Antiplatelet Aggregation Activity Research Articles

Extract of Ulmus macrocarpa Hance prevents thrombus formation through antiplatelet activity

Ulmus macrocarpa Hance (Ulmaceae) has been used as a traditional oriental medicine for the treatment of edema, mastitis, gastric cancer and inflammation. The aim of this study was to investigate the effects of Ulmus macrocarpa extract (UME) on thrombus formation in vivo, platelet activation ex vivo and fibrinolytic activity in vitro. To identify the antithrombotic activity of UME in vivo, we used an arterial thrombosis model. UME delayed the occlusion time by 13.4 and 13.9 min at doses of 300 and 600 mg/kg, respectively. UME significantly inhibited ex vivo platelet aggregation induced by collagen and adenosine 5'-diphosphate (ADP), respectively, but did not affect the coagulation times following activated partial thromboplastin and prothrombin activation. Therefore, to investigate the antiplatelet effect of UME, the effect of UME on collagen and ADP-induced platelet aggregation in vitro was examined. UME exhibited antiplatelet aggregation activity, induced by ADP and collagen. Furthermore, the fibrinolytic activity of UME was investigated. The results showed that UME significantly increased fibrinolysis at 1,000 mg/ml. In conclusion, the results suggested that UME may significantly inhibit artery thrombus formation in vivo, potentially due to antiplatelet activity, and also exhibits potential as a clot‑dissolving agent for thrombolytic therapy.

ChemInform Abstract: One Pot Synthesis and Biological Activity Evaluation of Novel Schiff Bases Derived from 2‐Hydrazinyl‐1,3,4‐thiadiazole.

AbstractCompounds (IVa,b, d) show antiplatelet aggregation activity comparable to that of indomethacin.

Evaluation of a multifunctional staphylokinase variant with thrombin inhibition and antiplatelet aggregation activities produced from salt-inducibleE.coliGJ1158

Reocclusion is one of the major root causes for secondary complications that arise during thrombolytic therapy. A multifunctional staphylokinase variant SRH (staphylokinase (SAK) linked with tripeptide RGD and didecapeptide Hirulog) with antiplatelet and antithrombin activities in addition to clot specific thrombolytic function, was developed to address the reocclusion problem. We preferred to use Escherichia coli GJ1158 as the host in this study for economic production of SRH by osmotic (0.3 mol/L sodium chloride) induction, to overcome the problems associated with the yeast expression system. The therapeutic potential of SRH was evaluated in the murine model of vascular thrombosis. The SAK protein (1 mg/kg body mass) and SRH protein (1 mg/kg and 2 mg/kg) were administered intravenously to the different treatment groups. The results have shown a dose-dependent antithrombotic effect in carrageenan-induced mouse tail thrombosis. The thrombin time, activated partial thromboplastin time, and prothrombin time were significantly prolonged (p < 0.05) in the SRH-infused groups. Moreover, SRH inhibited platelet aggregation in a dose-dependent manner (p < 0.05), while the bleeding time was significantly (p < 0.05) prolonged. All of these results inferred that the osmotically produced multifunctional fusion protein SRH (SAK-RGD-Hirulog) is a promising thrombolytic agent, and one which sustained its multifunctionality in the animal models.

유백피의 항혈전 활성 분획 및 유효성분에 관한 연구

Objectives : The purpose of this study was to identify active fraction and components from antiplatelet Ulmi cortex extract. Methods : The 70% ethanol extract of Ulmi cortex was subjected to column chromatography over D101 resin and eluted with an 20% (W1), 30% (W2), 40% (W3), 50%(W4), 70% (W5), and 100% ethanol (W6) to yield 6 fractions. W6 was further fractioned and its active components were purified using semi-preparative HPLC. The isolated compounds were identified by MS and NMR, and their contents were simultaneously analyzed using HPLC/UV. Antiplatelet aggregation activities of the fractions and the compounds were evaluated using rat platelet-rich plasma in presence of collagen (<TEX>$5{\mu}g/ml$</TEX>), arachidonic acid (0.05 U/ml), or thrombin (<TEX>$100{\mu}M$</TEX>). Results : Among six fractions, W3 prominently inhibited platelet aggregation. At the concentration of <TEX>$200{\mu}g/ml$</TEX>, W3 strongly inhibited arachidonic acid- and collagen-induced platelet aggregations by 78.2% and 65.9%, respectivley, and weakly inhibited thrombin-inducded platelet aggregation by 32.6%. Catechin, epicatehin, and catechin-7-O-<TEX>${\beta}$</TEX>-D-glucopyranoside were isolated from W3 and their contents were revealed to be 15.1%, 0.87%, and 0.32%. Catechin and epicatechin at the concentrations of <TEX>$100{\mu}M$</TEX> strongly inhibited collagen-induced platelet aggregation by 79.9% and 86.6%, respectively, but weakly inhibited arachidonic acid- and thrombin-induced platelet aggregations. Conclusions : A main active principle of anitplatelet Ulmi Cortex extract is W3 fraction, of which main active component is catechin considering its antiplatelet activity and content.

Chemical constituents of Callicarpa nudiflora and their anti-platelet aggregation activity

Two new triterpenoids, 2α,3α,19α,23-tetrahydroxyurs-12,20(30)-dien-28-oic acid (1) and 2α,3α,19α-trihydroxyurs-12-en-28-oic acid-28-O-β-d-xylopyranosyl (1→2)-β-d-glucopyranoside (2), and a new acylated flavone glycoside, luteolin 3′-O-(6″-E-caffeoyl)-β-d-glucopyranoside (3), together with three known compounds (4–6), were isolated from the leaves of Callicarpa nudiflora Hook. Their structures were elucidated on the basis of spectroscopic data and chemical methods. Anti-platelet aggregation activities of these compounds were evaluated in vitro. Compounds 1 and 2 showed inhibitory effects on ADP-induced platelet aggregation with EC50 values of 9.48μM and 25.31μM, respectively.

Flavonoids from Millettia nitida var. hirsutissima with their anticoagulative activities and inhibitory effects on NO production

Two new compounds, (2R)-7,3'-dihydroxy-6,4'-methoxyflavan (1) and (3R)-7,4'-dihydroxy-2'-methoxyisoflavan (2), along with 12 known flavonoids (3-14), were isolated from the vine stems of Millettia nitida var. hirsutissima. The structures of the isolated compounds were elucidated based on spectroscopic analyses and comparison of literature data. All of the isolates were evaluated for their effects on in-vitro anticoagulative assay and on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW264.7 macrophages. As a result, all compounds showed weak antiplatelet aggregation activities and compounds 4, 5, 7, 8 and 9 demonstrated antithrombin activity with a good dose-effect relationship from 5 to 100 μg mL⁻¹ in rabbit plasma. Compounds 8, 9, 10 and 14 exhibited inhibitory effects on LPS-induced NO production in RAW264.7 macrophages with IC₅₀ values of 4.79 ± 0.20, 8.23 ± 0.35, 5.23 ± 0.11 and 6.30 ± 0.30 μg mL⁻¹, respectively.

Towards dual antithrombotic compounds – Balancing thrombin inhibitory and fibrinogen GPIIb/IIIa binding inhibitory activities of 2,3-dihydro-1,4-benzodioxine derivatives through regio- and stereoisomerism

Enantiomers of 2,3-dihydro-1,4-benzodioxine derivatives possessing both thrombin and fibrinogen GPIIb/IIIa binding inhibitory activities were prepared from (R)- and (S)-glycidol as potential dual antithrombotic compounds. The influence of chirality and substitution pattern on thrombin inhibition and on inhibition of fibrinogen binding to GPIIb/IIIa was analyzed. Docking studies were used in an attempt to rationalize the results. The (S)-isomers of both 2,3-dihydro-1,4-benzodioxine regioisomers at positions 6 and 7 were found to be better thrombin inhibitors than the corresponding (R)-enantiomers, whereas we observed that stereochemistry does not display a consistent influence on fibrinogen GPIIb/IIIa binding inhibitory activity. Compound 11b, the (S)-isomer of the 6-substituted regioisomer, possessed the best balanced dual activity, with Ki(thrombin) = 1.67 ± 0.27 μM and IC50(GPIIb/IIIa) = 0.665 ± 0.26 μM, raising the hope that merging anticoagulant and platelet antiaggregatory activities in the same molecule could lead to successful multitarget antithrombotic agents.

The Cardioprotective Effects of Citric Acid and L-Malic Acid on Myocardial Ischemia/Reperfusion Injury

Organic acids in Chinese herbs, the long-neglected components, have been reported to possess antioxidant, anti-inflammatory, and antiplatelet aggregation activities; thus they may have potentially protective effect on ischemic heart disease. Therefore, this study aims to investigate the protective effects of two organic acids, that is, citric acid and L-malic acid, which are the main components of Fructus Choerospondiatis, on myocardial ischemia/reperfusion injury and the underlying mechanisms. In in vivo rat model of myocardial ischemia/reperfusion injury, we found that treatments with citric acid and L-malic acid significantly reduced myocardial infarct size, serum levels of TNF-α, and platelet aggregation. In vitro experiments revealed that both citric acid and L-malic acid significantly reduced LDH release, decreased apoptotic rate, downregulated the expression of cleaved caspase-3, and upregulated the expression of phosphorylated Akt in primary neonatal rat cardiomyocytes subjected to hypoxia/reoxygenation injury. These results suggest that both citric acid and L-malic acid have protective effects on myocardial ischemia/reperfusion injury; the underlying mechanism may be related to their anti-inflammatory, antiplatelet aggregation and direct cardiomyocyte protective effects. These results also demonstrate that organic acids, besides flavonoids, may also be the major active ingredient of Fructus Choerospondiatis responsible for its cardioprotective effects and should be attached great importance in the therapy of ischemic heart disease.

Synthesis of 6-Alkylamino-2-alkylthio-9-(2-hydroxyethyl)-8-methoxy-purines and Their Anti-platelet Aggregation Activities

以6-氯鸟嘌呤（1）为原料，与乙酸-2-溴-乙酯反应得到9-乙酰氧基乙基-2-氨基-6-氯嘌呤（2），2经溴代得到9-乙酰氧基乙基-2-氨基-6-氯-8-溴嘌呤（3），3在甲醇中与甲醇钠反应得到9．（2．羟基乙基）-2-氨基-8-甲氧基-6-氯嘌呤（4），对4的羟基进行乙酰化保护得到9-乙酰氧基乙基-2-氨基-8-甲氧基-6-氯嘌呤（5），5经重氮化反应后再与二烷基二硫醚反应得到9-乙酰氧基乙基-8-甲氧基-2-烷硫基-6-氯嘌呤（6），6与胺进行亲核取代反应得到9．乙酰氧基乙基-6-烷氨基-8-甲氧基-2-烷硫基嘌呤（7），7的羟基脱保护后得到9-（2-羟基乙基）-6．烷氨基-8-甲氧基-2-烷硫基嘌呤（8）．合成了24个未见报道的化合物3～8。它们的结构经1HNMR，13CNMR，IR及HRMS等手段得到表征。并对9个目标化合物8进行了抗血小板凝集活性测试．

Electrochemical synthesis of novel 1,3-indandione derivatives and evaluation of their antiplatelet aggregation activities.

Electrochemical oxidation of some selected catechol derivatives, using cyclic voltammetry, in the presence of different 2-aryl-1,3-indandiones as nucleophiles, resulted in electrochemical synthesis of new 1,3- indandione derivatives in an undivided cell in good yield and purity. A Michael addition mechanism was proposed for the formation of the analogs based on the reaction conditions which were provided in electrochemical cell. The in-vitro antiplatelet and anticoagulant activity of these compounds was evaluated, using arachidonic acid (AA) and adenosine diphosphate (ADP) as the platelet aggregation inducers. The results show that the incorporation of catechol ring in 1,3-indandione nucleus leads to the emergence of antiplatelet aggregation activity in these compounds. The compounds may exert their antiaggregation activity by interfering with the arachidonic acid pathway.

Six New Cyclic Peptides from the Roots of Gypsophila oldhamiana

Six new cyclic peptides, gypsophin A-F (1-6), were isolated from Gypsophila oldhamiana. Their structures were elucidated by extensive NMR and chemical degradation. Compound 3 exhibited moderate activity of antiplatelet aggregation in vitro.

Platelet Aggregation Pathway Network-Based Approach for Evaluating Compounds Efficacy

Traditional Chinese medicines (TCMs) contain a large quantity of compounds with multiple biological activities. By using multitargets docking and network analysis in the context of pathway network of platelet aggregation, we proposed network efficiency and network flux model to screen molecules which can be used as drugs for antiplatelet aggregation. Compared with traditional single-target screening methods, network efficiency and network flux take into account the influences which compounds exert on the whole pathway network. The activities of antiplatelet aggregation of 19 active ingredients separated from TCM and 14 nonglycoside compounds predicated from network efficiency and network flux model show good agreement with experimental results (correlation coefficient = 0.73 and 0.90, resp.). This model can be used to evaluate the potential bioactive compounds and thus bridges the gap between computation and clinical indicator.

In VitroCharacterization of a Multifunctional Staphylokinase Variant with Reduced Reocclusion, Produced from Salt InducibleE. coliGJ1158

The thrombolytic therapy with clinically approved drugs often ensues with recurrent thrombosis caused by thrombin-induced platelet aggregation from the clot debris. In order to minimize these problems, a staphylokinase (SAK)-based bacterial friendly multifunctional recombinant protein SRH (staphylokinase (SAK) linked with tripeptide RGD and dodecapeptide Hirulog (SRH)) was constructed to have Hirulog as an antithrombin agent and RGD (Arg-Gly-Asp) as an antiplatelet agent in the present study. This multifunctional fusion protein SRH was expressed in osmotically inducible E. coli GJ1158 as soluble form and purified with a yield of 0.27 g/L and functionally characterized in vitro. SRH retained the fibrinolytic activity and plasminogen activation rate comparable to the parental counterpart SAK. The antithrombin activity of SRH was significantly higher than SAK. The platelet rich clot lysis assay indicated that SRH had enhanced platelet binding activity and T 50% and C50 of SRH were significantly lower than that of SAK. Furthermore, SRH inhibited the ADP-induced platelet aggregation in dose-dependent manner while SAK had no significant effect on platelet aggregation. Thus, the current study suggests that the SAK variant produced from osmotically inducible GJ1158 is more potent thrombolytic agent with antithrombin and antiplatelet aggregation activities for reduction of reocclusion in thrombolytic therapy.

Novel Synthesis Approach and Antiplatelet Activity Evaluation of 6-Arylmethyleneamino-2-Alkylsulfonylpyrimidin-4(3&amp;lt;i&amp;gt;H&amp;lt;/i&amp;gt;)-one Derivatives and Its Nucleosides

A new and efficient procedure has been designed for the preparation of 6-arylmethylene-amino-2-alkyl sulfonyl-pyrimidine. The first alkylthio group was introduced into the pyrimidine ring by S-alkylation. The introduction of the second one was successfully achieved using the phosphorous oxychloride method to afford 4-chloro-2-alkylthio-pyrimidines. Subsequent nucleophilic displacement by the corresponding alkylamines followed by glycoside bromide addition conveniently gave a series of the target compounds. Thus, the two same or different alkylamino groups were easily introduced into the pyrimidine ring through the two different approaches. The human anti-platelet aggregation activity of the newly synthesized compounds was also described.

Mukia maderaspatana (Linn.) M. Roemer: A potentially antidiabetic and vasoprotective functional leafy-vegetable

Mukia maderaspatana (Linn.) M. Roemer, (Family: Cucurbitaceae) [syn.: Melothria maderaspatana (L.) Cogn.], is distributed throughout the tropics and subtropics of the Old World. Different organs of the drug-plant are utilised in Ayurveda, Siddha, Naturopathy and Folkloric traditional medicines of India as well as the indigenous medical systems of the Sub-Saharan African, Asian and Australian communities for health-care needs. The leafy vegetable is reported to exhibit potent antioxidant capacity in vitro and in vivo and to possess anti hypertensive, vasodialatory, antihyperglycemic, antihyperlipidemic, hepatoprotective, immunomodulatory, antiinflammatory, antirheumatic, antiulcer, anxiolytic, antimicrobial, and antiplatelet aggregation activities. The present review is an attempt to highlight, for the first time, the current clinical and experimental evidences available in literature on the extent of its potentials to protect against vascular events and diabetes.

One Pot Synthesis and Biological Activity Evaluation of Novel Schiff Bases Derived from 2-Hydrazinyl-1,3,4-thiadiazole

Considering the structural features of a group of known potent inhibitors of human platelet aggregation containing hydrazone structural backbone, a series of novel hydrazone derivatives of 2-hydrazinyl-1,3,4-thiadiazole were synthesized using a one-pot process and tested for their inhibitory activity against platelet aggregation induced by arachidonic acid and ADP. Among the derivatives, compounds 3l, 3o and 3p exhibited the highest antiplatelet aggregation activity. The derivatives were also screened for their potential antimycobacterial activity and compounds 3g, 3k, 3p and 3q were among the most active compounds.

Synthesis of Novel Indole Hydrazone Derivatives and Evaluation of Their Antiplatelet Aggregation Activity

Based on the existing reports regarding the antiplatelet aggregation activity of hydrazone derivatives, a series of indole hydrazone derivatives were considered as potential antiplatelet agents and synthesized. The structures of the synthesized compounds were confirmed by spectral data and elemental analysis. The new indole hydrazone derivatives were evaluated for their ability to inhibit platelet aggregation induced by adenosine diphosphate (ADP) and arachidonic acid (AA). Compounds 1h and 3h exhibited remarkable activity against arachidonic acid induced platelet aggregation with IC(50) values comparable to that of indomethacin and compound 1i efficiently inhibited platelet aggregation induced by both ADP and AA.

Metabolomic Investigation of the Anti-Platelet Aggregation Activity of Ginsenoside Rk1 Reveals Attenuated 12-HETE Production

Comprehensive metabolomics analysis is an effective method of measuring metabolite levels in the body following administration of a pharmaceutical compound and can allow for monitoring of the effects of the compound or assessment of appropriate treatment options for individual patients. In the present metabolomics study, samples pretreated with antiplatelet compounds were extracted and subjected to ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry. The acquired data were processed using peak clustering and evaluated by partial least-squares (PLS) and orthogonal projections to latent structures discriminant analyses (OPLS-DA). As a result, meaningful endogenous metabolites, namely eicosanoids and thromboxane B(2) (TXB(2)), were identified. TXB(2), a key element in platelet aggregation, was decreased upon ginsenoside Rk(1) treatment via inhibition of cyclooxygenase (COX) activity. One of the arachidonic acid (AA) metabolites, 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), was decreased significantly in the ginsenoside Rk(1)-treated platelets compared to the AA-induced group. In the mechanism study of ginsenoside Rk(1), a strong linkage to intracellular calcium levels, which induce platelet activation, was found. Additionally, the translocation of 12-LOX from cytosol to membrane, which is related with the intracellular calcium levels, was determined. Therefore, a decreased 12-HETE level induced by ginsenoside Rk(1) on antiplatelet aggregation is related to 12-LOX translocation resulting from decreased Ca(2+) levels. This study shows that global metabolomic analysis has potential for use in understanding the biological behavior of antiplatelet drugs.

Design, synthesis and in vitro activities on anti-platelet aggregation of 4-methoxybenzene-1,3-isophthalamides

On the purpose of searching for the structure–activity relationship (SAR) and obtaining novel anti-platelet drugs, 41 4-methoxybenzene-1,3-isophthalamides have been described the synthesis process and in vitro activities on anti-platelet aggregation. The target compounds have been classified into four series: series 1 (ortho-substituted phenyl: 1a–1j), series 2 (meta-substituted phenyl: 2a–2k), series 3 (para-substituted phenyl: 3a–3l) and series 4 (aromatic of no substituted group and aromatic heterocyclic substituted groups: 4a–4h). The chemical structures of the target compounds were confirmed by MS, IR, 1H NMR, and their in vitro activities on anti-platelet aggregation were tested and assessed by using Born test. The result showed that thirteen compounds 1c, 1d, 1i, 1j, 2g, 3a, 3c, 3d, 3f, 3h, 3l, 4b and 4c have superior anti-platelet aggregation activities than the reference drug Picotamide.

Two new nonacosanetriols from Ginkgo biloba sarcotesta

Two new fatty alcohols named as (7S,8R,11S)-nonacosanetriol (1) and (10R,12R,15S)-nonacosanetriol (2), along with eight known compounds including ginkgolic acid (3), hydroginkgolic acid (4), sciadopitysin (5), ginkgetin (6), isoginkgetin (7), ginkgolide A (8), ginkgolide B (9) and ginkgolide C (10) have been isolated from the petroleum ether extract of Ginkgo biloba sarcotesta. Their structures were elucidated by means of chemical and extensive spectroscopic analysis. The absolute stereochemistry of compounds 1 and 2 was elucidated on the spectroscopic analysis of the R- and S-MTPA esters. Compounds 1 and 2 exhibited slight activity of antithrombin and moderate activity of antiplatelet aggregation in vitro. This was the first report regarding the anticoagulative activities of biflavonoids in G. biloba, and isoginkgetin (7) showed significant antithrombin and antiplatelet aggregation activity.