Platelet Antiaggregating Agents Research Articles

Comparison of Various Solvent Extracts and Major Bioactive Components from Unsalt-Fried and Salt-Fried Rhizomes of Anemarrhena asphodeloides for Antioxidant, Anti-α-Glucosidase, and Anti-Acetylcholinesterase Activities.

The rhizome of Anemarrhena asphodeloides Bunge (AA, family Liliaceae) is a famous and frequently used herbal drug in the traditional medicine of Northeast Asia, under vernacular name “zhimu”. A. asphodeloides has been used as an anti-inflammatory, antipyretic, anti-platelet aggregation, anti-depressant, and anti-diabetic agent in traditional Chinese medicine. We examined the antioxidant, anti-acetylcholinesterase (AChE), and anti-α-glucosidase activities of various solvent extracts and the main bioactive compounds from the rhizome of A. asphodeloides. Acetone extract exhibited comparatively high antioxidant activities by 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and ferric-reducing antioxidant power (FRAP) assays. A water extract exhibited relatively strong antioxidant activity by superoxide radical scavenging test. Furthermore, dichloromethane, chloroform, and n-hexane extracts showed significant anti-α-glucosidase activities. Finally, ethanol and dichloromethane extracts exhibited relatively strong AChE inhibitory activity. HPLC analysis was used to examine and compare various solvent extracts for their compositions of isolates. We isolated four major chemical constituents and analyzed their antioxidant, anti-α-glucosidase, and AChE inhibitory activities. The bioactivity assays showed that mangiferin displayed the most potential antioxidant activities via FRAP, ABTS, DPPH, and superoxide assays and also exhibited the most effective anti-AChE and anti-α-glucosidase activities among all the isolates. The present study suggests that A. asphodeloides and its active extracts and components are worth further investigation and might be expected to develop as a candidate for the treatment or prevention of oxidative stress-related diseases, AChE inhibition, and hyperglycemia.

Diindolylmethane ameliorates platelet aggregation and thrombosis: In silico, in vitro, and in vivo studies

Diindolylmethane (DIM), a major metabolite of indole-3-carbinol (I3C), plays a vital role in the pharmacological actions of I3C. The role of DIM in the inhibition of platelet aggregation and thrombus generation is yet to be revealed. However, how DIM and I3C modulate the interaction of platelets with the glycoproteinVI (GPVI) and purinergic receptor Y12 (P2Y12) receptors is unknown. In silico studies revealed that the indole group of DIM and indole and the hydroxyl group of I3C are responsible for modulating platelet interaction with GPVI and P2Y12 receptors. In silico studies further predicted that DIM more superiorly modulates platelet interaction with GPVI and P2Y12 receptors than I3C. In vitro studies identified that DIM significantly inhibited platelet aggregation induced by adenosine diphosphate (ADP), collagen, thrombin, and arachidonic acid, increasing the thrombin-induced clot retraction size and clot retraction weight. Moreover, in vivo results of ferric chloride (FeCl3) induced carotid artery thrombus generation indicate that DIM significantly reduced the reactive oxygen species (ROS), hydrogen peroxide (H2O2), thromboxane 2 (TXB2), cyclooxygenase 1 (COX-1), prostaglandin E2 (PGE2), thrombus weight, increased the cyclic adenosine monophosphate (cAMP), and extended the time to occlusion (TTO). Furthermore, DIM did not show thrombolytic activity. Therefore, DIM acts as an antiplatelet aggregation and antithrombotic agent. Moreover, DIM is responsible for the antiplatelet aggregation and antithrombotic activity of I3C. Therefore, DIM could be used to treat thrombotic diseases.

IQCA-TAVV: To explore the effect of P-selectin, GPIIb/IIIa, IL-2, IL-6 and IL-8 on deep venous thrombosis.

Deep vein thrombosis (DVT) associates with considerable morbidity, functional disability and mortality. Due to the lack of suitable inhibitor the correlation of various factors in DVT onset remains unknown. In this context we analyzed the structure of anti-platelet aggregation agent, P-selectin down-regulator, GPIIb/IIIa down-regulator and anti-inflammatory agent, thereby designed N-(3S-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)- Thr-Ala-Arg-Gly-Asp(Val)-Val (IQCA-TAVV) as an inhibitor of DVT to receive evaluations. The docking predicted that IQCA-TAVV can target P-selectin and GPIIb/IIIa. The UV showed that IQCA-TAVV can act on P-selectin and GPIIb/IIIa. ELISA indicated that IQCA-TAVV concentration dependently inhibited activated platelets to express P-selectin and GPIIb/IIIa, and the minimal effective concentration was 1 nM. IC50 of IQCA-TAVV against platelet aggregation induced by arachidonic acid, adenosine diphosphate and platelet activating factor fell within a range of 0.13 nM to 0.30 nM. In vivo IQCA-TAVV dose-dependently inhibited venous thrombosis and the minimal effective dose was 1 nmol/kg. On ear edema model the anti-inflammation activity of 10 nmol/kg IQCA-TAVV equaled that of 1.1mmol/kg aspirin. The concentration of IL-2, IL-6 and IL-8 in the serum of the ear edema mice were also significantly decreased by 10 nmol/kg IQCA-TAVV. Even at 1 μmol/kg of dose IQCA-TAVV still did not injure the kidney, the liver, and the nerves of healthy mice. Thereby IQCA-TAVV depicts a relationship of three levels (inhibiting platelet activation, targeting externalized membrane receptor, decreasing serum inflammatory factor) for the down-regulation of P-selectin, GPIIb/IIIa, IL-2, IL-6 and IL-8 in DVT.

Studies on New Activities of Enantiomers of 2-(2-Hydroxypropanamido) Benzoic Acid: Antiplatelet Aggregation and Antithrombosis.

R-/S-2-(2-Hydroxypropanamido) benzoic acid (R-/S-HPABA), a marine-derived anti-inflammatory drug, however, the antiplatelet and antithrombotic effects have not been investigated. In this paper, the in vitro antiplatelet activities and in vivo antithrombotic effects of R-/S-HPABA were investigated, for the first time. The effects of R-/S-HPABA on platelet aggregation induced by adenosine diphosphate (ADP), collagen (COLL) and arachidonic acid (AA) were evaluated. In addition, the in vivo bleeding time, clotting time, collagen-epinephrine induced pulmonary thrombosis and common carotid artery thrombosis were also investigated in rats. R-/S-HPABA significantly inhibited ADP, COLL and AA induced platelet aggregation in rabbit platelet rich plasma in vitro compared with control group, to a degree similar to that of aspirin. Besides, R-/S-HPABA prolonged bleeding time and clotting time as well as increased the recovery rate obviously in pulmonary thrombosis. Moreover, the level of thromboxane B2 (TXB2) was decreased while the production of 6-keto-prostaglandin F1α (6-keto-PGF1α) was increased markedly by R-/S-HPABA. Furthermore, R-/S-HPABA reduced carotid artery thrombosis weight. These results illustrated that R-/S-HPABA could be a potent antiplatelet aggregation and antithrombotic agent.

Design, synthesis and evaluation of novel 2-amino-3-(naphth-2-yl)propanoic acid derivatives as potent inhibitors of platelet aggregation

Based upon LX2421, a previously identified antiplatelet aggregation agent, a series of novel 2-amino-3-(naphth-2-yl)propanoic acid derivatives were designed, synthesized and evaluated. Among them, compounds LX14 and LX25 were identified as promising antiplatelet aggregation agents. The in vitro biologic study demonstrated that LX14 can block platelet aggregation induced by four different inducers and displays comparable potency in inhibiting GPIIb/IIIa receptor in comparison with Tirofiban. In addition, LX14 has much lower risk of bleeding than Tirofiban and shows significant antithrombotic activity in vivo. Taking together, the results indicated that LX14 is a promising GPIIb/IIIa receptor antagonist against platelet aggregation worthy of further evaluation.

눈개승마 지상부의 항혈전 활성

The oriental traditional medicine, Aruncus dioicus var kamtschaticus (ADK) is used for hemostasis (blood stopping) and the promotion of blood circulation. Recently, the demands of the aerial part of ADK as edible mountain herbs are rapidly increased due to its unique fragrance and bioactivity. In this study, to evaluate the anti-thrombosis activity of ADK, ethanol extract and organic solvent fractions were prepared from aerial parts of ADK, and their anticoagulation and anti-platelet aggregation activities were determined. In an anticoagulation activity assay, the ethanol extract of ADK increased the thrombin time, prothrombin time, and activated partial thromboplastin time (aPTT) 1.4–2.3 times at a concentration of 5 mg/ml. Among the fractions, the ethylacetate fraction showed strong inhibitory effects against blood clotting factors, as shown in an extension of the aPTT. In contrast, the butanol fraction strongly promoted blood clotting. In an anti-platelet aggregation assay, the activity of the ethanol extract was comparable to that of aspirin, a commercial anti-platelet aggregation agent, and the butanol fraction showed 2-fold higher aggregation inhibitory activity than aspirin. The aforementioned ethanol extract and active fractions have ignorable hemolytic activity against human red blood cells up to a concentration of 0.5 mg/ml. Considering the high content of total polyphenol, total flavonoid, and total sugar of the ethylacetate and butanol fractions, the purified active substances have potential as safe and novel anti-thrombosis agents. This report provides the first evidence of anti-thrombosis activity of ADK.

Design, synthesis and biological evaluation of novel trimethylpyrazine-2-carbonyloxy-cinnamic acids as potent cardiovascular agents

A series of novel trimethylpyrazine-2-carbonyloxy-cinnamic acids and esters were designed, synthesized and evaluated for their inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation in vitro and also assayed for their protective effect against hydrogen peroxide (H2O2)-induced oxidative damage on Ea.hy926 cells. The results showed that many compounds exhibited high activity in one or both of the assays, of which, compound F′10 displayed the highest protective effect on the proliferation of the damaged Ea.hy926 cells (EC50 = 1.7 μM), presenting almost 40 times higher potency than that of lipoic acid, and compound F3 was the most active anti-platelet aggregation agent with IC50 = 9.6 μM, comparable to that of clopidogrel. The structure–activity relationships of these compounds were also discussed.

Pharmacodynamics and Pharmacokinetics of a Novel, Low-Dose, Soft-Gel Capsule of Acetylsalicylic Acid in Comparison with an Oral Solution After Single-Dose Administration to Healthy Volunteers: A Phase I, Two-Way Crossover Study

Low-dose acetylsalicylic acid (ASA; aspirin) is well-established as a platelet anti-aggregating agent for the secondary prevention of cardiovascular events. The objective of this study was to investigate the non-inferiority of a novel ASA 75 mg soft-gel capsule formulation compared with a marketed powder for oral solution in terms of reduction in serum thromboxane B2 (TXB2), a surrogate for platelet aggregation. Pharmacokinetics and tolerability of the products were also investigated. In this randomised, two-way crossover study, 46 male and female healthy subjects received a single dose of the investigational products in two periods separated by a 14-day washout. Serum TXB2 and plasma ASA were determined up to 24 h post-dose. Maximum percentage of TXB2 inhibition (I max) and area under the inhibition-time curve (AUICt) were calculated. Non-inferiority was assumed if the lower limits of the 95 % confidence intervals (CIs) for the two pharmacodynamic parameters were above 85 %. The 95 % CI lower limits were 95.35 % for I max and 86.12 % for AUICt, i.e. within the pre-specified delta. Time to achieve I max did not differ between treatments (p = 0.88). The two formulations were bioequivalent as regards the extent of ASA exposure (area under the plasma concentration-time curve from zero to time t [AUCt] 90 % CIs 96.67-113.37); a delayed ASA absorption (later time to reach maximum plasma concentration [t max], lower maximum plasma concentration [C max]) was observed for the test product. No treatment-related adverse events were reported. In healthy subjects, the 75 mg soft-gel capsules were not inferior to the oral solution in terms of serum TXB2 inhibition, indicating that the novel formulation could be an effective alternative in the secondary prevention of cardiovascular events.

Anticoagulation therapy a risk factor for the development of chronic subdural hematoma

ObjectiveChronic 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. MethodsWe 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. ResultsSeventy-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. ConclusionAnticoagulant 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.

Epicardial adipose tissue and idiopathic deep venous thrombosis: An association study

ObjectiveEpicardial fat (EpiF) reflects abdominal visceral adiposity and visceral fat plays an important role in the development of an unfavorable metabolic and atherosclerosis risk profile. An increased cardiovascular risk has been evidenced in patients with deep venous thrombosis (DVT). Advancing age is characterized by alterations of body fat mass and function In this study we studied the association between EpiF, DVT, age, obesity and other atherosclerosis risk factors. Methods and results77 patients were recruited: 44 men and 33 women, 38 without DVT (65.9 ± 16.3 years, range 26–92 years) and 39 with DVT (65.4 ± 17.2 years, range 28–90 years). The study design was balanced for established atherosclerosis risk factors (gender, obesity, smoking habits, dyslipidemia, diabetes mellitus, arterial hypertension), for previous cardiovascular events, for use of statins and platelet anti-aggregating agents. Multivariate regression model and RECPAM regression tree were used to study the association between EpiF thickness and the other potential risk factors. Patients with DVT showed a thicker EpiF with respect to those without DVT (12 ± 2 mm vs. 9 ± 2 mm respectively, p < 0.001). Multivariate linear regression model showed that DVT, obesity and age were positively associated with EpiF thickness after adjusting for the established atherosclerosis risk factors. Furthermore, the RECPAM analysis was performed to evaluate interactions between DVT, age and obesity: four main distinct and homogeneous subgroups of patients in terms of EpiF thickness were identified. The most important variable in partitioning patients was represented, as expected, by DVT (p < 0.001) followed by age (p = 0.004), while obesity did not contribute to the model as well as the other atherosclerosis risk factors. Patients with DVT and older than 41 years of age had higher EpiF thickness in respect of patients with DVT and younger than 41 years of age. In patients without DVT the estimated cut-off age was 50 years, and older patients had thicker EpiF in respect of patients younger than 50 years of age. Conclusion: DVT should be considered as strongly associated with EpiF thickness. Advancing age (with or without spontaneous DVT) is significantly associated with an increased EpiF thickness. The measurement of EpiF thickness, a valuable marker of cardio-metabolic risk, may represent a useful and reliable method to evaluate cardiovascular risk in patients with idiopathic deep phlebothrombosis.

Pd- and Cu-catalyzed C–H arylation of indazoles

The palladium- and copper-catalyzed C–H arylation reactions of 1H- and 2H-indazoles with haloarenes are described. A PdCl2/phen/Ag2CO3/K3PO4 catalytic system is effective for the C–H arylation of 1H- and 2H-indazoles with haloarenes, whereas a less expensive CuI/phen/LiOt-Bu catalytic system is applicable to the C–H coupling of substituted 2H-indazoles and iodoarenes. The utility of newly developed catalyst was demonstrated in the rapid synthesis of YC-1 (an antitumor agent) and YD-3 (platelet anti-aggregating agent). These new reactions represent important direct functionalization tools of indazoles, well-known bioisosteres of pharmaceutically important indole core.

Stable nanomicelles based on chitosan derivative: In vitro antiplatelet aggregation and adhesion properties

Amphiphilic chitosan derivative (SA-chitosan), water insoluble chitosan modified with salicylic acid (SA), possessed both antiplatelet aggregation and adhesion properties. Chemical structure was characterized by FTIR and 1H NMR. The SA substitution degree calculated by 1H NMR was 70.8%. SA-chitosan can form micelles (size: 292 ± 2 nm). The Critical aggregation concentration (CAC) value (1.216 × 10−4 mg/mL) and zeta potential (52 mV) indicated that they had excellent dispersion stability. TEM image suggested that the micelles were almost spherical. The result of in vitro antiplatelet activity revealed that the potential platelet aggregation inhibitory activity by different agonists was in a dose-dependent manner. At low SA-chitosan concentrations, antiplatelet aggregation capability of SA-chitosan was better than that of low-dose aspirin. The platelet adhesion test showed significant difference between the effect of SA-chitosan and that of the control group (p < 0.05). These results indicated that SA-chitosan can be potentially used as an antiplatelet aggregation and adhesion agent.

Ligustrazine derivatives. Part 5: Design, synthesis and biological evaluation of novel ligustrazinyloxy-cinnamic acid derivatives as potent cardiovascular agents

A series of novel ligustrazinyloxy-cinnamic acid derivatives were designed, synthesized and evaluated for their inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation in vitro, and also assayed for their protective effect against hydrogen peroxide (H2O2)-induced oxidative damage on ECV-304 cells. Some compounds exhibited high activity in one or both of the assays, of which, compound 2e displayed the highest protective effect on the proliferation of the damaged ECV-304 cells (EC50=0.020mM), and compound 2f was the most active anti-platelet aggregation agent (EC50=0.054mM). Structure–activity relationships were briefly discussed.

Increasing the symmetry of drug crystals: a monoclinic conformational polymorph of the platelet antiaggregating agent ticlopidine hydrochloride

Ticlopidine hydrochloride (TICLID®) is a platelet antiaggregating agent whose use as a potent antithrombotic pharmaceutical ingredient is widespread, even though this drug has not been well characterized in the solid state. Only the crystal phase used for drug product manufacturing is known. Here, a new polymorph of ticlopidine hydrochloride was discovered and its structure was determined. While the antecedent polymorph crystallizes in the triclinic space groupP , the new crystal phase was solved in the monoclinic space groupP21/c. Both polymorphs crystallize as racemic mixtures of enantiomeric (ticlopidine)+ cations. Detailed geometrical and packing comparisons between the crystal structures of the two polymorphs have allowed us to understand how different supramolecular architectures are assembled. It was feasible to conclude that the main difference between the two polymorphs is a rotation of about 120° on the bridging bond between the thienopyridine and o-chlorobenzyl moieties. The differential o-chlorobenzyl conformation is related to changeable patterns of weak intermolecular contacts involving this moiety, such as edge-to-face Cl⋯π and C–H⋯π interactions in the new polymorph and face-to-face π⋯π contacts in the triclinic crystal phase, leading to a symmetry increase in the ticlopidine hydrochloride solid state form described for the first time in this study. Other conformational features are slightly different between the two polymorphs, such as the thienopyridine puckerings and the o-chlorophenyl orientations. These conformational characteristics were also correlated to the crystal packing patterns.

What Lessons Have We Learned in the Past 40 Years?

Before 1970, there was no journal devoted to cerebral vascular disease. Only hypertension had been identified as a potentially treatable risk factor for stroke, and there were no established specific therapies for preventing or treating stroke. Imaging was limited to x-ray or x-ray with contrast (angiography, pneumoencephalography, or ventriculography) and very primitive ultrasound. In 1970, the journal Stroke was born and during the next 40 years many advancements occurred. CT, MRI, positron emission tomography, and ultrasound were introduced and further perfected as extremely effective diagnostic instruments. For the first time, we could visualize the nervous system and measure its function in vivo. The major risk factors were identified, and the significant effectiveness of preventive treatment was established for hypertension, tobacco use, lipidemia, and other potentially treatable risk factors. The value and the indications have been defined for platelet antiaggregating agents, thrombolytic therapy, statins, anticoagulant therapy for atrial fibrillation, carotid endarterectomy, and coiling for aneurysm and arteriovenous malformations. Genetics became a major tool in the investigation of cerebrovascular disease. Vascular dementia and its relationship to other dementias have been better identified. The lack of effectiveness of extracranial–intracranial bypass procedures in most ischemic vascular disease has been shown. Steady progress is being made in the understanding of the mechanisms of brain injury, repair, and plasticity. All these and more have been added to our knowledge. These are not the lessons, but they are the results of the lessons we have learned. To address these lessons, we need to go back even further than the past 40 years. Although I cannot equal Dr Barnett’s 65 years, my 56 years as a physician have led to similar conclusions. So, forgive us if we overlap. Like most of the older people in the field, our acceptance and crusade for the “lessons” were initiated and reinforced …

Timosaponin AIII, a saponin isolated from Anemarrhenaasphodeloides, ameliorates learning and memory deficits in mice

Anemarrhena asphodeloides Bunge (AA, family Liliaceae), which primarily contains xantones, such as mangiferin, and steroidal saponins, such as timosaponin AIII and sarsasapogenin, has been used as an anti-pyretic, anti-inflammatory, anti-diabetic, anti-platelet aggregation, and anti-depressant agent in traditional Chinese medicine. In the present study, the memory-enhancing effects of these saponins were investigated in scopolamine-treated mice. Among saponins, timosaponin AIII (TA3) significantly reversed the scopolamine-induced deficits in a passive avoidance test and in the Morris water maze test. TA3 also increased hippocampal acetylcholine levels in scopolamine-treated mice and dose-dependently inhibited acetylcholinesterase (AChE) activity (IC 50 value, 35.4 μM). When TA3 (50 mg/kg) was orally administered to mice and its blood concentration was measured by liquid chromatography and tandem mass spectrometry, the C max of TA3 occurred 4–6 h after TA3 treatment. The memory-enhancing effect of TA3 was greater when it was administered 5 h before the acquisition trial than 1 h before. Scopolamine treatment in mice increased brain levels of TNF-α and IL-1β expression. However, treatment with TA3 and scopolamine inhibited the increase of TNF-α and IL-1β expression. These results suggest that scopolamine may cause learning and memory deficits that are further complicated by inflammation. TA3 also inhibited the activation of NF-κB signaling in BV-2 microglia and in SK-N-SH neuroblastoma cells induced with TNF-α or scopolamine. Nevertheless, TA3 may ameliorate memory deficits, mainly by inhibiting AChE.

Ligustrazine derivatives. Part 3: Design, synthesis and evaluation of novel acylpiperazinyl derivatives as potential cerebrocardiac vascular agents

A series of novel acylpiperazinyl Ligustrazine derivatives was designed, synthesized, and their protective effects on damaged ECV-304 cells and antiplatelet aggregation activities were evaluated. The results showed that compound E33 displayed most potential protective effects on the ECV-304 cells damaged by hydrogen peroxide, and compound E1 was found to be the most active antiplatelet aggregation agent. Structure–activity relationships were briefly discussed.

Activation of tyrosine hydroxylase prevents pneumonia in a rat chronic cerebral hypoperfusion model

Pneumonia is a common complication with the highest attributable proportion of deaths in patients with stroke. Cilostazol is a potent type III phosphodiesterase inhibitor, approved as an anti-platelet aggregation agent. The present study was designed to determine the protective mechanism of cilostazol against post-stroke pneumonia using a rat chronic cerebral hypoperfusion model. Rats were subjected to bilateral common carotid artery ligation (LBCCA) and divided randomly into the vehicle group (n=72) and cilostazol group (n=72). Rats of each group were sacrificed at baseline and at days 14, 28 and 42 after LBCCA. Cilostazol significantly improved the swallowing reflex by shortening the latency to elicited swallowing and increasing the numbers of swallows (P<0.05) at 14 days of hypoperfusion. It also decreased the numbers of bacterial colonies grown in cultures from homogenized lungs. Cilostazol markedly upregulated cyclic AMP responsive element binding protein (CREB) phosphorylation, increased tyrosine hydroxylase (TH) expression in the substantial nigra, and maintained dopamine (84.7±2.3 vs. 79.2±4.1% control; P=0.0512) and substance P levels (86.6±7.9 vs. 73.9±6.5% control; P<0.05) in the striatum, compared with the vehicle group. Our results indicate that cilostazol improves the swallowing reflex by enhancing the expression of TH through the CREB phosphorylation signaling pathway, and suggest that cilostazol could be useful in preventing pneumonia in the chronic stage of stroke.

Design, synthesis, and biological activities of novel Ligustrazine derivatives

A series of novel Ligustrazine derivatives was designed, synthesized, and assayed for their protective effects on damaged ECV-304 cells and antiplatelet aggregation activities. The results showed that most Ligustrazine derivatives exhibited lower EC 50 values for protective effects on the ECV-304 cells damaged by hydrogen peroxide in comparison with Ligustrazine. And some Ligustrazine derivatives presented better antiplatelet aggregation activities than Ligustrazine. The derivatives containing the bisphenylmethyl pharmacophore ( 7a– c) exhibited highest potency. Compound 7a displayed most potential protective effects on the ECV-304 cells damaged by hydrogen peroxide, and compound 7c was found to be the most active antiplatelet aggregation agent. Structure–activity relationships were briefly discussed.

α-Bulnesene, a novel PAF receptor antagonist isolated from Pogostemon cablin

α-Bulnesene is a sesquiterpenoid isolated from the water extract of Pogostemon cablin. It showed a potent and concentration-dependent inhibitory effect on platelet-activating factor (PAF) and arachidonic acid (AA) induced rabbit platelet aggregation. In a radioligand binding assay for the PAF receptor, α-bulnesene competitively inhibited [ 3H]PAF binding to the PAF receptor with an IC 50 value of 17.62 ± 5.68 μM. α-Bulnesene also dose-dependently inhibited PAF-induced intracellular Ca 2+ increase in fluo-3/AM-loaded platelets (IC 50 values of 19.62 ± 1.32 μM). Furthermore, α-bulnesene inhibited AA-induced thromboxane B 2 (TXB 2) formation and prostaglandin E 2 (PGE 2) formation. These results indicate that the inhibitory effect of α-bulnesene on platelet aggregation was due to a dual activity; specifically the chemical blocked PAF-induced intracellular signal transduction and interfered with cyclooxygenase activity, which resulted in a decrease in thromboxane formation. This study is the first to demonstrate that α-bulnesene is a PAF receptor antagonist as well as an anti-platelet aggregation agent.