Biosynthesis of riddelliine: incorporation of [3,5-14C]trachelanthamidine and [5-3H]isoretronecanol into the retronecine moiety of the alkaloid

Abstract

The two isomeric 1-hydroxymethylpyrrolizidines, trachelanthamidine and isoretronecanol labelled with ¹⁴C and ³H, respectively, were synthesized and fed to Senecio riddellii plants, resulting in the formation of riddelliine specifically labelled in its retronecine moiety, tracheianthanamidine being the more efficient precursor (15.1% absolute incorporation).