title: Inhibition of rat platelet aggregation by Urtica dioica leaves extracts.
abstract: Platelet hyperactivity plays an important role in arterial thrombosis and atherosclerosis. The present study was undertaken to investigate the effects of different extracts of Urtica dioica leaves on platelet aggregation. Rat platelets were prepared and incubated in vitro with different concentrations of the tested extracts and aggregation was induced by different agonists including thrombin (0.5 U/mL), ADP (10 microm), epinephrine (100 microm) and collagen (5 mg/mL). The crude aqueous extract inhibited thrombin-induced platelet aggregation in a dose-dependent manner. At 1 mg/mL, the percent inhibition was 17.1 +/- 4.2%. Soxhlet extraction of the plant leaves with different successive solvents showed that the ethyl acetate extract exhibited the most antiaggregant effect with an inhibition of 76.8 +/- 6.1% at 1 mg/mL. Flavonoids isolated from the plant leaves, produced a strong inhibitory effect on thrombin-induced platelet aggregation with an IC(50) of 0.25 +/- 0.05 and 0.40 +/- 0.04 mg/mL for genins and heterosidic flavonoids, respectively. Flavonoids also markedly inhibited platelet aggregation induced by ADP, collagen and epinephrine. It is concluded that Urtica dioica has an antiplatelet action in which flavonoids are mainly implicated. These results support the traditional use of Urtica dioica in the treatment and/or prevention of cardiovascular disease.
authors.affiliation: Laboratoire de Physiologie et Ethnopharmacologie, UFR 'Physiologie et Pharmacologie', Département de biologie, Faculté des sciences, Université Mohamed Premier, BP 717, 60000 Oujda, Morocco.
authors.forename: Mohammed
authors.initials: M
authors.lastname: El Haouari
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bnouham
authors.forename: Mourad
authors.initials: M
authors.lastname: Bendahou
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aziz
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Ziyyat
authors.forename: Abdelkhaleq
authors.initials: A
authors.lastname: Legssyer
authors.forename: Hassane
authors.initials: H
authors.lastname: Mekhfi
mesh_terms: D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000517:prevention & control; D005260:Female; D008297:Male; D051379:Mice; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D026982:Urtica dioica / Q000737:chemistry*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D010936:Plant Extracts; D010975:Platelet Aggregation Inhibitors; D014700:Verapamil; D001241:Aspirin