Biosynthesis Of Tropic Acid Research Articles

The Biosynthesis of Tropic Acid: The Transcarboxylation Step

The Biosynthesis of Tropic Acid: The Transcarboxylation Step

ChemInform Abstract: Biosynthesis of Tropic Acid: A Reevaluation of the Stereochemical Course of the Conversion of Phenyllactate to Tropate in Datura stramonium.

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The Biosynthesis of Tropic Acid: A Reevaluation of the Stereochemical Course of the Conversion of Phenyllactate to Tropate in Datura stramonium

The Biosynthesis of Tropic Acid: A Reevaluation of the Stereochemical Course of the Conversion of Phenyllactate to Tropate in <i>Datura stramonium</i>

ChemInform Abstract: The Biosynthesis of Tropic Acid: The (R)‐D‐Phenyllactyl Moiety is Processed by the Mutase Involved in Hyoscyamine Biosynthesis in Datura stramonium.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The biosynthesis of tropic acid. Part 6. Enantioselective, intact incorporation of (R)-(+)-3-phenyllactic acid into the tropic acid ester alkaloids of Datura

(R)-(+)-11 and (S)-(–)3-Phenyl[1,3-13C2; 1-14C] lactic acid 13 were fed separately to Datura stramonium(Solanaceae)via the wick method. In a second feeding experiment (R)-(+)- and (S)-(–)-3-phenyl [1,3-13C2; 2-14C] lactic acid were administered via the roots. In both cases hyoscine (scopolamine) and hyoscyamine 1 and 2, respectively were isolated separately from the roots and aerial parts. The (R)-enantiomer 11 was more efficiently incorporated into the (S)-(–)-tropic acid 8 moiety of both bases. Examination of the 13C NMR spectra of the bases and of tropic acid, obtained by hydrolysis of hyoscyamine, showed 13C–13C spin–spin coupling indicating that the tropoyl ester (–)-hyoscyamine 9 is formed by direct rearrangement of the (R)-(+)-3-phenyllactic acid 11 ester of tropine (littorine).

The biosynthesis of tropic acid: the stereochemical course of the mutase involved in hyoscyamine biosynthesis in Datura stramonium

Incubation of (R,S)-DL-phenyl[2-3H]lactic acid with Datura stramonium generates hyoscyamine 2 with the tritium isotope located at C-3′ of the tropic acid ester moiety; the C-3′ hydroxymethyl group of 2 is converted into a chiral methyl group and is oxidised to generate chiral sodium acetate, with the (R) configuration (96% ee); the tritium is therefore located at the 3′-pro-S site of 2; it follows that the 3′-pro-R hydrogen is introduced with inversion of configuration by the mutase operating during hyoscyamine biosynthesis.

The biosynthesis of tropic acid: the (R)-D-phenyllactyl moiety is processed by the mutase involved in hyoscyamine biosynthesis in Datura stramonium

Incubations of (R)-D-phenyl[2-13C, 2H]lactic acid 5a and (S)-L-phenyl[2-13C, 2H]lactic acid 5b with transformed root cultures of Datura stramonium have revealed that the 13C–2H bond is retained, intact at C-3 of the tropate moiety of hyoscyamine, only in the case of the (R)-D enantiomer 5a( the deuterium is lost from the (S)-L-enantiomer 5b); therefore, it is the (R)-D-phenyllactate moiety of littorine which is the enantiomer processed by the mutase in hyoscyamine biosynthesis.

The rearrangement of phenyllactate in the biosynthesis of tropic acid

Phenyl[1,3- 13C 2]lactic acid was synthesized and fed to Datura stramonium via the wick method and via the roots. Hyoscine (scopolamine) and hyoscyamine were isolated, and examination of their 13C NMR spectra showed spin-spin coupling from the newly formed contiguous centres, indicating that tropic acid is formed by an intramolecular rearrangement of phenyllactate.

The biosynthesis of tropic acid in plants: evidence for the direct rearrangement of 3-phenyllactate to tropate

Dual labelled sodium (RS)-3-phenyl[2-13C, 2-2H]lactate was incubated with transformed root cultures of Datura stramonium and the incorporation of the label into the tropic acid ester moiety of hyoscyamine was assessed by 13C{1H} and 13C{1H,2H} NMR spectroscopy and by GC–MS analysis. It is demonstrated that the 13C–2H bond of sodium (RS)-3-phenyl[2-13C,2-2H]lactate is incorporated (GC–MS, M + 2, 17%) intact into the hydroxymethyl group at C-3′ of the (S)-tropoyl moiety. This result demonstrates unambiguously that 3-phenyllactate is a closer precursor to the tropate ester than phenylpyruvate or phenylalanine.

The obligatory role of phenyllactate in the biosynthesis of tropic acid

Phenyl[1- 14C] lactic acid and phenyl [2- 3H] lactic acid were synthesized by conventional routes and fed in admixture ( 3H: 14C ratio 10:1) to Datura stramonium via the roots. Hyoscine (scopolamine) and hyoscyamine were isolated and found to have essentially the same 3H: 14C ratios as the precursor (8.5 and 10.15, respectively). Hydrolysis of hyoscyamine showed that all the activity was present in the tropic acid moiety. The tropic acid was converted to atropic acid and then cleaved by means of osmium tetroxide and sodium metaperiodate to yield formaldehyde containing all the tritium and phenylglyoxylic acid containing all the 14C, a result which shows that the tritium at C-2 of the phenyllactate precursor labelled tropic acid in the hydroxymethyl group. These findings show that phenyllactate is an obligatory intermediate in the biosynthesis of tropic acid and that the rearrangement of the side-chain takes place at the phenyllactate and not the phenylpyruvate level.

Stereochemistry of the 1,2-migration of the carboxyl group that occurs during the biosynthesis of tropic acid from phenylalanine

(2S,3R)- and (2S,3S)-[1-14C,3-3H] phenylalanine were fed in separate experiments to Daturainnoxia plants. The distribution of isotopes in the resultant labeled hyoscyamine and scopolamine indicates that the biosynthesis of the acid moiety of these ester alkaloids, namely (S)-tropic acid, involves the migration of the carboxyl group of phenylalanine to its prochiral C-3 position with retention of configuration.

Chemistry of the tropane alkaloids. 34. 1,2-Migration of hydrogen during the biosynthesis of tropic acid from phenylalanine

Chemistry of the tropane alkaloids. 34. 1,2-Migration of hydrogen during the biosynthesis of tropic acid from phenylalanine

Biosynthesis of Tropic Acid in Datura innoxia Root Tissue

DL-Phenylalanine-1-14C, phenylacetic acid-1-14C, DL-tryptophan-(2-indolyl)-14C, DL-tryptophan-(benzene ring)-U-14C, L-serine-3-14C, and formic acid-14C were all utilized by Datura innoxia root tissue as precursors of tropic acid. All of these compounds were incorporated in a specific manner.

Biosynthesis of tropic acid in Datura innoxia

Phenylalanine-UL- 14 C, phenylalanine-1,3- 14 C, and shikimic acid-UL- 14 C were fed to mature Datura innoxia Mill. plants, and the radioactive hyoscyamine and scopolamine were extracted and degraded to determine the position of the radioactive carbon of the tropic acid moiety. The results indicated that all the carbons of tropic acid are derived from the carbons of phenylalanine and the carboxyl carbon of tropic acid is derived from the carboxyl carbon of phenylalanine by way of some intramolecular shift mechanism.

Further Studies on the Biosynthesis of Tropic Acid

<b>Further Studies on the Biosynthesis of Tropic Acid</b>