title: The antiplatelet activity of rutaecarpine, an alkaloid isolated from Evodia rutaecarpa, is mediated through inhibition of phospholipase C.
abstract: In this study, the mechanism involved in the antiplatelet activity of rutaecarpine in human platelet suspensions was investigated. In platelet suspensions (4.5 x 10(8)/ml), rutaecarpine (100 and 200 microM) did not influence the binding of FITC-triflavin to platelet glycoprotein IIb/IIIa complex. Additionally, rutaecarpine (200 microM) did not significantly change the fluorescence of platelet membrane labeled with diphenylhexatriene (DPH). On the other hand, rutaecarpine (50 and 100 microM) dose-dependently inhibited the increase in intracellular free Ca2+ of Fura 2-AM loaded platelets stimulated by collagen. Moreover, rutaecarpine (100 and 200 microM) did not significantly affect the thromboxane synthetase activity of aspirin-treated platelet microsomes. Furthermore, retaecarpine (100 and 200 microM) significantly inhibited [3H]arachidonic acid released in collagen-activated platelets but not in unactivated-platelets. Nitric oxide (NO) production in human platelets was measured by a chemiluminesence detection method in this study. Rutaecarpine (100 and 200 microM) did not significantly affect nitrate production in collagen (10 microg/ml)-induced human platelet aggregation. On the other hand, various concentrations of rutaecarpine (50, 100, and 200 microM) dose-dependently inhibited [3H]inositol monophosphate formation stimulated by collagen (10 microg/ml) in [3H]myoinositol-loaded platelets at different incubation times (1, 2, 3, and 5 minutes). It is concluded that the antiplatelet activity of rutaecarpine may possibly be due to the inhibition of phospholipase C activity, leading to reduce phosphoinositide breakdown, followed by the inhibition of thromboxane A2 formation, and then inhibition of [Ca2+]i mobilization of platelet aggregation stimulated by agonists.
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical College, Taiwan. sheujr@mail.tmc.edu.tw
authors.forename: J R
authors.initials: JR
authors.lastname: Sheu
authors.forename: Y C
authors.initials: YC
authors.lastname: Kan
authors.forename: W C
authors.initials: WC
authors.lastname: Hung
authors.forename: C H
authors.initials: CH
authors.lastname: Su
authors.forename: C H
authors.initials: CH
authors.lastname: Lin
authors.forename: Y M
authors.initials: YM
authors.lastname: Lee
authors.forename: M H
authors.initials: MH
authors.lastname: Yen
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors*
chemical_list: D000470:Alkaloids; D004365:Drugs, Chinese Herbal; D004791:Enzyme Inhibitors; D010975:Platelet Aggregation Inhibitors; D010738:Type C Phospholipases