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.
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.
The pathway starts with a tryptophan precursor which is subsequently oxidized by two cytochrome P450 enzymes.
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.]
Biological activity
Camalexin is cytotoxic against aggressive prostate cancer cell lines in vitro.
