The cruciferous phytoalexins brassinin and cyclobrassinin are intermediates in the biosynthesis of brassilexin

Following feeding experiments with the tetradeuterated cruciferous phytoalexins brassinin (5b) and cyclobrassinin (6b), leaves of Brassica carinata were elicited with the blackleg causing fungus Phoma lingam and incubated. Spectroscopic and HPLC analyses indicated that both brassinin (5a) and cyclobrassinin (6a) were incorporated into the cruciferous phytoalexin brassilexin (7a).