Camalexin

Camalexin

Names
IUPAC name 3-(1,3-Thiazol-2-yl)-1H-indole
Identifiers
CAS Number	135531-86-1
ChemSpider	552646
Jmol interactive 3D	Image
PubChem	636970
InChI InChI=1S/C11H8N2S/c1-2-4-10-8(3-1)9(7-13-10)11-12-5-6-14-11/h1-7,13H Key: IYODIJVWGPRBGQ-UHFFFAOYSA-N InChI=1/C11H8N2S/c1-2-4-10-8(3-1)9(7-13-10)11-12-5-6-14-11/h1-7,13H Key: IYODIJVWGPRBGQ-UHFFFAOYAV
SMILES c1ccc2c(c1)c(c[nH]2)c3nccs3
Properties
Chemical formula	C11H8N2S
Molar mass	200.26 g·mol^−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.^[1]

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. The pathway starts with a tryptophan precursor which is subsequently oxidized by two cytochrome P450 enzymes.^[2] The indole-3-acetaldoxime is then converted to indole-3-acetonitrile by another cytochrome P450, CYP71A13.^[3] A glutathione conjugate followed by a subsequent unknown enzyme is needed to form dihydrocamalexic acid.^[4][5] A final decarboxylation step by cytochrome P450 CYP71B15, also called phytoalexin deficient4 (PAD3) results in the final product, camalexin.^[6][7]

Biological activity

Camalexin is cytotoxic against aggressive prostate cancer cell lines in vitro.^[8]

References

1. Nafisi, Goregaoker, Botanga, Glawischnig, Olsen, et al. (2007) Arabidopsis Cytochrome P450 Monooxygenase 71A13 Catalyzes the Conversion of Indole-3-Acetaldoxime in Camalexin Synthesis. The Plant Cell Online. 19(6). 2039-2052
2. Glawischnig, Hansen, Olsen and Halkier (2004) Camalexin is synthesized from indole-3-acetaldoxime, a key branching point between primary and secondary metabolism in Arabidopsis. Proceedings of the National Academy of Sciences of the United States of America. 101(21). 8245-8250
3. Nafisi, Goregaoker, Botanga, Glawischnig, Olsen, et al. (2007) Arabidopsis Cytochrome P450 Monooxygenase 71A13 Catalyzes the Conversion of Indole-3-Acetaldoxime in Camalexin Synthesis. The Plant Cell Online. 19(6). 2039-2052
4. Su, Xu, Li, Lei, Zhao, et al. (2011) Glutathione-Indole-3-Acetonitrile Is Required for Camalexin Biosynthesis in Arabidopsis thaliana. The Plant Cell Online. 23(1). 364-380
5. Geu-Flores, Møldrup, Böttcher, Olsen, Scheel, et al. (2011) Cytosolic γ-Glutamyl Peptidases Process Glutathione Conjugates in the Biosynthesis of Glucosinolates and Camalexin in Arabidopsis. The Plant Cell Online. 23(6). 2456-2469
6. Zhou, Tootle and Glazebrook (1999) Arabidopsis PAD3, a Gene Required for Camalexin Biosynthesis, Encodes a Putative Cytochrome P450 Monooxygenase. The Plant Cell Online. 11(12). 2419-2428
7. Schuhegger, Nafisi, Mansourova, Petersen, Olsen, et al. (2006) CYP71B15 (PAD3) Catalyzes the Final Step in Camalexin Biosynthesis. Plant Physiology. 141(4). 1248-1254
8. Smith, Neal, Chetram, Vo, Mezencev, et al. (2013) The phytoalexin camalexin mediates cytotoxicity towards aggressive prostate cancer cells via reactive oxygen species. Journal of Natural Medicines. 67(3). 607-618