Lythraceae alkaloids, biosynthesis

A key stage in the biosynthesis of piperidine alkaloids is reached with the formation of A -piperideine. For the elaboration of diverse alkaloids, this intermediate undergoes condensation with a variety of nucleophiles, commonly a /3-keto-acid. (A similar situation is found for pyrrolidine alkaloid biosynthesis see, e.g., Scheme l).1,2 Existing evidence on Lythraceae alkaloid biosynthesis, taken up again below, indicated that condensation occurred in this case between A piperideine (17) and acetoacetic acid to give pelletierine (26), further elaboration yielding alkaloids like (22). In the event, however, labelled pelletierine was found not to be a precursor for (22) or (23).8 Negative evidence is always difficult to interpret, but is here made persuasive by the fact that other precursors that were fed concurrently were incorporated. Conclusive support for these results depended on others outlined below. 

Most of the work on the biosynthesis of Lythraceae alkaloids has been done by Spenser et al. (10, 84-87). First, the validity of the pelletierine hypothesis (c) of Ferris et al. (62) has been tested. The pelletierine (126) nucleus is generated from L-lysine (181) via cadaverine (182), and presumably A -piperideine (132) and its side chain originate from the acetate. Incorporation of radioactivity from 14C-labeled samples of these precursors to decodine (6) and decinine (2) in Decodon verticilatus has been investigated (85, 87). 

Other Sources of Imidazole Alkaloids Lythraceae alkaloids Maytansinoids Antitumor Activity Other Biological Activity Muscarine Alkaloids Naphthylisoquinoline Alkaloids Peptide Alkaloids Purine or Xanthine Alkaloids Biosynthesis... 

The biosynthesis of Lythraceae alkaloids is not well understood. Lysine serves as a precursor for part of the molecule all carbons except the carboxyl group of lysine are incorporated. Further, the lysine-derived portion enters the molecule via a symmetrical intermediate. Phenylalanine... 

Hedges SH, Herbert RB, Wormald PC (1983) Biosynthesis of lythraceae alkaloids Incorporation of DL-[4,5- C2,6- C] lysine and ds- and trans-4-(3,4-dihydroxyphenyl)-quinolizidin-2-one into vertine and lythrine. J Chem Soc Chem Commun 145-147... 

Lythraceae plant family and suggests that the metacyclophane and lactonic alkaloids have a common biosynthesis. 

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