Perhentidines A-C: macroline-macroline bisindoles from Alstonia and the absolute configuration of perhentinine and macralstonine

J Nat Prod. 2012 May 25;75(5):942-50. doi: 10.1021/np300120p. Epub 2012 May 4.

Abstract

Three new bisindole alkaloids of the macroline-macroline type, perhentidines A-C (1-3), were isolated from the stem-bark extract of Alstonia macrophylla and Alstonia angustifolia. The structures of these alkaloids were established on the basis of NMR and MS analyses. The absolute configurations of perhentinine (4) and macralstonine (5) were established by X-ray diffraction analyses, which facilitated assignment of the configuration at C-20 in the regioisomeric bisindole alkaloids perhentidines A-C (1-3). A potentially useful method for the determination of the configuration at C-20 based on comparison of the NMR chemical shifts of the bisindoles and their acetate derivatives, in these and related bisindoles with similar constitution and branching of the monomeric units, is also presented.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alstonia / chemistry*
  • Crystallography, X-Ray
  • Indole Alkaloids / chemistry*
  • Indole Alkaloids / isolation & purification*
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Oxindoles
  • Plant Bark / chemistry

Substances

  • Indole Alkaloids
  • Oxindoles
  • macralstonine
  • macroline
  • perhentidine A
  • perhentidine B
  • perhentidine C
  • perhentinine