Antimalarial 5,6-Dihydro-α-pyrones from Cryptocarya rigidifolia: Related Bicyclic Tetrahydro-α-Pyrones Are Artifacts1

J Nat Prod. 2015 Jun 26;78(6):1330-8. doi: 10.1021/acs.jnatprod.5b00187. Epub 2015 Jun 4.

Abstract

Antimalarial bioassay-guided fractionation of an EtOH extract of the root wood of Cryptocarya rigidifolia (Lauraceae) led to the isolation of the five new 5,6-dihydro-α-pyrones cryptorigidifoliols A-E (1-5) and the six bicyclic tetrahydro-α-pyrone derivatives cryptorigidifoliols F-K (6-11). The structure elucidations of all compounds were made on the basis of the interpretation of spectroscopic data and chemical derivatization, and the relative and absolute configurations were determined by NOESY, electronic circular dichroism (ECD), and (1)H NMR analysis of α-methoxyphenylacetyl (MPA) derivatives. The bicyclic tetrahydro-α-pyrone derivatives were identified as products of acid-catalyzed intramolecular Michael addition of the 5,6-dihydro-α-pyrones in the presence of silica gel. A structure-activity relationship study suggested that the presence of an α,β-unsaturated carbonyl moiety is not essential for potent antimalarial activity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antimalarials / chemistry
  • Antimalarials / isolation & purification*
  • Antimalarials / pharmacology*
  • Circular Dichroism
  • Cryptocarya / chemistry*
  • Crystallography, X-Ray
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Pyrones / chemistry
  • Pyrones / isolation & purification*
  • Pyrones / pharmacology*
  • Structure-Activity Relationship

Substances

  • Antimalarials
  • Pyrones