Anti-platelet effects of bioactive compounds isolated from the bark of Rhus verniciflua Stokes.
ABSTRACT It has previously been shown that EtOAc extracts of Rhus verniciflua Stokes (RVS) inhibit the platelet aggregation response. In this report, bioassay-guided fractionation using ADP-, arachidonic acid-, and collagen-induced human platelet aggregation by a whole blood aggregometer yielded the bioactive compounds isomaltol and pentagalloyl glucose from different highly effective fractions. In addition, column chromatography of fractions from RVS yielded another five compounds: butin, fisetin, sulfuretin, butein and 3,4',7,8-tetrahydroxyflavone. We investigated the effects of bioactive compounds from RVS fractions on several markers of platelet activation using receptor expression on platelet membranes, including glycoprotein IIb/IIIa (CD41), GPIIb/IIIa-like expression (PAC-1) and P-selectin (CD62), and intracelluar calcium mobilization responses by flow cytometry in healthy subjects. Dose-dependent inhibition of platelet aggregation and significantly decreased platelet activation were observed for the isomaltol- and pentagalloyl glucose-treated platelets, respectively. These results show that isomaltol and pentagalloyl glucose from the bark of Rhus verniciflua Stokes have potent anti-platelet activity and emphasize the need to further examine the mechanism of these active compounds for platelet modulation.
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ABSTRACT: Fermented Rhus verniciflua stem bark (FRVSB) extract, an urushiol-free extract of Rhus verniciflua Stokes (RVS) fermented with Fomitella fraxinea, has various biological activities. The present study was carried out to investigate the potential toxicity of the FRVSB extract following single and repeated oral administration to Sprague-Dawley rats. In the single dose toxicity study, the FRVSB extract was administered orally to male and female rats at single doses of 0, 2500, 5000, and 10,000mg/kg. No animals died and no toxic changes were observed in clinical signs, body weight, and necropsy findings during the 15-day period following administration. In the repeated dose toxicity study, the FRVSB extract was administered orally to male and female rats for 90days at doses of 0, 556, 1667, and 5000mg/kg/day. There were no treatment-related adverse effects in clinical signs, body weight, food and water consumption, ophthalmic examination, urinalysis, hematology, serum biochemistry, necropsy findings, organ weight, and histopathology at any dose tested. The approximate lethal dose of the FRVSB extract was >10,000mg/kg in both genders, the oral no-observed-adverse-effect level of the FRVSB extract was >5000mg/kg/day in both genders, and no target organs were identified.Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 02/2013; 55C:617-626. DOI:10.1016/j.fct.2013.01.043 · 2.61 Impact Factor
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ABSTRACT: Herbal remedies are used to treat a large variety of diseases, including blood-related disorders. However, a number of herbal preparations have been reported to cause variations in clotting time, this is mainly by disruption of the coagulation cascade. The compiling of plants investigated for effects on the coagulation cascade. Information was withdrawn from Google Scholar and the journal databases Scopus and PubMed. Sixty-five herbal remedies were identified with antiplatelet, anticoagulant, or coagulating ability. Bioactive compounds included polyphenols, taxanes, coumarins, saponins, fucoidans, and polysaccharides. Although research has been conducted on the effect of herbal remedies on coagulation, most information relies on in vitro assays. Contradictory evidence is present on bleeding risks with herbal uses, though herb-drug interactions pose a threat. As the safety of many herbals has not been proven, nor their effect on blood parameters determined, the use of herbal preparations before undergoing any surgical procedure should discontinued.Pharmaceutical Biology 12/2011; 50(4):443-52. DOI:10.3109/13880209.2011.611145 · 1.34 Impact Factor
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ABSTRACT: Hydrolysable tannins are phenolic phytochemicals that show high antioxidant and free-radical scavenging activities. For this reason their potential effects preventing oxidative related diseases, such as cardiovascular diseases, have been largely studied. In vitro studies show that ellagitannins, at concentrations in the range 10-100 μM, show some relevant anti-atherogenic, anti-thrombotic, anti-inflammatory and anti-angiogenic effects, supporting the molecular mechanisms for the vascular health benefits. While there is good evidence supporting the vascular effects in vitro, the evidence on animal models or humans is much scarcer. The in vitro results often do not match the findings in the in vivo studies. This could be explained by the low bioavailability of the antioxidant ellagitannins and ellagic acid. The main ellagitannin metabolites circulating in plasma are ellagic acid microbiota metabolites known as urolithins, and they have lost their free-radical scavenging activity. They are present in plasma as glucuronide or sulphate conjugates, at concentrations in the nM range. Future studies should focus in the bioavailable metabolites, urolithins, and in the form (conjugated with glucuronic acid or sulphate) and concentrations (nM range) in which they are found in plasma. In this review we critically discuss the role of ellagitannins and ellagic acid on vascular health.Molecular Aspects of Medicine 12/2010; 31(6):513-39. DOI:10.1016/j.mam.2010.09.005 · 10.30 Impact Factor