title: Modulation of platelet functions by crude rice (Oryza sativa) bran policosanol extract.
abstract: BACKGROUND
  Rice bran is bioactive-rich and has proven health benefits for humans. Moreover, its source, the brown rice has antioxidant, hypolipidemic and other functional properties that are increasingly making it a nutritional staple especially in Asian countries. This study investigated the antiplatelet aggregation mechanisms of crude hexane/methanolic rice bran extract, in which policosanol was the targeted bioactive. Platelets play a vital role in pathogenesis of atherosclerosis and cardiovascular diseases, and their increased activities could potentially cause arterial thrombus formation or severe bleeding disorders. Thus, in this study, platelet aggregation and adhesion of platelets to major components of basal lamina were examined in vitro. In addition, cellular protein secretion was quantified as a measurement of platelet activation.
  
  
  METHODS
  Adenosine diphosphate (ADP), collagen, and arachidonic acid (AA)-induced aggregation were studied using the microtiter technique. Rat platelets were pre-treated with various concentrations of policosanol extract, and the adhesion of platelets onto collagen- and laminin-coated surface (extracellular matrix) was studied using the acid phosphatase assay. The effect of crude policosanol extract on released proteins from activated platelets was measured using modified Lowry determination method.
  
  
  RESULTS
  Rice bran policosanol extract significantly inhibited in vitro platelet aggregation induced by different agonists in a dose dependent manner. The IC50 of ADP-, collagen-, and AA-induced platelet aggregation were 533.37 ± 112.16, 635.94 ± 78.45 and 693.86 ± 70.57 μg/mL, respectively. The present study showed that crude rice bran policosanol extract significantly inhibited platelet adhesion to collagen in a dose dependent manner. Conversely, at a low concentration of 15.625 μg/mL, the extract significantly inhibited platelet adhesion to laminin stimulated by different platelet agonists. In addition to the alteration of cell adhesive properties, cellular protein secretion of the treated platelets towards different stimulants were decreased upon crude extract treatment.
  
  
  CONCLUSIONS
  Our results showed that crude rice bran policosanol extract could inhibit in vitro platelet adhesion, aggregation and secretion upon activation using agonists. These findings serve as a scientific platform to further explore alternative therapies in cardiovascular diseases related to platelet malfunction.
authors.affiliation: Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
authors.forename: Wai-Teng
authors.initials: WT
authors.lastname: Wong
authors.affiliation: Laboratory of Molecular Biomedicine, Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. maznahis@upm.edu.my.|Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. maznahis@upm.edu.my.
authors.forename: Maznah
authors.initials: M
authors.lastname: Ismail
authors.affiliation: Precision Nutrition Innovation Institute, College of Public Health, Zhengzhou University, Zhengzhou, 450001, Henan Province, China. mustyimam@gmail.com.
authors.forename: Mustapha Umar
authors.initials: MU
authors.lastname: Imam
authors.affiliation: Cardiology Department, Affiliated Hospital of Chengde Medical University, 067000, Chengde, Hebei, China.
authors.forename: Yi-Da
authors.initials: YD
authors.lastname: Zhang
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004043:Dietary Fiber; D005233:Fatty Alcohols / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D012275:Oryza / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004043:Dietary Fiber; D005233:Fatty Alcohols; D010936:Plant Extracts; C080710:policosanol; D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D003094:Collagen
keywords: Adenosine diphosphate; Arachidonic acid; Collagen; Laminin; Platelet adhesion; Platelet aggregation; Protein secretion