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.
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.
Reininger
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Institute of Pharmaceutical Biology, Heinrich-Heine-Universität Düsseldorf, Germany.
Bauer
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D000818:Animals; D016718:Arachidonic Acid / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D051545:Cyclooxygenase 1 / Q000187:drug effects* / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000187:drug effects* / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000494:pharmacology*; D007124:Immunoenzyme Techniques / Q000379:methods*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D019787:Linoleic Acid / Q000494:pharmacology; D010946:Plants, Medicinal; D012680:Sensitivity and Specificity
D004365:Drugs, Chinese Herbal; D005231:Fatty Acids, Unsaturated; D007527:Isoenzymes; D016718:Arachidonic Acid; D019787:Linoleic Acid; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2