The rearrangement of phenyllactate in the biosynthesis of tropic acid

Phenyllactic acid but not tropic acid is an intermediate in the biosynthesis of tropane alkaloids in Datura and Brugmansia transformed root cultures

“…1). A similar shift was observed irrespective of whether labelled phenyllactic or phenylpyruvic acid was fed (Ansarin 1980;Ansarin et al 1985). The mechanism by which this occurs remains to be elucidated but it has recently been demonstrated that it occurs at the level of phenyllactic acid, not phenylpyruvic acid (Ansarin and Woolley 1993a,b;Chesters et al 1994).…”

“…Cultures were harvested at times after feeding as indicated in the text. [1,3-13C2]lactic acid (80.9% isotopic excess) was synthesised as described in Ansarin and Woolley (1994). ( Table 1.…”

Isotopically labelled tropane alkaloids. The synthesis of (RS)‐[3′, 3′‐2H2]‐ and (RS)‐[1′‐13C, 3′, 3′‐2H2]‐ hyoscyamines for metabolism studies in plants

“…The present paper reports the preparation of (RS)- [ (2) is formed by an intramolecular rearrangement of littorine (1). There is no evidence for the reversible oxidation of hyoscyamine (2) to aldehyde (3) Results and discussion A synthetic method was developed for the preparation of (RS)- [ [1 0 -13 C]-Phenylacetyl tropine (4a) was prepared following the classical preparation of tropine esters by acid catalysed esterification of tropine (5) and [1-13 C]-phenylacetic acid (6a) using dry HCl gas. 6 The product ester was dissolved in dilute sulfuric acid, treated with base and extracted into an organic solvent.…”

“…18 O at the C-3 0 oxygen of hyoscyamine during the rearrangement of littorine (1) to hyoscyamine (2). Liberation of the 18 O (29%) could arise either during the rearrangement 8 or has been suggested 9 as a consequence of the subsequent reversible metabolism of hyoscyamine (2) by a redox enzyme to aldehyde (3). Clearly if aldehyde (3) is generated then the 18 O could have exchanged to some extent with the aqueous medium in the plant cells.…”

Tropane and Granatane Alkaloid Biosynthesis: A Systematic Analysis

“…A branched-chain residue, tropic acid, is formed from the linear chain phenyllactic acid. To better understand this process, feeding studies of radiolabeled compounds have tried to elucidate the mechanism of this reaction [102][103][104][105][106]. Feeding studies and quantum chemistry calculations by Sandala et al have led to the hypothesis that a cytochrome p450 coupled with an alcohol dehydrogenase is involved in the conversion of the littorine (24) precursor into hyoscyamine (4) [107].…”