Biosynthesis of Mustard Oil Glucosides:

Apart from certain amino acids none of the nitrogenous intermediates involved in the biosynthesis of mustard oil glucosides have, untl now, been determined. Results consistent with the hypothesis — amino acids → aldehyde oximes → mustard oil glucosides — are presented for glucotropaeolin and gluconasturtin. Administration of dl ‐[2‐ 14 C]phenylalanine and [1‐ 14 C]phenylacetaldehyde oxime to Tropaeolum majus L. shoots resulted in a greater incorporation of the tracer from the latter into the aglycone moiety of glucotropaeolin; incorporation of 14 C from phenylacetaldehyde oxime into the aglycone was without randomization. Radioactive phenylacetaldehyde oxime was isolated from T. majus shoots which were fed dl ‐[2‐ 14 C]phenylalanine. The extent of conversion of 14 C into the aglycone of gluconasturtin was similar when 3‐phenyl[1‐ 14 C]propionaldehyde oxime and dl ‐2‐amino‐4‐phenyl[2‐ 14 C]butyric acid were fed to Nasturtium officinale R. Br. There was no randomization of labelled carbon in gluconasturtin aglycone derived from 3‐phenylpropionaldehyde oxime.