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Thrombosis is the leading cause of illness and mortality worldwide, posing a serious risk to human health and life. Because antithrombotic drugs can prevent the beginning and progression of thrombotic disorders, they are essential in the management of thrombotic diseases. The substantial side effects and unsatisfactory efficacy of present antithrombotic drugs stimulate the search for novel, effective, and safer antithrombotic therapies. Natural and synthetic coumarins have been shown to have antithrombotic action, specifically anticoagulation, and antiplatelet aggregation. In particular, coumarin-based medications like warfarin, phenprocoumon, and cloricromen have long been used to treat thrombosis in clinical settings. The favored structure for creating novel antithrombotic medications with diverse modes of action is coumarin, which has low toxicity. The goal of the current review is to consolidate recent findings on the development of coumarins as antithrombotic agents, with a focus on the connection between these compounds’ chemical compositions and therapeutic potency. It aims to offer promising suggestions for the identification of new coumarin compounds with potent antithrombotic properties.

Antiplatelet aggregation agents have demonstrated clinical benefits in the treatment of ischemic stroke. In our study, a series of novel nitric oxide (NO)-donating ligustrazine derivatives were designed and synthesized as antiplatelet aggregation agents. They were evaluated for the inhibitory effect on 5′-diphosphate (ADP)-induced and arachidonic acid (AA)-induced platelet aggregation in vitro. The results showed that compound 15d displayed the best activity in both ADP-induced and AA-induced assays, and compound 14a also showed quite better activity than ligustrazine. The preliminary structure-activity relationships of these novel NO-donating ligustrazine derivatives were discussed. Moreover, these compounds were docked with the thromboxane A2 receptor to study the structure-activity relationships. These results suggested that the novel NO-donating ligustrazine derivatives 14a and 15d deserve further study as potent antiplatelet aggregation agents.

Lusianthridin is a phenanthrene derivative isolated from Dendrobium venustum. Some phenanthrene compounds have antiplatelet aggregation activities via undefined pathways. This study aims to determine the inhibitory effects and potential mechanisms of lusianthridin on platelet aggregation. The results indicated that lusianthridin inhibited arachidonic acid, collagen, and adenosine diphosphate (ADP)-stimulated platelet aggregation (IC50 of 0.02 ± 0.001 mM, 0.14 ± 0.018 mM, and 0.22 ± 0.046 mM, respectively). Lusianthridin also increased the delaying time of arachidonic acid-stimulated and the lag time of collagen-stimulated and showed a more selective effect on the secondary wave of ADP-stimulated aggregations. Molecular docking studies revealed that lusianthridin bound to the entrance site of the cyclooxygenase-1 (COX-1) enzyme and probably the active region of the cyclooxygenase-2 (COX-2) enzyme. In addition, lusianthridin showed inhibitory effects on both COX-1 and COX-2 enzymatic activities (IC50 value of 10.81 ± 1.12 µM and 0.17 ± 1.62 µM, respectively). Furthermore, lusianthridin significantly inhibited ADP-induced suppression of cAMP formation in platelets at 0.4 mM concentration (p < 0.05). These findings suggested that possible mechanisms of lusianthridin on the antiplatelet effects might act via arachidonic acid-thromboxane and adenylate cyclase pathways.

Introduction: Ischemic stroke is the second most common chronic disease worldwide and is associated with high morbidity and mortality. Thromboembolism and platelet aggregation are the most characteristic features of stroke. Other than aspirin, no standard, accepted, or effective treatment for acute ischemic stroke has been established. Consequently, it is essential to identify novel therapeutic compounds for this condition. Methods: In this study, novel ozagrel/paeonol-containing codrugs were synthesized and characterized using 1 H-NMR, 13 C-NMR, and mass spectroscopy. Their antiplatelet aggregation activity was evaluated, with compound PNC 3 found to exhibit the best effect. Subsequently, studies were conducted to assess its neuroprotective effect, pharmacokinetic properties and model its binding mode to P2Y12 and TXA2, two proteins critical for platelet aggregation. Results: The results indicated that PNC3 has good bioavailability and exerts protective effects against oxygen-glucose deprivation injury in PC12 cells. Molecular docking analysis further demonstrated that the compound interacts with residues located in the active binding sites of the target proteins. Conclusion: The codrugs synthesized in this study display promising pharmacological activities and have the potential for development as an oral formulation.

Many Premna species have been used in traditional medicine to treat hypertension and cardiac insufficiency, and as a tonic for cardiac-related problems. Some have been reported to possess cardiovascular protective activity through several possible mechanisms, but not Premna foetida. In the present study, the methanol extract of P. foetida leaves (PFM) and its isolated compounds were evaluated for their ability to inhibit copper-mediated human low-density lipoprotein (LDL) oxidation and arachidonic acid (AA)- and adenosine diphosphate (ADP)-induced platelet aggregation. Six flavonoids, three triterpenoids, vanillic acid and stigmasterol were successfully isolated from PFM. Of the isolated compounds, quercetin was the most active against LDL oxidation (IC50 4.25 µM). The flavonols were more active than the flavones against LDL oxidation, suggesting that hydroxyl group at C-3 and the catechol moiety at B-ring may play important roles in protecting LDL from oxidation. Most tested flavonoids showed stronger inhibition towards AA-induced than the ADP-induced platelet aggregation with apigenin exhibiting the strongest effect (IC50 52.3 and 127.4 µM, respectively) while quercetin and kaempferol showed moderate activity. The results suggested that flavonoids, especially quercetin, apigenin and kaempferol were among the major constituents of P. foetida responsible for anti-LDL oxidation and anti-platelet aggregation.

Chronic subdural hematoma (CSDH) is a common disease among the elderly and with increasing incidence we have chosen to focus on associations between development and recurrence of CSDH and anticoagulation and/or antiplatelet agent therapy. We conducted a retrospective review of 239 patients undergoing surgery for CSDH over a period of six years (2006–2011). Risk factors such as age, head trauma, anticoagulant and/or antiplatelet agent therapy and co-morbidity were investigated along with gender, coagulation status, laterality, surgical method and recurrence. Seventy-two percent of the patients were male and the mean age was 71.8 years (range 28–97 years). Previous fall with head trauma was reported in 60% of the patients while 16% were certain of no previous head trauma. The majority of patients (63%) in the non-trauma group were receiving anticoagulants and/or antiplatelet agent therapy prior to CSDH presentation, compared to 42% in the trauma group. Twenty-four percent experienced recurrence of the CSDH. There was no association between recurrence and anticoagulant and/or antiplatelet agent therapy. Anticoagulant and/or antiplatelet aggregation agent therapy is more prevalent among non-traumatic CSDH patients but does not seem to influence the rate of CSDH recurrence.

3,4-Dihydroxyacetophenone (DHAP) exerts therapeutic effects on cardiovascular disease and pulmonary heart disease. However, it is not utilized as a clinical drug due to its rapid metabolism, short-acting effect and low oral bioavailability. In the present study, three derivatives of DHAP, including 4-acetyl-1,2-phenylene dipropionate (APDP), 1-(3-hydroxy-4-phenoxy-phenyl)-ethanone (HPPE) and a polymer derivative, PEG-DHAP, were synthesized via the esterification or etherification of hydroxyls at C3 and C4, which are the prime metabolism sites of DHAP. The physicochemical properties, pharmacokinetic and antiplatelet aggregation activities of these derivatives were measured to determine whether they can improve the defects of DHAP. The results revealed that APDP and HPPE exhibited markedly lower water solubility and higher oil-water partition coefficients compared to DHAP. APDP rapidly transformed into DHAP in vivo and in vitro, indicating that there were no significant differences in the values of mean residence time in vivo [MRT (0-t)], half-life [t1/2], oral bioavailability and antiplatelet aggregation activity in vivo and in vitro between the two agents. HPPE partially released DHAP for a period of time following oral administration. PEG-DHAP contained 12.47% DHAP dispersed into nanoparticles with a mean particle size of 260.90 nm. This was administered in aqueous solution and was demonstrated to release DHAP slowly following oral administration. These two derivatives significantly prolonged the in vivo acting time and increased the oral bioavailability of DHAP: Following intragastric administration, their MRT (0-t) and t1/2 values were 3.55-11.47- and 6.63-11.25-fold higher compared with those of DHAP, respectively. Additionally, their relative bioavailability was 394.79 and 331.88%, respectively, and they exhibited longer acting times of significant antiplatelet aggregation activity. The results of the present study may thus provide a reference for the development of DHAP as an oral drug. Furthermore, the results if this study may prove to be useful to researchers addressing the issue of the poor bioavailability of phenolic drugs.

The aim of the present study was to report on a complete synthetic approach, namely benzylation-hydrolysis-acylation‑hydrogenation, to the synthesis of regioselectively acylated quercetin analogues using low‑cost rutin as a starting material. Three quercetin analogues, quercetin‑3‑O‑propionate (Q‑pr), quercetin‑3‑O‑butyrate (Q‑bu) and quercetin‑3‑O‑valerate (Q‑va), containing 3‑, 4‑ and 5‑carbon aliphatic acyl chains, respectively, were synthesized and characterized with 1H nuclear magnetic resonance (NMR), 13C NMR and mass spectrometry. Compared with quercetin, all three analogues exhibited improved lipophilicity. The lipophilicity of the analogue increased with increasing acyl chain length. Q‑va exhibited the highest lipophilicity among the three analogues, but a lower water solubility compared with quercetin. By contrast, Q‑pr and Q‑bu exhibited 8.2‑ and 4.7‑fold higher water solubility compared with quercetin, respectively. The in vitro and in vivo studies demonstrated that Q‑pr and Q‑bu were more effective whereas Q‑va was less effective in inhibiting platelet aggregation compared with quercetin. These results indicated that the water solubility and the lipophilicity of the analogues must be improved in order to achieve higher antiplatelet activity, and an optimal acyl chain length is crucial for the synthesized quercetin analogues to be more effective.

Apyrase is one of the essential platelet aggregation inhibitors in hematophagous arthropods due to its ability to hydrolyze ATP and ADP molecules. Here, an apyrase (TNapyrase) with antiplatelet aggregation activity was purified and characterized from the nymphs of the camel tick Hyalomma dromedarii through anion exchange and gel filtration columns. The homogeneity of TNapyrase was confirmed by native-PAGE, SDS-PAGE as well as with isoelectric focusing. Purified TNapyrase had a molecular mass of 25 kDa and a monomer structure. TNapyrase hydrolyzed various nucleotides in the order of ATP > PPi > ADP > UDP > 6GP. The Km value was 1.25 mM ATP and its optimum activity reached at pH 8.4. The influence of various ions on TNapyrase activity showed that FeCl2, FeCl3 and ZnCl2 are activators of TNapyrase. EDTA inhibited TNapyrase activity competitively with a single binding site on the molecule and Ki value of 2 mM. Finally, TNapyrase caused 70% inhibition of ADP-stimulated platelets aggregation and is a possible target for antibodies in future tick vaccine studies.

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide and, together with associated risk factors such as diabetes, hypertension, and dyslipidaemia, greatly impact patients’ quality of life and health care systems. This burden can be alleviated by fomenting lifestyle modifications and/or resorting to pharmacological approaches. However, due to several side effects, current therapies show low patient compliance, thus compromising their efficacy and enforcing the need to develop more amenable preventive/therapeutic strategies. In this scenario, medicinal and aromatic plants are a potential source of new effective agents. Specifically, plants from the Allioideae subfamily (formerly Alliaceae family), particularly those from the genus Allium and Tulbaghia, have been extensively used in traditional medicine for the management of several CVDs and associated risk factors, mainly due to the presence of sulphur-containing compounds. Bearing in mind this potential, the present review aims to gather information on traditional uses ascribed to these genera and provide an updated compilation of in vitro and in vivo studies validating these claims as well as clinical trials carried out in the context of CVDs. Furthermore, the effect of isolated sulphur-containing compounds is presented, and whenever possible, the relation between composition and activity and the mechanisms underlying the beneficial effects are pointed out.