Novel antiplatelet activity of protocatechuic acid through the inhibition of high shear stress-induced platelet aggregation

Network pharmacology and experimental verification to explore the anti-superficial thrombophlebitis mechanism of Mailuo shutong pill

ETHNOPHARMACOLOGICAL RELEVANCE

Mailuo shutong pill (MLST) has been widely used in clinical treatment of superficial thrombotic phlebitis (STP). Nevertheless, the major active components of MLST and the mechanism of synergistic action have not been reported.

AIM OF THE STUDY

The present study aimed to evaluate the improving effects and the underlying mechanism of MLST on mannitol-induced STP in rabbits.

MATERIAL AND METHODS

In this study, Ultrahigh-performance liquid chromatography electrospray ionization quadrupole-exactive orbitrap mass spectrometry (UHPLC-ESI-Q-Exactive-Orbitrap-MS) was used to analyze and identify the chemical composition of MLST and the prototype components absorbed into the blood. Then, according to the prototype components in serum, the targets and mechanisms of MLST were explored by applying network pharmacology. The rabbit model of STP was established by injecting 20% mannitol into bilateral auricular vein. The pathological changes of rabbit ear tissues, inflammatory factors, coagulation function and hemorheology were detected. In addition, molecular docking verified the interaction between the main active ingredient and the key target. Finally, the PI3K/AKT pathway and its regulated downstream pathways were verified by Western blot.

RESULTS

A total of 96 MLST components and 53 prototypical components absorbed into the blood were successfully identified. Based on network pharmacology, PI3K/AKT pathway and 10 chemical components closely related to this pathway were obtained. Hematoxylin-eosin (HE) staining results indicated that MLST effectively improved of the pathological damage of ear tissues. MLST decreased levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and C-reactive protein (CRP). The expression of platelets (PLT) and fibrinogen concentration (FIB) was decreased, while prothrombin time (PT) and activated partial thromboplastin time (APTT) were prolonged. In addition, the plasma viscosity and whole blood viscosity in the MLST groups were significantly decreased. The more important discovery was that the expressions of P-PI3K, VEGF, P-AKT, P-IκB-α, P-NF-κB, NLRP3, ASC, Cleaved IL-1β and Cleaved Caspase-1 were effectively reversed after treatment with MLST.

CONCLUSIONS

This study comprehensively analyzed and characterized the chemical composition of MLST and the prototypical components absorbed into the blood. This study strongly confirmed the pharmacodynamic effect of MLST on STP. More importantly, this pharmacodynamic effect was achieved through inhibition of the PI3K/AKT pathway and its regulated NF-κB and NLRP3 pathways.

Urinary Exosomal Metabolites: Overlooked Clue for Predicting Cardiovascular Risk

Over the last decade, increasing research has focused on urinary exosomes (UEs) in biological fluids and their relationship with physiological and pathological processes. UEs are membranous vesicles with a size of 40-100 nm, containing a number of bioactive molecules such as proteins, lipids, mRNAs, and miRNAs. These vesicles are an inexpensive non-invasive source that can be used in clinical settings to differentiate healthy patients from diseased patients, thereby serving as potential biomarkers for the early identification of disease. Recent studies have reported the isolation of small molecules called exosomal metabolites from individuals' urine with different diseases. These metabolites could utilize for a variety of purposes, such as the discovery of biomarkers, investigation of mechanisms related to disease development, and importantly prediction of cardiovascular diseases (CVDs) risk factors, including thrombosis, inflammation, oxidative stress, hyperlipidemia as well as homocysteine. It has been indicated that alteration in urinary metabolites of N1-methylnicotinamide, 4-aminohippuric acid, and citric acid can be valuable in predicting cardiovascular risk factors, providing a novel approach to evaluating the pathological status of CVDs. Since the UEs metabolome has been clearly and precisely so far unexplored in CVDs, the present study has specifically addressed the role of the mentioned metabolites in the prediction of CVDs risk factors.

Protocatechuic acid boosts continual efferocytosis in macrophages by derepressing KLF4 to transcriptionally activate MerTK

Macrophages clear apoptotic cells through a process called continual efferocytosis. We found that protocatechuic acid (PCA), a polyphenolic compound abundant in fruits and vegetables, increased the continual efferocytic capacity of macrophages and inhibited the progression of advanced atherosclerosis. PCA reduced the intracellular amounts of microRNA-10b (miR-10b) by promoting its secretion in extracellular vesicles, which led to an increase in the abundance of the miR-10b target Krüppel-like factor 4 (KLF4). In turn, KLF4 transcriptionally induced the gene encoding Mer proto-oncogene tyrosine kinase (MerTK), an efferocytic receptor for the recognition of apoptotic cells, resulting in increased continual efferocytic capacity. However, in naive macrophages, the PCA-induced secretion of miR-10b did not affect KLF4 and MerTK protein abundance or efferocytic capacity. In mice, oral administration of PCA increased continual efferocytosis in macrophages residing in the peritoneal cavities, thymi, and advanced atherosclerotic plaques through the miR-10b-KLF4-MerTK pathway. In addition, pharmacological inhibition of miR-10b with antagomiR-10b also increased the efferocytic capacity of efferocytic but not naive macrophages in vitro and in vivo. Together, these data describe a pathway that promotes continual efferocytosis in macrophages through miR-10b secretion and a KLF4-dependent increase in MerTK abundance, which can be activated by dietary PCA and which has implications for understanding the regulation of continual efferocytosis in macrophages.

Antiplatelet Aggregation Properties of Cirsilineol: A Novel Inhibitor of Blood Coagulation Factor Xa

A small natural substance called cirsilineol (CSL), which was discovered in the plant Artemisia vestita, is lethal to many cancer cells and has antioxidant, anticancer, and antibacterial properties. Here, we investigated the underlying mechanisms of the antithrombotic action of CSL. We demonstrated that CSL has antithrombotic efficacy comparable to rivaroxaban, a direct blood coagulation factor Xa (FXa) inhibitor employed as a positive control, in inhibiting the enzymatic activity of FXa and the platelet aggregation induced by adenosine diphosphate (ADP) and U46619, a thromboxane A2 analog. The expression of P-selectin, the phosphorylation of myristoylated alanine-rich C kinase substrate by U46619 or ADP, and the activation of PAC-1 in platelets were inhibited by CSL. Nitric oxide production was increased by CSL in ADP- or U46619-treated human umbilical vein endothelial cells (HUVECs), although excessive endothelin-1 secretion was suppressed. CSL demonstrated strong anticoagulant and antithrombotic effects in a mouse model of arterial and pulmonary thrombosis. Our findings suggest that CSL is a potential pharmacological candidate for a novel class of anti-FXa and antiplatelet medications.

Cytotoxicity profiling of choline chloride-based natural deep eutectic solvents

This study aims to examine in detail for the first time the cytotoxic profile of twelve choline chloride-based deep eutectic solvents (NADES) against HT-29, Caco-2, MCF-7, and MRC-5 cell lines. All NADES systems were synthesized by microwave synthesis using choline chloride as a hydrogen bond acceptor (HBA) and selected sugars, alcohols, organic acids, and urea as hydrogen bond donors (HBD) with the addition of 20% water (w/w) to all systems. It was observed that the cytotoxic effect predominantly depended on the structure of HBD. Acidic systems, where HBDs were organic acids showed the highest cytotoxic effects in all investigated cell lines. The cytotoxicity depended mostly on the concentration of the NADES system in the cell medium as well as on the chemical constitution of the investigated systems. The highest cytotoxic effects showed acidic systems, especially to the HT-29 cell line. The EC₅₀ value for the citric acid-based system was 3.91 mg mL^-1 for the HT-29 cell line which was the most vulnerable to acidic NADES systems.

Pathology of catheter-related complications: what we need to know and what should be discovered

Despite the considerable efforts made to increase the prevalence of autogenous fistula in patients on hemodialysis, tunneled cuffed catheters are still an important access modality and used in a high percentage of the hemodialysis population. However, because of the conundrum posed by tunneled cuffed catheters, patients can develop a multitude of complications, including thrombosis, infections, formation of a fibrin sheath, and central vein stenosis, resulting in increased morbidity and mortality as well as placing a heavy burden on the healthcare system. However, with an increasing number of studies now focusing on how to manage these catheter-related complications, there has been less translational research on the pathology of these complications. This review of the most recent literature provides an update on the pathological aspects of catheter-related complications, highlighting what we need to know and what is yet to be discovered. The future research strategies and innovations needed to prevent these complications are also addressed.

In Vitro Antithrombotic, Hematological Toxicity, and Inhibitor Studies of Protocatechuic, Isovanillic, and p-Hydroxybenzoic Acids from Maclura Tricuspidata (Carr.) Bur

In blood coagulation, circulating platelets and coagulation factors are crucial for the primary process because thrombi are generated by fibrin clotting with fibrinogen, thrombin, FXIIIa, and platelet activation. Therefore, strategies to reduce the activity of key coagulation factors, or interfere with their functions and delay the activation of platelets can be used as important tools to suppress excessive blood clot formation and platelet hyperactivation. This study examined the antithrombotic activity and hematological toxicity of PA, IVA, and 4-HA isolated from M. tricuspidata (Carr.) Bur in several in vitro experiments and inhibitor assays. We found that PA, IVA, and 4-HA attenuated the formation of fibrin polymers/clots and degraded the blood clots. These compounds inhibited the activities of procoagulant proteases and fibrinoligase, and prolonged the coagulation time. There was a significant reduction in platelet function and ATP or serotonin levels in thrombin-activated platelets. An inhibitor study showed that PA exhibited a mixed inhibition type for thrombin, an uncompetitive inhibition type for FXa, and a non-competitive inhibition type for FXIIIa and IVA, while 4-HA exhibited an uncompetitive inhibition type for thrombin and non-competitive inhibition type for FXa and FXIIIa. These three compounds (up to 50 μg/mL) were not toxic to blood cells.

Inhibition of factor Xa activity, platelet aggregation, and experimentally induced thrombosis by Sparstolonin B

BACKGROUND

Sparstolonin B (SsnB) is an isocumarin compound extracted from medicinal plants such as Sparganium stoloniferum and Scirpus yagara with well documented anti-inflammatory activity. Here we examined if SsnB also possesses antithrombotic activity and the underlying mechanisms.

METHODS

Anti-thrombotic effects of SsnB were determined by measuring in vitro/ex vivo/in vivo clotting times, platelet aggregation assay, production and activity of factor Xa, nitric oxide, and expressions of relative proteins.

RESULTS

Treatment with SsnB prolonged the clotting time of human platelet-poor serum at concentrations comparable to the clinical anticoagulant rivaroxaban (as a positive control) and inhibited human platelet aggregation induced by adenosine diphosphate (ADP) or the thromboxane A2 analog U46619. SsnB also inhibited U46619-induced and ADP-induced phosphorylation of phospholipase C (PLC)γ2/protein kinase C (PKC) and intracellular calcium mobilization, both of which are required for platelet aggregation. In addition, SsnB inhibited expression of the cell adhesion factors P-selectin and PAC-1. SsnB increased production of the vasodilator nitric oxide and suppressed secretion of the vasoconstrictor endothelin-1 from ADP- or U46619-treated human umbilical vein endothelial cells. Further, SsnB reduced coagulation factor Xa (FXa) catalytic activity and production by endothelial cells as well as FXa-induced platelet aggregation.

CONCLUSION

Finally, SsnB injection reduced thrombus formation time, number, size, and related mortality in mouse models of thromboembolism. SsnB is a promising antithrombotic agent targeting both FXa and platelet aggregation pathways, which can overcome the side effects of existing antithrombotic agents.

Current update on herbal sources of antithrombotic activity—a comprehensive review

Background

Herbs are commonly used to treat cardiovascular diseases in various traditional medicine. On the other hand, herb-drug interactions are most commonly encountered with conventional antiplatelet and anticoagulant drug prescriptions. This review presents a compilation of plants investigated for antiplatelet and anticoagulation recently and enumerates their possible lead compounds responsible for its action for paving further drug discovery and knowledge update.

Main body of the abstract

Information about the herbs was withdrawn from the PubMed database of the previous 5 years. We also hand-searched the bibliography of relevant articles for the acquisition of additional information. About 72 herbal sources were identified with the effect of antiplatelet activity, antithrombotic activity, and anticoagulant activity. Bioactive compounds and various secondary metabolites responsible for it, such as alkaloids, saponins, flavonoids, coumarins, polyphenols, furan derivatives, iridoid glycosides, sesquiterpenes, aporphine compounds, were reported.

Conclusion

Newer pharmacological moieties are needed to prevent or reduce the adverse effects of current anti-thrombotic agents and to improve the safety of patients and cost-effectiveness.

Role of Phaseolus vulgaris L. in the Prevention of Cardiovascular Diseases-Cardioprotective Potential of Bioactive Compounds

In terms of safe and healthy food, beans play a relevant role. This crop belongs to the species of Phaseolusvulgaris L., being the most consumed legume worldwide, both for poor and developed countries, the latter seek to direct their diet to healthy feeding, mainly low in fat. Phaseolus vulgaris L. stands out in this area-an important source of protein, vitamins, essential minerals, soluble fiber, starch, phytochemicals, and low in fat from foods. This species has been attributed many beneficial properties for health; it has effects on the circulatory system, immune system, digestive system, among others. It has been suggested that Phaseolus vulgaris L. has a relevant role in the prevention of cardiovascular events, the main cause of mortality and morbidity worldwide. Conversely, the decrease in the consumption of this legume has been related to an increase in the prevalence of cardiovascular diseases. This review will allow us to relate the nutritional level of this species with cardiovascular events, based on the correlation of the main bioactive compounds and their role as cardiovascular protectors, in addition to revealing the main mechanisms that explain the cardioprotective effects regulated by the bioactive components.

Regulation of Key Antiplatelet Pathways by Bioactive Compounds with Minimal Bleeding Risk

Cardiovascular disease is strongly influenced by platelet activation. Platelet activation and thrombus formation at atherosclerotic plaque rupture sites is a dynamic process regulated by different signaling networks. Therefore, there are now focused efforts to search for novel bioactive compounds which target receptors and pathways in the platelet activation process while preserving normal hemostatic function. The antiplatelet activity of numerous fruits and vegetables and their multiple mechanisms of action have recently been highlighted. In this review, we review the antiplatelet actions of bioactive compounds via key pathways (protein disulfide isomerase, mitogen-activated protein kinases, mitochondrial function, cyclic adenosine monophosphate, Akt, and shear stress-induced platelet aggregation) with no effects on bleeding time. Therefore, targeting these pathways might lead to the development of effective antiplatelet strategies that do not increase the risk of bleeding.

Nanotechnological Manipulation of Nutraceuticals and Phytochemicals for Healthy Purposes: Established Advantages vs. Still Undefined Risks

Numerous foods, plants, and their bioactive constituents (BACs), named nutraceuticals and phytochemicals by experts, have shown many beneficial effects including antifungal, antiviral, anti-inflammatory, antibacterial, antiulcer, anti-cholesterol, hypoglycemic, immunomodulatory, and antioxidant activities. Producers, consumers, and the market of food- and plant-related compounds are increasingly attracted by health-promoting foods and plants, thus requiring a wider and more fruitful exploitation of the healthy properties of their BACs. The demand for new BACs and for the development of novel functional foods and BACs-based food additives is pressing from various sectors. Unfortunately, low stability, poor water solubility, opsonization, and fast metabolism in vivo hinder the effective exploitation of the potential of BACs. To overcome these issues, researchers have engineered nanomaterials, obtaining food-grade delivery systems, and edible food- and plant-related nanoparticles (NPs) acting as color, flavor, and preservative additives and natural therapeutics. Here, we have reviewed the nanotechnological transformations of several BACs implemented to increase their bioavailability, to mask any unpleasant taste and flavors, to be included as active ingredients in food or food packaging, to improve food appearance, quality, and resistance to deterioration due to storage. The pending issue regarding the possible toxic effect of NPs, whose knowledge is still limited, has also been discussed.

(Poly)phenol-Rich Diets in the Management of Endothelial Dysfunction in Diabetes Mellitus: Biological Properties in Cultured Endothelial Cells

Processed and ready-to-eat foods become routinely consumed resulting in a sharp rise of sugar intake in people's daily diets. The inclusion of fresh fruits and vegetables rich in (poly)phenols has been encouraged by the World Health Organization (WHO) as part of the daily choices to ameliorate endothelial dysfunction and ease the socio-economic burden of diabetes. Research in Food, Nutrition, and Cell Metabolism areas is revealing that the health benefits of (poly)phenol-rich foods go beyond their antioxidant properties and are in fact key modulators of redox and glycaemia status, and inflammatory response contributing to improved endothelial function and vascular health in diabetes. Other beneficial aspects include appetite modulation, regulation of hydrolytic enzymes involved in sugar and lipid metabolism, and mediation of cell-cell aggregation events. This work overviews the current knowledge on the biological properties of ingested (poly)phenols in cultured endothelial cells with emphasis on the circulating (poly)phenols, providing support to (poly)phenol-rich diets as alternatives to drug-based therapies in the prevention, treatment, and management of diabetes. A critical evaluation on the caveats and challenges involve in current experimental cell-based designs and approaches adopted is also discussed.

Application of a Simple Microfluidic Chip Analysis Technology to Evaluate the Inhibitory Role of Protocatechuic Acid on Shear-Induced Platelet Aggregation

This study aimed to develop a simple microfluidic chip analysis technology to study the inhibitory effect of protocatechuic acid on shear-induced platelet aggregation. The microfluidic chip designed in this study simulates 80% fixed narrow microchannels. This microchannel narrow model uses the finite element analysis module of the three-dimensional modeling software solidwork to analyze fluid dynamic behavior. Blood treated with protocatechuic acid at 1, 2, 4, 8, or 16 µg/mL was passed through the microchannel stenosis model at a shear rate of 10,000 s⁻¹. The platelet adhesion and aggregation behaviors were then measured using fluorescence microscopy and observed in real time. Simultaneously, the antiplatelet aggregation effect of protocatechuic acid was analyzed using thromboelastography and photoelectric turbidimetry. The designed stenosis model of the microfluidic chip can produce a gradient of fluid shear rate, and the gradient of fluid shear rate can induce platelet aggregation. Under this model, the degree of platelet adhesion and aggregation increased as the shear rate increased. In the experimental concentration range of 0–8 µmol/mL, protocatechuic acid exerted a concentration-dependent inhibition of platelet aggregation. In contrast, thromboelastography and photoelectric turbidimetry failed to demonstrate an inhibitory effect. The microfluidic chip analysis technology developed in this study can be used to study the effect of protocatechin in inhibiting platelet aggregation induced by shear rate in vitro. This technology is simple to operate and can be used as a new type of antiplatelet aggregation analysis technology for screening studies of novel potential antiplatelet aggregation drugs.

Going "Green" in the Prevention and Management of Atherothrombotic Diseases: The Role of Dietary Polyphenols

During the 20th century processed and ready-to-eat foods became routinely consumed resulting in a sharp rise of fat, salt, and sugar intake in people's diets. Currently, the global incidence of obesity, raised blood lipids, hypertension, and diabetes in an increasingly aged population contributes to the rise of atherothrombotic events and cardiovascular diseases (CVD) mortality. Drug-based therapies are valuable strategies to tackle and help manage the socio-economic impact of atherothrombotic disorders though not without adverse side effects. The inclusion of fresh fruits and vegetables rich in flavonoids to human diets, as recommended by WHO offers a valuable nutritional strategy, alternative to drug-based therapies, to be explored in the prevention and management of atherothrombotic diseases at early stages. Though polyphenols are mostly associated to color and taste in foods, food flavonoids are emerging as modulators of cholesterol biosynthesis, appetite and food intake, blood pressure, platelet function, clot formation, and anti-inflammatory signaling, supporting the health-promoting effects of polyphenol-rich diets in mitigating the impact of risk factors in atherothrombotic disorders and CVD events. Here we overview the current knowledge on the effect of polyphenols particularly of flavonoid intake on the atherothrombotic risk factors and discuss the caveats and challenges involved with current experimental cell-based designs.

Protocatechuic Acid Protects Platelets from Apoptosis via Inhibiting Oxidative Stress-Mediated PI3K/Akt/GSK3β Signaling

Oxidative stress plays crucial roles in initiating platelet apoptosis that facilitates the progression of cardiovascular diseases (CVDs). Protocatechuic acid (PCA), a major metabolite of anthocyanin cyanidin-3-O-β-glucoside (Cy-3-g), exerts cardioprotective effects. However, underlying mechanisms responsible for such effects remain unclear. Here, we investigate the effect of PCA on platelet apoptosis and the underlying mechanisms in vitro. Isolated human platelets were treated with hydrogen peroxide (H₂O₂) to induce apoptosis with or without pretreatment with PCA. We found that PCA dose-dependently inhibited H₂O₂-induced platelet apoptosis by decreasing the dissipation of mitochondrial membrane potential, activation of caspase-9 and caspase-3, and decreasing phosphatidylserine exposure. Additionally, the distributions of Bax, Bcl-xL, and cytochrome c mediated by H₂O₂ in the mitochondria and the cytosol were also modulated by PCA treatment. Moreover, the inhibitory effects of PCA on platelet caspase-3 cleavage and phosphatidylserine exposure were mainly mediated by downregulating PI3K/Akt/GSK3β signaling. Furthermore, PCA dose-dependently decreased reactive oxygen species (ROS) generation and the intracellular Ca²⁺ concentration in platelets in response to H₂O₂. N-Acetyl cysteine (NAC), a ROS scavenger, markedly abolished H₂O₂-stimulated PI3K/Akt/GSK3β signaling, caspase-3 activation, and phosphatidylserine exposure. The combination of NAC and PCA did not show significant additive inhibitory effects on PI3K/Akt/GSK3β signaling and platelet apoptosis. Thus, our results suggest that PCA protects platelets from oxidative stress-induced apoptosis through downregulating ROS-mediated PI3K/Akt/GSK3β signaling, which may be responsible for cardioprotective roles of PCA in CVDs.

Chemical profiling of Honghua Xiaoyao tablet and simultaneous determination of its quality markers by liquid chromatography-tandem mass spectrometry combined with chemometrics methods

Discovering marker components of traditional Chinese medicine formulas is challenging because of the hundreds of components they inherently contain. This study first proposed a reliable and validated method for the comprehensive profiling of chemical constituents in Honghua Xiaoyao tablet by using high-performance liquid chromatography coupled with mass spectrometry. After searching within the in-house library, a total of 55 constituents were unambiguously characterized or tentatively identified through reference standards and by comparing mass spectrometry data with literature values. Quantitative analysis of 14 compounds, which were selected as the quality marker components based on a serum pharmacochemistry study, has been performed by triple-quardrupole mass spectrometry technique. Multiple chemometric methods, including principal components analysis and hierarchical cluster analysis, were subsequently used to analyze the quantitative results, classify samples from three manufacturers, and distinguish the analytical markers. In method validation results, 14 quality marker compounds have shown good linearity (R² ≥ 0.9965) with a relative wide concentration range and acceptable recovery at 98.39-102.46%. The proposed approach provides the chemical evidence for revealing the material basis of Honghua Xiaoyao tablet, and establishes a reliable statistical analysis-based strategy of quality marker investigation for controlling its quality.

Novel factor Xa inhibitor, maslinic acid, with antiplatelet aggregation activity

As antithrombotic effects of maslinic acid (MA) have not yet been studied, MA-mediated downregulation of coagulation factor Xa (FXa) and platelet aggregation was studied. We show that MA inhibited the enzymatic activity of FXa and platelet aggregation, induced by adenosine diphosphate (ADP) and a thromboxane A₂ (TXA₂ ) analog, U46619 with a similar antithrombotic efficacy to rivaroxaban, a direct FXa inhibitor used as a positive control. Mechanistically, MA suppressed U46619- or ADP-induced phosphorylation of myristoylated alanine-rich C kinase substrate, and the expression of P-selectin, and activated PAC-1 in platelets. MA increased generation of nitric oxide, but downregulated excessive secretion of endothelin-1 in ADP- or U46619-treated human umbilical vein endothelial cells. In arterial and pulmonary thrombosis mouse model, MA showed prominent anticoagulant and antithrombotic effects. Our data suggest MA as a candidate molecule for a new class of drugs targeting anti-FXa and antiplatelet.

Glucose challenge metabolomics implicates the change of organic acid profiles in hyperlipidemic subjects

Hyperlipidemia (HLP) is a major risk factor of diabetes and cardiovascular disease. Here, we applied gas chromatography-mass spectrometry to study differences in postprandial organic acid profiles in healthy and HLP subjects. In fasting status, six intermediates of the tricarboxylic acid cycle showed significant differences in HLP and healthy controls (P < 0.05). The percentage changes of 17 metabolites including three intermediates of the tricarboxylic acid cycle were significantly different during the oral glucose tolerance test. Postprandial changes in ethylmalonic acid and pimelic acid were negatively associated with HOMA-IR (homeostasis model assessment of insulin resistance; all P < 0.05) in the HLP group. Postprandial metabolism of organic acid profiles revealed energy metabolism perturbations in HLP. Our findings provide new insights into the complex physiological regulation of HLP postprandial metabolism.

Antithrombotic effect of SP-8008, a benzoic acid derivative, through the selective inhibition of shear stress-induced platelet aggregation

Background and Purpose

Bleeding is one of the most critical adverse effects of antithrombotic drugs, and many efforts have been made to discover novel antiplatelet agents without bleeding complications. Shear stress‐induced platelet aggregation (SIPA), where the interaction of von Willebrand factor (vWF) and platelet glycoprotein (GP) Ib constitutes the initial step, is a promising target to overcome bleeding problems, as SIPA occurs only in pathological conditions. Here, we describe SP‐8008, a novel modulator of vWF–GP Ib interactions and evaluated its antiplatelet/antithrombotic effects.

Experimental Approach

Newly synthesized compounds were screened for antiplatelet effects in vitro, using human platelets exposed to high shear stress. Aggregation, intracellular calcium level, granule secretion, and integrin activation were assessed. Molecular modelling using virtual docking and flow cytometry were used to evaluate effects on vWF–GP Ib interactions. Antithrombotic effects in vivo were determined in rats, using arterial thrombosis and shear stress‐specific thrombosis. Transection tail bleeding time was used to evaluate adverse effects.

Key Results

SP‐8008 was a potent inhibitor of SIPA, with IC₅₀ of 1.44 ± 0.09 μM. SP‐8008 effectively and broadly blocked shear stress‐induced platelet activation events, without any significant toxicity. Importantly, SP‐8008 was highly selective against SIPA, effectively interfering with vWF–GP Ib engagement. Most importantly, SP‐8008 exerted significant antithrombotic effects in vivo in both shear stress‐specific and arterial thrombosis, without prolonging bleeding time.

Conclusions and Implications

Our results demonstrated that SP‐8008 can be a novel selective antiplatelet agent with improved safety profile.

Antithrombotic Effects of Paeoniflorin from Paeonia suffruticosa by Selective Inhibition on Shear Stress-Induced Platelet Aggregation

Antiplatelet agents are important in the pharmacotherapeutic regime for many cardiovascular diseases, including thrombotic disorders. However, bleeding, the most serious adverse effect associated with current antiplatelet therapy, has led to many efforts to discover novel anti-platelet drugs without bleeding issues. Of note, shear stress-induced platelet aggregation (SIPA) is a promising target to overcome bleeding since SIPA happens only in pathological conditions. Accordingly, this study was carried out to discover antiplatelet agents selectively targeting SIPA. By screening various herbal extracts, Paeonia suffruticosa and its major bioactive constituent, paeoniflorin, were identified to have significant inhibitory effects against shear-induced aggregation in human platelets. The effects of paeoniflorin on intraplatelet calcium levels, platelet degranulation, and integrin activation in high shear stress conditions were evaluated by a range of in vitro experiments using human platelets. The inhibitory effect of paeoniflorin was determined to be highly selective against SIPA, through modulating von Willebrand Factor (vWF)-platelet glycoprotein Ib (GP Ib) interaction. The effects of paeoniflorin on platelet functions under high shear stress were confirmed in the ex vivo SIPA models in rats, showing the good accordance with the anti-SIPA effects on human platelets. Treatment with paeoniflorin significantly prevented arterial thrombosis in vivo from the dose of 10 mg/kg without prolonging bleeding time or blood clotting time in rats. Collectively, our results demonstrated that paeoniflorin can be a novel anti-platelet agent selectively targeting SIPA with an improved safety profile.

Reshaped as polyester-based nanoparticles, gallic acid inhibits platelet aggregation, reactive oxygen species production and multi-resistant Gram-positive bacteria with an efficiency never obtained

Natural polyphenols such as Gallic Acid (GA) form an important class of bioactive chemical entities that, having innumerable biological properties, could represent a safer alternative to common drugs against several disorders, including platelet aggregation, radical oxygen species (ROS) hyperproduction, oxidative stress (OS) and bacterial infections. Unfortunately, their clinical uses are limited by pharmacokinetics drawbacks and high sensitivity to environmental factors. In order to overcome these problems and to exploit the GA curative potentials, it has been linked to a biodegradable nanospherical dendrimer matrix, capable of protecting it, thus obtaining a GA-enriched nanosized dendrimer (GAD) endowed with a strong antioxidant capacity. GAD activity as an inhibitor of platelet aggregation and ROS accumulation and its antibacterial efficiency are evaluated here and compared to those of free GA, obtaining outcomes never achieved. Regarding platelet aggregation induced by thrombin and collagen, the GAD proved to be stronger by 7.1 and 7.3 times, respectively. Furthermore, the GAD showed a ROS inhibitory activity higher than that of GA by 8.1 (thrombin) and 6.9 (collagen) times. Concerning the antibacterial activities, evaluated on eleven multi-resistant Gram-positive strains of clinical relevance, the GAD is far more potent than GA, by exerting a growth inhibitory activity at MIC (μM) concentrations lower by factors in the range 12-50.

Microbial Metabolites of Flavan-3-Ols and Their Biological Activity

Flavan-3-ols are the main contributors to polyphenol intake. Many varying beneficial health effects in humans have been attributed to them, including the prevention of cardiovascular disease and cancer. Nevertheless, the mechanisms by which these flavonoids could exert beneficial functions are not entirely known. Several in vitro studies and in vivo animal models have tried to elucidate the role of the specific colonic metabolites on the health properties that are attributed to the parent compounds since a larger number of ingested flavan-3-ols reach the colon and undergo there microbial metabolism. Many new studies about this topic have been performed over the last few years and, to the best of our knowledge, no scientific literature review regarding the bioactivity of all identified microbial metabolites of flavan-3-ols has been recently published. Therefore, the aim of this review is to present the current status of knowledge on the potential health benefits of flavan-3-ol microbial metabolites in humans while using the latest evidence on their biological activity.

Recent advances in microfluidic platelet function assays: Moving microfluidics into clinical applications

The analysis of platelet aggregation and thrombosis kinetics has significantly advanced with progress in microfluidic technology. However, the results of platelet aggregation tests do not fully reflect the observed clinical outcomes. To address the present unmet clinical needs, the basic but essential biology of platelets should be reconsidered in relation to the characteristics of microfluidic systems employed for platelet tests. To this end, the present article provides an overview of commercially available point of care devices and focuses on recent microfluidic studies, describing their measurement principles. We critically discuss the characteristics of the microfluidics systems used to evaluate the complex processes underlying platelet aggregation, and that are specifically designed to mimic the pathophysiological environment of blood vessels, including hemodynamic factors as well as blood vessel injury. To this end, we summarize unsolved issues related to the application of platelet function tests based on microfluidics. Overall, we confirm that platelet function tests based on microfluidics provide a versatile platform that encompasses a variety of basic research, as well as clinical diagnostic applications.

Effects of anthocyanins and their gut metabolites on adenosine diphosphate-induced platelet activation and their aggregation with monocytes and neutrophils

Accumulating evidence suggests that anthocyanins play an important role in the cardioprotective effects associated with consumption of anthocyanin-rich foods. These benefits may partly be attributed to their effects on platelets, significant contributors to cardiovascular disease development. This study aimed to investigate the impact of physiologically relevant concentrations of anthocyanins and their metabolites on platelet activation and platelet-leukocyte aggregation. Whole blood from seven healthy volunteers was treated with anthocyanins: cyanidin-3-arabinoside, cyanidin-3-glucoside, cyanidin-3-galactoside, delphinidin-3-glucoside and peonidin-3-glucoside at 0.1 μM concentration or gut metabolites: 4-hydroxybenzaldehyde, protocatechuic, vanillic, ferulic and hippuric acids at 0.5 μM, 0.2 μM, 2 μM, 1 μM, 2 μM concentration, respectively. Markers of adenosine diphosphate-induced platelet activation (P-selectin and GPIIb-IIIa expression) and platelet-monocyte and platelet-neutrophil aggregation were analyzed using flow cytometry. Cyanidin-3-arabinoside, delphinidin-3-glucoside, and peonidin-3-glucoside decreased agonist-induced P-selectin expression, while cyanidin-3-galactoside and cyanidin-3-arabinoside reduced platelet-neutrophil aggregation. Hippuric and protocatechuic acids inhibited P-selectin expression, ferulic acid reduced platelet-monocyte aggregation, while 4-hydroxybenzaldehyde affected P-selectin expression, platelet-neutrophil and monocyte aggregation. Only cyanidin-3-glucoside and protocatechuic acid decreased GPIIb-IIIa expression. These results demonstrate the bioactivity of anthocyanins and their gut metabolites at physiologically relevant concentrations on platelet function and interaction with leukocytes, presenting mechanisms by which they contribute to the beneficial effects of habitual consumption of anthocyanin-rich foods on cardiovascular health.

Evaluation of the antiaggregant activity of ascorbyl phenolic esters with antioxidant properties

Beneficial effects of the antioxidant L-ascorbic acid (Asc) in human health are well known. Its particular role in hemostasis deserves further consideration, since it has been described a dose-dependent effect of Asc in platelet activity. Contrary, it has been demonstrated that phenolic compounds have inhibitory effects on platelet aggregation stimulated by the physiological agonist thrombin (Thr). Here, we have evaluated the actions of three synthetic phenolic esters of Asc: L-ascorbyl 6-protocatechuate (Prot Asc), L-ascorbyl 6-gallate (Gal Asc), and L-ascorbyl 6-caffeate (Caf Asc). All these Asc derivatives exhibited greater radical scavenging activity than Asc, and in experiments using human platelets from healthy subjects, they do not evoke changes in platelet viability upon their administration. Nevertheless, these compounds altered platelet calcium homeostasis in response to Thr, although Prot Asc induced a smaller effect than Gal Asc, Caf Asc, and Asc. As a consequence, platelet aggregation was also impaired by these compounds, reporting Prot Asc and Caf Asc a weaker antiaggregant action than Gal Asc and Asc. Treatments with Gal Asc and Caf Asc altered in larger extent the phosphorylation pattern of pp60(Src) and mammalian target of rapamycin (mTOR) evoked by stimulating human platelets with Thr. Summarizing, Prot Asc is the ascorbyl phenolic ester with the strongest antioxidant properties and weakest antiaggregant actions, and its use as antioxidant may be safer than the rest of derivatives in order to prevent thrombotic alteration in patients that need treatment with antioxidant therapies.

Bioavailability, bioactivity and impact on health of dietary flavonoids and related compounds: an update

There is substantial interest in the role of plant secondary metabolites as protective dietary agents. In particular, the involvement of flavonoids and related compounds has become a major topic in human nutrition research. Evidence from epidemiological and human intervention studies is emerging regarding the protective effects of various (poly)phenol-rich foods against several chronic diseases, including neurodegeneration, cancer and cardiovascular diseases. In recent years, the use of HPLC-MS for the analysis of flavonoids and related compounds in foods and biological samples has significantly enhanced our understanding of (poly)phenol bioavailability. These advancements have also led to improvements in the available food composition and metabolomic databases, and consequently in the development of biomarkers of (poly)phenol intake to use in epidemiological studies. Efforts to create adequate standardised materials and well-matched controls to use in randomised controlled trials have also improved the quality of the available data. In vitro investigations using physiologically achievable concentrations of (poly)phenol metabolites and catabolites with appropriate model test systems have provided new and interesting insights on potential mechanisms of actions. This article will summarise recent findings on the bioavailability and biological activity of (poly)phenols, focusing on the epidemiological and clinical evidence of beneficial effects of flavonoids and related compounds on urinary tract infections, cognitive function and age-related cognitive decline, cancer and cardiovascular disease.

Plant food anthocyanins inhibit platelet granule secretion in hypercholesterolaemia: Involving the signalling pathway of PI3K-Akt

Controlling platelet granule secretion has been considered an effective strategy to dampen thrombosis and prevent atherosclerosis. Anthocyanins are natural plant pigments and possess a wide range of biological activities, including cardiovascular protective activity. In the present study we explored the effects and the potential mechanisms of anthocyanins on platelet granule secretion in hypercholesterolemia. In a randomised, double-blind clinical trial, 150 hypercholesterolaemic individuals were treated with purified anthocyanins (320 mg/day) or placebo for 24 weeks. Anthocyanins consumption significantly reduced plasma levels of β-thromboglobulin (β-TG), soluble P-selectin, and of Regulated on Activation Normal T cell Expressed and Secreted (RANTES) as compared with the placebo. A minor reduction in platelet factor 4 (PF4) and transforming growth factor β1 (TGF-β1) levels were also observed. In in vitro experiments, we observed that puriӿed anthocyanin mixture, as well as its two main anthocyanin components, delphinidin-3-glucoside (Dp-3-g) and cyanidin-3-glucoside (Cy-3g) directly inhibited platelet á-granule, dense granule, and lysosome secretion evaluated by P-selectin, RANTES, β-TG, PF4, TGF-β1, serotonin, ATP, and CD63 release. Further, anthocyanins inhibited platelet PI3K/Akt activation and consequently attenuated eNOS phosphorylation and cGMP production, thus interrupting MAPK activation. LY294002, a PI3K inhibitor, did not cause additional inhibitory efficacy, indicating that anthocyanin-induced effects may be involved in inhibition of the PI3K/Akt signalling pathway. These results provide evidence that by inhibiting platelet granule secretion, anthocyanins may be a potent cardioprotective agent.

Blood flow in hemodialysis catheters: a numerical simulation and microscopic analysis of in vivo-formed fibrin

Although catheters with side holes allow high flow rate during hemodialysis, they also induce flow disturbances and create a critical hemodynamic environment that can favor fibrin deposition and thrombus formation. This study compared the blood flow and analyzed the influence of shear stress and shear rate in fibrin deposition and thrombus formation in nontunneled hemodialysis catheters with unobstructed side holes (unobstructed device) or with some side holes obstructed by blood thrombi (obstructed device). Computational fluid dynamics (CFD) was performed to simulate realistic blood flow under laminar and turbulent conditions. The results from the numerical simulations were compared with the fibrin distribution and thrombus architecture data obtained from scanning electron microscopy (SEM) and two photons laser scanning microscopy (TPLSM) on human thrombus formed in catheters removed from patients. CFD showed that regions of flow eddies and separation were mainly found in the venous holes region. TPLSM characterization of thrombi and fibrin structure in patient samples showed fibrin formations in accordance with simulated flux dynamics. Under laminar flow conditions, the wall shear stress close to border holes increased from 87.3±0.2 Pa in the unobstructed device to 176.2±0.5 Pa in the obstructed one. Under turbulent flow conditions, the shear stress increased by 47% when comparing the obstructed to the unobstructed catheter. The shear rates were generally higher than 5000/s and therefore sufficient to induce fibrin deposition. This findings were supported by SEM data documenting a preferential fibrin arrangement on side hole walls.

The cardioprotective effects of citric Acid and L-malic Acid on myocardial ischemia/reperfusion injury

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

Mulberry leaf extract inhibits the development of atherosclerosis in cholesterol-fed rabbits and in cultured aortic vascular smooth muscle cells

This study used high-cholesterol-fed New Zealand white rabbits and aortic vascular smooth muscle cells (VSMCs) to investigate the impact of mulberry leaf extract (MLE) on the development of atherosclerosis. The results show that the major components of MLE are polyphenols, flavonoids, carbohydrates, proteins, and lipids, and the major contituents of mulberry leaf polyphenol extract (MLPE) are polyphenols and flavonoids. In addition to improvement of liver function, the atheroma burden and levels of serum cholesterol, triglycerides, and low-density lipoprotein (LDL) are also significantly reduced after MLE treatment. MLE and MLPE improved endothelial function, inhibited proliferation and migration of aortic VSMCs, and reduced atheromas in the vascular wall. In conclusion, this study demonstrates that, in addition to exerting hypolipidemic effects, MLE and MLPE can effectively inhibit proliferation and migration of aortic VSMCs, improve vascular endothelial function, and reduce atheroma burden, thereby preventing atherosclerosis.