A 9-cis-epoxycarotenoid dioxygenase inhibitor for use in the elucidation of abscisic acid action mechanisms

Bioorg Med Chem. 2006 Aug 15;14(16):5555-61. doi: 10.1016/j.bmc.2006.04.025. Epub 2006 May 6.


The plant hormone abscisic acid (ABA) accumulates in response to drought stress and confers stress tolerance to plants. 9-cis-Epoxycarotenoid dioxygenase (NCED), the key regulatory enzyme in the ABA biosynthesis pathway, plays an important role in ABA accumulation. Treatment of plants with abamine, the first NCED inhibitor identified, inhibits ABA accumulation. On the basis of structure-activity relationship studies of abamine, we identified an inhibitor of ABA accumulation more potent than abamine and named it abamineSG. An important structural feature of abamineSG is a three-carbon linker between the methyl ester and the nitrogen atom. Treatment of osmotically stressed plants with 100 microM abamineSG inhibited ABA accumulation by 77% as compared to the control, whereas abamine inhibited the accumulation by 35%. The expression of AB A-responsive genes and ABA catabolic genes was strongly inhibited in abamineSG-treated plants under osmotic stress. AbamineSG is a competitive inhibitor of the enzyme NCED, with a K(i) of 18.5 microM. Although the growth of Arabidopsis seedlings was inhibited by abamine at high concentrations (>50 microM), an effect that was unrelated to the inhibition of ABA biosynthesis, seedling growth was not affected by 100 microM abamineSG. These results suggest that abamineSG is a more potent and specific inhibitor of ABA biosynthesis than abamine.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / biosynthesis
  • Abscisic Acid / chemistry
  • Abscisic Acid / pharmacology*
  • Anisoles / chemistry
  • Anisoles / pharmacology*
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Base Sequence
  • Carbon / chemistry
  • Dioxygenases
  • Enzyme Inhibitors / pharmacology*
  • Fabaceae / enzymology
  • Fabaceae / genetics
  • Glycine / analogs & derivatives*
  • Glycine / chemistry
  • Glycine / pharmacology
  • Molecular Sequence Data
  • Oxygenases / antagonists & inhibitors*
  • Plant Growth Regulators / biosynthesis
  • Plant Growth Regulators / pharmacology*
  • Plant Proteins
  • Reverse Transcriptase Polymerase Chain Reaction
  • Structure-Activity Relationship
  • gamma-Aminobutyric Acid / analogs & derivatives*
  • gamma-Aminobutyric Acid / chemistry
  • gamma-Aminobutyric Acid / pharmacology


  • Anisoles
  • Enzyme Inhibitors
  • Plant Growth Regulators
  • Plant Proteins
  • abamine
  • abamineSG
  • gamma-Aminobutyric Acid
  • Abscisic Acid
  • Carbon
  • Oxygenases
  • Dioxygenases
  • 9-cis-epoxy-carotenoid dioxygenase
  • Glycine