title: Inhibitory effects of Bulnesia sarmienti aqueous extract on agonist-induced platelet activation and thrombus formation involves mitogen-activated protein kinases.
abstract: BACKGROUND
  B. sarmienti has long been recognized in folk medicine as a medicinal plant with various medicinal uses. Traditionally, it has been appreciated for the skin-healing properties of its essence. The bark has also been employed to treat stomach and cardiovascular disorders and reported to have antitumor, antioxidant and anti-inflammatory activities. However, information on its antiplatelet activity is limited.
  
  
  OBJECTIVE
  To examined the effects of B. sarmienti aqueous extract (BSAE) in platelet physiology.
  
  
  METHODS
  The anti-platelet activity of BSAE was studied using rat platelets for in vitro determination of the extract effect on agonist-induced platelet aggregation, ATP secretion, [Ca(2+)](i) mobilization and MAP kinase phosphorylation. The extract in vivo effects was also examined in arterio-venous shunt thrombus formation in rats, and tail bleeding time in mice.
  
  
  RESULTS
  HPLC chromatographic analysis revealed that B. sarmienti extract contained (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), and (-)-epicatechin gallate (ECG). BSAE, significantly and dose dependently, inhibited collagen, thrombin, or ADP-induced platelet aggregation. The 50 percent inhibitory concentrations (IC(50)) of the extract for collagen, thrombin and ADP-induced platelet aggregation were 45.3+/-2.6, 100+/-5.6 and 110+/-4.6 microg/ml, respectively. Collagen activated ATP release and thrombin-induced intracellular Ca(2+) concentration were reduced in BSAE-treated platelets. In addition, the extract in vivo activity showed that BSAE at 100 mg/kg significantly attenuated thrombus formation in rat extracorporeal shunt model while mice tail bleeding time was not affected. Moreover, BSAE attenuated p38 mitogen-activated protein kinase (p38 MAPK), c-Jun N-terminal kinase 1 (JNK1) and extracellular-signal-regulated protein kinase 2 (ERK2) phosphorylations.
  
  
  CONCLUSIONS
  BSAE inhibits platelet activation, granule secretion, aggregation, and thrombus formation without affecting bleeding time, and that this effect is mediated by inhibition of P38, JNK1 and ERK2 phosphorylations. The ability of BSAE to inhibit platelet function might be relevant in cases involving aberrant platelet activation where the plant extract could be considered as a candidate to anti-platelet and antithrombotic agent.
authors.affiliation: College of Veterinary Medicine, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: S M
authors.initials: SM
authors.lastname: Kamruzzaman
authors.forename: Mehari
authors.initials: M
authors.lastname: Endale
authors.forename: Won Jun
authors.initials: WJ
authors.lastname: Oh
authors.forename: Seung-Chun
authors.initials: SC
authors.lastname: Park
authors.forename: Kil-Soo
authors.initials: KS
authors.lastname: Kim
authors.forename: Joo Heon
authors.initials: JH
authors.lastname: Hong
authors.forename: Yi-Seong
authors.initials: YS
authors.lastname: Kwak
authors.forename: Bong-Sik
authors.initials: BS
authors.lastname: Yun
authors.forename: Man Hee
authors.initials: MH
authors.lastname: Rhee
mesh_terms: D000818:Animals; D001760:Bleeding Time / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D020128:Inhibitory Concentration 50; D008297:Male; D008519:Medicine, Traditional; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013927:Thrombosis / Q000517:prevention & control*; D028461:Zygophyllaceae / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D020928:Mitogen-Activated Protein Kinases