Determination of the enantiomeric purity of the phytoalexins spirobrassinins by 1H NMR using chiral solvation.

A simple and inexpensive method for enantiomeric discrimination of the phytoalexins spirobrassinin (1), 1-methoxyspirobrassinin (2) and synthetic analog 1-methylspirobrassinin (6) using the chiral solvating agent 2,2,2-trifluoro-1-(9-anthryl)ethanol in C(6)D(6) is described. Using this method the enantiomeric composition of each sample can be determined accurately by (1)H NMR and the compounds can be recovered readily by chromatography.

Transformation of the host-selective toxin destruxin B by wild crucifers: probing a detoxification pathway.

The destruxin B detoxification pathway present in Sinapis alba is also present in three unrelated species, Camelina sativa, Capsella bursa-pastoris, and Eruca sativa, suggesting a conservation of this pathway across crucifers. The chemical structure of a destruxin B metabolite, (6'-O-malonyl)hydroxydestruxin B beta-D-glucopyranoside, was also establised. Considering that Camelina sativa and Capsella bursa-pastoris detoxify destruxin B and produce the phytoalexins camalexins, these wild crucifers appear to represent unique and perhaps useful sources of blackleg resistance in strategic plant breeding.

Assembling the biosynthetic puzzle of crucifer metabolites: indole-3-acetaldoxime is incorporated efficiently into phytoalexins but glucobrassicin is not.

First biosynthetic studies utilizing tetradeuterated precursors indicate that the indole glucosinolate glucobrassicin is not a precursor of the phytoalexin brassinin, and that indole-3-acetaldoxime is an efficient precursor.