Droserone from cell cultures of Triphyophyllum peltatum (Dioncophyllaceae) and its biosynthetic origin

The growth and droserone content of callus cultures of Triphophyllum peltatum grown in liquid 1/5 Linsmaier and Skoog medium was studied. During a lag phase in growth, droserone concentrations in the medium reached a value of 2.1 mg g(-1) fr. wt. After this maximum Value the concentration decreased slightly to 1.8 mg g(-1) fr, wt., while the growth of the calli was enhanced (25% increase in fr. wt. within 7 days). Plumbagin and isoshinanolone were likewise present ill the medium. By feeding C-13(2)-labelled acetate to the cultures the biosynthesis of droserone was elucidated. The incorporation of whole Ct-units unambiguously shows its acetogenic origin and fits well in the biosynthetic scheme suggested for the structurally - and biogenetically - related naphthylisoquinoline alkaloids. (C) 2000 Elsevier Science Ltd. All rights reserved.