Baicalein is a potent in vitro inhibitor against both reticulocyte 15-human and platelet 12-human lipoxygenases

Bioorg Med Chem. 2006 Jun 15;14(12):4295-301. doi: 10.1016/j.bmc.2006.01.057. Epub 2006 Feb 24.


Lipoxygenases (LO) have been implicated in asthma, immune disorders, and various cancers and as a consequence, there is great interest in isolating selective LO isozyme inhibitors. Currently, there is much use of baicalein as a selective human platelet 12-LO (12-hLO) inhibitor, however, our current steady-state inhibition data indicate that baicalein is not selective against 12-hLO versus human reticulocyte 15-LO-1 (15-hLO-1) (15/12=1.3), in vitro. However, in the presence of detergents baicalein is slightly more selective (15/12=7) as seen by the steady-state inhibition kinetics, which may imply greater selectivity in a cell-based assay but has yet to be proven. The mechanism of baicalein inhibition of 15-hLO-1 is reductive, which molecular modeling suggests is through direct binding of the catecholic moiety of baicalein to the iron. A structurally related flavonoid, apigenin, is not reductive, however, molecular modeling suggests a hydrogen bond with Thr591 may account for its inhibitor potency.

Publication types

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

MeSH terms

  • Apigenin / chemistry
  • Apigenin / pharmacology
  • Arachidonate 12-Lipoxygenase / isolation & purification
  • Arachidonate 15-Lipoxygenase / isolation & purification
  • Binding Sites
  • Blood Platelets / enzymology*
  • Flavanones / chemistry
  • Flavanones / pharmacology*
  • Humans
  • In Vitro Techniques
  • Kinetics
  • Ligands
  • Lipoxygenase Inhibitors*
  • Models, Molecular
  • Molecular Conformation
  • Protein Conformation
  • Reticulocytes / enzymology*
  • Structure-Activity Relationship


  • Flavanones
  • Ligands
  • Lipoxygenase Inhibitors
  • baicalein
  • Apigenin
  • Arachidonate 12-Lipoxygenase
  • Arachidonate 15-Lipoxygenase