Prostaglandin-H-synthase (PGHS)-1 and -2 microtiter assays for the testing of herbal drugs and in vitro inhibition of PGHS-isoenzyms by polyunsaturated fatty acids from Platycodi radix

Phytomedicine. 2006 Feb;13(3):164-9. doi: 10.1016/j.phymed.2005.03.006. Epub 2005 Sep 15.

Abstract

In order to test inhibition of prostaglandin-H-synthase-1 and -2 (PGHS-1 and -2) by plant extracts, we have established two enzyme based in vitro assays with enzyme immunoassay (EIA) evaluation. The assays have been evaluated with known synthetic inhibitors and with plant extracts. In a screening of traditionally used Chinese herbs for anti-inflammatory activity, a series of n-hexane and dichloromethane extracts showed significant inhibitory effect in comparison with the known specific PGHS-2 inhibitors NS-398 (IC(50) = 2.6 microM) and nimesulide (IC(50) = 36 microM). The lipophilic extracts of the Chinese drug Jiengeng, the dried roots of Platycodon grandiflorum (Jacq.) A. DC. (Campanulaceae), showed good inhibitory activity against both PGHS isoenzymes. The directly prepared DCM-extract exhibited better activity against PGHS-2 (IC(50) = 4.0 microg/ml) than against PGHS-1 (IC(50) = 17.6 microg/ml). We identified fatty acids as main active constituents and quantified them. Linoleic acid showed the highest content (ca. 20% of the dried extract) and a high and preferential PGHS-2 inhibitory activity (IC(50) (PGHS-1) = 20 microM; IC(50) (PGHS-2) = 2 microM). The comparison of the concentration of linoleic acid and the inhibitory activity of the direct DCM-extract showed, that linoleic acid is mainly responsible for the in vitro activity of the extract on PGHS-2.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Arachidonic Acid / chemistry
  • Chromatography, High Pressure Liquid / methods
  • Cyclooxygenase 1 / drug effects*
  • Cyclooxygenase 1 / metabolism
  • Cyclooxygenase 2 / drug effects*
  • Cyclooxygenase 2 / metabolism
  • Drugs, Chinese Herbal / pharmacology*
  • Fatty Acids, Unsaturated / analysis
  • Fatty Acids, Unsaturated / pharmacology*
  • Immunoenzyme Techniques / methods*
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / drug effects
  • Isoenzymes / metabolism
  • Linoleic Acid / pharmacology
  • Plants, Medicinal*
  • Sensitivity and Specificity

Substances

  • Drugs, Chinese Herbal
  • Fatty Acids, Unsaturated
  • Isoenzymes
  • Arachidonic Acid
  • Linoleic Acid
  • Cyclooxygenase 1
  • Cyclooxygenase 2