Gaboroquinones A and B and 4'-O-demethylknipholone-4'-O-beta-D-glucopyranoside, phenylanthraquinones from the roots of Bulbine frutescens

J Nat Prod. 2002 Aug;65(8):1117-21. doi: 10.1021/np0201218.

Abstract

The novel phenylanthraquinones 4'-O-demethylknipholone-4'-O-beta-D-glucopyranoside (2) and gaboroquinones A (3) and B (4) were isolated from the African medicinal plant Bulbine frutescens. Biaryl 2 represents the first phenylanthraquinone glucoside, while 3 and 4 are the first side-chain-hydroxylated phenylanthraquinones. Their constitutions were determined by spectroscopic analysis, in particular by HMBC, HMQC, and ROESY NMR investigations, and by chemical transformations. The axial configurations were elucidated chemically, by deglucosylation of 2 and by side-chain deoxygenation of 3 and 4 to give the known phenylanthraquinones 4'-O-demethylknipholone (5), isoknipholone (6), and knipholone (1), respectively, and chiroptically, by CD investigations. Compounds 2, 3, and 4 showed moderate to good antiplasmodial and antitrypanosomal activities in vitro.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anthraquinones / chemistry
  • Anthraquinones / isolation & purification*
  • Anthraquinones / pharmacology
  • Antimalarials / chemistry
  • Antimalarials / isolation & purification*
  • Antimalarials / pharmacology
  • Botswana
  • Circular Dichroism
  • Glucosides / chemistry
  • Glucosides / isolation & purification*
  • Glucosides / pharmacology
  • Molecular Conformation
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Oxidation-Reduction
  • Plant Roots / chemistry
  • Plants, Medicinal / chemistry*
  • Plasmodium falciparum / drug effects
  • Trypanocidal Agents / chemistry
  • Trypanocidal Agents / isolation & purification*
  • Trypanocidal Agents / pharmacology
  • Trypanosoma / drug effects

Substances

  • 4'-O-demethylknipholone-4'-O-glucopyranoside
  • Anthraquinones
  • Antimalarials
  • Glucosides
  • Trypanocidal Agents
  • gaboroquinone A
  • gaboroquinone B
  • knipholone