Antioxidant activity, NMR, X-ray, ECD and UV/vis spectra of (+)-terrein: Experimental and theoretical approaches

Zuhra Bashir Khalifa Al Trabolsy, elhassane anouar, Nur Shahidatul Shida Zakaria, Manar Zulkeflee, Mizaton Hazizul Hasan, Maisarah Mohd Zin, Rohaya Ahmad, Sadia Sultan, Jean Frédéric F. Weber

Research output: Contribution to journalJournal articlepeer-review

17 Scopus citations

Abstract

Fungal metabolite terrein isolated from Aspergillus terreus is endowed with diverse biological and antioxidant activities. To determine the stereochemistry of the isolated terrein, we combined spectroscopic methods (CD and NMR spectra) and theoretical calculations (DFT and TD-DFT methods). Stereochemistry effects on the antioxidant activity of isolated terrein were evaluated by calculating bond dissociation enthalpies (BDEs), ionization potentials (IPs) and spin density delocalization of terrein and isoterrein stereoisomers with B3P86/6-31+G (d, p) method in gas and polarizable continuum model. The results showed a good agreement between experimental data and theoretical calculations which confirmed the (+)-terrein stereochemistry of isolated metabolite. Theoretical calculations showed that the antioxidant activity is relatively influenced by isomeric geometry of the terrein (a variation of 2 kcal/mol between BDEs of terrein and isoterrein isomers), while chirality has no influence on the antioxidant activity [0.2 kcal/mol difference between BDEs of (+)- and (-)-terrein]. The low antioxidant activity of (+)-terrein with respect to trolox and ascorbic acid was explained by the positive free Gibbs energy of the hydrogen atom transfer (HAT) mechanism and high BDE values of the 2-OH active site.

Original languageEnglish
Pages (from-to)102-110
Number of pages9
JournalJournal of Molecular Structure
Volume1060
Issue number1
DOIs
StatePublished - 24 Feb 2014
Externally publishedYes

Keywords

  • Antioxidant activity
  • Aspergillus terreus
  • DFT
  • ECD spectra
  • Terrein

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