Biosynthetic insights provided by unusual sesterterpenes from the medicinal herb Aletris farinosa

Challinor, Victoria L., Johnston, Ryne C., Bernhardt, Paul V., Lehmann, Reginald P., Krenske, Elizabeth H. and De Voss, James J. (2015) Biosynthetic insights provided by unusual sesterterpenes from the medicinal herb Aletris farinosa. Chemical Science, 6 10: 5740-5745. doi:10.1039/c5sc02056e


Author Challinor, Victoria L.
Johnston, Ryne C.
Bernhardt, Paul V.
Lehmann, Reginald P.
Krenske, Elizabeth H.
De Voss, James J.
Title Biosynthetic insights provided by unusual sesterterpenes from the medicinal herb Aletris farinosa
Formatted title
Biosynthetic insights provided by unusual sesterterpenes from the medicinal herb Aletris farinosa
Journal name Chemical Science   Check publisher's open access policy
ISSN 2041-6539
2041-6520
Publication date 2015-07-03
Year available 2015
Sub-type Article (original research)
DOI 10.1039/c5sc02056e
Open Access Status DOI
Volume 6
Issue 10
Start page 5740
End page 5745
Total pages 6
Place of publication Cambridge, United Kingdom
Publisher Royal Society of Chemistry
Language eng
Abstract A series of novel sesterterpenes (2-6) have been isolated from the roots of Aletris farinosa and structurally characterized by MS, NMR, and X-ray crystallography in conjunction with computational modeling. Their structures provide new insights into the mechanisms of sesterterpene biosynthesis. Specifically, we propose with support from density functional theory computations that the configuration at a single stereocenter determines the fate of a key tetracyclic carbocationic intermediate, derived from an oxidogeranylfarnesol precursor. Whereas one epimer of the carbocation undergoes H(+) elimination to give 6, the other undergoes a spectacular cascade of seven 1,2-methyl and hydride migrations leading to the previously unreported carbon skeleton of 5. Theoretical calculations suggest that the cascade is triggered by substrate preorganization in the enzyme active site.
Formatted abstract
A series of novel sesterterpenes (2–6) have been isolated from the roots of Aletris farinosa and structurally characterized by MS, NMR, and X-ray crystallography in conjunction with computational modeling. Their structures provide new insights into the mechanisms of sesterterpene biosynthesis. Specifically, we propose with support from density functional theory computations that the configuration at a single stereocenter determines the fate of a key tetracyclic carbocationic intermediate, derived from an oxidogeranylfarnesol precursor. Whereas one epimer of the carbocation undergoes H+ elimination to give 6, the other undergoes a spectacular cascade of seven 1,2-methyl and hydride migrations leading to the previously unreported carbon skeleton of 5. Theoretical calculations suggest that the cascade is triggered by substrate preorganization in the enzyme active site.
Keyword Chemistry, Multidisciplinary
Chemistry
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID FT120100632
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Chemistry and Molecular Biosciences
 
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