Juglone: A Natural Herbicide (Allelopath) Historical

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Juglone A Natural Herbicide(Allelopath)

• Historical Profile/Toxicity?
• Isolation
• Synthesis
• Mechanism
• Characterization
• Recent Studies
• Future plans
• Acknowledgement

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JUGLONEC10H6O3
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1,4-Naphthalenedione, 5-hydroxy- Formula
C10H6O3 Molecular Weight 174.15 CAS
Registry Number 481-39-0 Chemical
Structure
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Other Names 1,4-Naphthoquinone, 5-hydroxy-
Akhnot C.I. Natural Brown 7 C.I. 75500
Iuglon Juglane Juglon Juglone Nucin
Regianin Walnut Extract Yuglon
5-Hydroxy-1,4-naphthoquinone 5-Hydroxy-1,4-naphth
osemiquinone 5-Hydroxynaphthoquinone
8-Hydroxy-1,4-naphthoquinone Jugnlon NCI 2323
Oil Red BS 1,4-Naphthoquinone, 8-hydroxy-
5-Hydroxy-1,4-naftochinon Lawsone
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Historical Profile of JugloneThe Birth of
Allelopathy (1950)

• Toxicity of Juglone has been and continues to
  be an unsolved Problem!

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• 1925 - Massey reported experiments showing a
  toxic effect of walnut bark on tomato plants.
• 1927 - Schneiderhan reported killing of apple
  trees near walnuts.
• 1950 - Davis reported that isolated Juglone
  was highly toxic when injected into alfalfa and
  tomato plants.

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• 1940 - MacDaniels and Muenscher reported a
  3-year greenhouse study showing no toxicity by
  Juglone on tomato plants, alfalfa, and apple
  trees.
• 1950 - USDA published a press release under the
  title Test Clears Walnut Reputation. claiming
  no evidence of any toxic effect by Juglone on
  Tomatoes. Birth of Allelopathy!

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• 1951 - Brooks studied the controversy for 12
  years on 218 species. He confirmed Masseys
  earlier work suggesting that the toxicity
  appeared only when the roots were in contact
  with each other.
• Dow Chemical reported that UV light was essential
  for the secretion of Juglone, which explained the
  negative toxicity reported by MacDaniels and
  Muenscher in 1940.

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• 1975 - An extensive study at Ithaca, New York
  confirmed the toxicity of Juglone with the
  following assertions
• Antagonism between walnut and other plants has
  been observed.
• The substance responsible for this antagonism is
  Juglone.
• Root to root contact must exist for toxicity to
  occur.

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Isolation of Juglone

• Isolation was done by extracting crushed hull
  with petroleum ether. Recrystallization produced
  orange needles with MP of 153-159 C

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Synthesis of Juglone

• Sodium dichromate in water is carefully added to
  conc. sulfuric acid. To this slurry, add
  1,5-dihydroxynaphthalene. The mixture is then
  heated to no more than 50C for thirty min. Crude
  product is recrystallized from hexane.
  Yellow-orange needles were produced with MP
  148-153C.

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Juglone
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Molecular Mass Fragments
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Recent Studies

• Krajci, W. M., and Lynch, D. L. (1978). The
  inhibition of various micro-organisms by crude
  walnut hull extracts and Juglone. Microbios
  Letters. 4, 175-181

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• Craton, D. W., and Williams, R. D. (1980).
  Juglone Dermatitis Allergy or Irritant? Indiana
  Academy of Science. 90 98-102

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• Clark, A. M., Jurgens, T. A., and Hufford, C. D.
  (1990). Antimicrobial Activity of Juglone.
  Phytotherapy Research. 4, 11-14.

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• Galey, F. D., Whiteley, H. E., Goetz, T. E.,
  Kuenstler, A. R. Davis, C. A., and Beasley V. R.
  (1991). Black walnut (Juglans nigra) Toxicosis A
  Model for Equine Laminitis. J. Comp. Path. 104,
  313-326.

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Future Plans

• To setup an experiment to test and compare the
  allelopathic activity of both the isolated and
  synthesized Juglone on earth and space tomatoes.

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Acknowledgements

• Kelly Wentz-Hunter
• Sherry Litko
• __________________________
• University of St. Francis
• NASA Tomato Space Program

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• Thank you
• Professor Salim M. Diab
• Department of Natural Sciences
• University of St. Francis
• Joliet, Illinois 60435
• sdiab_at_stfrancis.edu
• 2000