Synthesis of 12-quinoline substituted andrographolide derivatives and their preliminary evaluation as anti-aggregation drugs

Based on the structure of the natural product andrographolide, a series of novel 12-quinoline substituted derivatives 9 were designed and synthesized. In preliminary biological evaluation, these synthesized compounds showed prominent anti-platelet aggregation activities in response to thrombin and adenosine diphosphate (ADP) agonists. Among them, compound 9o (inhibition rate 55.73%, IC50 0.36 µM/L) had the highest anti-platelet aggregation activity induced by ADP. Compound 9q (inhibition rate 54.31%, IC50 0.30 µM/L) showed the highest anti-platelet aggregation activity induced by thrombin. Most of the derivatives had no significant cytotoxicity. Our research results provide a novel candidate drug structure for anti-platelet aggregation and enrich the scope of application of andrographolide derivatives.

Vascular Stents Coated with Electrospun Drug-Eluting Material: Functioning in Rabbit Iliac Artery

A stenting procedure aimed at blood flow restoration in stenosed arteries significantly improves the efficiency of vascular surgery. However, the current challenge is to prevent neointimal growth, which reduces the vessel lumen, in the stented segments in the long run. We tested in vivo drug-eluting coating applied by electrospinning to metal vascular stents to inhibit the overgrowth of neointimal cells via both the drug release and mechanical support of the vascular wall. The blend of polycaprolactone with human serum albumin and paclitaxel was used for stent coating by electrospinning. The drug-eluting stents (DESs) were placed using a balloon catheter to the rabbit common iliac artery for 1, 3, and 6 months. The blood flow rate was ultrasonically determined in vivo. After explantation, the stented arterial segment was visually and histologically examined. Any undesirable biological responses (rejection or hemodynamically significant stenosis) were unobservable in the experimental groups. DESs were less traumatic and induced weaker neointimal growth; over six months, the blood flow increased by 37% versus bare-metal stents, where it increased by at least double the rate. Thus, electrospun-coated DESs demonstrate considerable advantages over the bare-metal variants.

Synthesis and in vitro anti-platelet aggregation activities of 2-methoxy-5-arylamido-N-(pyridin-3-yl-methyl)benzamides

In order to discover novel compounds with anti-platelet aggregation activities, a series of novel 2-methoxy-5-arylamido-N-(pyridin-3-ylmethyl)benzamides (1a-n) were synthesized and their anti-platelet aggregation activities were evaluated by the turbidimetric method in response to the following agonists: adenosine diphosphate (ADP) (5 mM/L), arachidonic acid (AA) (20 µM/L), and collagen (1 mg/mL). Those synthesized compounds that have better in vitro activities were subjected to cell toxicity tests via cell counting kit-8 (CCK-8) assay. The biological evaluation revealed that compound 1a (IC₅₀ : 0.21 µM/L) exhibited the highest anti-platelet aggregation activities when ADP was selected as an inducer, and compound 1b (IC₅₀ : 0.23 µM/L) showed the best activities when AA was selected as inducer, and compound 1m (inhibition rate: 55.06%) had significant anti-platelet aggregation activities when collagen was selected as inducer among all target compounds. Moreover, the effect of cell toxicity exhibited that none of the compounds had obvious cell toxicity against L929 cells. Therefore, 2-methoxy-5-arylamido-N-(pyridin-3-ylmethyl)benzamides have the potential to become a novel kind of anti-platelet drugs and deserve further study.

[Budget impact analysis of antiplatelet therapy with ticagrelor and clopidogrel in patients with acute coronary syndrome after coronary artery bypass surgery]

AIM

Clinical and economic examinations were made to study whether it is appropriate to use antiplatelet therapy (APT) with ticagrelor in combination with acetylsalicylic acid (ASA) versus a combination of clopidogrel and ASA in patients with acute coronary syndrome (ACS) following coronary artery bypass surgery (CABS).

MATERIAL AND METHODS

A budget impact analysis was used. Data on the efficiency and safety of APT were taken from a relevant analysis in the subgroups of the randomized controlled trial PLATO. Direct medical cost due to APT and expenses on therapy for acute myocardial infarction, stroke, and massive bleeding, and those on medical care for patients dying from cardiovascular events and other causes, as well as indirect cost - gross domestic product (GDP) losses due to untimely death, were taken into account. The findings were assessed from the perspectives of society.

RESULTS

The analysis indicated that direct medical costs per patient following CABS, both in case of calculation based on the recorded price for ticagrelor and on the median registered prices for clopidogrel generics, and based on the auction prices for comparison agents proved to be lower when clopidogrel was administered because of the higher cost of ticagrelor-based APT. At the same time GDP losses due to untimely death, as calculated per patient with ACS during post-CABS therapy with clopidogrel + ASA, were more than twice above average losses per patient taking ticagrelor in combination with ACA (107,122 and 221,645 rubles, respectively). From the registered price for ticagrelor and the median registered prices for clopidogrel generics, the total costs per patient with ACS following CABS were lower if Brilinta was used in combination with ASA versus therapy with clopidogrel in combination with ASA (210,092 and 273,257 rubles per year, respectively; the cost savings were 63,165 rubles per patient per year when ticagrelor was administered). On the basis of the auction prices for comparison drugs, the total costs per patient with ACS after CABS proved to be lower if Brilinta was used in combination with ASA versus therapy with brand name clopidogrel in combination with ASA (201,018 and 293,982 rubles per patients year, respectively; the cost savings were 92,963 rubles per patient per year when ticagrelor was used).

CONCLUSION

The use of ticagrelor in combination with ASA ensures resource savings to treat ACS patients undergoing CABS as compared with a regiment including a combination of clopidogrel and ASA.

Perioperative management of patient with intracoronary stent presenting for noncardiac surgery

As the number of percutaneous coronary interventions increase annually, patients with intracoronary stents (ICS) who present for noncardiac surgery (NCS) are also on the rise. ICS is associated with stent thrombosis (STH) and requires mandatory antiplatelet therapy to prevent major adverse cardiac events. The risks of bleeding and ischemia remain significant and the management of these patients, especially in the initial year of ICS is challenging. The American College of Cardiologists guidelines on the management of patients with ICS recommend dual antiplatelet therapy (DAT) for minimal 14 days after balloon angioplasty, 30 days for bare metal stents, and 365 days for drug-eluting stents. Postponement of elective surgery is advocated during this period, but guidelines concerning emergency NCS are ambiguous. The risk of STH and surgical bleeding needs to be assessed carefully and many factors which are implicated in STH, apart from the type of stent and the duration of DAT, need to be considered when decision to discontinue DAT is made. DAT management should be a multidisciplinary exercise and bridging therapy with shorter acting intravenous antiplatelet drugs should be contemplated whenever possible. Well conducted clinical trials are needed to establish guidelines as regards to the appropriate tests for platelet function monitoring in patients undergoing NCS while on DAT.

Anti-platelet and anti-thrombogenic effects of shikimic acid in sedentary population

This ex vivo study was performed to evaluate the anti-platelet and anti-thrombogenic potential of shikimic acid (SA), a plant phenolic metabolite. Fasting blood samples were collected from 22 sedentary participants to analyse the effect of varying concentrations of SA (0.1 mM, 0.2 mM, 0.5 mM, 1 mM and 2 mM) on platelet surface-marker expression, platelet aggregation and biomarkers of thrombogenesis. Monocyte-platelet aggregates (CD14/CD42b) and platelet endothelial cell adhesion molecule-1 (PECAM-1 or CD31), effective indicators of thrombus formation were evaluated. Procaspase-activating compound 1 (PAC-1) and P-selectin or CD62P were used to assess platelet activation-related thrombogenesis. Adenosine diphosphate (ADP) was used to stimulate the P2Y1/P2Y12 pathway of platelet activation to mimic the in vivo thrombogenic pathway. Platelet aggregation studies utilised both ADP and collagen as exogenous platelet agonists to target both P2Y1/P2Y12 and GPVI pathways of thrombus formation. It was observed with flow cytometry that SA produced a significant antiplatelet effect on PAC-1 (p = 0.03 at 2 mM) and CD62P (p = 0.017, p = 0.036 at 1 mM and 2 mM respectively) expression in addition to lowering monocyte-platelet aggregate formation (p = 0.013, p < 0.01 and p < 0.01 at 0.5 mM, 1 mM and 2 mM respectively). SA at 1 mM concentration reduced PECAM-1 expression (p = 0.035), signifying a reduction to endothelial leucocyte migration during thrombus growth. SA did not demonstrate a platelet aggregation inhibitory effect by targeting the GPVI collagen pathway but reduced ADP induced platelet aggregation at 2 mM concentration (p < 0.01 at 2 mM). The results suggest that SA, an active metabolite of polyphenol-rich food intake, could play an important role in reducing platelet activation, aggregation related thrombus formation and biomarkers of thrombogenesis in sedentary individuals.

Synthesis and antiplatelet activity of antithrombotic thiourea compounds: biological and structure-activity relationship studies

The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p) displayed IC₅₀ values ranging from 29 to 84 µM with direct influence over in vitro PGE₂ and TXA₂ formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE₂ and TXB₂ production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

The ex vivo antiplatelet activation potential of fruit phenolic metabolite hippuric acid

Active metabolite of polyphenol intake, hippuric acid, reduces platelet activation-related conformational change and de-granulationex vivothereby alleviating thrombogenesis.

Perioperative Management of the Patient with a Coronary Artery Stent

The need for the preoperative continuation of chronic antiplatelet therapy with coronary artery stents can be challenging and remains controversial.

Preoperative management of antiplatelet drugs for a coronary artery stent: how can we hit a moving target?

Background

With the advent of percutaneous coronary intervention, specifically the bare metal stent and subsequently, the drug-eluting stent, the scope of interventional cardiology has greatly increased. Aspirin, in combination with a thienopyridine is the present-day cornerstone of oral antiplatelet therapy after coronary artery stent placement. Continuing this chronic antiplatelet therapy, to mitigate a perioperative major adverse cardiac event, can be challenging and remains controversial in patients with a coronary artery stent undergoing non-cardiac surgery. We describe here the rationale for and successful use of an alternate approach to formulating local institutional management protocols for patients with a coronary artery stent, undergoing an elective surgical procedure.

Discussion

A recent systematic review identified 11 clinical practice guidelines for the perioperative management of antiplatelet therapy in patients with a coronary stent who need non-cardiac surgery. However, there is significant variance and inadequacy with these current applicable professional society guidelines. Moreover, persistently variable success has been experienced in translating even well-grounded national clinical guidelines into local practice, including in the perioperative setting. Under the auspices of a broadly multidisciplinary institutional task force and applying the Consensus-Oriented Decision-Making model, we created two evidence-informed and local expert opinion-supported standardized clinical assessment and management plans for the preoperative management of antiplatelet therapy in patients with a coronary artery stent.

Summary

Patient care can be optimized via evidence-based, yet locally developed and reiterative standardized clinical assessment and management plans for patients with coronary artery stents undergoing surgical procedures. Such standardized clinical assessment and management plans can result in greater consistency in care, providing a positive feedback loop in which the care plan itself can be continuously reevaluated, improved, and brought up to date with the most recent available data and knowledge.

A review of the mechanisms and effectiveness of dietary polyphenols in reducing oxidative stress and thrombotic risk

Dietary sources of polyphenols, which are derivatives and/or isomers of flavones, isoflavones, flavonols, catechins and phenolic acids, possess antioxidant properties and therefore might be important in preventing oxidative-stress-induced platelet activation and attenuating adverse haemostatic function. Free radicals, including reactive oxygen and nitrogen species, promote oxidative stress, leading to platelet hyperactivation and the risk of thrombosis. The consumption of antioxidant/polyphenol rich foods might therefore impart anti-thrombotic and cardiovascular protective effects via their inhibition of platelet hyperactivation or aggregation. Most commonly-used anti-platelet drugs such as aspirin block the cyclooxygenase (COX)-1 pathway of platelet activation, similar to the action of antioxidants with respect to neutralising hydrogen peroxide (H2 O2 ), with a similar effect on thromboxane production via the COX-1 pathway. Polyphenols also target various additional platelet activation pathways (e.g. by blocking platelet-ADP, collagen receptors); thus alleviating fibrinogen binding to platelet surface (GPIIb-IIIa) receptors, reducing further platelet recruitment for aggregation and inhibiting platelet degranulation. As a result of the ability of polyphenols to target additional pathways of platelet activation, they may have the potential to substitute or complement currently used anti-platelet drugs in sedentary, obese, pre-diabetic or diabetic populations who can be resistant or sensitive to pharmacological anti-platelet therapy.

Antiplatelet Treatment in the Secondary Prevention of Coronary and Cerebrovascular Disease

Ischemic heart disease and cerebrovascular disease remain major health problems with associated mortality and quality-of-life consequences. Antiplatelet agents, including thienopyridines and the new P2Y12 inhibitors, have been shown to improve survival in the secondary prevention setting. We review the available evidence on the effectiveness and safety of previous established as well as novel antithrombotic agents in the secondary prevention of cardiovascular disease with a special focus on cerebrovascular disease.

The effects of aminoglycoside antibiotics on platelet aggregation and blood coagulation

OBJECTIVE

To investigate the effects of different aminoglycoside antibiotics on platelet aggregation and blood coagulation, as well as the underlying mechanisms.

METHOD

Blood samples were collected and prepared as platelet-rich plasma and platelet-poor plasma samples. Then assigned into different groups for the following antibiotics treatments: gentamicin, streptomycin, etimicin, amikacin, and kanamycin, as group 0 mg/L, group 30 mg/L, group 91mg/L, and group 910 mg/L for each drugs. The maximum platelet aggregation rate induced by adenosine diphosphate, expression levels of CD62p and FIB-R, prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen were measured. The sodium citrate and sodium heparin were used in whole blood tests for the whole blood coagulation time as well as the Ca(2+) in blood plasma.

RESULTS

Amikacin and gentamicin could inhibit the aggregation of platelets, which contributed to the whole blood clotting disorder.

CONCLUSION

Amikacin and gentamicin might inhibit the platelet aggregation by blocking the activation and release of FIB-R or probably the inhibition of endogenous clotting factor as well. This effect was not dependent on calcium ions.