Strobilurin

Strobilurins are a group of natural products and their synthetic analogs. A number of strobilurins are used in agriculture as fungicides. They are part of the larger group of Q_oIs (Quinone outside Inhibitors), which act to inhibit the respiratory chain at the level of Complex III.

The first parent natural products, strobilurins A and B, were extracted from the fungus Strobilurus tenacellus.<ref>Template:Cite journal</ref> Commercial strobilurin fungicides<ref>Peter Jeschke, Matthias Witschel, Wolfgang Krämer, Ulrich Schirmer (eds.): Modern Crop Protection Compounds, 3rd edition, Wiley-VCH, 2019, Template:ISBN.</ref> were developed through optimization of photostability and activity.<ref>Template:Cite journal</ref> Strobilurins represented a major development in fungus-based fungicides. First released in 1996, there are now ten major strobilurin fungicides on the market, which account for 23-25 % of the global fungicide sales.<ref> Template:Cite journal (pdf link) </ref> Examples of commercialized strobilurin derivatives are azoxystrobin, kresoxim-methyl, picoxystrobin, fluoxastrobin, oryzastrobin, dimoxystrobin, pyraclostrobin and trifloxystrobin.

Strobilurins are mostly contact fungicides with a long half time as they are absorbed into the cuticle and not transported any further. They have a suppressive effect on other fungi, reducing competition for nutrients; they inhibit electron transfer in mitochondria, disrupting metabolism and preventing growth of the target fungi.<ref name=Schaefer>Template:Cite book</ref>

Natural strobilurins

Strobilurin A

File:Strobilurin A.svg

Strobilurin A (also known as mucidin) is produced by Oudemansiella mucida, Strobilurus tenacellus, Bolinea lutea, and others.<ref name=Lorenzen>Template:Cite journal</ref><ref name=Anke>Template:Cite book</ref><ref name="Zakharychev-Kovalenko-1998">Template:Cite journal</ref> When first isolated it was incorrectly assigned as the E E E geometric isomer but was later identified by total synthesis as being the E Z E isomer, as shown.<ref name=Schaefer>Template:Cite book</ref>Template:Rp

9-Methoxystrobilurin A

9-Methoxystrobilurin A is produced by Favolaschia spp.<ref name=Anke/>

Strobilurin B

File:Strobilurin B.svg

Strobilurin B is produced by S. tenacellus.<ref name=Anke/>

Strobilurin C

File:Strobilurin C.svg

Strobilurin C is produced by X. longipes and X. melanotricha.<ref name=Anke/><ref name="Zakharychev-Kovalenko-1998" />

Strobilurin D and G

File:Strobilurin D.svg

Strobilurin D is produced by Cyphellopsis anomala.<ref name="Zakharychev-Kovalenko-1998" /> Its structure was originally incorrectly assigned and is now considered to be identical to that of strobilurin G, produced by B. lutea.<ref name=Anke/><ref name="Zakharychev-Kovalenko-1998" /> A related material, hydroxystrobilurin D, with an additional hydroxyl group attached to the methyl of the main chain is produced by Mycena sanguinolenta.<ref name=Anke/>

Strobilurin E

File:Strobilurin E.svg

Strobilurin E is produced by Crepidotus fulvotomentosus<ref name="Zakharychev-Kovalenko-1998" /> and Favolaschia spp.<ref name=Anke/>

Strobilurin F2

File:Strobilurin F2.svg

Strobilurin F2 is produced by B. lutea.<ref name=Lorenzen/>

Strobilurin H

File:Strobilurin H.svg

Strobilurin H is produced by B. lutea.<ref name=Anke/> The natural product with a phenolic hydroxy group in place of the aromatic methoxy group of strobilurin H is called strobilurin F1 and is found in C. anomala<ref name="Zakharychev-Kovalenko-1998" /> and Agaricus spp.<ref name=Lorenzen/>

Strobilurin X

File:Strobilurin X.svg

Strobilurin X is produced by O. mucida.<ref name=Anke/><ref name="Zakharychev-Kovalenko-1998" />

Oudemansins

The oudemansins are closely related to the strobilurins and are also quinone outside inhibitors.<ref name=Anke/>

File:Oudemansins general.svg

Oudemansin A with R₁ = R₂ = H was first described in 1979, after being isolated from mycelial fermentations of the basidiomycete fungus Oudemansiella mucida.<ref>Template:Cite journal</ref> Later it was found in cultures of the basidiomycete fungi Mycena polygramma and Xerula melanotricha. The latter fungus also produces oudemansin B, with R₁ = MeO and R₂ = Cl. Oudemansin X, with R₁ = H and R₂ = MeO was isolated from Oudemansiella radicata.<ref name=Lorenzen/>

Synthetic strobilurins

The discovery of the strobilurin class of fungicides led to the development of a group of commercial fungicides used in agriculture. Examples are shown below.<ref name=Schaefer/>

• Azoxystrobin.svg

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• Trifloxystrobin.svg

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• Kresoxim-methyl-2D-skeletal.png

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• Pyraclostrobin.png

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See also

• Plant pathology

External links

• Template:Citation
• Template:Citation, from: David Moore, Geoffrey D. Robson, Anthony P. J. Trinci, 21st Century Guidebook to Fungi, 2nd edition.