THE CHEMISTRY OF JUGLONE

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• THE CHEMISTRY OF JUGLONE
• A DETECTIVE STORY
• OF
• UNSOLVED MYSTERY

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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.
• NOTE 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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• 1999 Recent studies by Boyer at Cornell found
  the following
• Juglone extract from unripe walnuts can cause a
  sedative effect in different species of animals.
  In one study , goldfish, mice, rats, and rabbits
  all experienced a depressant effect from the
  juglone.
• Rabbits also experienced a rise in ear
  temperature due to vasodilation.
• It also dilated the coronary arteries of rabbits
  heart. However, juglone does not appear to have
  any effect on the blood pressure and heart rate
  of dogs.

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• When rats were fed juglone, an accumulation of
  abdominal fluid accompanied by proteins, a loss
  of fluid from lung tissues, and a decrease in
  plasma proteins occurred.
• There was also an increase in plasma potassium,
  but not in plasma sodium. These findings suggest
  that juglone may increase capillary permeability.
  

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• Dogs administered juglone intravenously also
  experienced fluid loss in the lungs. In addition,
  experimental dogs had an increased hematocrit and
  blood specific gravity, but a lower plasma
  specific gravity.
• This also gives evidence that juglone is toxic to
  cell membranes, increasing capillary
  permeability.
• Several studies have been done on horses in an
  attempt to determine whether or not juglone is
  the toxic compound in black walnuts that causes
  laminitis in horses.

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• A juglone-ethanol solution administered to ponies
  via a stomach tube resulted in symptoms of mild
  laminitis in two of four ponies.
• Juglone applied topically to horses' forelimbs
  resulted in increased digital pulses after 3
  hours and in increased skin temperatures after
  five hours. Laminitis and increased hoof
  temperature were not noticed.

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• Horses receiving juglone intravenously had an
  anaphylactic type of response. Respiratory rates
  increased, fluid accumulated in the lungs, but
  the ponies did not show any signs of laminitis.
• An anaphylactic response only occurred in ponies
  that had previously been exposed to juglone.

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• In Summary
• The physiological action of juglone and its
  allelopathic effects are not well understood.
• Research has shown that juglone may alter the
  normal oxygen uptake of mitochondria and may also
  impair photosynthesis which would lead to
  decreased growth rates of the effected plants.

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Our ResearchI 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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II 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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III Spectral Characterization
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H-NMR Parameter
Parts Per Million Hz D (A) 7.579 D
(B) 7.601 D (C) 7.243 D (D)
11.834 J (A,B) 7.56 J (A,C) 1.19
J (A,D) 0.0 J
(B,C) 8.44 J (B,D) 0.37 J (C,D) 0.0
D (E) 6.917
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C-13 NMR Carbon Assignment Integration Parts Per
Million 1 309 190.26 2 258
184.19 3 608 161.45 4
845 139.57 5 1000
138.62 6 938 136.54 7 454
131.78 8 814 124.48 9
969 119.13 10 381
114.97
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Juglone
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Molecular Mass Fragments
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Current Goals Summer 2003

• - Examine the allelopathy of Juglone on Tomato
  Plants
• Decide most effective solvent
• Decide range of effective concentrations of
  Juglone
• Design and set-up experiment
• Collect data
• Test allelopathy on Space and Earth Tomatoes

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Progress

• 1. That ethanol is the ideal solvent of choice.
• 2. That Juglone concentrations of 5, 10, 50,
  100, and 250, 500, and 1000 µM were adequate.
• 3. Our team of four students tried to duplicate
  their data with inconclusive results.
• 4. Work on these goals shall resume Spring and
  Summer 2005 (any interested students?)
• (Dr. Angie Hejl working with Mr. Sebastian Ribi,
  a graduate student from Switzerland

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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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Acknowledgements

• University of St. Francis (USF)
• Kelly Wentz-Hunter (Ph.D.)
• Sherry Litko (BS, USF)
• Kerri Banser (BS, USF)
• Kristina Taylor (BS, USF)
• Brian Herbst (Senior at USF)
• Hadyn Hollister (Senior at USF)
• NASA Tomato Space Program

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• Thank you
• Dr. Salim M. Diab
• Professor of Chemistry
• University of St. Francis
• Lewis University
• Joliet, Illinois 60435
• sdiab_at_stfrancis.edu
• 815-740-3855
• 2004