Phytoalexins from the crucifer rutabaga: structures, syntheses, biosyntheses, and antifungal activity.
Phytoalexins are inducible chemical defenses produced de novo by plants in response to diverse forms of stress, including microbial attack. Our search for phytoalexins from economically important crucifers lead us to examine rutabaga tubers (Brassica napus L. ssp. rapifera). Three new phytoalexins, named isalexin (9), brassicanate A (10), and rutalexin (11), were isolated together with five known phytoalexins, brassinin (4), 1-methoxybrassinin (5), spirobrassinin (13), brassicanal A (14), and brassilexin (15). The chemical structures of the new phytoalexins were proven by syntheses, and their biological activity against four plant pathogens were determined. Biosynthetic studies using tetra- and pentadeuterated precursors established that indolyl-3-acetaldoxime (22) and brassinin (4) are precursors of brassicanate A (10) and rutalexin (11) and that cyclobrassinin (23) is a biosynthetic precursor of rutalexin (11), whereas tryptamine (24) is not a precursor of rutabaga phytoalexins.
Pedras
M Soledade C
MS
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon SK S7N 5C9, Canada. soledade.pedras@usask.ca
Montaut
Sabine
S
Suchy
Mojmir
M
D000818:Animals; D000935:Antifungal Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D029688:Brassica napus / Q000737:chemistry*; D005658:Fungi / Q000187:drug effects; D015394:Molecular Structure; D010936:Plant Extracts / Q000096:biosynthesis / Q000138:chemical synthesis / Q000494:pharmacology; D012717:Sesquiterpenes; D013729:Terpenes; D000094162:Phytoalexins
D000935:Antifungal Agents; D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D000094162:Phytoalexins