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

The biosynthesis of plant alkaloids and nitrogenous microbial metabolites

“…On the basis of results obtained with radioactive precursors in Decodon verticillutus, it has been concluded that C-6 to C-10 of the Lythraceae alkaloids decodine and decinine (20) loids, namely vertine (26) and lythrine (21), in a different plant (Heimia saficifofia).20 In each of ( 21) and ( 26) the 13C n.m.r. spectra showed enrichment of (2-7, C-8, and C-9 by the label in the precursor, and only of these carbon atoms.…”

“…11, p. 4). Examination of the methoxyhydroxy-quinolizidinones (27), ( 28), (30), and (3 1) as precursors for vertine (26) and lythrine (21) gave negative results, but the dihydroxy-quinolizidinones (29) and (32) were satisfactorily incorporated into the alkaloids; the cis-precursor (29) almost exclusively labelled the cis-alkaloid (26) and the trans-precursor (32) predominantly labelled the tram-alkaloid (21). 2o These results suggest not only that dihydroxy-quinolizidinones [as (29)J are intermediates in the biosynthesis of ( 21) and (26) but also that no O-methylation occurs until after the quinolizidinone stage of biosynthesis, conceivably not until after phenol oxidative coupling to give the (21)/(26) skeleton.…”

Reactions of the Lythraceae alkaloids. Regio and stereoselective methoxylations and hydroxylations of lythrine

“…Systematic names can be derived from the core name ly111rut1 assigned to the basic structure below with the numbering system according to ref. 6 in the nmr of 8 had splittings of 3 and 10cps and were thus a much broader pattern). Since no other change could be detected from a spectral comparison of 7 and 8, the two compounds were assigned epimeric structures at C13.…”

Biosynthesis of Lythraceae Alkaloids: Incorporation of DL-{4,5-13C2, 6-14C}lysine and cis-and trans-4-(3,4-dihydroxyphenyl)-quinolizidin-2-one Into Vertine and Lythrine

“…Study of the biosynthesis of the Lythraceae alkaloids of Decodon verticillatus, such as decodine [7], has shown that they are constituted from one molecule of L-lysine [1} (2) and two of phenylalanine [4] (3). Lysine, its decarboxylation product cadaverine [2} (3) and A^piperideine {33 all serve as precursors for ring A (C-6 to C-10) of decodine [7].…”

“…Phenylalanine [4] has been shown to be incorporated into decinine [8] and decodine [7] as two C6-C3 units: C-2 and C-l 1 of 7 and 8 both derive from C-l of the amino acid (C-4, -3, -13, and -12 also originate in phenylalanine) (3).…”