Oxycarboxin Explained

Oxycarboxin is an organic chemical used in agriculture to protect crops from fungal diseases. It was first marketed by Uniroyal in 1969 using their brand name Plantvax. The compound is an anilide which combines a heterocyclic acid with aniline to give an inhibitor of succinate dehydrogenase (SDHI).[1] [2] [3]

Synthesis

Oxyxarboxin was first made by the oxidation of carboxin, as disclosed in patents filed by Uniroyal.[4]

Ethyl 2-chloroacetoacetate is treated with 2-mercaptoethanol and base, followed by cyclisation and water removal under acidic conditions. The resultant ethyl ester of the 1,4-oxathiine heterocycle is then formed into an amide with aniline using standard conditions via the carboxylic acid and acid chloride. This gives carboxin in high overall yield.[5] The synthesis is completed by treatment with 30% hydrogen peroxide in acetic acid.[4]

Mechanism of action

Carboxin and oxycarboxin act by inhibition of succinate dehydrogenase (SDHI):[6] they bind to the quinone reduction site of the enzyme complex, preventing ubiquinone from doing so. As a consequence, the tricarboxylic acid cycle and electron transport chain cannot function.[7] [8]

Uses

Oxycarboxin is used to control rust diseases (e.g. soybean rust) at an application rate of 200–400 g/ha.[9]

History

Oxycarboxin has been commercially available since 1969, when it was introduced under the brand name Plantvax.[10]

Notes and References

  1. Book: 10.1002/9783527693931.ch31 . Fungicidal Succinate-Dehydrogenase-Inhibiting Carboxamides . Bioactive Carboxylic Compound Classes: Pharmaceuticals and Agrochemicals . 2016 . Walter . Harald . Lamberth . Clemens . Jürgen . Dinges . Wiley . 405–425 . 9783527339471 .
  2. Ackermann. Peter. Margot. Paul. Müller. Franz. Fungicides, Agricultural. Ullmann's Encyclopedia of Industrial Chemistry. 2000. 10.1002/14356007.a12_085. 3527306730.
  3. Book: Shanmugasundaram . S.. Yeh. C.C. . Hartman. G.L. . Talekar. N.S. . Vegetable Soybean Research Needs for Production and Quality Improvement . 1991. Asian Vegetable Research and Development Center. Taipei. 9789290580478. 86–87. 6 February 2016.
  4. US . 3402241 . patent . 1968-09-17 . 1965-11-05 . 1965-11-05 . von Schmeling, B. . Kulka, M. . Harrison, W.A. . Control of plant fungal and bacterial diseases with 2, 3-dihydro-5-carboximido-6-methyl-1, 4-oxathiin, mono-and di-oxides . Uniroyal Inc.
  5. 10.1126/science.152.3722.659 . Systemic Fungicidal Activity of 1,4-Oxathiin Derivatives . 1966 . von Schmeling . B. . Kulka . Marshall . Science . 152 . 3722 . 659–660 . 17779512 . 1966Sci...152..659V . 27561137 .
  6. 10.1017/S0016672300016098 . Three genes determine the carboxin sensitivity of mitochondrial succinate oxidation in Aspergillus nidulans . 1975 . Gunatilleke . I. A. U. N. . Arst . H. N. . Scazzocchio . C. . Genetical Research . 26 . 3 . 297–305 . 178574 . free .
  7. 10.1074/jbc.M311876200 . free . The Quaternary Structure of the Saccharomyces cerevisiae Succinate Dehydrogenase . 2004 . Oyedotun . Kayode S. . Lemire . Bernard D. . Journal of Biological Chemistry . 279 . 10 . 9424–9431 . 14672929 .
  8. 10.1016/j.cropro.2010.02.019 . Progress in understanding molecular mechanisms and evolution of resistance to succinate dehydrogenase inhibiting (SDHI) fungicides in phytopathogenic fungi . 2010 . Avenot . Hervé F. . Michailides . Themis J. . Crop Protection . 29 . 7 . 643–651 .
  9. Book: 0948404019 . The Pesticide Manual - A World Compendium . Eighth . Worthing C.R. . British Crop Protection Council . 1987. 624.
  10. Web site: Oxycarboxin . University of Hertfordshire . Pesticide Properties Database . 2023-06-15 . 2023-08-07 .

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