p-Terphenyl curtisian E inhibits in vitro platelet aggregation via cAMP elevation and VASP phosphorylation

p-Terphenyl glucosides from the culture broth of Phlebiopsis castanea

A new p-terphenyl derivative, hydroxystrepantibin D (1), was isolated along with two known p-terphenyls (2 and 3) from the culture broth of Phlebiopsis castanea. These compounds were isolated using silica gel column chromatography, reversed-phase medium-pressure liquid chromatography, Sephadex LH-20 column chromatography, and preparative HPLC. Their structures were determined based on spectroscopic methods. These compounds exhibited free radical scavenging activities with IC₅₀ values in the range from 22.2 to 158.4 μM against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical and in the range from 161.1 to 356.1 μM against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

Non-peptide secondary metabolites from poisonous mushrooms: overview of chemistry, bioactivity, and biosynthesis

Covering: up to June 2021A wide variety of mushrooms have traditionally been recognized as edible fungi with high nutritional value and low calories, and abundantly produce structurally diverse and bioactive secondary metabolites. However, accidental ingestion of poisonous mushrooms can result in serious illnesses and even death. Chemically, mushroom poisoning is associated with secondary metabolites produced in poisonous mushrooms, causing specific toxicity. However, many poisonous mushrooms have not been fully investigated for their secondary metabolites, and the secondary metabolites of poisonous mushrooms have not been systematically summarized for details such as chemical composition and biosynthetic mechanisms. The isolation and identification of secondary metabolites from poisonous mushrooms have great research value since these compounds could be lethal toxins that contribute to the toxicity of mushrooms or could provide lead compounds with remarkable biological activities that can promote advances in other related disciplines, such as biochemistry and pharmacology. In this review, we summarize the structures and biological activities of secondary metabolites identified from poisonous mushrooms and provide an overview of the current information on these metabolites, focusing on their chemistry, bioactivity, and biosynthesis.

Vasodilator-stimulated phosphoprotein-phosphorylation by ginsenoside Ro inhibits fibrinogen binding to αIIb/β3 in thrombin-induced human platelets

BACKGROUND

Glycoprotein IIb/IIIa (αIIb/β3) is involved in platelet adhesion, and triggers a series of intracellular signaling cascades, leading to platelet shape change, granule secretion, and clot retraction. In this study, we evaluated the effect of ginsenoside Ro (G-Ro) on the binding of fibrinogen to αIIb/β3.

METHODS

We investigated the effect of G-Ro on regulation of signaling molecules affecting the binding of fibrinogen to αIIb/β3, and its final reaction, clot retraction.

RESULTS

We found that G-Ro dose-dependently inhibited thrombin-induced platelet aggregation and attenuated the binding of fibrinogen to αIIb/β3 by phosphorylating cyclic adenosine monophosphate (cAMP)-dependently vasodilator-stimulated phosphoprotein (VASP; Ser157). In addition, G-Ro strongly abrogated the clot retraction reflecting the intensification of thrombus.

CONCLUSION

We demonstrate that G-Ro is a beneficial novel compound inhibiting αIIb/β3-mediated fibrinogen binding, and may prevent platelet aggregation-mediated thrombotic disease.

Antithrombotic activities of ferulic acid via intracellular cyclic nucleotide signaling

Ferulic acid (FA) produces protective effects against cardiovascular dysfunctions. However, the mechanisms of FA is still not known. Here we examined the antithrombotic effects of FA and its potential mechanisms. Anticoagulation assays and platelet aggregation was evaluated in vitro and in vivo. Thromboxane B2 (TXB2), cyclic adenosine monophosphate(cAMP), and cyclic guanosine monophosphate (cGMP) was determined using enzyme immunoassay kits. Nitric oxide (NO) production was measured using the Griess reaction. Protein expression was detected by Western blotting analysis. Oral administration of FA prevented death caused by pulmonary thrombosis and prolonged the tail bleeding and clotting time in mice,while, it did not alter the coagulation parameters, including the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). In addition, FA (50-200 µM) dose-dependently inhibited platelet aggregation induced by various platelet agonists, including adenosine diphosphate (ADP), thrombin, collagen, arachidonic acid (AA), and U46619. Further, FA attenuated intracellular Ca(2)(+) mobilization and TXB2 production induced by the platelet agonists. FA increased the levels of cAMP and cGMP and phosphorylated vasodilator-stimulated phosphoprotein (VASP) while decreased phospho-MAPK (mitogen-activated protein kinase) and phosphodiesterase (PDE) in washed rat platelets, VASP is a substrate of cyclic nucleotide and PDE is an enzyme family responsible for hydrolysis of cAMP/cGMP. These results suggest that antithrombotic activities of FA may be regulated by inhibition of platelet aggregation, rather than through inhibiting the release of thromboplastin or formation of thrombin. The mechanism of this action may involve activation of cAMP and cGMP signaling.

Effect of Cordycepin-Enriched WIB801C from Cordyceps militaris Suppressing Fibrinogen Binding to Glycoprotein IIb/IIIa

In this study, we investigated the effects of cordycepin-enriched (CE)-WIB801C, a n-butanol extract of Cordyceps militaris-hypha on collagen-stimulated platelet aggregation. CE-WIB801C dose dependently inhibited collagen-induced platelet aggregation, and had a synergistic effect together with cordycepin (W-cordycepin) from CE-WIB801C on the inhibition of collagen-induced platelet aggregation. CE-WIB801C and cordycepin stimulated the phosphorylation of VASP (Ser(157)) and the dephosphorylation of PI3K and Akt, and inhibited the binding of fibrinogen to glycoprotein IIb/IIIa (αIIb/β3) and the release of ATP and serotonin in collagen-induced platelet aggregation. A-kinase inhibitor Rp-8-Br-cAMPS reduced CE-WIB801C-, and cordycepin-increased VASP (Ser(157)) phosphorylation, and increased CE-WIB801C-, and cordycepin-inhibited the fibrinogen binding to αIIb/β3. Therefore, we demonstrate that CE-WIB801C-, and cordycepin-inhibited fibrinogen binding to αIIb/β3 are due to stimulation of cAMP-dependent phosphorylation of VASP (Ser(157)), and inhibition of PI3K/Akt phosphorylation. These results strongly indicate that CE-WIB801C and cordycepin may have preventive or therapeutic potential for platelet aggregation-mediated diseases, such as thrombosis, myocardial infarction, atherosclerosis, and ischemic cerebrovascular disease.

Effects of peroxisome proliferator-activated receptor γ in simvastatin antiplatelet activity: influences on cAMP and mitogen-activated protein kinases

Statins are widely used as hypolipidemic drugs, and have beneficial effects in reducing cardiovascular events. In addition, recent studies on the pleiotropic effects of statins (i.e., simvastatin) reveal that these drugs have many additional anti-atherogenic effects, including antiplatelet activity. The mechanisms may be partly related to activation of peroxisome proliferator-activated receptors (PPARs), which are present in human platelets, and whose activation inhibits platelet aggregation. However, the details of the signaling pathway by which simvastatin inhibits platelet activation via PPARs have not yet been completely established. The aim of this study was to examine the mechanisms by which the PPAR-mediated pathways contribute to the antiplatelet activity of simvastatin. Simvastatin (3-50 μM) induced PPARα and PPARγ activation in a dose-dependent manner in washed platelets. Additionally, simvastatin inhibited collagen-induced platelet aggregation, expression of CD62 and PAC-1, and Ca(2+) mobilization. These effects of simvastatin on platelet responses were strongly reduced by adding a selective PPARγ antagonist (GW9662), but not PPARα antagonist (GW6471). Moreover, in the presence of GW9662, simvastatin-mediated increase of cyclic adenosine monophosphate (cAMP) production, vasodilator-stimulated phosphoprotein (VASP) Ser(157) phosphorylation and inhibition of Akt phosphorylation were markedly reversed. Furthermore, simvastatin was found to inhibit phosphorylation of mitogen-activated protein kinases (MAPKs, i.e., p38 MAPK, ERK) by increasing the association between PPARγ and the components of MAPKs after platelet activation. Taken together, the present results confirm that simvastatin inhibition of platelet activation is mediated by PPARγ-dependent processes, which involves mediating MAPKs signaling, increase of cAMP formation and VASP Ser(157) phosphorylation, inhibition of Akt phosphorylation and intracellular Ca(2+) mobilization.

Antiplatelet properties of natural products

Cardiovascular diseases (CVD) and its main underlying cause, atherothrombosis, are the major culprits of morbidity and mortality worldwide. Apart from the treatment of cardiovascular risk factors and the use of antithrombotic agents there is considerable interest in the role of natural food products and their bioactive components in the prevention and treatment of cardiovascular disorders. The consumption of healthy diets rich in functional foods, such as the Mediterranean diet, has shown to exert profound cardioprotective effects in the primary and secondary prevention of CVD. Moreover, accumulating data have attributed these beneficial effects, at least in part, to the modulation of key players in the pathogenesis of atherosclerosis, including amelioration in the lipid profile and vascular function and a decrease in oxidative stress and inflammation. Although with a much less clear picture, natural dietary compounds have also demonstrated to exert antiplatelet activities, further contributing to reduce the thrombotic risk. This article provides a brief overview of the atherothrombotic process to further provide an up-to-date review of the antiplatelet properties exerted by natural products and/or food-derived bioactive constituents - including ω-3 PUFA, olive oil, garlic and onions, tomatoes, mushrooms, polyphenol-rich beverages, and flavonol-rich cocoa - as well as to describe the mechanisms underlying these antiplatelet activities.