The Biosynthesis of Some Isothiocyanates and Oxazolidinethiones in Rape (Brassica campestris L.)

The incorporation of the radioactivity from acetate-1-(14)C, acetate-2-(14)C, dl-methionine-1-(14)C, dl-methionine-2-(14)C, dl-methionine-3,4-(14)C, dl-homomethionine-2-(14)C, dl-allyl-glycine-2-(14)C, and dl-2-amino-5-hydroxyvalerate-2-(14)C into the aglycones of progoitrin, gluconapin, and glucobrassicanapin of maturing rape plants (Brassica campestris L.) was investigated. Radioactivity from dl-methionine-2-(14)C, dl-methionine-3,4-(14)C, dl-homomethionine-2-(14)C, and acetate-2-(14)C were incorporated into the 3 major thioglucosides. The other organic compounds were poorly incorporated except for dl-allylglycine-2-(14)C into glucobrassicanapin. The results obtained suggest that the rape plant can synthesize amino acids by the condensation of acetate (as acetyl CoA) to alpha-keto acids to yield a homologue of the original amino acid. These newly formed amino acids are then employed to synthesize the 3 major thioglucosides.