The cruciferous phytoalexins rapalexin A, brussalexin A and erucalexin: chemistry and metabolism in Leptosphaeria maculans.
The interactions of the cruciferous phytoalexins rapalexin A (1), brussalexin A (2) and erucalexin (3) with the fungal plant pathogen Leptosphaeria maculans were analyzed and their inhibitory activities against this pathogen were determined. The reaction of L. maculans to N-methyl S-(indolyl-3-methyl)carbamodithioate, an analogue of brussalexin A, was also investigated. Rapalexin A was resistant to metabolism and was the most inhibitory of all compounds tested, suggesting that increasing concentrations of rapalexin A in Brassica species would improve their disease resistance to L. maculans. By contrast, erucalexin was quickly detoxified by reduction to yield 3-dihydroerucalexins. The relative configurations of the diastereomeric mixture of dihydroerucalexins were established by 1D (1)H nuclear Overhauser enhancement spectroscopy (NOE). Brussalexin A was chemically unstable decomposing mainly to indolyl-3-methanol, a product with anti-cancer properties. For this reason, brussalexin A might be of interest to use as a prodrug.
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK, Canada S7N 5C9. s.pedras@usask.ca
M Soledade C
MS
Pedras
Vijay K
VK
Sarma-Mamillapalle
D000935:Antifungal Agents / Q000138:chemical synthesis / Q000378:metabolism; D001711:Biotransformation; D007211:Indoles / Q000138:chemical synthesis / Q000378:metabolism*; D017879:Isothiocyanates / Q000138:chemical synthesis / Q000378:metabolism*; D004718:Saccharomycetales / Q000187:drug effects / Q000378:metabolism*; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000378:metabolism*; D013237:Stereoisomerism; D013844:Thiazoles / Q000138:chemical synthesis / Q000378:metabolism*; D013859:Thiocarbamates / Q000138:chemical synthesis / Q000378:metabolism*; D000094162:Phytoalexins
D000935:Antifungal Agents; D007211:Indoles; D017879:Isothiocyanates; D013141:Spiro Compounds; D013844:Thiazoles; D013859:Thiocarbamates; C522561:brussalexin A; D000094162:Phytoalexins; C511235:erucalexin; C518225:rapalexin A