The biosynthesis of the Lythraceae alkaloids. I. The lysine-derived fragment

Abstract

The biosynthesis of decodine (7) and decinine (9), Lythraceae alkaloids containing a trans-fused quinolizidine nucleus, was studied in intact plants of Decodonverticillatus (L.) Ell. Nonrandom incorporation of radioactivity from 14C-labelled samples of lysine, cadaverine, and Δ1-piperideine was demonstrated by partial degradation. Pelletierine did not serve as a precursor of the alkaloids. It was also shown, by means of 3H,14C-labelled tracers, that the alkaloids are derived from L-lysine whereas pipecolic acid, which is present in the plant, is derived from D-lysine.

The biosynthesis of the Lythraceae alkaloids. II. The phenylalanine-derived fragments

“…The experiment with [3-14C]phenylalanine (experiment 11) showed that the distribution of label within decodine (5) in D. verticillatus (C-13 58%, C-1 33%) was very similar to that found earlier in cryogenine (25) derived from the same precursor in H. salicifolia (C-13 61%, C-1 31%(3), C-13 46%, C-1 33% (26)), indicating a close correspondence in the origin of two alkaloids of different ring stereochemistry in two different plant species.…”

“…Alkaloids with trnt~s-ringjunction cis-ring junction e.g., decodine (5) and e.g., vertine (25) and decinine (6) decamine ( found in cryogenine (25) in H. salicifolia (3,26). The distribution of label in the alkaloids obtained in experiment 12 is entirely different.…”

“…Decodine which was isolated, was radioactive and was degraded by chromic acid oxidation and the partial degradation products, p-alanine (C-7 to C-9), yaminobutyric acid (C-6 to C-9) and 2-piperidylacetic acid (C-3 to C-9), were isolated as described in the preceding paper (25). The 2-piperidylacetic acid accounted for the entire activity of the intact alkaloid.…”

“…These experiments were performed as described in the preceding paper (25). The details of the feeding experiments and the specific activities of the samples of decodine and decinine isolated from individual experiments are summarized in Table 1.…”

“…The first paper of this series (25) dealt with the status of lysine and its metabolites in the biosynthesis of decodine (5) and decinine (6), phenylquinolizidine lactone alkaloids from Decodon uerticillatus. In the present investigation, the question is examined whether it is a C6-C, unit, or a C6-C, unit, derived from phenylalanine, which is implicated in the biosynthesis of the phenylquinolizidinol system of the Decodon alkaloids.…”