Strobilurins are a group of natural products and their synthetic analogs. A number of strobilurins are used in

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...

as fungicides. They are part of the larger group of QIs (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''. Commercial strobilurin fungicides were developed through optimization of photostability and activity. 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. Examples of commercialized strobilurin derivatives are

azoxystrobin Azoxystrobin is the ISO common name for an organic compound that is used as a fungicide. It is a broad spectrum systemic active ingredient widely used in agriculture to protect crops from fungal diseases. It was first marketed in 1996 using the ...

, 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

nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excr ...

s; they inhibit

electron transfer Electron transfer (ET) occurs when an electron relocates from an atom or molecule to another such chemical entity. ET is a mechanistic description of certain kinds of redox reactions involving transfer of electrons. Electrochemical processes ar ...

in mitochondria, disrupting

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

and preventing growth of the target fungi.

Natural strobilurins

Strobilurin A

: Strobilurin A (also known as mucidin) is produced by '' Oudemansiella mucida'', '' Strobilurus tenacellus'', '' Bolinea lutea'', and others. 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.

9-Methoxystrobilurin A

9-Methoxystrobilurin A is produced by ''Favolaschia'' spp.

Strobilurin B

: Strobilurin B is produced by ''S. tenacellus''.

Strobilurin C

: Strobilurin C is produced by '' X. longipes'' and '' X. melanotricha''.

Strobilurin D and G

: Strobilurin D is produced by '' Cyphellopsis anomala''. Its structure was originally incorrectly assigned and is now considered to be identical to that of strobilurin G, produced by ''B. lutea''. A related material, hydroxystrobilurin D, with an additional hydroxyl group attached to the methyl of the main chain is produced by '' Mycena sanguinolenta''.

Strobilurin E

: Strobilurin E is produced by ''

Crepidotus fulvotomentosus ''Crepidotus'' is a genus of fungi in the family Crepidotaceae. Species of ''Crepidotus'' all have small, convex to fan-shaped sessile caps and grow on wood or plant debris. The genus has been studied extensively, and monographs of the North Amer ...

'' and ''

Favolaschia ''Favolaschia'' is a genus of fungi in the family Mycenaceae. The genus has a widespread distribution, and contains about 50 species. Like the genus Favolus, the name is derived from the Latin ''favus'' meaning ''honeycomb'', as the fungi with t ...

'' spp.

Strobilurin F2

: Strobilurin F2 is produced by ''B. lutea''.

Strobilurin H

: Strobilurin H is produced by ''B. lutea''. 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'' and '' Agaricus spp.

Strobilurin X

: Strobilurin X is produced by ''O. mucida''.

Oudemansins

The oudemansins are closely related to the strobilurins and are also quinone outside inhibitors. : Oudemansins general

Oudemansin A with R₁ = R₂ = H was first described in 1979, after being isolated from mycelial fermentations of the basidiomycete fungus ''Oudemansiella mucida''. Later it was found in cultures of the basidiomycete fungi ''

Mycena polygramma ''Mycena polygramma'', commonly known as the grooved bonnet, is a species of mushroom in the family Mycenaceae. The inedible fruit bodies are small, pale gray-brown mushrooms with broadly conical caps, pinkish gills. They are found in small tr ...

'' 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 ''Hymenopellis radicata'', commonly known as the deep root mushroom or the rooting shank, is a widespread agaric readily identified by its deeply rooted stalk ( stipe). Description The cap is medium to large, flat, grayish or yellowish brown ...

''.

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. Image:Azoxystrobin.svg, Image:Trifloxystrobin.svg, Image:Kresoxim-methyl-2D-skeletal.png, Image:Pyraclostrobin.png,

References

External links

* * {{citation , url=http://www.davidmoore.org.uk/21st_Century_Guidebook_to_Fungi_PLATINUM/Ch18_04.htm , title=Agricultural mycocides for the 21st century: strobilurins , archive-url=https://web.archive.org/web/20190908155044/http://www.davidmoore.org.uk/21st_Century_Guidebook_to_Fungi_PLATINUM/Ch18_04.htm , archive-date=2019-09-08 , access-date=2019-09-08 , url-status=live , from: David Moore, Geoffrey D. Robson, Anthony P. J. Trinci, ''21st Century Guidebook to Fungi'', 2nd edition. Fungicides Respiratory toxins Complex III inhibitors Strobilurins