ADP-induced Platelet Aggregation Research Articles

Coumarin Derivatives Inhibit ADP-Induced Platelet Activation and Aggregation

Coumarin was first discovered in Tonka bean and then widely in other plants. Coumarin has an anticoagulant effect, and its derivative, warfarin, is a vitamin K analogue that inhibits the synthesis of clotting factors and is more widely used in the clinical treatment of endovascular embolism. At present, many artificial chemical synthesis methods can be used to modify the structure of coumarin to develop many effective drugs with low toxicity. In this study, we investigated the effects of six coumarin derivatives on the platelet aggregation induced by adenosine diphosphate (ADP). We found that the six coumarin derivatives inhibited the active form of GPIIb/IIIa on platelets and hence inhibit platelet aggregation. We found that 7-hydroxy-3-phenyl 4H-chromen-4-one (7-hydroxyflavone) had the most severe effect. In addition, we further analyzed the downstream signal transduction of the ADP receptor, including the release of calcium ions and the regulation of cAMP, which were inhibited by the six coumarin derivatives selected in this study. These results suggest that coumarin derivatives inhibit coagulation by inhibiting the synthesis of coagulation factors and they may also inhibit platelet aggregation.

Identification of a Distinct Platelet Phenotype in the Elderly: ADP Hypersensitivity Coexists With Platelet PAR (Protease-Activated Receptor)-1 and PAR-4-Mediated Thrombin Resistance.

Thrombin (via PAR [protease-activated receptor]-1 and PAR-4) and ADP (via P2Y12 receptors) are potent endogenous platelet activators implicated in the development of cardiovascular disease. We aimed to assess whether platelet pathways alter with aging. We characterized platelet activity in community-dwelling volunteers (n=174) in the following age groups: (1) 20 to 30 (young); (2) 40 to 55 (middle-aged); (3) ≥70 years (elderly). Platelet activity was assessed by aggregometry; flow cytometry (surface markers [P-selectin: alpha granule release, CD63: dense granule release, PAC-1: measure of conformationally active GPIIb/IIIa at the fibrinogen binding site]) measured under basal conditions and after agonist stimulation [ADP, thrombin, PAR-1 agonist or PAR-4 agonist]); receptor cleavage and quantification; fluorometry; calcium flux; ELISA. The elderly had higher basal platelet activation than the young, evidenced by increased expression of P-selectin, CD63, and PAC-1, which correlated with increasing inflammation (IL [interleukin]-1β/IL-6). The elderly demonstrated higher P2Y12 receptor density, with greater ADP-induced platelet aggregation (P<0.05). However, elderly subjects were resistant to thrombin, achieving less activation in response to thrombin (higher EC50) and to selective stimulation of both PAR-1 and PAR-4, with higher basal PAR-1/PAR-4 cleavage and less inducible PAR-1/PAR-4 cleavage (all P<0.05). Thrombin resistance was attributable to a combination of reduced thrombin orienting receptor GPIbα (glycoprotein Ibα), reduced secondary ADP contribution to thrombin-mediated activation, and blunted calcium flux. D-Dimer, a marker of in situ thrombin generation, correlated with platelet activation in the circulation, ex vivo thrombin resistance, and circulating inflammatory mediators (TNF [tumor necrosis factor]-α/IL-6). Aging is associated with a distinctive platelet phenotype of increased basal activation, ADP hyperreactivity, and thrombin resistance. In situ thrombin generation associated with systemic inflammation may be novel target to prevent cardiovascular disease in the elderly.

Exploring the Q-markers of Angelica sinensis (Oliv.) Diels of anti-platelet aggregation activity based on spectrum-effect relationships.

The radix of Angelica sinensis (Oliv.) Diels (RAS) is widely used in medicinal and dietary applications in China, and has the function for replenishing and invigorating the blood, stopping pain and moistening the intestines. In this study, RAS from the main geoherb regions showed better efficacy in inhibiting Adenosine diphosphate- or arachidonic acid-induced platelet aggregation than those from non-geoherb regions. In addition, the HPLC fingerprints of 30 batches of RAS, as part of the comprehensive evaluation of RAS, were established and used for spectral efficiency to screen the quality markers for anti-platelet aggregation activities. Five compounds in RAS-senkyunolide I, uridine, guanine, ferulic acid and adenosine-were demonstrated to contribute significantly to the anti-platelet aggregation activity. These bioactive compounds, especially senkyunolide I and ferulic acid with stronger activities, could be used as quality markers of RAS for quality control of RAS.

Four-Week Supplementation of Water-Soluble Tomato Extract Attenuates Platelet Function in Chinese Healthy Middle-Aged and Older Individuals: A Randomized, Double-Blinded, and Crossover Clinical Trial.

Background and AimsPlatelets are linked to atherosclerotic development and pathological thrombosis. Single dose of water-soluble tomato extract (WTE) which is a natural extraction can exert anti-platelet effects after 3 or 7 h in British healthy people. However, the effects of WTE supplementation on platelet function in Chinese healthy middle-aged and older individuals have not been studied, and the effects or safety of 4-week WTE supplementation also remain unclear. The present study aims to determine the effects of WTE on platelet function, and explore the safety of 4-week WTE supplementation in Chinese healthy middle-aged and older individuals.MethodsA randomized, double-blinded, and crossover clinical trial was conducted. Firstly, 105 individuals were randomly divided into two groups that received WTE (150 mg/day) or placebo for 4 weeks. Then, after a washout period of 2 weeks, two groups exchanged groups and continued for another 4-week intervention. Platelet aggregation, P-selectin, activated GPIIbIIIa, plasma platelet factor 4 (PF4), β-thromboglobulin (β-TG), and thromboxane B2 (TXB2) were tested at baseline, 4, 6, and 10 weeks.ResultsCompared with the placebo group, 150 mg/day WTE supplement for 4 weeks significantly reduced ADP-induced or collagen-induced platelet aggregation (−10.8 ± 1.8 or −3.9 ± 1.5%, P < 0.05), ADP-induced or collagen-induced platelet P-selectin expression (−6.9 ± 1.5 or −6.6 ± 1.3%, P < 0.05), ADP-induced or collagen-induced activated GPIIbIIIa (−6.2 ± 2.0 or −3.8 ± 2.0%, P < 0.05). Besides, 4-week intervention of 150 mg WTE per day also resulted in significant reductions in plasma PF4 (−120.6 ± 33.2 ng/mL, P < 0.05) and β-TG (−129.7 ± 27.5 ng/mL, P < 0.05) and TXB2 (−42.0 ± 4.0 ng/mL, P < 0.05), while had no effects on coagulation function and liver or renal function. Interestingly, 2-week washout period is enough to reverse the inhibitory effect of 4-week WTE supplementation on platelet function.ConclusionWTE supplementation for 4 weeks could moderately reduce platelet activation, aggregation, and granule secretion in Chinese healthy middle-aged and older individuals, and these effects are safe. After 2-week washout period, the inhibitory effect of 4-week WTE on platelet function can be eliminated.Clinical Trial Registration[http://www.chictr.org.cn/], identifier [ChiCTR-POR-17012927].

Ticagrelor prevents infective endocarditis by mitigating Staphylococcus aureus virulence

Infective endocarditis (IE) is a deadly disease mainly caused by the gram-positive and highly virulent bacteria Staphylococcus aureus (SA). Due to lack of efficacy of current antibiotic therapy, there is an urgent need to discover new strategies that could prevent this disease. To assess the ability of the antiplatelet drug ticagrelor, which also displays antibacterial activity against gram-positive bacteria, to prevent SAIE. We used a mouse model of infective endocarditis induced by a SAIE clinical isolate. Ticagrelor was administered orally at a conventional dosage (3 mg/kg, single dose) prior to infection and local histamine infusion on the aortic valve. Infected vegetation presence was determined by Gram staining on heart sections after three days. Antibacterial effect of ticagrelor at dosages equivalent to plasma levels achieved in patients (0.75–1.25 μg/mL) was assessed in vitro in human blood. Ticagrelor significantly prevented the formation of infected vegetation, with IE in only 14.3% of ticagrelor-treated mice ( n = 21) compared to 52.3% of vehicle-treated mice ( n = 37). Ex vivo ADP-induced platelet aggregation assays confirmed rapid reversibility of antiplatelet activity (4 hours), which made it unlikely that solely the antiplatelet effect would explain IE prevention by ticagrelor. Bacterial survival in blood was not diminished three days post-infection. We therefore assessed whether ticagrelor could affect bacterial virulence. We found that growing SA in the presence of 1.25 μg/mL ticagrelor inhibited a-toxin RNA expression and protein secretion, which was corroborated with drastically reduced hemolysis and platelet aggregation induced by bacterial supernatants. Ticagrelor-treated bacteria could no longer adhered to fibrinogen, and in whole blood perfusion experiments, flow-dependent bacterial adhesion on activated endothelial cells was severely impaired. Our study demonstrates the unprecedented ability of ticagrelor to prevent IE by a novel mechanism of directly mitigating bacterial virulence. Hence, clinical trials using ticagrelor as adjunct therapy to antibiotics in patients at risk for IE are warranted.

Palmatine Derivatives as Potential Antiplatelet Aggregation Agents via Protein Kinase G/Vasodilator-Stimulated Phosphoprotein and Phosphatidylinositol 3-Kinase/Akt Phosphorylation.

Sixty palmatine (PMT) derivatives were synthesized and evaluated for antiplatelet aggregation taking berberine as the lead, and the structure-activity relationship was first systematically described. Among them, compound 2v showed the best potency in reducing adenosine diphosphate (ADP)-induced platelet aggregation in a dose-dependent manner. It greatly suppressed ADP-induced platelet aggregation, activation, and Akt phosphorylation in vitro and ex vivo after oral administration to mice. It also effectively inhibited carrageenan-induced thrombus formation in the mouse tail and lung, as well as reduced the serum P-selectin level. Compound 2v might simultaneously bind to protein kinase G to improve vasodilator-stimulated phosphoprotein phosphorylation and bind to phosphatidylinositol 3-kinase to inhibit Akt phosphorylation, which synergically reduced platelet aggregation, thereby achieving antithrombotic efficacy. Therefore, PMT derivatives constituted a novel family of antiplatelet aggregation agents with the advantage of a good safety profile, worthy of further investigation.

Antiplatelet Activity of Riamilovir under Conditions of Lipopolysaccharide Intoxication.

We studied the effect of antiviral agent riamilovir on ADP-induced platelet aggregation in the absence and presence of LPS. Unlike acetylsalicylic acid (reference drug), riamilovir did not exhibit antiplatelet effect in vitro. However, it markedly suppressed platelet reactivity in LPS-treated blood samples and was 2.2-fold superior to acetylsalicylic acid in terms of IC50 value. In in vivo experiments, riamilovir under conditions of hypercytokinemia blocked platelet aggregation in rats by 64%.

ACTION OF VENOM OF VIPERA SNAKE OF UKRAINE ON BLOOD COAGULATION in vitro

Aim. In this study we focused on the search of fibrinogen-targeted proteases in the venom of Vipera renardi, Vipera nikolskii and Vipera berus. Venom of Vipera berus was also fractionated on Q-sepharose and action of separated fractions on human blood plasma, platelets and red cells was studied. Methods. Analysis of protein mixtures was performed using SDS-PAGE. Аction on the blood coagulation system was analyzed using the APTT assay. Identification of protein components with fibrinolytic activity was performed using enzyme-electrophoresis with fibrinogen as the substrate. Fractionation of V. berus venom was performed on Q-sepharose using FPLC system Acta Prime. Action of separated fractions on ADP-induced platelet aggregation in platelet rich blood plasma was analyzed using Aggregometer AP 2110. Hemolytic action of fractions was estimated using fresh human red cells. Amount of released hemoglobin was estimated by spectrophotometry on Optizen POP. Results. All studied venoms had different protein compositions with major protein fractions in the range from 25 kDa to 130 kDa. Both V. berus and V. nikolskii venoms taken in 1:200 dilutions reduced the time of clotting in APTT test from 25 to 13 s. In contrast, V. renardi venom in the same dilution prolonged the clotting time from 25 s to 180 s that we assumed as the result of fibrinogen-specific protease presence. According to enzyme-electrophoresis data all studied venoms contained fibrinogen-specific proteases with the apparent molecular weights for V. berus, V. nikolskii – 25-55 kDa. and V. renardi – 55-75 kDa. Fractionation of crude venom of V. berus allowed obtaining several fractions eluted at different concentrations of NaCl: 0.1; 0.2; 0.3; 0.5 М. Non-binded fraction was also collected. Conclusions. Thus, the components of Vipera venoms living in Ukraine can be used for basic biochemical research. At the same time, care should be taken in the case of envenomation, as the presence of fibrinogenolytic enzymes in the venom can lead to hemorrhage. Further characterization of fibrinogen-specific protease from V. berus venom is a promising task for biotechnology.

Does thromboelastography predict bleeding in patients treated with clopidogrel or ticagrelor in off-pump coronary artery bypass grafting?

ObjectivesWe sought to investigate the predictive value of platelet function assessment for bleeding in clopidogrel- or ticagrelor-treated patients undergoing off-pump coronary artery bypass grafting (OPCABG). MethodsThis prospective study included patients treated with acetylsalicylic acid and clopidogrel or acetylsalicylic acid and ticagrelor and scheduled for OPCABG. The percentage of platelet aggregation was evaluated by thromboelastography. Postoperative blood loss was measured as the chest tube drainage (CTD) and excessive blood loss was settled as CTD with more than 600 mL at first postoperative 12 h. Major bleeding complications were defined by Bleeding Academic Research Consortium (BARC) type 4-CABG related bleeding or class 3 or class 4 bleeding in universal definition of perioperative bleeding (UDPB) in adult cardiac surgery. ResultsA total of 434 consecutive patients were included. There was a negative correlation (r = −0.133, P = 0.0056) between ADP-induced platelet aggregation and CTD at 12 h. The platelet aggregation exhibited a moderate performance (AUC = 0.616) for predicting excessive postoperative blood loss. Multivariable analysis showed that ADP-induced platelet aggregation <33.45% (OR = 2.976, 95% CI: 1.325–6.711, P = 0.008) was independently associated with excessive postoperative blood loss. However, the percentage of ADP-induced platelet aggregation predicted neither UDPB-defined nor BARC-defined major bleeding. Instead, P2Y12 receptor antagonist discontinuation time was independently related to the risk of major bleeding complication. ConclusionsADP-induced platelet aggregation detected by thromboelastography was negatively related to postoperative blood loss and platelet aggregation <33.45% was associated with excessive postoperative blood loss. However, platelet function assessment by thromboelastography failed to predict major bleeding complications.

Influence of Humoral Factors on Hemostatic Properties of Blood In Vitro in Rats.

An important role in the implementation of many physiological and pathological processes is played by the functional state of the components of the hemostasis system, the activity of which is largely determined by the influence of various humoral factors. We studied the effects of lactate, nitric oxide, and sodium glutamate on aggregation activity of platelets and coagulation properties of rat plasma in vitro. The most pronounced effect was produced by lactic acid, which manifested in a dose-dependent decrease in the parameters of ADP-induced platelet aggregation and a two-phase change in blood coagulability with progressive acidification of the medium. Nitric oxide induced less pronounced decrease in the aggregation activity of platelets. Sodium glutamate, on the contrary, stimulated platelet aggregation and similar to nitric oxide did not affect coagulation status of the plasma.

A study of microRNA-223 in evaluating platelet reactivity in patients with acute ischemic stroke.

To investigate the relationship between plasma microRNA-223 expression and platelet reactivity in patients with acute ischemic stroke (AIS) and to evaluate its predictive value in clopidogrel resistance or high on-treatment platelet reactivity (HTPR). A total of 120 patients with acute ischemic stroke were screened in this study, and 60 patients were included in the acute ischemic stroke group according to the inclusion criteria and platelet reactivity after clopidogrel treatment. control group was 60 non-ischemic stroke patients hospitalized. The levels of phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and adenosine diphosphate-induced platelet aggregation (ADP-PAg) in platelets were detected by flow cytometry. The expression level of plasma microRNA-223 was detected before and after clopidogrel treatment using quantitative real-time polymerase chain reaction (PcR). The AIS group was then divided into the clopidogrel non-HTPR and the clopidogrel HTPR groups based on the relative inhibition rate. We found that: 1) the VASP platelet reactivity index (PRI) was positively correlated with ADP-PAg; 2) before administration, the plasma microRNA-223 expression level and VASP-PRI were higher in the AIS group than in the control group; 3) after administration, the expression level of microRNA-223 was negatively correlated with VASP-PRI; 4) before and after treatment, the plasma microRNA-223 expression level in the clopidogrel HTPR group was lower than in the non-AIS patients; 5) before treatment, there was an interaction between the expression level of microRNA-223 in the plasma and the cYP2c19 loss-of-function (LOF) allele. The study showed that decreased plasma microRNA-223 expression levels in AIS patients indicate an increased risk of clopidogrel HTPR. carrying cYP2c19 LOF alleles may result in the microRNA-223 expression being more distinct. The combined detection of plasma microRNA-223 and cYP2c19 gene polymorphisms may be effective in predicting the occurrence of clopidogrel HTPR in patients with AIS.

Safety, pharmacokinetics and pharmacodynamics of an original glycoprotein IIb/IIIa inhibitor in healthy volunteers: results of the clinical trial

Aim. To study the tolerability, safety, pharmacokinetics (PK) and pharmacodynamics of single intravenous infusions of Angipur in healthy male volunteers.Material and methods. The Phase I trial included 20 healthy male volunteers (mean age, 30,8±7,7 years; mean body weight, 77,4±12,1 kg). Angipur (0,02% concentrate for solution for infusion) was administered to every subject in single doses 0,015, 0,05, 0,09 mg/kg for 3 consecutive days. Volunteers were divided in 6 groups (1, 1, 3, 5, 5, 5); every following group was recruited only after the previous one finished the study. The following were assessed: rate and severity of adverse events (AEs), key PK parameters of Angipur and its antiplatelet activity by impedance aggregometry.Results. No moderate or severe AEs, as well as no serious AEs were reported according to obtained data of clinical and laboratory monitoring of healthy subjects. Totally 6 mild AEs were registered in 4 subjects. Four AEs (mild hematological deviations and episode of nose bleed) were classified as possibly related to study drug and 1 AE (positive fecal occult blood test) — probably related. Key PK parameters of Angipur in single intravenous doses 0,015, 0,05 и 0,09 mg/kg were determined as follows: Cmax — 12,44±4,689, 46,10±14,295, 92,48±33,896 ng/ml; Vd — 304,01±55,300, 299,67±64,244, 252,96±47,790 l; T1/2 — 6,72±1,290, 6,84±2,341, 6,06±2,287 h; Cl — 32,19±6,919, 32,29±8,357, 31,55±10,113 l/h, respectively. Dose proportionality (linear PK) for parameters Cmax, AUC0-t and AUC0-∞ was established. Dose-dependent reduction of ADP-induced platelet aggregation degree and area under curve was revealed at period of 15 min to 2-4 h after Angipur infusion in doses 0,05 and 0,09 mg/kg.Conclusion. Results of phase I clinical trial demonstrated good tolerability of single intravenous infusions of Angipur (0,015, 0,05 и 0,09 mg/kg) in healthy subjects. We determined key PK parameters and indicated dose-dependent antiplatelet activity of Angipur.

Comparative analysis of hemostasis system state indicators in severe COVID-19

Introduction. Clinical experience in managing patients with a new coronavirus infection caused by the SARS-CoV-2 allowed to identify specific hemostasis disorders, and enables to introduce the concept of COVID-associated coagulopathy. The aim of the study was to assess the direction of coagulogram parameter changes, whole blood clotting parameters and characteristics of platelet and plasma hemostasis in patients with severe COVID-19. Materials and methods. The parameters of the hemostasis system were assessed using venous blood of 12 patients with severe COVID-19 and 16 healthy volunteers. The whole blood clotting process was investigated by low-frequency piezothromboelastography. The platelet count and indicators of spontaneous and ADP-induced platelet aggregation were estimated with the help of a laser platelet aggregation analyzer. Fibrinolytic activity of plasma, plasminogen activity, content of fibrinogen, D-dimer, PTT, APTT, PTI and INR were assessed. Results. An increased level of fibrinogen, a 6-fold increased D-dimer level, and increased PTT were found in patients with severe COVID-19. The patient platelets count was reduced by 51 % (p &lt;0.05), spontaneous platelet aggregation remained at nearly normal level. Almost complete inhibition of ADP-induced platelet reactivity and inhibition of XIIa-dependent fibrinolysis was revealed, despite an increased by 19.3 % (p &lt;0.05) plasminogen activity. Parameters of the whole blood coagulation process pointed a pronounced activation of platelet hemostasis, a significant intensification of the polymerization stage of clot formation and an increased intensity of clot lysis and retraction. Conclusion. The significant increase of D-dimer level and paradoxical inhibition of plasma fibrinolytic activity revealed by test of XIIa-dependent fibrinolysis (in contrast to the increased intensity of clot lysis when assessing the coagulation of whole blood) indicate the complex pathogenic mechanisms of coagulopathy caused by SARS-CoV-2 infection, and the involvement of blood cells and the vascular wall in the process of pathological thrombus formation.

Antiplatelet and myocardial protective effect of Shexiang Tongxin Dropping Pill in patients undergoing percutaneous coronary intervention: A randomized controlled trial

BackgroundHigh on-clopidogrel platelet reactivity could be partially explained by loss-of-function alleles of CYP2C19, the enzyme that converts clopidogrel into its active form. Shexiang Tongxin Dropping Pill (STDP) is a traditional Chinese medicine to treat angina pectoris. STDP has been shown to improve blood flow in patients with slow coronary flow and attenuate atherosclerosis in apolipoprotein E-deficient mice. However, whether STDP can affect platelet function remains unknown. ObjectiveThe purpose of this study is to examine the potential effects of STDP on platelet function in patients undergoing percutaneous coronary intervention (PCI) for unstable angina. The interaction between the effects of STDP with polymorphisms of CYP2C19 was also investigated. Design, participants and interventionThis was a single-center, randomized controlled trial in patients undergoing elective PCI for unstable angina. Eligible subjects were randomized to receive STDP (210 mg per day) plus dual antiplatelet therapy (DAPT) with clopidogrel and aspirin or DAPT alone. Main outcome measuresThe primary outcome was platelet function, reflected by adenosine diphosphate (ADP)-induced platelet aggregation and platelet microparticles (PMPs). The secondary outcomes were major adverse cardiovascular events (MACEs) including recurrent ischemia or myocardial infarction, repeat PCI and cardiac death; blood biomarkers for myocardial injury including creatine kinase-MB isoenzyme (CK-MB) and high-sensitive troponin I (hsTnI); and biomarkers for inflammation including intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1) and galectin-3. ResultsA total of 118 subjects (mean age: [66.8 ± 8.9] years; male: 59.8%) were included into analysis: 58 in the control group and 60 in the STDP group. CYP2C19 genotype distribution was comparable between the 2 groups. In comparison to the control group, the STDP group had significantly lower CK-MB (P < 0.05) but similar hsTnI (P > 0.05) at 24 h after PCI, lower ICAM-1, VCAM-1, MCP-1 and galectin-3 at 3 months (all P < 0.05) but not at 7 days after PCI (P > 0.05). At 3 months, the STDP group had lower PMP number ([42.9 ± 37.3] vs. [67.8 ± 53.1] counts/μL in the control group, P = 0.05). Subgroup analysis showed that STDP increased percentage inhibition of ADP-induced platelet aggregation only in slow metabolizers (66.0% ± 20.8% in STDP group vs. 36.0% ± 28.1% in the control group, P < 0.05), but not in intermediate or fast metabolizers. The rate of MACEs during the 3-month follow-up did not differ between the two groups. ConclusionSTDP produced antiplatelet, anti-inflammatory and cardioprotective effects. Subgroup analysis indicated that STDP inhibited residual platelet reactivity in slow metabolizers only. Trial registrationThis study was registered on www.chictr.org.cn: ChiCTR-IPR-16009785.

Effects of electronic cigarette flavorants on human platelet aggregation ex vivo

Because little is known about the effects of individual flavorants in electronic cigarette (e-cig) fluids on human platelet aggregation, we tested for the direct effects of 15 common e-cig flavorants on adenosine diphosphate (ADP)-induced human platelet aggregation ex vivo. To better understand a potential mechanism of action of flavorants, we quantified 2 phases of aggregation. Human platelet-rich plasma (PRP) was obtained from whole blood of healthy volunteers and used in a platelet aggregometry assay. PRP was incubated with 1 of 15 different flavorant compounds (e.g., benzyl alcohol, eugenol, citronellol, menthol, menthone, diacetyl, maltol, limonene, methylbutyric acid, isoamyl acetate, acetylpyridine, eucalyptol, 2,5-dimethylpyrazine, cinnamaldehyde, and vanillin) at 100 µM for 5 min at 37 °C prior to addition of ADP (10 µM). Subsequent ADP-induced platelet aggregation was tracked for 5 min using an aggregometer. Aggregation curves were analyzed for flavorant-induced effects on total (%) aggregation, Phase 1 and Phase 2 components, and compared with their ADP-only control via One-Way ANOVA. Notably, eugenol significantly inhibited total aggregation; an effect due solely to inhibition of Phase 2. No other flavor tested had any effect on total or phase-specific ADP-induced platelet aggregation. These results indicate that parent flavorant compounds commonly found in e-cig liquids neither activate nor inhibit ADP-induced human platelet aggregation. However, as flavorants are chemically altered during heating of e-cig, thermally-derived products of flavorants (e.g., flavor acetals) also will need to be tested for effects on platelet activation.

Editor's Summaries of the Articles Published in This Issue of Phytopharmacological Communications

In this issue, Iram and colleagues described their study on the anti-inflammatory potential of Medicago laciniata, Afzal and her colleagues rationalized the traditional use of Peganum harmala in cardiovascular diseases, Aisha and her colleagues summarized studies showing inhibition of tau by medicinal plants and phytocompounds isolated from them for the treatment of Alzheimer’s disease, Zia-Ul-Hq et al, compiled investigations in which adenosine diphosphate-induced platelet aggregation is shown to be inhibited by medicinal plants, and Ullah and his colleagues reviewed studies showing potential calcium channel blockers from medicinal plants and provided their insights and recommended their further investigation in clinical trials.

Natural Sources of Inhibition of Adenosine Diphosphate-Induced Platelet Aggregation

Natural Sources of Inhibition of Adenosine Diphosphate-Induced Platelet Aggregation

Гемостаз та запалення у пацієнтів із політравмою

Актуальність. Причинами смерті при тяжких травмах є як ушкодження, несумісні з життям, так і тяжкі кровотечі. Коагулопатію, асоційовану з травмою, виявляють у 46 % пацієнтів уже на місці події та у 60 % пацієнтів — при надходженні на лікування. Мета: встановити наявність зв’язку між показниками загальної відповіді організму на запалення та показниками судинно-тромбоцитарного і коагуляційного гемостазу у пацієнтів з політравмою. Матеріали та методи. Проведено проспективне обсерваційне дослідження 20 пацієнтів віком від 19 до 55 років з політравмою, які перебували на лікуванні у відділенні анестезіології з ліжками інтенсивної терапії в Комунальному некомерційному підприємстві «8-ма міська клінічна лікарня м. Львова». Пацієнтів оцінювали за Injury Severity Score (ISS) та шкалою APACHE II (Acute Physiology And Chronic Health Evaluation II) з урахуванням тривалості синдрому загальної відповіді організму на запалення і лікування у відділенні інтенсивної терапії (ВІТ) та госпіталізації. Етапи дослідження: надходження на лікування у ВІТ (d1), третя доба (d3), п’ята доба (d5). Основними оцінюваними клінічними маркерами були показники: загальної відповіді організму на запалення, судинно-тромбоцитарного гемостазу (внутрішньосудинна активація тромбоцитів, агрегація тромбоцитів, індукована адреналіном і аденозиндифосфатом), коагуляційного гемостазу (міжнародне нормалізоване відношення, активований частковий тромбопластиновий час, рівень загального фібриногену та D-димерів). Результати. Встановлено наявність вірогідного (p &lt; 0,05) позитивного кореляційного зв’язку між співвідношенням рівнів дискоехіноцитів до сфероехіноцитів та рівнем загального фібриногену на етапі d1, а також тенденцію (p = 0,09) до наявності позитивного кореляційного зв’язку між цим співвідношенням та температурою тіла пацієнта. Виявлено вірогідний (p &lt; 0,05) зворотний кореляційний зв’язок між цим співвідношенням і рівнем тяжкості стану пацієнтів за шкалою APACHE II та прямий вірогідний (p &lt; 0,05) кореляційний зв’язок із тривалістю госпіталізації у ВІТ, а також тенденції до зворотного кореляційного зв’язку з тяжкістю ушкоджень за шкалою ISS (p = 0,07) та до прямого кореляційного внаслідок Systemic Inflammatory Response Syndrome (SIRS) (p = 0,12). Висновки. У пацієнтів із політравмою встановлено: наявність вірогідного (p &lt; 0,05) позитивного кореляційного зв’язку між співвідношенням дискоехіноцити/сфероехіноцити та рівнем загального фібриногену; тенденцію (p = 0,09) до позитивного кореляційного зв’язку між цим співвідношенням та температурою тіла пацієнта; вірогідний (p &lt; 0,05) зворотний кореляційний зв’язок з рівнем тяжкості стану пацієнтів за шкалою APACHE II; прямий вірогідний (p &lt; 0,05) кореляційний зв’язок з тривалістю госпіталізації у ВІТ; тенденцію (p = 0,07) до зворотного кореляційного зв’язку з тяжкістю ушкоджень за шкалою ISS та тенденцію (p = 0,12) до прямого кореляційного зв’язку з тривалістю SIRS.

Antiplatelet and Antithrombotic Effects of Isaridin E Isolated from the Marine-Derived Fungus via Downregulating the PI3K/Akt Signaling Pathway.

Isaridin E, a cyclodepsipeptide isolated from the marine-derived fungus Amphichorda felina (syn. Beauveria felina) SYSU-MS7908, has been demonstrated to possess anti-inflammatory and insecticidal activities. Here, we first found that isaridin E concentration-dependently inhibited ADP-induced platelet aggregation, activation, and secretion in vitro, but did not affect collagen- or thrombin-induced platelet aggregation. Furthermore, isaridin E dose-dependently reduced thrombosis formation in an FeCl3-induced mouse carotid model without increasing the bleeding time. Mechanistically, isaridin E significantly decreased the ADP-mediated phosphorylation of PI3K and Akt. In conclusion, these results suggest that isaridin E exerts potent antithrombotic effects in vivo without increasing the risk of bleeding, which may be due to its important role in inhibiting ADP-induced platelet activation, secretion and aggregation via the PI3K/Akt pathways.

Effects of Clopidogrel, Prasugrel and Ticagrelor on Microvascular Function and Platelet Reactivity in Patients With Acute Coronary Syndrome Undergoing Coronary Artery Stenting. A Randomized, Blinded, Parallel Group Trial.

Aims: In this pre-specified analysis of the “endothelium, stent and antiplatelet therapy” study, we investigate the impact of antiplatelet therapies on microvascular function in patients undergoing stenting for an acute coronary syndrome.Methods and Results: Fifty-six patients [age: 63(55–67) years, males, 10 diabetics, 27 non-ST-elevation myocardial infarction] were randomized to receive clopidogrel, ticagrelor or prasugrel in form of oral loading 2 h before stenting followed by oral therapy. Investigators were blinded to the allocation. Laser-Doppler microvascular function and ADP-induced platelet aggregation capacity were measured at baseline, 2 h after oral antiplatelet loading, and 1 day, 1 week and 1 month after stenting during chronic therapy with the same antiplatelet agent. Platelet aggregation decreased in all groups 2 h after oral loading, with a significantly larger effect in the prasugrel group (P = 0.009). Similarly, prasugrel and ticagrelor loading was followed by an increase in microvascular reactive hyperemia (P = 0.007 and P = 0.042 compared to clopidogrel). This effect disappeared one day after coronary intervention, with a significant decrease in the prasugrel group (P = 0.026). Similarly, analysis of microvascular conductance showed a larger increase in the prasugrel group 2 h after loading (P = 0.022 among groups), and a decrease in all groups after stenting.Conclusions: Oral loading with prasugrel (and less consistently ticagrelor) is associated with improved microvascular function and stronger platelet inhibition in acute coronary syndrome patients. The microvascular effect was however lost 1 day after stenting and during subsequent follow-up. Further studies are necessary to clarify the the long-term effects and potential benefits of P2Y12 inhibitors on microvascular damage.ClINICALTRIALS.gov N°: NCT01700322EUDRACT-N°: 2011-005305-73.