Biosynthetic Relationship between Acutumine and Dechloroacutumine in Menispermum dauricum Root Cultures

Abstract

  The biosynthetic relationship between acutumine 1 and dechloroacutumine 2 was studied using ¹³C-labeled tyrosine and ³H-labeled 2 as tracers. ¹³C-NMR spectra of ¹³C-labeled 1 and 2 showed that the alkaloids, each composed of two molecules of tyrosine, are derived from the same biosynthetic pathway. Feeding Menispermum dauricum (Menispermaceae) roots, cultured in a chloride-enriched medium, with ³H-labeled 2 demonstrated that 1 is the only alkaloid metabolite of 2. Conversion (5%) of the exogenously applied 2, taken up by the roots, into 1 showed that 2 is the precursor of 1. Incomplete conversion of 2 into 1 suggests accumulation of the exogenously applied 2 in cell organelles and/or compartmentation of the enzymes involved in the biosynthesis of 1.