# Capsidiol

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Capsidiol
> Markdown URL: https://mediated.wiki/source/Capsidiol.md
> Source: https://en.wikipedia.org/wiki/Capsidiol
> Source revision: 1315020530
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

**Capsidiol** is a [terpenoid](/source/Terpenoid) compound that accumulates in tobacco *Nicotiana tabacum* and chili pepper *Capsicum annuum* in response to fungal infection.[1] Capsidiol is categorized under the broad term of [phytoalexin](/source/Phytoalexin), a class of low molecular weight plant secondary metabolites that are produced during infection.[2] [Phytoalexins](/source/Phytoalexins) are also characterized as a part of a two pronged response to infection which involves a short term response consisting of production of [free radicals](/source/Free_radicals) near the site of infection and a long term response involving the production of hormones and an increase in enzymes to biosynthesize phytoalexins such as capsidiol.

## Mechanism of production

Capsidiol is produced in the pepper fruit *[Capsicum annuum](/source/Capsicum_annuum)* or [tobacco](/source/Tobacco) *[Nicotiana tabacum](/source/Nicotiana_tabacum)* after infection by the [oomycete](/source/Oomycete) water-mold *[Phytophthora capsici](/source/Phytophthora_capsici)*. In pepper or tobacco fields, the oomycete is soil-borne and initially infects roots, collars and lower leaves. Sporangia are moved within fields by contact with field equipment, clothing, gloves, tools etc. and initial infections spread [zoospores](/source/Zoospore) through splashing of water from irrigation or rain.[3] Initial responses to infection include production of radical oxygen species, including H2O2.[4] Exogenous treatment with H2O2 alone has been shown to induce capsidiol production.[4] Capsidiol production is then increased in response to radical oxygen species production.[citation needed]

## Biosynthesis

Capsidiol is a bicyclic [terpene](/source/Terpene) that is biosynthetically derived from the [mevalonate pathway](/source/Mevalonate_pathway) via [farnesyl pyrophosphate](/source/Farnesyl_pyrophosphate) (FPP). The *E*,*E*-farnesyl cation is first created by the loss of [pyrophosphate](/source/Pyrophosphate). Kinetic studies have indicated that turnover appears to be limited by a chemical step after the initial loss of pyrophosphate.[5] Crystal structures of recombinant tobacco 5-epi-[aristolochene](/source/Aristolochene) synthase (TEAS), alone and also complexed with two FPP analogues have been reported and analyzed to suggest the following mechanism of biosynthesis.[6] The *E*,*E*-farnesyl cation undergoes cyclization to form the germacryl cation. The second ring closure gives the bicyclic eudesmyl cation, which is stabilized by various dipole interactions, then H-2 migrates to C-3 producing a tertiary cation at C-2 (farnesyl numbering).[5] Production of 5-epi-aristolochene from FPP by 5-epi-aristolochene 3-hydroxylase, a sesquiterpene cyclase, is considered the critical step in capsidiol biosynthesis.[1] [Aristolochene](/source/Aristolochene) synthase enzymes from *[Penicillium roqueforti](/source/Penicillium_roqueforti)*, *[Nicotiana tabacum](/source/Nicotiana_tabacum)* have been purified and their crystal structures have been reported suggesting different stereochemistries for aristolochene.[5][6] *[Penicillium roqueforti](/source/Penicillium_roqueforti)'*s [enzyme](/source/Enzyme) appears to synthesizes aristolochene by way of (*S*)-[germacrene](/source/Germacrene) A, however, the *[Nicotiana tabacum](/source/Nicotiana_tabacum)* enzyme 5-epi-aristolochene synthase produces the diastereoisomeric product by way of (*R*)-[germacrene](/source/Germacrene) A.[5]

## References

1. Maldonado-Bonilla LD, Betancourt-Jiménez M, Lozoya-Gloria E (2008) "Local and systemic gene expression of sesquiterpene phytoalexin biosynthetic enzymes in plant leaves". *European J. Plant Path.* **121(4)**, 439-449.

1. Hammerschmidt R. (1999). "Phytoalexins: What have we learned after 60 years?" *Anni. Rev. Phytopathol*. **37**, 285-306.

1. Uchida J.Y.; Aragaki M. (1980). "Chemical Stimulation of oospore formation in *Phytophthoracapsici*". *Mycologia* **72**, 1103-1108.

1. Arreola-Cortes A.; Castro-Mercado E.; Lozoya-Gloria E.; Garcia-Pineda E. (2007). "Capsidiol production in pepper fruits (*Capsicum annuum*) induced by arachidonic acid is dependent of an oxidative burst". *Physiol. Mol. Plant Pathol.* **70(1-3)**: 69-76.

1. Dewick P.M. (2002)."The biosynthesis of C5-C25 terpenoid compounds". *Nat. Prod. Rep.* **16**, 97-130

1. Starks C.M.; Back K.; Chappell J.; Noel J.P.; (1997) Structural Basis for Cyclic Terpene Biosynthesis by Tobacco 5-Epi-Aristolochene Synthase. *Science* **277**, 1815-1820

---
Adapted from the Wikipedia article [Capsidiol](https://en.wikipedia.org/wiki/Capsidiol) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Capsidiol?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.