Antiaggregatory Effects Research Articles

A Compound Isolated from Phyllanthus tenellus Demonstrates Metabolic and Vascular Effects In Vitro.

Common chronic conditions such as metabolic syndrome and diabetes are increasingly associated to metabolic and cardiovascular complications. Although Phyllanthus tenellus leaves have been used in decoctions as a popular remedy to control blood glucose levels and hypertension, its use needs a scientific basis. This study was therefore undertaken to report a phytochemical analysis of P. tenellus leaves and to test if the main active compound has potential to simultaneously tackle several pathophysiological features of metabolic syndrome and diabetes-related metabolic and vascular disorders such as hyperglycaemia, increased platelet activation, and endothelial dysfunction. We performed a partition of the methanolic extract of P. tenellus leaves among different organic solvents followed by chromatographic separation guided by the rat liver microsomal glucose-6-phosphatase assay. Two known tannins were identified by spectroscopic methods as pinocembrin-7-O-[3″-O-galloyl-4″,6″-(S)-hexahydroxydiphenoyl]-α-D-glucose, named P7OG by us, and gemin D. The structural determination of the isolated compounds was based on spectral data. The ability of the main active component, P7OG, to inhibit human platelet aggregation and to modify vascular reactivity of rat aortic rings incubated with high glucose (D-glucose 55 mM) was then evaluated. P7OG was further able to inhibit platelet aggregation induced by adenosine 5'-diphosphate and collagen, showed vasorelaxant effects in arteries precontracted with phenylephrine, and reverted the endothelium-dependent impairment effect of high glucose in rat aortic rings. In conclusion, one tannin isolated from P. tenellus showed promising metabolic, antiaggregant, and vascular effects, which suggests the potential beneficial use of P. tenellus to tackle complex cardiometabolic diseases.

In vitro analysis of the effect of contrast agents on the antiaggregant effects of P2Y12 inhibitors

ObjectivesThe contrast agents have different molarities and ionic structures. The high osmolar contrast agents could increase platelet aggregation but the ionic contrast agents decrease platelet aggregation. However there is insufficient data on whether the antiaggregan effect of P2Y12 inhibitors used during coronary interventions are affected by the contrast agents. This study aimed to evaluate the in vitro effects of different contrast agents on the antiaggregant activity of P2Y12 inhibitors (clopidogrel, ticagrelor and prasugrel). Materials and methodsThirty patients (who underwent percutaneous coronary interventions and were treated with a P2Y12 inhibitor for a minimum of 10 days) and five healthy volunteers were divided into four groups: the clopidogrel (10 patients), ticagrelor (10 patients), prasugrel (10 patients) and control (five volunteers) groups. Antiaggregant activity was measured by using the Verify-Now method and was represented as P2Y12 reaction unit (PRU) values. Three tubes of blood were collected from the participants in the three patient groups and in the control group; as the contrast material, 10% iohexol was added to a second tube, and 10% iodixanol was added to a third tube. PRU values of the control and the contrast tubes were measured at 5 min and at 30 min after the contrast material was added. ResultsIohexol and iodixanol led to a significant decrease in the PRU values in the control group (iohexol: 188.4 ± 39.2 vs 142.4 ± 17.0, p = .04; iodixanol: 188.4 ± 39.2 vs 159.2 ± 33.7, p = .04) and in the clopidogrel group (iohexol: 140.8 ± 50.8 vs 106.3 ± 44.4, p = .04; iodixanol: 140.8 ± 50.8 vs 109.4 ± 47.6, p = .009) but not in the ticagrelor and prasugrel groups. The PRU values were significantly lower in the ticagrelor (23.1 ± 26.2) and prasugrel (23.4 ± 27.5) groups than in the clopidogrel (140.8 ± 50.8) and control (188.4 ± 39.2) groups (p < .01), and the PRU values for the ticagrelor and prasugrel groups were similar for both the 5-min and 30-min time periods (p > .05). The antiaggregant activities of iohexol and iodixanol were observed to be similar at the 5- and 30-minute time points for all of the groups (p > .05). ConclusionIohexol and iodixanol had in vitro antiaggregant effects, and their antiaggregant effects were similar. Iohexol and iodixanol increased the clopidogrel antiaggregant activity in vitro, but they did not significantly alter the antiaggregant activities of prasugrel and ticagrelor.

Influence of flavonoids' lipophilicity on platelet aggregation.

Flavonoids are natural polyphenolic compounds present in a wide spectrum of plants that have a beneficial effect on human health. In the context of cardiovascular diseases related to plaque and thrombus formation, flavonoids exhibit an anti-aggregatory effect. Previously, it has been reported that all tested flavonoids exhibit an antiaggregatory effect on platelet aggregation when measured by impedance aggregometry on whole blood, in the test of aggregation induced by adenosine diphosphate (ADP). As not all flavonoids have the same targets within signaling pathways, an assumption of a common non-specific mechanism related to lipophilicity is to be considered. To test this hypothesis, reverse-phase thin layer chromatography was used to assess the lipophilicity of flavonoids; impedance aggregometry was used for testing of platelet aggregation and flow cytometry to monitor the influence of flavonoids on platelet activation. Lipophilicity analysis showed a highly negative correlation of logP and MINaAC for groups of flavones and flavanones. As determined by flow cytometry, the exposition of receptors necessary for the promotion of platelet activation and primary clot formation was diminished, i.e., lowered expression of the activated form of integrin αIIbβ3 was observed in the presence of flavanone. Platelet membrane stabilization by flavonoids as a mechanism of antiaggregatory effect has been supported by impedance aggregometry experiments when specific inhibitors of platelet aggregation signaling pathways (U73122, indomethacin, verapamil) were used in the presence of a weak (ADP) and a strong (TRAP-6) agonist of aggregation. While individual flavonoids can have specific targets within aggregation signaling pathways, all flavonoids share a common non-specific mechanism of platelet aggregation inhibition related to their lipophilicity and membrane stabilization that, to some extent, contributes to their antiaggregatory effect.

Antithrombotic activity of flavonoids and polyphenols rich plant species.

Cardiovascular diseases represent one of the most notable health problems of the modern civilization. Stroke and heart attack often lead to lethal outcome; essential problem underneath being thrombus formation. Prophylactic approaches include acetylsalicylic acid and clopidogrel therapy on the level of primary hemostasis, i.e., primary clot formation. In the last five years, in the USA, health care expenses related to cardiovascular diseases have increased 50 %, to over 350 billion dollars. Thus, application of plant species and medicinal plants rich in polyphenols in prevention of thrombus formation are of interest. This is supported by the fact that the number of publications on antiaggregatory effect of polyphenols has doubled in the last decade. In this review we focus on antiaggregatory effect of most abundant polyphenols - flavonoids, the effect of plant extracts rich in polyphenols (propolis, species Salvia sp., Calamintha nepeta L., Lavandula angustifolia Mill., Melissa officinalis L, Mentha x piperita L., Ocimum basilicum L., Origanum vulgare L., Rosmarinus officinalis L.) on platelet aggregation, association of chemical composition and antioxidant properties with the observed biological effect, and possible clinical significance of the published results.

P6006Pathogenesis of symptomatic crises in patients with coronary artery spasm: evidence for acute damage to vascular glycocalyx and to circulating platelets

Abstract Background Coronary artery spasm (CAS) is known to occur commonly even in a “pure culture”, but little is known regarding the precipitation of the symptomatic crises which characterize this disorder. There have been recent reports of the occurrence of plaque erosion and intracoronary thrombosis during CAS crises. We have recently shown that (1) the anti-aggregatory effects of nitric oxide (NO) are impaired in CAS patient and (2) release into plasma of the endothelial glycocalyx component syndecan-1 (SD-1) occurs during acute episodes of CAS, suggesting glycocalyx erosion by inflammatory enzyme release. Objective In the current study, we sought to determine whether this phenomenon is accompanied by damage to circulating platelets and whether activation of mast cells may represent a possible precipitant. Methods In patients with acute episodes and chronic phases of CAS (n=10), as well as normal subjects (n=12), plasma concentrations of SD-1, of platelet-derived microparticles (PMPs), of the mast cell enzyme tryptase and of malondialdehyde (MDA), a measure of oxidative stress, were evaluated. Results The results are summarized in the table. Symptomatic crises were associated with substantial elevation of SD-1 concentrations and also those of PMPs and of tryptase, relative to chronic status. However, MDA concentrations did not vary significantly during acute episodes. Impact of acute exacerbation of CAS on markers of glycocalyx shedding (SD-1), platelet activation (PMP counts), mast cell activation (tryptase) and oxidative stress (MDA) Parameter Acute CAS Chronic CAS p* Normal subjects** SD-1 (μg/L) 50.3±3.9 14.3±4.7 &lt;0.0001 12.7±2.4 PMPs (counts) 24200±8100 4800±1010 0.02 10400±2900 Tryptase (μg/L) 4.4±0.4 4.1±0.4 0.03 &lt;12.0 MDA (μM) 3.2±0.2 3.1±0.1 NS 3.09±0.15 *Acute vs. chronic; **provided for reference only. Conclusion (1) The combination of SD-1 release and formation of PMPs suggests that CAS crises reflect both glycocalyx “shedding” and platelet activation/apoptosis, a combination which would facilitate coronary thrombosis. (2) CAS crises are associated with mast cell activation, which may contribute to the above vascular/platelet damage.

Изменение активности различных антиагрегантов тромбоцитов при их облучении импульсным магнитным полем высокой напряженности

Pulse magnetic fields are widely used in modern technology. We studied the antiaggregation properties of pentoxifylline and aspirin irradiated by a pulsed magnetic field at certain parameters: intensity H, frequency f, number of pulses n. The impact of a pulsed magnetic field was carried out both on powdered and dissolved drugs in solution. The aim of the study is to study the effect of high-intensity PMF on the antiplatelet activity of pentoxifylline and aspirin Evaluation of the anti-aggregation effect was carried out using the method of thromboelastography. on a TEG 5000 apparatus. In the analysis of thromboelastograms, the general coagulation tendency was, the functional activity of platelets and fibrinogen, the activity of fibrinolysis, and the physicomechanical properties of the formed clots were determined. Since thrombosis poses a threat to human health, today the use of antiplatelet agents for the prevention of cardiovascular disease is beyond doubt. It was found that exposure to a pulsed magnetic field causes significant changes in the antiplatelet activity of only the pentoxifylline molecule. The effect of PMF on the aspirin molecule has not been identified. This is due, in one hand, to a significant difference in the structure of molecules, as well as to the reaction mechanism in which the studied antiplatelet agents are involved. It can be predicted that the effect of pulsed fields on drugs, which are heterocyclic compounds, antimetabolites, and competitive enzyme inhibitors, can enhance the biological effect of these drugs. A hypothesis was put forward to increase the antiplatelet activity of pentoxifylline by exposure to PMF associated with a change in the conformation of the molecule and an increase in affinity for the active site of cAMP-phosphodiesterase.

On the anticoagulant and antiaggregatory properties of a glucosamine sulfate molecule

Glucosamine is part of the human metabolome required for the biosynthesis of polymer glycosaminoglycans in connective tissue. In addition, the glucosamine molecule itself has anti-inflammatory and regenerative properties. This paper presents the results of a systematic analysis of fundamental and clinical studies, which indicate the anticoagulant and antiaggregatory effects of a highly purified pharmaceutical substance of microcrystalline glucosamine sulfate (mGS). The main molecular mechanisms of its antithrombotic effects are most probably the mGS molecular mimicry of heparan sulfate activity, the activation of CD44 receptor, and the inactivation of the NF-KB signaling pathways in platelets. A quantitative chemoreactome study has shown that the antithrombotic effects of mGS in the human reactome are due to the inhibition of: ’) proper platelet aggregation; 2) platelet adhesion and activation receptors; 3) endogenous synthesis of thromboxanes; 4) coagulation by reducing the activity of coagulation factors.

Protective Effects of a Neurohypophyseal Hormone Analogue on Prion Aggregation, Cellular Internalization, and Toxicity.

Herein, we report novel neuroprotective activity of the neurohypophyseal hormone analogue desmopressin (DDAVP) against toxic conformations of human prion protein. Systematic analysis using biophysical techniques in conjunction with surface plasmon resonance, high-end microscopy, conformational antibodies, and cell-based assays demonstrated DDAVP's specific binding and potent antiaggregating effects on prion protein (rPrPres). In addition to subjugating conformational conversion of rPrPres into oligomeric forms, DDAVP also exhibits potent fibril modulatory effects. It eventually ameliorated neuronal toxicity of rPrPres oligomers by significantly reducing their cellular internalization. Molecular dynamics simulations showed that DDAVP prevents β-sheet transitions in the N-terminal amyloidogenic region of prion and induces antagonistic mobilities in its α2-α3 and β2-α2 loop regions. Collectively, our data proposes DDAVP as a new structural motif for rational drug discovery against prion diseases.

Impaired adenylate cyclase signaling in acute myocardial ischemia: Impact on effectiveness of P2Y12 receptor antagonists

IntroductionP2Y12 receptor antagonists reduce risk of thrombotic complications after stent implantation but increase bleeding risk. Activation of P2Y12 receptors by ADP causes Gi-protein-mediated inhibition of adenylate cyclase (AC), thus limiting platelet response to anti-aggregatory effect of prostacyclin (PGI2). However, P2Y12 blockade reverses this ADP-induced suppression of the platelet PGI2/AC signaling pathway. We previously demonstrated that impairment of this pathway predicts poor response to clopidogrel. ObjectivesTo identify clinical correlates of variability in PGI2/AC signaling, and to assess the impact of such variability on individual responses to the direct P2Y12 receptor antagonists ticagrelor (in vivo) and 2-methyl-thioadenosine-monophosphate (2MeSAMP) (in vitro). Patients/MethodsWe compared the inhibitory effects of prostaglandin E1 (PGE1) and the PGI2 analog Iloprost (Ilt) on platelet aggregation in whole blood samples from healthy control subjects (n = 17), and patients with stable angina pectoris (SAP; n = 35) or acute coronary syndromes (ACS; n = 23), with or without associated diabetes/hyperglycemia. ResultsCompared to control subjects, patients with ACS and – to a lesser extent – those with SAP, exhibited impaired responses to PGE1, accentuated in the presence of hyperglycemia. Efficacy of ticagrelor treatment, measured as change in platelet reactivity index, was directly related to pre-treatment PGE1 response, both at univariate and multivariate analysis. There was a strong correlation between extent of inhibition of platelet aggregation, whether by PGE1 or Ilt, and the anti-aggregatory effect of 2MeSAMP in vitro. ConclusionsThe integrity of PGI2/AC signaling, which is impaired in the presence of ACS and hyperglycemia, predetermines the anti-aggregatory efficiency of P2Y12 receptor antagonists.

The role of disaccharides for protein–protein interactions – a SANS study

ABSTRACTThe disaccharide trehalose has shown outstanding anti-aggregation properties for proteins, which are highly important for the possibility to treat neurodegenerative diseases, such as Alzheimer’s and Huntington’s disease. However, the role and mechanism of trehalose for such stabilising effects are still largely unknown, partly because a direct structural picture of how trehalose organises around proteins in an aqueous system is missing. Here we compare small-angle neutron scattering (SANS) data on myoglobin in aqueous solutions of either sucrose or trehalose, in order to investigate their effect on protein–protein interactions. We find that both trehalose and sucrose induces a well-defined protein–protein distance, which could explain why these inhibit protein–protein interactions and associated protein aggregation. It does not however explain the superior anti-aggregation effect of trehalose and suggests that the local solvent structures are highly important for explaining the protein stabilisation mechanism. In a broader perspective, these findings are important for understanding the role of sugars in biological stabilisation, and could provide a structural explanation for why trehalose is a promising candidate for the treatment of neurodegenerative and other protein aggregation related diseases.

Hypercholesterolemia impairs the Glucagon-like peptide 1 action on platelets: Effects of a lipid-lowering treatment with simvastatin

BackgroundThe incretin hormone Glucagon-like peptide 1(GLP-1) plays a pivotal role in maintaining glucose homeostasis with effects also on the cardiovascular system. GLP-1 influences platelet functions by increasing the inhibitory action of nitric oxide (NO) and reducing oxidative stress. To date, the role of hypercholesterolemia (HyC) on platelet GLP-1 effects needs to be elucidated. MethodsForty-five subjects with primary HyC and twenty normocholesterolemic controls (NoC) were enrolled. In platelets from all subjects, the native GLP-1 (7-36), the truncated GLP-1 (9-36) and the GLP-1 analogue Liraglutide were evaluated in their ability to interfere with the activation of NO/PKG/VASP, PI-3K/Akt e MAPK/ERK-1/2 pathways and oxidative stress. Furthermore, in HyC subjects the role of a lipid-lowering therapy with statin on GLP-1 related peptide effects on platelet function was evaluated. ResultsUnlike in NoC, in platelets from HyC subjects the GLP-1 related peptides GLP-1 (7-36), GLP-1 (9-36) and Liraglutide all failed to: i) increase the antiaggregating effects of NO and the NO-induced VASP-ser239 phosphorylation, ii) decrease phosphorylation levels of Akt and ERK-2 and iii) reduce reactive oxygen species (ROS) generation. The treatment with simvastatin (40 mg/die) in HyC (n = 18) significantly reduced total and LDL cholesterol levels, platelet aggregability/activation, ROS production and NO action but did not modify platelet sensitivity to the GLP-1 effects. ConclusionCollectively, these results indicate that hypercholesterolemia per se is characterized by a resistance to GLP-1 effects on platelets and this impairment is not corrected by treatment with simvastatin.

Anti-aggregant effect of butanolic extract of Rubia tinctorum L on platelets in vitro and ex vivo

Natural deep eutectic solvents (DESs) were investigated as potential green extraction solvents in the ultrasound-assisted extraction (UAE) of flavonoids from Rubia truppeliana and R. cordifolia fruit. Lactic acid was selected as the optimal hydrogen bond donor for five solvents in the screening of DESs. To optimize the extraction of Rubia fruit flavonoids using DES and UAE, a Box–Behnken experimental design was developed. The optimal conditions were: liquid–solid ratio, 30; extraction temperature, 70 °C; and extraction time, 40 min. The corresponding yields were 49.41 mg/g for total flavonoids from Rubia truppeliana (TFT) and 55.15 mg/g for that of Rubia cordifolia (TFC). The extracts obtained under the optimum extraction conditions showed excellent antioxidant activities in DPPH, ABTS, and FRAP assays. The results demonstrated that the extraction using DES and UAE is an eco-friendly method for the extraction of flavonoids from Rubia fruit.

Influence of different supplementation on platelet aggregation in patients with rheumatoid arthritis.

Long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) have been reported to reduce platelet aggregation. Our aim was to prospectively assess the potential influence of different supplementation omega-3 PUFA on the antiplatelet effects in rheumatoid arthritis (RA) patients. The study included 60 patients with RA at the Department of Rheumatology, Clinical Center Kragujevac. Patients were divided into three groups depending on who used concentrated fish oil only or concentrated fish oil in combination with evening primrose oil or control group without supplementation in a period of 3months. Platelet aggregation was measured using the multiplate analyzer and expressed through the value of adenosine diphosphate (ADP) test, aranchidonic acid-induced aggregation (ASPI) test, thrombin receptor-activating peptide (TRAP) test (to assess baseline platelet aggregation), and the ratio of ADP/TRAP and ASPI/TRAP representing the degree of inhibition of platelet aggregation compared to the basal value. The platelet function analysis in whole blood was performed 18-24h before starting supplementation and after 90days. Considerations were taken in the representation of demographic, clinical characteristics, and laboratory parameters between the groups. Patients who used concentrated fish oil only had a significantly lower value of the ratio of ADP/TRAP (0.68 ± 0.20) compared to patients without supplementation (0.83 ± 0.12; p = 0.008), while there was no statistically significant difference in values of other laboratory parameters of platelet function between other groups. Co-administration of supplementation-concentrated fish oil may reduce platelet aggregation in adults with RA. • Omega-3 PUFAs are essential for health and are known to possess anti-inflammatory properties, improving cardiovascular health as well as benefiting inflammatory diseases.. • In this paper, we report on anti-aggregation effects n-3 PUFAs and ɤ-linolenic acid in RA. • The risk of cardiovascular morbidity and mortality is increased in RA, and dietary supplementation of n-3 PUFA may have preventive potential for the cardiovascular management in rheumatoid arthritis.

Anle138b prevents PrP plaque accumulation in Tg(PrP-A116V) mice but does not mitigate clinical disease.

Anle138b is an anti-aggregating compound previously shown to delay the onset of scrapie, a transmissible prion disease, although its in vivo efficacy against other prion disease subtypes has not been fully assessed. TgGSS mice that model Gerstmann-Sträussler-Scheinker disease (GSS) via expression of mouse PrPA116V accumulate PrP amyloid plaques in their brains and develop progressive ataxia leading to death in ~160 days. When allowed to feed on food pellets containing anle138b from weaning until death, the brains of TgGSS mice displayed significant reductions in PrP plaque burden, insoluble PrP, and proteinase K-resistant PrPSc at end stage, compared with TgGSS mice allowed to feed on placebo food pellets. Despite these effects on biological markers of disease, there was no difference in the onset of symptoms or the age at death between the two treatment groups. In contrast, scrapie-inoculated wild-type mice treated with anle138b survived nearly twice as long (254 days) as scrapie-inoculated mice fed placebo (~136 days). They also displayed greater reductions in insoluble and PK-resistant PrPSc than TgGSS mice. Although these results support an anti-aggregating effect of anle138b, the discordance in clinical efficacy noted between the two prion disease models tested underscores the pathophysiological differences between them and highlights the need to consider differences in susceptibilities among prion subtypes when assessing potential therapies for prion diseases.

The Direct Thrombin Inhibitors Dabigatran and Lepirudin Inhibit GPIbα-Mediated Platelet Aggregation.

The direct thrombin inhibitor (DTI) dabigatran is a non-vitamin K antagonist oral anticoagulant for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. In addition to its anti-thrombotic efficacy, dabigatran has been suggested to exert some pro-thrombotic effect due to fostering the ligation of thrombin to its high affinity platelet receptor glycoprotein (GP) Ibα in patients with atrial fibrillation. On the other hand, we provided evidence that a member of another class of DTIs, lepirudin, stimulates the inhibitory cyclic guanosine monophosphate (cGMP)/soluble guanylate cyclase pathway in human platelets. Here, we investigated the effect of lepirudin and dabigatran spiked to platelets from healthy volunteers on GPIbα-mediated platelet aggregation and agglutination. Ristocetin/von Willebrand factor (vWF)-induced aggregation of platelets in the presence or absence of plasma was significantly inhibited by lepirudin, dabigatran and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone (PPACK). However, ristocetin/vWF-mediated platelet agglutination and binding of vWF to platelets were not affected by the DTIs. The anti-aggregatory effect was confirmed by using the GPIbα-specific agonist echicetin beads for human and murine platelets. DTIs diminished echicetin beads-induced Syk Y352 phosphorylation (used here as readout for an early signal occurring during echicetin-induced platelet aggregation), but did not inhibit adenosine diphosphate- or thromboxane A2-induced platelet aggregation. Thrombin was not generated in response to ristocetin/vWF or echicetin beads and therefore did not explain the inhibitory effect of the DTIs. Therapeutic concentration of lepirudin and dabigatran did not affect significantly platelet vasodilator-stimulated phosphoprotein S239 phosphorylation or cGMP and cyclic adenosine monophosphate levels. These data suggest that the DTIs, lepirudin and dabigatran, impair platelet activation measured during platelet aggregation induced by ristocetin/vWF or echicetin beads.

Amino Acids as Additives against Amorphous Aggregation: In Vitro and In Silico Study on Human Lysozyme.

The effect of 16 amino acids (AA) with various physicochemical properties was investigated on human lysozyme (HL) heat-induced amorphous aggregation. UV-Visible spectrophotometry was used to monitor the kinetics of aggregation in the absence and presence of AA, and transmission electron microscopy (TEM) images were taken from the aggregates. To conduct in silico experiments, Autodock vina was used for docking of AA into protein (via YASARA interface), and FTmap information was checked for an insight onto putative binding sites. Prediction of aggregation-prone regions of lysozyme was made by AGGRESCAN and Tango. Among all tested AA, phenylalanine had the best anti-aggregation effect, followed by lysine. In addition, based on in silico tests, Trp 109 and Val 110 of lysozyme are suggested to be of importance in the aggregation process of the enzyme. In conclusion, phenylalanine, arginine, and lysine were found to affect the nucleation phase of lysozyme aggregation and could be considered as suitable stabilizing structures for this enzyme.

Cardiovascular Effects of Flavonoids.

Cardiovascular Disease (CVD) is the major cause of death worldwide, especially in Western society. Flavonoids are a large group of polyphenolic compounds widely distributed in plants, present in a considerable amount in fruit and vegetable. Several epidemiological studies found an inverse association between flavonoids intake and mortality by CVD. The antioxidant effect of flavonoids was considered the main mechanism of action of flavonoids and other polyphenols. In recent years, the role of modulation of signaling pathways by direct interaction of flavonoids with multiple protein targets, namely kinases, has been increasingly recognized and involved in their cardiovascular protective effect. There are strong evidence, in in vitro and animal experimental models, that some flavonoids induce vasodilator effects, improve endothelial dysfunction and insulin resistance, exert platelet antiaggregant and atheroprotective effects, and reduce blood pressure. Despite interacting with multiple targets, flavonoids are surprisingly safe. This article reviews the recent evidence about cardiovascular effects that support a beneficial role of flavonoids on CVD and the potential molecular targets involved.

ASSOCIATION OF PLATELET-DERIVED MICROVESICLES WITH HIGH ON-TREATMENT PLATELET REACTIVITY IN CONVALESCENT ISCHEMIC STROKE PATIENTS TREATED WITH ACETYLSALICYLIC ACID

Elevated concentrations of platelet-derived microvesicles are found in cerebrovascular diseases. The impact of acetylsalicylic acid on these microvesicles remains inconsistent, despite its well-established effect on platelet aggregation. High residual platelet aggregation is defined as high on-treatment platelet reactivity, while “treatment failure” is the occurrence of vascular events despite antiplatelet treatment. The aim of this study was to determine whether the antiaggregatory effect of acetylsalicylic acid correlates with platelet-derived microvesicles in convalescent ischaemic stroke patients and cardiovascular risk factor controls as well as to evaluate the association between high on-treatment platelet reactivity and recurrent vascular events with the studied platelet-derived microvesicle parameters. The study groups consisted of 76 convalescent stroke patients and 74 controls. Total platelet-derived microvesicles, annexino-positive microvesicles number, and platelet-derived microvesicles with surface expression of proinflammatory (CD40L, CD62P, CD31) and procoagulant (PS, GPIIb/IIIa) markers were characterized and quantified using flow cytometry. Cyclooxygenase-1-specific platelet responsiveness, with whole blood impedance platelet aggregation under arachidonic acid stimulation and the serum concentration of thromboxane B2, were evaluated. Neither acetylsalicylic acid intake nor modification of its daily dose caused statistically significant differences in the studied microvesicle parameters. Additionally, no statistically significant differences in the studied microvesicle parameters were revealed between high on-treatment platelet reactivity and non-high on-treatment platelet reactivity subjects in either study subgroup. However, elevated concentrations of PAC-1+/CD61+, CD62P+/CD61+ and CD31+/CD61+ microvesicles were found in stroke patients with treatment failure, defined in this study as a recurrent vascular events in a one-year follow-up period. This study revealed no relationship between circulating microvesicle number and platelet aggregation. The procoagulant and proinflammatory phenotype of circulating platelet-derived microvesicles might contribute to acetylsalicylic acid treatment failure.

Colorimetric sensing strategy for heparin assay based on PDDA-induced aggregation of gold nanoparticles.

Herein, we report a highly sensitive colorimetric sensor for the detection of heparin based on its anti-aggregation effect of the PDDA–gold nanoparticle colloidal system. PDDA-induced non-crosslinking aggregation of gold nanoparticles is firstly investigated and the phenomenon of heparin mediated color recovery is then observed, which can be used to indicate the concentration of heparin. This method is proved to be highly sensitive and selective. Moreover, it has been successfully applied to determine human blood serum samples, the results of which demonstrate great potential practical utility with simple operations.

Anti-aggregation effect on platelets of Indiplon a hypnotic sedative non-benzodiazepine drug

Cardiovascular diseases are one of the main public health problems, and many of them, their pathophysiology involves alterations in platelet activity. Platelet activation is an essential event that is regulated by the intracellular concentrations of Ca2+ and cAMP. Interestingly, it has been shown that the activation of adenosine A2A receptors increases cAMP levels and produces the inhibition of platelet aggregation, which appears as a potential target for regulation of platelet activity. Therefore, we tried to activate A2A receptors using Indiplon, a drug developed for the treatment of insomnia, and analyze its effect on platelet activity in vitro. Our results indicate that Indiplon is able to interact in silico with the adenosine A2A receptor (ΔGbind of -73.321 kcal/mol, similar to that obtained with adenosine), which is involved in the regulation of platelet cAMP levels. In functional studies using PRP, a reduction in platelet aggregation induced by ADP was observed in the presence of Indiplon at 500 μM with a percentage of inhibition 70%, where the use of specific inhibitors (ZM241385 and MSX-2) of the A2A receptor also blocked these effects reducing the percentage of inhibition to 41% and 34.1%, respectively. Also, the use of Indiplon produced a decrease in the expression in the membrane of P-selectin. Thus, Indiplon acts as an A2A receptor agonist and whose activation results in inhibition of platelet aggregation and activation, showing a possible cardiovascular protective role.