title: Helenalin and 11 alpha,13-dihydrohelenalin, two constituents from Arnica montana L., inhibit human platelet function via thiol-dependent pathways.
abstract: This study investigates the effect on human platelet function of two sesquiterpene lactones from Arnica montana L., helenalin (H) and 11 alpha,13-dihydrohelenalin (DH). Both compounds inhibited collagen-induced platelet aggregation, thromboxane formation and 5-hydroxytryptamine secretion in a concentration-dependent manner at 3-300 microM. When arachidonic acid was used as stimulus, thromboxane formation remained unaffected despite of inhibition of platelet aggregation. Both H and DH reduced the number of acid-soluble sulfhydryl groups in platelets, by up to 78% at anti-aggregatory concentrations. Moreover, H- and DH-induced platelet inhibition could be prevented by the thiol containing amino acid cysteine. It is concluded that H and DH inhibit platelet function via interaction with platelet sulfhydryl groups, probably associated with reduced phospholipase A2 activity.
authors.affiliation: Institut für Pharmakologie, Heinrich-Heine-Universität Düsseldorf, FRG.
authors.forename: H
authors.initials: H
authors.lastname: Schröder
authors.forename: W
authors.initials: W
authors.lastname: Lösche
authors.forename: H
authors.initials: H
authors.lastname: Strobach
authors.forename: W
authors.initials: W
authors.lastname: Leven
authors.forename: G
authors.initials: G
authors.lastname: Willuhn
authors.forename: U
authors.initials: U
authors.lastname: Till
authors.forename: K
authors.initials: K
authors.lastname: Schrör
mesh_terms: D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D003545:Cysteine / Q000494:pharmacology; D006801:Humans; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*; D045789:Sesquiterpenes, Guaiane; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013929:Thromboxane B2 / Q000096:biosynthesis
chemical_list: D001095:Arachidonic Acids; D010975:Platelet Aggregation Inhibitors; D012717:Sesquiterpenes; D045789:Sesquiterpenes, Guaiane; D013439:Sulfhydryl Reagents; D016718:Arachidonic Acid; D012701:Serotonin; C001329:helenalin; D013929:Thromboxane B2; D010741:Phospholipases A; D054467:Phospholipases A2; D003545:Cysteine