juglone concentrations that are at or below those common in nature.[19][20]In addition to these inhibitions, juglone has been shown to alter the relationship between plants and water because of its effect onstomatalfunctioning.[21]

The rise in popularity ofalley croppingwith black walnut trees and maize in theAmerican Midwest,due to the high value of black walnut trees, has led to certain studies being conducted about the particular relationship between the two species. Research has shown that juglone affects the yield of maize crops; however, the practice ofpruningand usage ofroot barriersgreatly reduce these effects.[22]

Some plants and trees are resistant to juglone including some species ofmaple(Acer),birch(Betula), andbeech(Fagus).[citation needed]

It is highly toxic to many insect herbivores. However, some of them, exampleActias luna(Luna moth), can detoxify juglone (and relatednaphthoquinones) to non-toxic 1,4,5-trihydroxynaphthalene.It has also shownanthelmintic(expelling parasitic worms) activity on mature and immatureHymenolepis nanain mice.[23]Naphthoquinonic compounds also exhibit antimicrobial activity.[24][25][26]

Uses

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Juglone is occasionally used as aherbicide.Traditionally, juglone has been used as a natural dye for clothing and fabrics, particularlywool,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 ashair dyes.

See also

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References

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  1. ^Juglone toxicityArchived2015-02-12 at theWayback Machine
  2. ^abSoderquist, Charles J. (1973). "Juglone and allelopathy".Journal of Chemical Education.50(11): 782–3.Bibcode:1973JChEd..50..782S.doi:10.1021/ed050p782.PMID4747927.
  3. ^Cook, M.T. (1921). "Wilting caused by walnut trees".Phytopathology.11:346.
  4. ^Schneiderhan, F.J. (1926). "Apple disease studies in northern Virginia".Virginia Agricultural Experiment Station Bulletin.245:1–35.
  5. ^Massey, A.B. (1928). "Are nut trees poisonous to other trees and plants?".Flower Grower.15:4.
  6. ^Willis, Rick J. (2007-10-12).The History of Allelopathy.Springer Science & Business Media.ISBN9781402040931.
  7. ^Miller, A.G. (1926). "Walnuts and apples".Farm Journal.1926 (July): 17.
  8. ^Brown, B.I. (1942). "Injurious influence of bark of black walnut on seedlings of tomato and alfalfa".North Nut Growers Association Annual Report.33:97–102.
  9. ^M. Strugstad (2012). "A Summary of Extraction, Synthesis, Properties, and Potential Uses of Juglone: A Literature Review".Journal of Ecosystems and Management.13(3): 72–82.
  10. ^Gerald Booth "Naphthalene Derivatives" inUllmann's Encyclopedia of Industrial Chemistry,2005, Wiley-VCH, Weinheim.doi:10.1002/14356007.a17_009.
  11. ^abJ. Khalafy; 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.
  12. ^Combes, M. R. (1907)."Bulletin de la Société chimique de France".Combes, Bull. Soc. Chim.(in French).1(4): 800–816.Retrieved14 October2016.
  13. ^Cosmulescu, Sina Niculina; Trandafir, Ion; Achim, Gheorghe; Botu, Mihai; Baciu, Adrian; Gruia, Marius (15 June 2010)."Phenolics of Green Husk in Mature Walnut Fruits".Notulae Botanicae Horti Agrobotanici Cluj-Napoca.38(1): 53–56.doi:10.15835/nbha3814624(inactive 1 November 2024).ISSN1842-4309.Retrieved11 October2016.{{cite journal}}:CS1 maint: DOI inactive as of November 2024 (link)
  14. ^Gries, G.A. (1943). "Juglone - the active agent in walnut toxicity".Northern Nut Growers Association Annual Report.34:52–55.
  15. ^Schmidt, S.K. (1988). "Degradation of juglone by soil bacteria".Journal of Chemical Ecology.14(7): 1561–1571.doi:10.1007/bf01012522.PMID24276429.S2CID527864.
  16. ^Fisher, R.F. (1987). "Juglone inhibits pine growth under certain moisture regimes".Soil Sci. Soc. Am. J.42(5): 801–803.doi:10.2136/sssaj1978.03615995004200050030x.
  17. ^abSuchard, Oliver; Kane, Ronan; Roe, Bernard J.; Zimmermann, Elmar; Jung, Christian; Waske, Prashant A.; Mattay, Jochen; Oelgemöller, Michael (2006). "Photooxygenations of 1-naphthols: An environmentally friendly access to 1,4-naphthoquinones".Tetrahedron.62(7): 1467.doi:10.1016/j.tet.2005.11.021.
  18. ^Rietveld, W J (1983). "Allelopathic effects of juglone on germination and growth of several herbaceous and woody species".J. Chem. Ecol.9(2): 295–308.CiteSeerX10.1.1.550.5739.doi:10.1007/bf00988047.PMID24407348.S2CID23491349.
  19. ^Koeppe, D.E. (1972). "Some reactions of isolated corn mitochondria influenced by juglone".Physiol. Plant.27:89–94.doi:10.1111/j.1399-3054.1972.tb01142.x.
  20. ^Hejl, A.M.; Einhellig, F.A.; Rasmussen, J.A. (1993). "Effects of juglone on growth, photosynthesis, and respiration".J. Chem. Ecol.19(3): 559–568.doi:10.1007/bf00994325.PMID24248956.S2CID22740992.
  21. ^Einhelling F.A. 1986 Mechanisms and modes of action of allelochemicals.In The Science of Allelopathy.Eds. A R Putnam and C S Tang. pp 171–188. John Wiley & Sons, New York
  22. ^Jose, Shibu; Gillespie, Andrew R. (1998). "Allelopathy in black walnut (Juglans nigraL.) alley cropping. I. Spatio-temporal variation in soil juglone in a black walnut–corn (Zea maysL.) alley cropping system in the midwestern USA ".Plant and Soil.203(2): 191–197.doi:10.1023/A:1004301309997.S2CID41384254.
  23. ^Dama L.B.; Jadhav B.V. (1997). "Anthelmintic effect of Juglone on mature and Immature Hymenolepis nana in mice".Riv. Di Parassitol.2:301–302.
  24. ^Dama L.B.; Poul B.N.; Jadhav B.V. (1998). "Antimicrobial activity of Napthoquinonic compounds".J. Ecotoxicol.Environ. Monit.8:213–215.
  25. ^Dama L.B.; Poul B.N.; Jadhav B.V; 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.
  26. ^Dama L.B. (2002). "Effect of naturally occurring napthoquinones [sic] on root- knot nematode Meloidogyne spp ".Indian Phytopathology.55(1): 67–69.
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