Antiplatelet Effects Research Articles

Microfluidic Chip and Flow Cytometry for Examination of the Antiplatelet Effect of Ticagrelor

Objective To examine the antiplatelet effect of ticagrelor by microfluidic chip and flow cytometry under shear stress in vitro. Methods Microfluidic chip was used to examine the effect of ticagrelor on platelet aggregation at the shear rates of 300/s and 1500/s.We adopted the surface coverage of platelet aggregation to calculate the half inhibition rate of ticagrelor.The inhibitory effect of ticagrelor on ADP-induced platelet aggregation was verified by optical turbidimetry.Microfluidic chip was used to construct an in vitro vascular stenosis model,with which the platelet reactivity under high shear rate was determined.Furthermore,the effect of ticagrelor on the expression of fibrinogen receptor (PAC-1) and P-selectin (CD62P) on platelet membrane activated by high shear rate was analyzed by flow cytometry. Results At the shear rates of 300/s and 1500/s,ticagrelor inhibited platelet aggregation in a concentration-dependent manner,and the inhibition at 300/s was stronger than that at 1500/s (both P<0.001).Ticagrelor at a concentration ≥4 μmol/L almost completely inhibited platelet aggregation.The inhibition of ADP-induced platelet aggregation by ticagrelor was similar to the results under flow conditions and also in a concentration-dependent manner.Ticagrelor inhibited the expression of PAC-1 and CD62P. Conclusion We employed microfluidic chip to analyze platelet aggregation and flow cytometry to detect platelet activation,which can reveal the responses of different patients to ticagrelor.

Paclitaxel exerts antiplatelet and antithrombotic activities: Additional benefit from use of paclitaxel-coated balloons and -eluting stents in coronary revascularization and prevention of in-stent restenosis

IntroductionPaclitaxel is a microtubule-stabilizing drug used to treat several types of cancer, including ovarian and breast cancer. Because of its antiproliferative effect on vascular smooth muscle cells, balloons and stents are coated with paclitaxel for use in coronary revascularization and prevention of in-stent restenosis (ISR). However, mechanisms underlying ISR are complicated. Platelet activation is one of the major causes of ISR after percutaneous coronary intervention. Although the antiplatelet activity of paclitaxel was noted in rabbit platelets, the effect of paclitaxel on platelets remains unclear. This study investigated whether paclitaxel exhibits antiplatelet activity in human platelets. Methods and resultsPaclitaxel inhibited platelet aggregation induced by collagen but not that induced by thrombin, arachidonic acid, or U46619, suggesting that paclitaxel is more sensitive to the inhibition of collagen-induced platelet activation. Moreover, paclitaxel blocked collagen receptor glycoprotein (GP) VI downstream signaling molecules, including Lyn, Fyn, PLCγ2, PKC, Akt, and MAPKs. However, paclitaxel did not directly bind to GPVI and cause GPVI shedding, as detected by surface plasmon resonance and flow cytometry, respectively, indicating that paclitaxel may interfere with GPVI downstream signaling molecules, such as Lyn and Fyn. Paclitaxel also prevented granule release and GPIIbIIIa activation induced by collagen and low convulxin doses. Moreover, paclitaxel attenuated pulmonary thrombosis and delayed platelet thrombus formation in mesenteric microvessels without significantly affecting hemostasis. ConclusionPaclitaxel exerts antiplatelet and antithrombotic effects. Thus, paclitaxel may provide additional benefits beyond its antiproliferative effect when used in drug-coated balloons and drug-eluting stents for coronary revascularization and prevention of ISR.

Anti-platelet effects of Artesunate through Regulation of Cyclic Nucleotide on Collagen-induced Human Platelets

Anti-platelet effects of Artesunate through Regulation of Cyclic Nucleotide on Collagen-induced Human Platelets

Dipyridamole enhances the anti-cancer ability of aspirin against colorectal cancer by inducing apoptosis in an unfolded protein response-dependent manner.

Available evidence indicates that dipyridamole enhances the anti-thrombotic effects of aspirin for the prevention of secondary strokes. Aspirin is a well-known non-steroid anti-inflammatory drug. This anti-inflammatory property has turned aspirin into a potential drug for inflammation-related cancers such as colorectal cancer (CRC). Here, we aimed to explore whether the anti-cancer effect of aspirin against CRC could be improved by combined administration with dipyridamole. Population-based clinical data analysis was conducted to assess a possible therapeutic effect of combined dipyridamole and aspirin treatment in inhibiting CRC compared with either monotherapy. This therapeutic effect was further verified in different CRC mouse models, i.e. an orthotopic xenograft mouse model, an AOM/DSS mouse model, anApcmin/+ mouse model and a patient derived xenograft (PDX) mouse model. The in vitro effects of the drugs on CRC cells were tested using CCK8 and flow cytometry assays. RNA-Seq, Western blotting, qRT-PCR and flow cytometry were used to identify the underlying molecular mechanisms. We found that dipyridamole combined with aspirin had a better inhibitory effect on CRC than either monotherapy alone. The enhanced anti-cancer effect of the combined use of dipyridamole with aspirin was found to rely on the induction of an overwhelmed endoplasmic reticulum (ER) stress and subsequent pro-apoptotic unfolded protein response (UPR), which was different from the anti-platelet effect. Our data indicate that the anti-cancer effect of aspirin against CRC may be enhanced by combined administration with dipyridamole. In case further clinical studies confirm our findings, these may be repurposed as adjuvant agents.

Panax notoginseng saponins promote hair follicle growth in mice via Wnt/β-Catenin signaling pathway.

Panax notoginseng saponins (PNS), the active ingredients of the traditional Chinese medicine Panax notoginseng, have strong neuroprotective and anti-platelet aggregation effects. To investigate whether PNS can promote hair follicle growth in C57BL/6J mice, the optimal concentration of PNS was initially determined, followed by clarification of the mechanism underlying their effects. Twenty-five male C57BL/6J mice had the hair on a 2 × 3cm2 area of the dorsal skin shaved and were equally divided into five groups: control group, 5% minoxidil (MXD) group, and three PNS treatment groups [2% (10mg/kg), 4% (20 mg/kg), and 8% (40 mg/kg) PNS]. They were then intragastrically administered the corresponding drugs for 28 days. The effects of PNS on C57BL/6J mice were analyzed by subjecting their dorsal depilated skin samples to different assessments, including hematoxylin and eosin staining, immunohistochemistry, immunofluorescence, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting (WB). The group with 8% PNS exhibited the largest number of hair follicles from 14 days onwards. Compared with the control group, the number of hair follicles increased significantly in the mice treated with 8% PNS and 5% MXD, which significantly increased in a PNS-dose-dependent manner. Immunohistochemistry and immunofluorescence results revealed that treatment with 8% PNS activated the metabolism of hair follicle cells, with them showing higher rates of proliferation and apoptosis than those in the normal group. In qRT-PCR and WB analysis, the expression of β-catenin, Wnt10b, and LEF1 was upregulated in the PNS and MDX groups compared with that in the control group. Examination of the WB bands revealed that the greatest inhibitory effect of Wnt5a occurred in mice in the 8% PNS group. PNS may promote the growth of hair follicles in mice, with 8% PNS demonstrating the strongest effect. The mechanism behind this may be related to the Wnt/β-catenin signaling pathway.

Antiplatelet Effect of Daphnetin Is Regulated by cPLA2-Mediated Thromboxane A2 Generation in Mice.

Coumarin derivatives have been recognized for their antithrombotic, anti-inflammatory, and antioxidant properties, and daphnetin is one of the natural coumarin derivatives isolated from Daphne Koreana Nakai. Although the pharmacological value of daphnetin is well documented in diverse biological activities, its antithrombotic effect has not been studied to date. Here, we characterized the role and underlying mechanism of daphnetin in the regulation of platelet activation using murine platelets. In order to check the effect of daphnetin on platelet function, we first measured the effect of daphnetin on platelet aggregation and secretion. Collagen-induced platelet aggregation and dense granule secretion were partially inhibited by daphnetin. Interestingly, 2-MeSADP-induced secondary waves of aggregation and secretion were completely inhibited by daphnetin. It is known that 2-MeSADP-induced secretion and the resultant secondary wave of aggregation are mediated by the positive feedback effect of thromboxane A2 (TxA2) generation, suggesting the important role of daphnetin on TxA2 generation in platelets. Consistently, daphnetin did not affect the 2-MeSADP-induced platelet aggregation in aspirinated platelets where the contribution of TxA2 generation was blocked. Additionally, platelet aggregation and secretion induced by a low concentration of thrombin, which is affected by the positive feedback effect of TxA2 generation, were partially inhibited in the presence of daphnetin. Importantly, 2-MeSADP- and thrombin-induced TxA2 generation was significantly inhibited in the presence of daphnetin, confirming the role of daphnetin on TxA2 generation. Finally, daphnetin significantly inhibited 2-MeSADP-induced cytosolic phospholipase A2 (cPLA2) and ERK phosphorylation in non-aspirinated platelets. Only cPLA2 phosphorylation, not ERK phosphorylation, was significantly inhibited by daphnetin in aspirinated platelets. In conclusion, daphnetin plays a critical role in platelet function by inhibiting TxA2 generation through the regulation of cPLA2 phosphorylation.

NOOTROPICS: A LONG WAY IN HALF A CENTURY

Introduction. Currently, there are drugs that can improve cognitive processes. They are nootropics. The term "nootropics" was introduced in 1972, when piracetam's memory-enhancing properties were discovered, and this group of drugs has served the human benefit for half a century. The purpose of the work is to analyze known facts and new trends in the development of nootropics as a pharmacological group. Materials and methods. Internet resources (PubMed, Google Scholar, CrossRef) are used to search for information. Original research articles, meta-analyses and systematic reviews are included in the study. Attention was focused on providing an up-to-date overview of known means. Main part. For classification, the distribution of nootropics according to the mechanism of action is proposed. Nootropics have both a receptor mechanism of action and improve the supply of glucose and oxygen to the brain, the synthesis of proteins, nucleic acids and phospholipids, eliminate oxygen free radicals, have an antiplatelet effect, and optimize cerebral blood circulation. They are used for the treatment of psycho-organic syndrome. Nootropics are effective in providing benign senile disease, in children with minimal brain dysfunction syndrome, in case of encephalopathy and myalgic encephalomyelitis. Nootropics are indicated for patients with Alzheimer's disease, schizophrenia, hyperkinetic disorder. They are well tolerated. Their effectiveness depends on the dose, and after the disappearance of the disorder, the treatment should be continued for at least 2-3 weeks. Nootropics attract the attention of practically healthy individuals, in particular, students, but their use by healthy people is against concern due to the absence of clinical evidence of effectiveness, safety and social consequences. Some of the most famous nootropic drugs are piracetam, pyritinol, nicergoline, and vinpocetine, which have certain shades of pharmacodynamics, dosage, and side effects. Conclusions. Therefore, all nootropics improve cognitive function, especially in cases of the damage or degeneration, are well tolerated and should be prescribed by a specialist in each specific case. New research is needed to confirm or simplify the beneficial effects of nootropics in healthy individuals.

Effect of low-dose aspirin on urinary 11-dehydro-thromboxane B2 in the ASCEND (A Study of Cardiovascular Events iN Diabetes) randomized controlled trial

BackgroundAspirin is widely used for cardioprotection with its antiplatelet effects due to the blocking of thromboxane A2 production. However, it has been suggested that platelet abnormalities in those with diabetes prevent adequate suppression with once daily aspirin.MethodsIn the ASCEND randomized double-blind trial of aspirin 100 mg once daily versus placebo in participants with diabetes but no history of cardiovascular disease, suppression was assessed by measuring 11-dehydro-thromboxane B2 excretion in urine (U-TXM) in a randomly selected sample of 152 participants (76 aspirin arm, 74 placebo arm), plus 198 (93 aspirin arm, 105 placebo arm) adherent to study drugs and selected to maximize the numbers ingesting their last tablet 12–24 h before urine sampling. U-TXM was assayed using a competitive ELISA assay in samples mailed a mean of 2 years after randomization, with time since taking last aspirin/placebo tablet recorded at the time of sample provision. Effective suppression (U-TXM < 1500 pg/mg creatinine) and percentage reductions in U-TXM by aspirin allocation were compared.ResultsIn the random sample, U-TXM was 71% (95% CI 64–76%) lower among aspirin vs placebo-allocated participants. Among adherent participants in the aspirin arm, U-TXM was 72% (95% CI 69–75%) lower than in the placebo arm and 77% achieved effective suppression overall. Suppression was similar among those who ingested their last tablet more than 12 h before urine sampling with levels in the aspirin arm 72% (95% CI 67–77%) lower than in the placebo arm and 70% achieving effective suppression.ConclusionsDaily aspirin significantly reduces U-TXM in participants with diabetes, including at 12–24 h after ingestion.Trial registrationISRCTN ISRCTN60635500. Registered on 1 Sept 2005; ClinicalTrials.gov NCT00135226. Registered on 24 Aug 2005.

Development of a Novel Apigenin Dosage form as a Substitute for the Modern Triple Antithrombotic Regimen

The simultaneous administration of three antiplatelet agents has been proposed as an efficient strategy for the secondary prevention of atherothrombotic events and is included in the European guidelines. However, this strategy presented an increased risk of bleeding; therefore, the identification of new antiplatelet agents, with improved efficacy and diminished side effects, is of great importance. In silico studies, UPLC/MS Q-TOF plasma stability, in vitro platelet aggregation experiments, and pharmacokinetic studies were exploited. In the present study, it has been predicted that the flavonoid apigenin could target different platelet activation pathways, including P2Y12, protease-activated receptor-1 (PAR-1), and cyclooxygenase 1 (COX-1). To enhance apigenin's potency, hybridization with docosahexaenoic acid (DHA) was performed, as fatty acids have illustrated potent efficacy against cardiovascular diseases (CVDs). The new molecular hybrid, termed 4'-DHA-apigenin, demonstrated enhanced inhibitory activity against platelet aggregation induced by thrombin receptor activator peptide-6 (TRAP-6), adenosine diphosphate (ADP), and arachidonic acid (AA), with respect to the parent apigenin. The 4'-DHA-apigenin hybrid illustrated an almost 2-fold enhanced inhibitory activity, with respect to apigenin, and an almost 3-fold enhanced inhibitory activity, with respect to DHA, for the ADP-induced platelet aggregation. Additionally, the hybrid presented a more than 12-fold enhanced inhibitory activity with respect to DHA for the TRAP-6 induced platelet aggregation. Furthermore, a 2-fold enhanced inhibitory activity was recorded for the 4'-DHA-apigenin hybrid for the AA-induced platelet aggregation with respect to apigenin. To surmount the reduced LC-MS based plasma stability, a novel dosage form in olive oil has been developed. The 4'-DHA-apigenin olive oil-based formulation presented an enhanced antiplatelet inhibitory effect in three activation pathways. To further explore the pharmacokinetic profile of 4'-DHA-apigenin in olive oil formulations, a UPLC/MS Q-TOF protocol has been established to quantify the serum levels of apigenin after oral administration to C57BL/6J wild type mice. The olive oil-based formulation of 4'-DHA-apigenin demonstrated an increase in apigenin bioavailability of 262 %. This study may offer a new therapeutic strategy tailored to improve the treatment of CVDs.

Cytosolic perfluorocarbon delivery to platelets via albumin for antithrombotic therapy.

Thrombosis is a major contributor to global disease burden. Antiplatelet therapy is the critical approach to prevent thrombosis by reducing platelet reactivity. However, classical antiplatelet strategies generally interfere with platelet integrin αIIbβ3-mediated platelet activation, thereby facing severe bleeding risk. To break the limitation, we described an integrin αIIbβ3-independent antiplatelet method by cytosolic delivery of nanoscale perfluorocarbon (PFC) to platelets via albumin carrier. Denatured albumin was found to build high affinity with platelets to mediate cytosolic PFC delivery. While, cytosolic PFC impaired cytoskeleton reorganization during platelet activation to inhibit relevant platelet functions, but avoided to interfere with integrin αIIbβ3. We proved that this αIIbβ3-indenpendent antiplatelet pattern showed potential antiplatelet effect with low bleeding risk to prevent thrombosis in various thrombosis models. Together, cytosolic PFC delivery via albumin is a promising antiplatelet approach, and will provide an alternative regimen for current antithrombotic therapy.

The inhibitory effect of isoliquiritigenin on human platelets in vitro.

Platelets play important roles in several physiological and pathological processes. Multiple antiplatelet drugs have been developed for clinical practice. The active components of traditional Chinese medicine with antithrombotic effects are promising drugs to modulate platelet function. In our study, the antiplatelet effect of isoliquiritigenin (ILTG) and its mechanisms were examined. Human platelet-rich plasma and a washed platelet suspension were prepared. Platelets were stimulated using collagen, thrombin, or adenosine diphosphate (ADP). The platelet lumi-aggregometer was applied to detect the aggregation of platelets and the release of adenosine triphosphate (ATP). The expression of P-selectin and the activation of integrin αIIbβ3 were detected using flow cytometry. The spreading of platelets on a fibrinogen-coated surface was visualized using immunofluorescent staining. The mechanisms of the antiplatelet effect were investigated using Western blotting. In this study, ILTG inhibited collagen- and thrombin-induced platelet aggregation, the release of dense granules and α-granules, and the activation of integrin αIIbβ3 in a dose-dependent manner. In addition, ILTG suppressed the spreading of platelets on immobilized fibrinogen. In collagen-activated platelets, ILTG markedly inhibited the expression of phosphorylation of phospholipase C gamma-2 (PLCγ2) and protein kinase B (Akt). These results indicated that ILTG could inhibit the collagen- and thrombin-induced platelet aggregation and granule release via the glycoprotein VI-mediated signal pathway in vitro.

Electrochemical Biosensor for Detection of the CYP2C19*2 Allele Based on Exonuclease Ⅲ

Currently, the therapeutic effect of clopidogrel differs considerably among individuals and is thought to be closely related to the genetic polymorphism of CYP2C19. The CYP2C19*2 gene can reduce the antiplatelet aggregation effect of clopidogrel, which increases the risk of major cardiovascular adverse events in patients. In this research, we report a new type of biosensor for the highly sensitive detection of the CYP2C19*2 gene based on exonuclease III assisted electric signal amplification and the use of calixarene to enrich electrical signal substances. Specifically, under the best conditions, the logarithmic concentrations of the analytes have a good linear relationship with the peak current in the range of 0.01 fM to 100 pM and the detection limit is 13.49 aM. The results have also shown that this method has good selectivity, high sensitivity, and stability, etc., and will provide a very promising application for the detection of the CYP2C19*2 gene and other biological molecules by replacing corresponding nucleic acid sequences.

Progress and Understandings in the Pharmacological Repositioning Scenario

In order to present an overview of pharmacological repositioning in terms of clinical applicability, a narrative review was applied, based on the PCC strategy. The search was carried out in February 2022, highlighting the concepts on the subject, not requiring the opinion of a committee for its development. Numerous drugs were randomly repositioned. It is noteworthy that during clinical trials, unexpected side effects made its reuse possible. The antiplatelet effect of aspirin is already elucidated, however, research reveals potential in oncology. Therefore, there is a need to explore the biochemistry and the interaction with organic and pathological targets, visualizing the applicability of known drugs in solving urgent problems.

Effect of Antiplatelet and Anticoagulant Agents on Outcomes Following Emergent Surgery for Traumatic Brain Injuries.

Traumatic brain injury (TBI) is the largest cause of death from injury in the United States. This study utilized the Michigan Trauma Quality Improvement Program (MTQIP) database to determine the effect that antiplatelets and anticoagulants (AP/AC) have on outcomes following emergent surgery for TBI patients. Patients were included with age ≥18years, maximum head/neck abbreviated injury score (AIS) ≥2, and underwent a neurosurgical procedure within 24hours. Patients were excluded if they had an AIS ≥3 in other body region or no signs of life at initial evaluation. Within the 1,932 patients analyzed, 139 (8.74%) were in the warfarin with or without (+/-) aspirin cohort, 101 (6.35%) in the direct oral anticoagulants (DOAC) +/- aspirin cohort, 169 (10.62%) in the clopidogrel +/- aspirin cohort, and 1,182 (74.29%) in the no AP/AC cohort (control group). After controlling for demographic and clinical characteristics, no significant difference in mortality rates was observed in the treatment groups (P > 0.05). However, our subgroup analysis did reveal a significantly higher mortality rate within the warfarin and aspirin subgroup when compared to the control group (odds ratio [OR], 2.368; confidence interval [CI], 1.306-4.294, P = 0.005). With regards to hospital complications, there was a significant increase in this outcome within the DOAC +/- aspirin (OR, 1.825; CI, 1.143-2.915, P = 0.012) and clopidogrel +/- aspirin (OR, 1.82; CI, 1.244-2.663, P=0.002) groups. Patients on AP/AC who experience a TBI requiring an emergent operation do not have an increased risk of mortality compared to patients not on AP/AC.

SC-560 and mofezolac isosteres as new potent COX-1 selective inhibitors with antiplatelet effect.

Selective cyclooxygenase (COX)-1 inhibitors can be employed as potential cardioprotective drugs. Moreover, COX-1 plays a key role in inflammatory processes and its activity is associated with some types of cancer. In this work, we designed and synthesized a set of compounds that structurally mimic the selective COX-1 inhibitors, SC-560 and mofezolac, the central cores of which were replaced either with triazole or benzene rings. The advantage of this approach is a relatively simple synthesis in comparison with the syntheses of parent compounds. The newly synthesized compounds exhibited remarkable activity and selectivity toward COX-1 in the enzymatic in vitro assay. The most potent compound, 10a (IC50 = 3 nM for COX-1 and 850 nM for COX-2), was as active as SC-560 (IC50 =2.4nMforCOX-1 and470nMforCOX-2)toward COX-1 and it was even more selective. The in vitro COX-1 enzymatic activity was further confirmed in the cell-based whole-blood antiplatelet assay, where three out of four selected compounds (10a,c,d, and 3b) exerted outstanding IC50 values in the nanomolar range (9-252 nM). Moreover, docking simulations were performed to reveal key interactions within the COX-1 binding pocket. Furthermore, the toxicity of the selected compounds was tested using the normal human kidney HK-2 cell line.

Roles of light transmission aggregometry and CYP2C19 genotype in predicting ischaemic complications during interventional therapy for intracranial aneurysms

Background and purposeLight transmission aggregometry (LTA) and CYP2C19 genotype analysis are commonly used to evaluate the antiplatelet effects of clopidogrel during the interventional treatment of intracranial aneurysms. The aim of...

Enhanced metabolic activation of and platelet response to clopidogrel in T cell-deficient mice through induction of Cyp2c and Cyp3a and inhibition of Ces1

BackgroundT cells and platelets reciprocally coordinate mutual functions through crosstalk or interaction. However, it is not known whether metabolic activation of and platelet response to clopidogrel could be changed if T cells were deficient or impaired in some cases and, if any, how it would work. ObjectivesThe objective of this study was to dissect the potential changes in platelet responses to and metabolic activation of clopidogrel in the case of T cell deficiency and to elucidate their mechanisms involved. MethodsBALB/c athymic nude mice or euthymic mice (controls) pretreated with cyclosporine A (CsA), thymosin α1 (Tα1), or their combination were used to investigate the changes in ADP-induced platelet activation and aggregation, systemic exposure of clopidogrel and its metabolites, and mRNA/protein expression and activity levels of clopidogrel-metabolizing enzymes in the liver, respectively. ResultsNude mice exhibited significantly enhanced antiplatelet effects of clopidogrel due to increased formation of clopidogrel active metabolite in the liver, where the enzyme activity levels of Cyp2c and Cyp3a were significantly elevated compared with control mice. Furthermore, the effects of CsA pretreatment on the metabolism of clopidogrel in euthymic mice were identical to those seen in athymic mice. As expected, concomitant use of Tα1 reversed all the observed effects of CsA on clopidogrel metabolism and relevant metabolic enzymes. ConclusionsT cell deficiency or suppression enhances the antiplatelet effects of clopidogrel due to the boosted metabolic activation of clopidogrel in the liver through a dramatic induction of Cyp2c and Cyp3a in mice, suggesting that the metabolism of substrate drugs of Cyp2c and Cyp3a may be enhanced by T cell impairment.

Aspirin Therapy, Cognitive Impairment, and Dementia—A Review

Background: Dementia is associated with a greater burden of cardiovascular risk factors. There is a significant vascular contribution to dementia, and aspirin may play a role in targeting this vascular dysregulation via its anti-inflammatory and antiplatelet effects. We provide an overview of the effects of aspirin therapy on the prevention of dementia and cognitive decline in patients with or without dementia and/or cognitive impairment. Methods: We performed a search for studies enrolling adults with or without dementia or MCI and comparing aspirin with placebo, usual care, or active control with respect to cognitive outcomes. Results: We describe aspirin’s effects on the primary prevention of cognitive impairment and various subtypes of dementia, as well as its role in cognitive decline in certain subsets of patients, including those with cerebral small vessel disease (CVSD), coronary heart disease (CHD), and gender differences. Overall, the benefits of aspirin in preventing dementia and cognitive decline remain inconclusive. The majority of cohort studies investigating aspirin’s role in preventing cognitive decline or dementia looked promising, but this was not supported in most randomised controlled trials. However, aspirin may still be beneficial in certain subgroups of patients (such as CHD, VD, and CSVD) and warrants further investigation.

The Use of Triphenyl Phosphonium Cation Enhances the Mitochondrial Antiplatelet Effect of the Compound Magnolol.

Although platelets are anucleated cells, they have fully functional mitochondria, and currently, it is known that several processes that occur in the platelet require the action of mitochondria. There are plenty of mitochondrial-targeted compounds described in the literature related to cancer, however, only a small number of studies have approached their interaction with platelet mitochondria and/or their effects on platelet activity. Recent studies have shown that magnolia extract and mitochondria-targeted magnolol can inhibit mitochondrial respiration and cell proliferation in melanoma and oral cancer cells, respectively, and they can also induce ROS and mitophagy. In this study, the effect of triphenylphosphonium cation, linked by alkyl chains of different lengths, to the organic compound magnolol on human-washed platelets was evaluated. We demonstrated that the addition of triphenylphosphonium by a four-carbon linker to magnolol (MGN4) considerably enhanced the Magnolol antiplatelet effect by a 3-fold decrease in the IC50. Additionally, platelets exposed to MGN4 5 µM showed several differences from the control including increased basal respiration, collagen-induced respiration, ATP-independent respiration, and reduced ATP-dependent respiration and non-mitochondrial respiration.

Fatty acids negatively regulate platelet function through formation of noncanonical 15-lipoxygenase-derived eicosanoids.

The antiplatelet effect of polyunsaturated fatty acids is primarily attributed to its metabolism to bioactive metabolites by oxygenases, such as lipoxygenases (LOX). Platelets have demonstrated the ability to generate 15-LOX-derived metabolites (15-oxylipins); however, whether 15-LOX is in the platelet or is required for the formation of 15-oxylipins remains unclear. This study seeks to elucidate whether 15-LOX is required for the formation of 15-oxylipins in the platelet and determine their mechanistic effects on platelet reactivity. In this study, 15-HETrE, 15-HETE, and 15-HEPE attenuated collagen-induced platelet aggregation, and 15-HETrE inhibited platelet aggregation induced by different agonists. The observed anti-aggregatory effect was due to the inhibition of intracellular signaling including αIIbβ3 and protein kinase C activities, calcium mobilization, and granule secretion. While 15-HETrE inhibited platelets partially through activation of peroxisome proliferator-activated receptor β (PPARβ), 15-HETE also inhibited platelets partially through activation of PPARα. 15-HETrE, 15-HETE, or 15-HEPE inhibited 12-LOX in vitro, with arachidonic acid as the substrate. Additionally, a 15-oxylipin-dependent attenuation of 12-HETE level was observed in platelets following ex vivo treatment with 15-HETrE, 15-HETE, or 15-HEPE. Platelets treated with DGLA formed 15-HETrE and collagen-induced platelet aggregation was attenuated only in the presence of ML355 or aspirin, but not in the presence of 15-LOX-1 or 15-LOX-2 inhibitors. Expression of 15-LOX-1, but not 15-LOX-2, was decreased in leukocyte-depleted platelets compared to non-depleted platelets. Taken together, these findings suggest that 15-oxylipins regulate platelet reactivity; however, platelet expression of 15-LOX-1 is low, suggesting that 15-oxylipins may be formed in the platelet through a 15-LOX-independent pathway.