:Camalexin
{{Chembox
| ImageFile = Camalexin.svg
| ImageSize = 150px
| PIN = 3-(1,3-Thiazol-2-yl)-1H-indole
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|Section1={{Chembox Identifiers
| CASNo = 135531-86-1
| PubChem = 636970
| ChemSpiderID = 552646
| SMILES = c1ccc2c(c1)c(c[nH]2)c3nccs3
| InChI = 1/C11H8N2S/c1-2-4-10-8(3-1)9(7-13-10)11-12-5-6-14-11/h1-7,13H
| InChIKey = IYODIJVWGPRBGQ-UHFFFAOYAV
| StdInChI = 1S/C11H8N2S/c1-2-4-10-8(3-1)9(7-13-10)11-12-5-6-14-11/h1-7,13H
| StdInChIKey = IYODIJVWGPRBGQ-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
| C=11 | H=8 | N=2 | S=1
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
| Solubility =
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|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
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Camalexin (3-thiazol-2-yl-indole) is a simple indole alkaloid found in the plant Arabidopsis thaliana and other crucifers. The secondary metabolite functions as a phytoalexin to deter bacterial and fungal pathogens.{{Cite journal | doi = 10.1105/tpc.107.051383 | pmid = 17573535 | pmc = 1955726 | title = Arabidopsis Cytochrome P450 Monooxygenase 71A13 Catalyzes the Conversion of Indole-3-Acetaldoxime in Camalexin Synthesis | journal = The Plant Cell | volume = 19 | issue = 6 | pages = 2039–2052 | year = 2007 | last1 = Nafisi | first1 = Majse | last2 = Goregaoker | first2 = Sameer | last3 = Botanga | first3 = Christopher J. | last4 = Glawischnig | first4 = Erich | last5 = Olsen | first5 = Carl E. | last6 = Halkier | first6 = Barbara A. | last7 = Glazebrook | first7 = Jane }}
Structure
The base structure of camalexin consists of an indole ring derived from tryptophan. The ethanamine moiety attached to the 3 position of the indole ring is subsequently rearranged into a thiazole ring.
Biosynthesis
While the biosynthesis of camalexin in planta has not been fully elucidated, most of the enzymes involved in the pathway are known and involved in a metabolon complex.{{Cite journal | doi = 10.1105/tpc.19.00403 | title = The formation of a camalexin-biosynthetic metabolon | journal = The Plant Cell | pages = 2697–2710 | year = 2019 | last1 = Mucha | first1 = Stefanie | last2 = Heinzlmeir | first2 = Stephanie | last3 = Kriechbaumer | first3 = Verena | last4 = Strickland | first4 = Benjamin | last5 = Kirchhelle | first5 = Charlotte | last6 = Choudhary | first6 = Manisha | last7 = Kowalski | first7 = Natalie | last8 = Eichmann | first8 = Ruth | last9 = Hueckelhoven | first9 = Ralph | last10 = Grill | first10 = Erwin | last11 = Kuster | first11 = Bernhard | last12 = Glawischnig | first12 = Erich | volume = 31 | issue = 11 | pmid = 31511315 | pmc = 6881122 | doi-access = free }} The pathway starts with a tryptophan precursor which is subsequently oxidized by two cytochrome P450 enzymes.{{Cite journal | doi = 10.1073/pnas.0305876101 | pmid = 15148388 | pmc = 419588 | title = Camalexin is synthesized from indole-3-acetaldoxime, a key branching point between primary and secondary metabolism in Arabidopsis | journal = Proceedings of the National Academy of Sciences | volume = 101 | issue = 21 | pages = 8245–8250 | year = 2004 | last1 = Glawischnig | first1 = E. | last2 = Hansen | first2 = B. G. | last3 = Olsen | first3 = C. E. | last4 = Halkier | first4 = B. A. | bibcode = 2004PNAS..101.8245G | doi-access = free }} The indole-3-acetaldoxime is then converted to indole-3-acetonitrile by another cytochrome P450, CYP71A13. A glutathione conjugate followed by a subsequent unknown enzyme is needed to form dihydrocamalexic acid.{{Cite journal | doi = 10.1105/tpc.110.079145 | pmid = 21239642 | pmc = 3051237 | title = Glutathione-Indole-3-Acetonitrile is Required for Camalexin Biosynthesis in Arabidopsis thaliana | journal = The Plant Cell | volume = 23 | issue = 1 | pages = 364–380 | year = 2011 | last1 = Su | first1 = Tongbing | last2 = Xu | first2 = Juan | last3 = Li | first3 = Yuan | last4 = Lei | first4 = Lei | last5 = Zhao | first5 = Luo | last6 = Yang | first6 = Hailian | last7 = Feng | first7 = Jidong | last8 = Liu | first8 = Guoqin | last9 = Ren | first9 = Dongtao }}{{Cite journal | doi = 10.1105/tpc.111.083998 | pmid = 21712415 | pmc = 3160024 | title = Cytosolic γ-Glutamyl Peptidases Process Glutathione Conjugates in the Biosynthesis of Glucosinolates and Camalexin in Arabidopsis | journal = The Plant Cell | volume = 23 | issue = 6 | pages = 2456–2469 | year = 2011 | last1 = Geu-Flores | first1 = Fernando | last2 = Møldrup | first2 = Morten Emil | last3 = Böttcher | first3 = Christoph | last4 = Olsen | first4 = Carl Erik | last5 = Scheel | first5 = Dierk | last6 = Halkier | first6 = Barbara Ann }} A final decarboxylation step by cytochrome P450 CYP71B15, also called phytoalexin deficient4 (PAD3) results in the final product, camalexin.{{Cite journal | doi = 10.1105/tpc.11.12.2419 | pmid = 10590168 | pmc = 144139 | title = Arabidopsis PAD3, a Gene Required for Camalexin Biosynthesis, Encodes a Putative Cytochrome P450 Monooxygenase | journal = The Plant Cell | volume = 11 | issue = 12 | pages = 2419–2428 | year = 1999 | last1 = Zhou | first1 = Nan | last2 = Tootle | first2 = Tina L. | last3 = Glazebrook | first3 = Jane }}{{Cite journal | doi = 10.1104/pp.106.082024 | pmid = 16766671 | title = CYP71B15 (PAD3) Catalyzes the Final Step in Camalexin Biosynthesis | journal = Plant Physiology | volume = 141 | issue = 4 | pages = 1248–1254 | year = 2006 | last1 = Schuhegger | first1 = Regina | last2 = Nafisi | first2 = Majse | last3 = Mansourova | first3 = Madina | last4 = Petersen | first4 = Bent Larsen | last5 = Olsen | first5 = Carl Erik | last6 = Svatoš | first6 = Aleš | last7 = Halkier | first7 = Barbara Ann | last8 = Glawischnig | first8 = Erich | pmc = 1533948 | doi-access = free }}
Biological activity
Camalexin is cytotoxic against aggressive prostate cancer cell lines in vitro.{{Cite journal | doi = 10.1007/s11418-012-0722-3 | pmid = 23179315 | pmc = 3644009 | title = The phytoalexin camalexin mediates cytotoxicity towards aggressive prostate cancer cells via reactive oxygen species | journal = Journal of Natural Medicines | volume = 67 | issue = 3 | pages = 607–618 | year = 2013 | last1 = Smith | first1 = Basil A. | last2 = Neal | first2 = Corey L. | last3 = Chetram | first3 = Mahandranauth | last4 = Vo | first4 = Baohan | last5 = Mezencev | first5 = Roman | last6 = Hinton | first6 = Cimona | last7 = Odero-Marah | first7 = Valerie A. }}