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

Abstract

Lysine is incorporated specifically, and via a symmetrical intermediate, into ring A of vertine (3) and lythrine (6); the cis-and trans-quinolizidinones, (9) and (lo), are, respectively and specifically, effective precursors for (3) and (6), and the corresponding mono-0-methyl ethers (11)-( 14) are not u t i I ized for a I ka lo id biosy n t hesis.

The use of stable isotopes in biosynthetic studies

“…A 1,2-migration can be detected by appropriate double labelling with carbon-13. During biosynthetic work on riboflavin (129) (see also Section 3.2.8), feeding [I ,3-13C2]glycerol (128) to Ashbya gossypii resulted not only in the pattern of labelling that was anticipated, i.e. at C-3' and C-5' of the ribityl moiety, but also showed that a skeletal rearrangement had taken place, because there was a one-bond carbon-carbon coupling between C-7a and C-7 and between C-9 and C-9a in the 13C n.m.r.…”

“…13C homoscalar correlation (13C COSY), permits the connectivity of coupled carbons to be observed with slightly less sensitivity but with simpler acquisition of ~p e c t r a . ' ~-~~~~ 223 In addition to being used in studies of the biosynthesis of riboflavin (129),205 this technique was effective in determining the arrangement of units in cationomycin (160a) that had been obtained from experiments in which [1,2-13C2]-and [2-13C]-acetate were fed to Actinomadura azurea. 163 The latter precursor gave samples of (1 60) that were labelled at adjacent carbons because there had been extensive randomization of label via the citric acid cycle (see Section 3.2.5).…”

“…163 The latter precursor gave samples of (1 60) that were labelled at adjacent carbons because there had been extensive randomization of label via the citric acid cycle (see Section 3.2.5). The homoscalar correlation approach was also used to monitor the metabolism of 13C-labelled glycine (82) artifacts than 13C homonuclear two-dimensional J-resolved spectra in studies on riboflavin (129) After an examination of the excellent magnetic properties of tritium (spin = k, nuclear moment = 2.96, relative magnetogyric ratio = 1.067) it can be suggested that, in principle, it is the ideal isotope for tracer studies in which n.m.r. spectra are used.68.226 Its extremely low natural abundance further enhances the sensitivity of detection of tritium label.…”

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

“…Using a different plant, which produces different alkaloids, we have carried out experiments with 13C-labeled lysine in order to garner independent evidence on the manner of lysine utilization in the biosynthesis of Lythraceae alkaloids. We have also obtained results which point to the later stages of biosynthesis being very interesting (1). RESULTS…”

The Phenyl- and Biphenyl-Quinolizidines of In-Vitro-Grown Heimia salicifolia

“…This monograph demonstrates that, although the structure of the alkaloids has been firmly established, work is still needed to establish completely the biogenesis of the alkaloids. Although radiotracer incorporation studies (20)(21)(22)(23) have shown that the biphenylquinolizidine lactones (as 1, Table 1) are derived from one mole of lysine (17), (20,21), one mole of acetate or malonate (18) (21) and two moles of phenylalanine (19) (1) Vertine (Cryogenineb,c). aWe would like to refer to the reason for adopting only in its modified form (20) the numbering proposed by I.D.…”