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

agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

fungicide Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...

s. They are part of the larger group of QIs (Quinone outside Inhibitors), which act to inhibit the

respiratory chain An electron transport chain (ETC) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this ...

at the level of

Complex III Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...

. 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 a broad spectrum systemic fungicide widely used in agriculture to protect crops from fungal diseases. It was first marketed in 1996 using the brand name Amistar and by 1999 it had been registered in 48 countries on more than 50 cr ...

, kresoxim-methyl, picoxystrobin, fluoxastrobin, oryzastrobin, dimoxystrobin,

pyraclostrobin Pyraclostrobin is a quinone outside inhibitor ( QI)-type fungicide used in agriculture. Among the QIs, it lies within the strobilurin chemical class. Use Pyraclostrobin is used to protect ''Fragaria'', ''Rubus idaeus'', ''Vaccinium corymbosum'' ...

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 excret ...

s; they inhibit

electron transfer Electron transfer (ET) occurs when an electron relocates from an atom, ion, or molecule, to another such chemical entity. ET describes the mechanism by which electrons are transferred in redox reactions. Electrochemical processes are ET reactio ...

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

, disrupting

metabolism Metabolism (, from ''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 cellular processes; the co ...

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 Geometry (; ) is a branch of mathematics concerned with properties of space such as the distance, shape, size, and relative position of figures. Geometry is, along with arithmetic, one of the oldest branches of mathematics. A mathematician w ...

but was later identified by

total synthesis Total synthesis, a specialized area within organic chemistry, focuses on constructing complex organic compounds, especially those found in nature, using laboratory methods. It often involves synthesizing natural products from basic, commercially ...

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 In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

group attached to the methyl of the main chain is produced by ''

Mycena sanguinolenta ''Mycena sanguinolenta'', commonly known as the bleeding bonnet, the smaller bleeding Mycena, or the terrestrial bleeding Mycena, is a species of mushroom in the family Mycenaceae. It is a common and widely distributed species, and has been fo ...

''.

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 Sessility (botany), sessile caps and grow on wood or plant debris. The genus has been studied extensively, and monograp ...

'' 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

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

ic hydroxy group in place of the aromatic methoxy group of strobilurin H is called strobilurin F1 and is found in ''C. anomala'' and ''

Agaricus ''Agaricus'' is a genus of mushroom-forming fungi containing both edible and poisonous species, with over 400 members worldwide and possibly again as many disputed or newly discovered species. The genus includes the common ("button") mushroom ...

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. : Oudemansin A with R₁ = R₂ = H was first described in 1979, after being isolated from mycelial fermentations of the

basidiomycete Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basid ...

fungus ''Oudemansiella mucida''. 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''.

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