Configurational assignments of conformationally restricted bis-monoterpene hydroquinones: Utility in exploration of endangered plants

  • Authors: Oh, Joonseok; Bowling, John J.; Chittiboyina, Amar G.; Doerksen, Robert J.; Ferreira, Daneel; Leininger, Theodor D.; Hamann, Mark T.
  • Publication Year: 2013
  • Publication Series: Scientific Journal (JRNL)
  • Source: Biochimica et Biophysica Acta 1830:4229-4234. DOI 10.1016/j.bbagen.2013.04.029

Abstract

Endangered plant species are an important resource for new chemistry. Lindera melissifolia is native to the Southeastern U.S. and scarcely populates the edges of lakes and ponds. Quantum mechanics (QM) used in combination with NMR/ECD is a powerful tool for the assignment of absolute configuration in lieu of X-ray crystallography. Methods: The EtOAc extract of L. melissifolia was subject to chromatographic analysis by VLC and HPLC. Spin–spin coupling constant (SSCC) were calculated using DFT at the MPW1PW91/6-31G(d,p) level for all staggered rotamers. ECD calculations employed Amber* force fields followed by PM6 semi-empirical optimizations. Hetero- and homo-nuclear coupling constants were extracted from 1D 1H, E.COSY and HETLOC experiments. Results: Two meroterpenoids, melissifolianes A (1) and B (2) were purified and their 2-D structures elucidated using NMR and HRESIMS. The relative configuration of 1 was established using the combination of NOE-based distance restraints and the comparisons of experimental and calculated SSCCs. The comparison of calculated and experimental ECD assigned the absolute configuration of 1. The relative configuration of a racemic mixture, melissifoliane B (2) was established utilizing J-based analysis combined with QM and NMR techniques.Conclusion Our study of the Lindera melissifolia metabolome exemplifies how new chemistry remains undiscovered among the numerous endangered plant species and demonstrates how analysis by ECD and NMR combined with various QM calculations is a sensible approach to support the stereochemical assignment of molecules with conformationally restricted conformations. General significance: QM–NMR/ECD combined approaches are of utility for unambiguous assignment of 3-D structures, especially with limited plant material and when a molecule is conformationally restricted. Conservation of an endangered plant species can be supported through identification of its new chemistry and utilization of that chemistry for commercial purposes

  • Citation: Oh, Joonseok; Bowling, John J.; Chittiboyina, Amar G.; Doerksen, Robert J.; Ferreira, Daneel; Leininger, Theodor D.; Hamann, Mark T. 2013. Configurational assignments of conformationally restricted bis-monoterpene hydroquinones: Utility in exploration of endangered plants. Biochimica et Biophysica Acta 1830:4229-4234. DOI 10.1016/j.bbagen.2013.04.029
  • Keywords: Configuration determination Ab initio calculation Conformation analysis Natural product NMR/CD spectroscopy Endangered species
  • Posted Date: September 24, 2013
  • Modified Date: August 20, 2014
  • Print Publications Are No Longer Available

    In an ongoing effort to be fiscally responsible, the Southern Research Station (SRS) will no longer produce and distribute hard copies of our publications. Many SRS publications are available at cost via the Government Printing Office (GPO). Electronic versions of publications may be downloaded, printed, and distributed.

    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
    • Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
    • To view this article, download the latest version of Adobe Acrobat Reader.