A pyran-2-one and four meroterpenoids from Thapsia transtagana and their implication in the biosynthesis of transtaganolides

Rubal, Juan J.; Moreno‐Dorado, F. Javier; Guerra, Francisco M.; Jorge, Zacarías D.; Saouf, Abderrahmane; Akssira, Mohamed; Mellouki, Fouad; Romero-Garrido, Raúl; Massanet, Guillermo M.

doi:10.1016/j.phytochem.2007.06.023

Cited by 27 publications

(33 citation statements)

References 12 publications

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“…in order to investigate the distribution of these specific highly bioactive thapsigargins, the mechanism of biosynthesis of thapsanes and guaianolides has not been elucidated. However, probable biochemical precursors such as hydrocarbon or oxygenated sesquiterpenes have previously been identified in several Thapsia species [4–6,13], and recently the first putative enzyme in thapsigargin biosynthesis was characterized from Thapsia garganica [14]. Additionally, research into the biosynthesis of sesquiterpene lactones from Asteraceae species, despite differences in their basic stereochemistry, provides a basis from which one can infer the likely mechanism of Apiaceae-type sesquiterpene lactone biosynthesis.…”

Section: Introductionmentioning

confidence: 99%

Transcriptome Analysis of Thapsia laciniata Rouy Provides Insights into Terpenoid Biosynthesis and Diversity in Apiaceae

Drew

Dueholm

Weitzel

et al. 2013

IJMS

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Thapsia laciniata Rouy (Apiaceae) produces irregular and regular sesquiterpenoids with thapsane and guaiene carbon skeletons, as found in other Apiaceae species. A transcriptomic analysis utilizing Illumina next-generation sequencing enabled the identification of novel genes involved in the biosynthesis of terpenoids in Thapsia. From 66.78 million HQ paired-end reads obtained from T. laciniata roots, 64.58 million were assembled into 76,565 contigs (N50: 1261 bp). Seventeen contigs were annotated as terpene synthases and five of these were predicted to be sesquiterpene synthases. Of the 67 contigs annotated as cytochromes P450, 18 of these are part of the CYP71 clade that primarily performs hydroxylations of specialized metabolites. Three contigs annotated as aldehyde dehydrogenases grouped phylogenetically with the characterized ALDH1 from Artemisia annua and three contigs annotated as alcohol dehydrogenases grouped with the recently described ADH1 from A. annua. ALDH1 and ADH1 were characterized as part of the artemisinin biosynthesis. We have produced a comprehensive EST dataset for T. laciniata roots, which contains a large sample of the T. laciniata transcriptome. These transcriptome data provide the foundation for future research into the molecular basis for terpenoid biosynthesis in Thapsia and on the evolution of terpenoids in Apiaceae.

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Section: Introductionmentioning

confidence: 99%

Transcriptome Analysis of Thapsia laciniata Rouy Provides Insights into Terpenoid Biosynthesis and Diversity in Apiaceae

Drew

Dueholm

Weitzel

et al. 2013

IJMS

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“…Appendino et al proposed a biogenetic hypothesis for transtaganolides based on their meroterpenoid nature, but our subsequent isolation of 7‐ O ‐geranylscopoletin ( I ), the pyran‐2‐one IV , and transtaganolides E and F (Figure ) from Th. transtagana allowed us to propose another possible biogenesis (Scheme ) . The biogenesis would begin by direct oxidation of coumarin I to arene oxide II followed by electrocyclic ring‐opening (ERO) to afford oxepin III .…”

Section: Introductionmentioning

confidence: 99%

Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran‐2‐one Aromaticity‐Mediated Regioselective Control and Biogenetic Implications

2020

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The synthetic feasibility of the oxidative cleavage: epoxidation of 7‐O‐geranylscopoletin followed by electrocyclic ring‐opening, proposed in the biogenesis of transtaganolides/basiliolides is studied. Unlike the proposed pericyclic reactions, this pathway has not yet been addressed. Three synthetic strategies have been tested consisting of: i) Baeyer–Villiger oxidation of p‐quinoids, ii) hydrolysis of quinone monoketals, or iii) direct fragmentation by using oxygen donors. Oxidation of the benzene ring of hydroxylated coumarins has been achieved using peroxyacids, but cleavage took place between undesired positions. The aromaticity conservation of the pyran‐2‐one cycle during oxidation is the controlling factor of these observed regioselectivities. The use of a 4,5‐dihydroxy‐2‐methoxycinnamate model, in which the pyran‐2‐one ring does not exert influence on oxidation, has allowed the design of a synthetic sequence toward an analogue of the natural pyran‐2‐one isolated from Thapsia transtagana, key in the biogenesis. Mechanistic proposals for the obtained results as well as their biogenetic implications are raised.

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“…The absolute configurations of these compounds are also disclosed and discussed within the context of existing biosynthetic hypotheses. [6b,[7] …”

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confidence: 99%

“…As previously proposed by Massanet and co-workers, pyrone 29 can instead be viewed as a decomposition product of epoxide 35 or oxepine 36 , which can be derived from co-isolated coumarin 34 by oxidation (Figure 2b). [7] Furthermore, these high energy intermediates ( 35 and 36 ) could undergo a series of non-enzymatic, pericyclic transformations to produce the natural products.…”

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confidence: 99%

Total Syntheses of (−)‐Transtaganolide A, (+)‐Transtaganolide B, (+)‐Transtaganolide C, and (−)‐Transtaganolide D and Biosynthetic Implications

et al. 2013

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A pyran-2-one and four meroterpenoids from Thapsia transtagana and their implication in the biosynthesis of transtaganolides

Cited by 27 publications

References 12 publications

Transcriptome Analysis of Thapsia laciniata Rouy Provides Insights into Terpenoid Biosynthesis and Diversity in Apiaceae

Transcriptome Analysis of Thapsia laciniata Rouy Provides Insights into Terpenoid Biosynthesis and Diversity in Apiaceae

Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran‐2‐one Aromaticity‐Mediated Regioselective Control and Biogenetic Implications

Total Syntheses of (−)‐Transtaganolide A, (+)‐Transtaganolide B, (+)‐Transtaganolide C, and (−)‐Transtaganolide D and Biosynthetic Implications

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