A Comprehensive Literature Review on Cardioprotective Effects of Bioactive Compounds Present in Fruits of Aristotelia chilensis Stuntz (Maqui).

Some fruits and vegetables, rich in bioactive compounds such as polyphenols, flavonoids, and anthocyanins, may inhibit platelet activation pathways and therefore reduce the risk of suffering from CVD when consumed regularly. Aristotelia chilensis Stuntz (Maqui) is a shrub or tree native to Chile with outstanding antioxidant activity, associated with its high content in anthocyanins, polyphenols, and flavonoids. Previous studies reveal different pharmacological properties for this berry, but its cardioprotective potential has been little studied. Despite having an abundant composition, and being rich in bioactive products with an antiplatelet role, there are few studies linking this berry with antiplatelet activity. This review summarizes and discusses relevant information on the cardioprotective potential of Maqui, based on its composition of bioactive compounds, mainly as a nutraceutical antiplatelet agent. Articles published between 2000 and 2022 in the following bibliographic databases were selected: PubMed, ScienceDirect, and Google Scholar. Our search revealed that Maqui is a promising cardiovascular target since extracts from this berry have direct effects on the reduction in cardiovascular risk factors (glucose index, obesity, diabetes, among others). Although studies on antiplatelet activity in this fruit are recent, its rich chemical composition clearly shows that the presence of chemical compounds (anthocyanins, flavonoids, phenolic acids, among others) with high antiplatelet potential can provide this berry with antiplatelet properties. These bioactive compounds have antiplatelet effects with multiple targets in the platelet, particularly, they have been related to the inhibition of thromboxane, thrombin, ADP, and GPVI receptors, or through the pathways by which these receptors stimulate platelet aggregation. Detailed studies are needed to clarify this gap in the literature, as well as to specifically evaluate the mechanism of action of Maqui extracts, due to the presence of phenolic compounds.

[Bufei Yishen formula attenuates cigarette smoke extract-induced airway mucus hypersecretion by regulating Notch signaling pathway].

OBJECTIVE: To explore the mechanism of Bufei Yishen formula (BYF) on attenuating cigarette smoke extract (CSE)-induced airway mucus hypersecretion by regulating Notch signaling pathway. METHODS: The human airway epithelial cell 16HBE was cultured in vitro, and the cells in logarithmic growth phase were used for the experiments. (1) Intervention condition screening experiment: the 16HBE cells were grouped, methylthiazolyldiphenyl-tetrazolium (MTT) method and enzyme-linked immunosorbent assay (ELISA) were used to detect the effects of different concentrations of CSE (2.5%, 5%, 10%, 20%, 40%), different concentrations of BYF drug-containing serum (5%, 10%, 20%, 40%), and different concentrations of Notch signal pathway blocker DAPT (5, 10, 20, 40 µmol/L) on cell activity and secretion of mucin 5AC (MUC5AC) levels. In addition, a blank control group was set up to screen out the best conditions for preparing CSE-induced cell mucus hypersecretion model and BYF and DAPT intervention. (2) Intervention experiment: the 16HBE cells were divided into four groups. The blank control group was not given any treatment; the 16HBE cells were induced by 10% CSE for 24 hours to prepare mucus hypersecretion model in the CSE model group; the cells in the CSE+BYF group and CSE+DAPT group were given 10% BYF or 20 µmol/L DAPT, respectively, for intervention at the same time for 24 hours. Real-time fluorescent quantitative polymerase chain reaction (qPCR) was used to detect the mRNA expressions of MUC5AC, Notch3 and hairy and enhancer of split 1 (HES1) in the cells. Western blotting was used to detect the protein expressions of Notch3 and HES1 in the cells. RESULTS: (1) Results of the screening experiment of intervention conditions: compared with the blank control group, 10% CSE induction for 24 hours was the best condition for establishing cell mucus hypersecretion model that neither affected cell viability nor increased the secretion of MUC5AC; while 10% BYF and 20 µmol/L DAPT was the optimal intervention condition. (2) Intervention experiment results: compared with the blank control group, the mRNA expressions of MUC5AC, Notch3, and HES1 and the protein expressions of Notch3 and HES1 in the CSE model group were significantly increased, indicating that CSE activated Notch3 and HES1 signal activation and induced 16HBE cells to secrete mucus protein. Compared with the CSE model group, BYF and DAPT could significantly down-regulate the mRNA and protein expressions of MUC5AC, Notch3, and HES1 in cells [MUC5AC mRNA (2-ΔΔCT): 1.03±0.13, 0.96±0.05 vs. 1.35±0.07, Notch3 mRNA (2-ΔΔCT): 1.10±0.14, 1.10±0.02 vs. 1.31±0.15, HES1 mRNA (2-ΔΔCT): 1.26±0.10, 1.14±0.15 vs. 1.45±0.08, Notch3 protein (Notch3/GAPDH): 0.10±0.03, 0.16±0.03 vs. 0.31±0.09, HES1 protein (HES1/GAPDH): 0.37±0.06, 0.34±0.08 vs. 0.50±0.05, all P < 0.05]. CONCLUSIONS: The mechanism of BYF attenuating mucus hypersecretion of 16HBE cells induced by CSE was associated with the inhibition of Notch signaling pathway activation.

Superiority of cilostazol among antiplatelet FDA-approved drugs against COVID 19 Mpro and spike protein: Drug repurposing approach.

Coronavirus disease 2019 (COVID 19) was first identified in Wuhan, China near the end of 2019. To date, COVID-19 had spread to almost 235 countries and territories due to its highly infectious nature. Moreover, there is no vaccine or Food and Drug Administration (FDA)-approved drug. More time is needed to establish one of them. Consequently, the drug repurposing approach seems to be the most attractive and quick solution to accommodate this crisis. In this regard, we performed molecular docking-based virtual screening of antiplatelet FDA-approved drugs on the key two viral target proteins: main protease (Mpro ) and spike glycoprotein (S) as potential inhibitor candidates for COVID-19. In the present study, 15 antiplatelet FDA-approved drugs were investigated against the concerned targets using the Molecular Docking Server. Our study revealed that only cilostazol has the most favorable binding interaction on Mpro (PDB ID: 6LU7) and cilostazol, iloprost, epoprostenol, prasugrel, and icosapent ethyl have a higher binding affinity on spike glycoprotein (S) (PDB ID: 6VYB) compared with recent anti-CoVID-19. Therefore, cilostazol is a promising FDA drug against COVID-19 by inhibiting both Mpro and S protein. The insights gained in this study may be useful for quick approach against COVID-19 in the future.

Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods.

Blood feeding arthropods, such as leeches, ticks, flies and mosquitoes, provide a privileged source of peptidic anticoagulant molecules. These primarily operate through inhibition of the central coagulation protease thrombin by binding to the active site and either exosite I or exosite II. Herein, we describe the rational design of a novel class of trivalent thrombin inhibitors that simultaneously block both exosites as well as the active site. These engineered hybrids were synthesized using tandem diselenide-selenoester ligation (DSL) and native chemical ligation (NCL) reactions in one-pot. The most potent trivalent inhibitors possessed femtomolar inhibition constants against α-thrombin and were selective over related coagulation proteases. A lead hybrid inhibitor possessed potent anticoagulant activity, blockade of both thrombin generation and platelet aggregation in vitro and efficacy in a murine thrombosis model at 1 mg kg-1 . The rational engineering approach described here lays the foundation for the development of potent and selective inhibitors for a range of other enzymatic targets that possess multiple sites for the disruption of protein-protein interactions, in addition to an active site.

The regulatory role of curcumin on platelet functions.

Curcumin, the main ingredient of Curcuma longa L., has been used as a spice and as a herbal medicine with different therapeutic characteristics for centuries in Asian countries. This phytochemical has been shown to possess beneficial antiplatelet activity that has introduced it as a promising candidate for the treatment of thromboembolism, atherothrombosis, and inflammatory diseases. Platelet dysfunction under different circumstances may lead to cardiovascular disease, and curcumin has been shown to have beneficial effects on platelet dysfunction in several studies. Therefore, this narrative review is aimed to summarize available evidence on the antiplatelet activity of curcumin and related molecular mechanisms for this activity.

Antiplatelets and profibrinolytic activity of Citrullus colocynthis in control and high-fat diet-induced obese rats: mechanisms of action.

The current study aimed to investigate the effect of Citrullus colocynthis (C. colocynthis) hydro-alcoholic extract on blood haemostasis in control and high-fat diet (HFD) induced obese rats. In control rats, the extract significantly enhanced bleeding time and plasma levels of tPA and significantly decreased plasma levels PAI-1 and serum levels of thromboxane B2 leading to inhibition of platelets aggregation. In HFD induced obese rats, similar effects were seen and the extract was also able to reverse HFD induced increases in fibrinogen and VWF. Searching for the mechanism, C. colocynthis acts by (1) inhibiting of food intake, (2) inhibiting the activity of pancreatic lipase, (3) decreasing levels of TNF-α and IL-6 and (4) decreasing circulatory levels of the prothrombotic adipokine, leptin and enhanced circulatory levels of the antithrombic adipokines and adiopnectin. In conclusion, C. colocynthis has antiplatelets and profibrinolytic activity in both control and HFD induced obese rats.

Development of Novel High Density Gastroretentive Multiparticulate Pulsatile Tablet of Clopidogrel Bisulfate Using Quality by Design Approach.

Myocardial infarction, i.e., heart attack, is a fatal condition which is on the increase all over the world. It is reported that a large number of heart attack occur in morning hours which are attributable to platelet aggregation. Chronotherapy at this stage can be crucial. Clopidogrel bisulfate (CLB) is an antiplatelet agent and has become a drug of choice for prevention of heart attack. It is soluble in acidic pH and has a narrow absorption window. So, its long residence time in stomach is desirable. Therefore, a novel high density tablet was developed comprising multiparticulate pellets with pulsatile release necessary to maintain chronotherapy of heart attack. The pellets were prepared by extrusion-spheronization and coated in fluidized bed processor with different coating material to achieve pulsatile release. The size, shape of pellets, and drug release were evaluated. High density tablet containing coated pellets was formulated and evaluated for retention in stomach. Quality by design tools was used to design and optimize the processes. Timed release observed by dissolution study showed lag time of 6 h followed by burst release of drug up to 94% in 1 h. Density of tablets was found to be 2.2 g cm-3 which is more than gastric fluid. In vivo x-ray studies in rabbit revealed 8 h of gastric retention of tablet at the bottom of the stomach. Thus, CLB high density pulsatile system looks to open up a window of opportunity for developing formulations with drugs that are stable in gastric region and needed chronotheraupetic activity.

Xanthohumol from hop cones (Humulus lupulus L.) prevents ADP-induced platelet reactivity.

Hop cones (Humulus lupulus L.), very rich source of phenolic compounds, possessing anticancer, antioxidant and anti-inflammatory activities, are considered as beneficial diet ingredients improving human health. In this study, the antiplatelet action of xanthohumol (XN), the principal flavonoid in hop cones, was investigated. XN significantly attenuated ADP-induced blood platelet aggregation (97.2 ± 35.7 AU for 6 µg/ml of XN vs. 120.4 ± 30.1 AU for 0.17% dimethyl sulfoxide (DMSO), p < 0.001) and significantly reduced the expression of fibrinogen receptor (activated form of GPIIbIIIa) on platelets' surface (47.6 ± 15.8 for 1.5 µg/ml XN, 44.6 ± 17.3% for 3 µg/ml XN vs. 54.5 ± 19.2% for control or 43.3 ± 18.4% for 6 µg/ml XN vs. 49.7 ± 19.4% for 0.17% DMSO, p < 0.05 or less). These findings suggest that the phenolic compounds originating from hops (XN) have a novel role as antiplatelet agents and can likely be used as dietary supplements in prophylactic approaches.

CYP2C19 LOF and GOF-Guided Antiplatelet Therapy in Patients with Acute Coronary Syndrome: A Cost-Effectiveness Analysis.

PURPOSE: This study aimed to examine the cost-effectiveness of CYP2C19 loss-of-function and gain-of-function allele guided (LOF/GOF-guided) antiplatelet therapy in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). METHODS: A life-long decision-analytic model was designed to simulate outcomes of three strategies: universal clopidogrel (75 mg daily), universal alternative P2Y12 inhibitor (prasugrel 10 mg daily or ticagrelor 90 mg twice daily), and LOF/GOF-guided therapy (LOF/GOF allele carriers receiving alternative P2Y12 inhibitor, wild-type patients receiving clopidogrel). Model outcomes included clinical event rates, quality-adjusted life-years (QALYs) gained and direct medical costs from perspective of US healthcare provider. RESULTS: Base-case analysis found nonfatal myocardial infarction (5.62%) and stent thrombosis (1.2%) to be the lowest in universal alternative P2Y12 inhibitor arm, whereas nonfatal stroke (0.72%), cardiovascular death (2.42%), and major bleeding (2.73%) were lowest in LOF/GOF-guided group. LOF/GOF-guided arm gained the highest QALYs (7.5301 QALYs) at lowest life-long cost (USD 76,450). One-way sensitivity analysis showed base-case results were subject to the hazard ratio of cardiovascular death in carriers versus non-carriers of LOF allele and hazard ratio of cardiovascular death in non-carriers of LOF allele versus general patients. In probabilistic sensitivity analysis of 10,000 Monte Carlo simulations, LOF/GOF-guided therapy, universal alternative P2Y12 inhibitor, and universal clopidogrel were the preferred strategy (willingness-to-pay threshold = 50,000 USD/QALY) in 99.07%, 0.04%, and 0.89% of time, respectively. CONCLUSIONS: Using both CYP2C19 GOF and LOF alleles to select antiplatelet therapy appears to be the preferred antiplatelet strategy over universal clopidogrel and universal alternative P2Y12 inhibitor therapy for ACS patients with PCI.

Improved Biological Activities of Isoepoxypteryxin by Biotransformation.

Isoepoxypteryxin is the major coumarin of a Japanese medicinal plant Angelica shikokiana. This research was designed to study the effect of structural changes through fungal biotransformation on the reported biological activities of isoepoxypteryxin. Among the tested microorganisms, only Cordyceps sinensis had enzymes that could catalyze the ester hydrolysis and the reductive cleavage of the epoxide ring of isoepoxypteryxin, separately, to give two more polar metabolites (+)-cis-khellactone (P1) and a new coumarin derivative (+)-cis-3'-[(2-methyl-3-hydroxybutanoyl)oxy]-4'-acetoxy-3',4'-dihydroseselin (P2), respectively. The polar metabolite P2 showed stronger cytotoxicity and higher selectivity than isoepoxypteryxin. On the molecular level, P2 showed more in vitro inhibition of both tubulin polymerization and histone deacetylase 8 (HDAC8). Similarly, P2 showed more neuroprotection against amyloid beta fragment 1 - 42 (Aß1 - 42 )-induced neurotoxicity in human neuroblastoma cells (SH-SY5Y) and exhibited more inhibition of the in vitro aggregation of Aß1 - 42 . Both metabolites showed stronger antiplatelet aggregation by increased inhibition of thromboxane-A2 synthase (TXS) activity and thromboxane-A2 (TXA2) production. This study is the first to describe the improved cytotoxic, neuroprotective, and antiplatelet aggregation activities of isoepoxypteryxin through its biotransformation by C. sinensis.

Discovery of novel antagonists of glycoprotein IIb/IIIa-mediated platelet aggregation through virtual screening.

The glycoprotein IIb/IIIa receptor is the final common pathway of platelet aggregation, regardless of the agonist, and thus represents an ideal therapeutic target for blocking thrombus formation. RUC-2 is a novel glycoprotein IIb/IIIa inhibitor of adenosine-5'-diphosphate (ADP)-induced platelet aggregation, importantly which exhibits a unique mode of binding with respect to classical Arg-Gly-Asp (RGD)-based glycoprotein IIb/IIIa antagonists. To identify new chemotypes that inhibit glycoprotein IIb/IIIa-mediated platelet aggregation like RUC-2, we performed a combination of structure-based pharmacophore screening and structure-based virtual screening approach to screen over 7.3 million small molecules based on the RUC-2-glycoprotein IIb/IIIa crystal structure. Three of the eleven hit compounds identified by virtual screening showed promising activity with IC50 values between 16.9 and 90.6µmolL(-1) in a human platelet aggregation assay induced by ADP and thrombin. The binding conformations of these three were analyzed to provide a rationalization of their activity profile. These compounds may serve as potential novel scaffolds for further development of glycoprotein IIb/IIIa antagonists.

Xanthomicrol: a comprehensive review of its chemistry, distribution, biosynthesis and pharmacological activity.

Highly methoxylated flavones, which have known potential as cancer chemopreventive agents, accumulate on the leaf surfaces of some plant species and their physiological role is to protect the plant against harmful UV radiation. Xanthomicrol is one of the methoxylated flavones currently attracting most attention from researchers worldwide because of its promising pharmacological activities, including anti-spasmodic, anti-platelet and anti-cancer effects, among others. This review covers the chemistry and biological origin, distribution and pharmacological activity of xanthomicrol. Knowledge of the botanical distribution of this compound will not only encourage the use of plant sources for pharmacological purposes, but will also serve as a reference in the search for this valuable flavonoid in another genus or family. New approaches to xanthomicrol production are also described, including biotechnological attempts to develop xanthomicrol-producing plant cell factories.

Platelet P2Y12 receptors are involved in the haemostatic effect of notoginsenoside Ft1, a saponin isolated from Panax notoginseng.

BACKGROUND AND PURPOSE: Saponins isolated from Panax notoginseng (Burk.) F.H. Chen have been shown to relieve thrombogenesis and facilitate haemostasis. However, it is not known which saponin accounts for this haemostatic effect. Hence, in the present study we aimed to identify which saponins contribute to its haemostatic activity and to elucidate the possible underlying mechanisms. EXPERIMENTAL APPROACH: Platelet aggregation was analysed using a platelet aggregometer. Prothrombin time, activated partial thromboplastin time and thrombin time were measured using a blood coagulation analyser, which was further corroborated with bleeding time and thrombotic assays. The interaction of notoginsenoside Ft1 with the platelet P2Y12 receptor was determined by molecular docking analysis, cytosolic Ca(2+) and cAMP measurements, and phosphorylation of PI3K and Akt assays. KEY RESULTS: Among the saponins examined, Ft1 was the most potent procoagulant and induced dose-dependent platelet aggregation. Ft1 reduced plasma coagulation indexes, decreased tail bleeding time and increased thrombogenesis. Moreover, it potentiated ADP-induced platelet aggregation and increased cytosolic Ca(2+) accumulation, effects that were attenuated by clopidogrel. Molecular docking analysis suggested that Ft1 binds to platelet P2Y12 receptors. The increase in intracellular Ca(2+) evoked by Ft1 in HEK293 cells overexpressing P2Y12 receptors could be blocked by ticagrelor. Ft1 also affected the production of cAMP and increased phosphorylation of PI3K and Akt downstream of P2Y12 signalling pathways. CONCLUSION AND IMPLICATIONS: Ft1 enhanced platelet aggregation by activating a signalling network mediated through P2Y12 receptors. These novel findings may contribute to the effective utilization of this compound in the therapy of haematological disorders.

Inhibition of platelet activation by lachrymatory factor synthase (LFS)-silenced (tearless) onion juice.

Onion and garlic are renowned for their roles as functional foods. The health benefits of garlic are attributed to di-2-propenyl thiosulfinate (allicin), a sulfur compound found in disrupted garlic but not found in disrupted onion. Recently, onions have been grown with repressed lachrymatory factor synthase (LFS) activity, which causes these onions to produce increased amounts of di-1-propenyl thiosulfinate, an isomer of allicin. This investigation into the key health attributes of LFS-silenced (tearless) onions demonstrates that they have some attributes more similar to garlic and that this is likely due to the production of novel thiosulfinate or metabolites. The key finding was that collagen-induced in vitro platelet aggregation was significantly reduced by tearless onion extract over normal onion extract. Thiosulfinate or derived compounds were shown not to be responsible for the observed changes in the inflammatory response of AGS (stomach adenocarcinoma) cells to tumor necrosis factor alpha (TNFα) when pretreated with model onion juices. A preliminary rat feeding trial indicated that the tearless onions may also play a key role in reducing weight gain.

Development of a reservoir-type transdermal delivery system containing eucalyptus oil for tetramethylpyrazine.

The purpose of this study was to formulate a reservoir-type transdermal delivery system (TDS) for 2,3,5,6-tetramethylpyrazine (TMP) to enable the delivery of a sufficient dose through human skin to achieve an effective therapeutic plasma concentration. To improve the penetration of TMP in the reservoir-type TDS, several chemical penetration enhancers were investigated using in vitro rat dorsal skin permeation studies. Eucalyptus oil was found to enhance the permeation of TMP to the greatest extent, with the optimal concentration being 5% and the flux being 542.6 ± 49.7 µg/cm(2)/h, which was 4.5-fold greater than control with no enhancer (p < 0.01). The flux of the optimized reservoir-type TDS permeated through the human epidermis was 346.0 ± 27.7 µg/cm(2)/h. Based on the in vitro human skin permeation flux and the pharmacokinetics parameters observed, the clinical surface area of the TDS patch was predicted to be 20 cm(2). The in vivo study conducted in rabbits showed that the TMP TDS patch containing 5% eucalyptus oil had a more favorable pharmacokinetic profile, with a lower C(max) and prolonged T(max) and mean residence time than that observed with the oral administration of TMP. The TMP reservoir-type TDS was shown to be a promising alternative route to oral administration or intravenous infusion of TMP.

Modulatory effects of Pycnogenol in a rat model of insulin-dependent diabetes mellitus: biochemical, histological, and immunohistochemical evidences.

A number of experimental and clinical findings have consistently demonstrated the protective effects of Pycnogenol (PYC) in the management of diabetes. However, the protective mechanism by which PYC provides protection in a model type I diabetes has not been studied. This study examines the beneficial effect of PYC on hyperglycemia, inflammatory markers, and oxidative damage in diabetic rats. We also evaluated the possible mechanism of action of PYC which might be that it stimulates beta islet expression, which has been implicated in the process of insulin secretion and diabetes management. Diabetes was induced in rats by an intraperitoneal injection of streptozotocin (STZ; 60 mg/kg body weight) followed by free access to 5 % glucose for the next 24 h. Four days after STZ injection, rats were supplemented with PYC (10 mg/kg body weight) for 4 weeks. At the end of the experiment, blood was drawn, and rats were then sacrificed, and their livers and pancreases were dissected for biochemical and histological assays. The level of fasting blood glucose and glycosylated hemoglobin significantly increased but amylase, insulin, and hepatic glycogen level decreased in the STZ group. PYC significantly augmented these effects in STZ + PYC group. The STZ group showed elevated level of nitric oxide, tumor necrosis factor-α, and interleukin-1beta in serum which were decreased by PYC treatment. Moreover, PYC significantly ameliorated increased thiobarbituric reactive substances, protein carbonyl, and decreased levels of glutathione, glutathione-s-transferase, and catalase activity in the liver and pancreas of the STZ rats. Histopathological and immunohistochemical examination also revealed a remarkable protective effect of PYC. The study suggests that PYC is effective in reducing diabetic-related complications in a type I model of diabetes and might be beneficial for the treatment of diabetic patients.

Dose-effect and metabolism of docosahexaenoic acid: pathophysiological relevance in blood platelets.

Docosahexaenoic acid (DHA) is known as a major nutrient from marine origin. Considering its beneficial effect in vascular risk prevention, the effect of DHA on blood components, especially platelets, will be reviewed here. Investigating the dose-effect of DHA in humans shows that daily intake lower than one gram/day brings several benefits, such as inhibition of platelet aggregation, resistance of monocytes against apoptosis, and reinforced antioxidant status in platelets and low-density lipoproteins. However, higher daily intake may be less efficient on those parameters, especially by losing the antioxidant effect. On the other hand, a focus on the inhibition of platelet aggregation by lipoxygenase end-products of DHA is made. The easy conversion of DHA by lipoxygenases and the formation of a double lipoxygenation product named protectin DX, reveal an original way for DHA to contribute in platelet inhibition through both the cyclooxygenase inhibition and the antagonism of thromboxane A2 action.

The polyphenol-rich extracts from black chokeberry and grape seeds impair changes in the platelet adhesion and aggregation induced by a model of hyperhomocysteinemia.

OBJECTIVE: The mechanism action of the polyphenol-rich extracts from berries of Aronia melanocarpa (black chokeberry) and from grape seeds in the defence against homocysteine (Hcy) and its derivatives action in blood platelets is still unknown. In this study, the influence of the aronia extract and grape seeds extract (GSE) on the platelet adhesion to collagen and fibrinogen and the platelet aggregation during a model of hyperhomocysteinemia was investigated. The aim of our study in vitro was also to investigate superoxide anion radicals (O2⁻•) production after incubation of platelets with Hcy, HTL and the aronia extract and GSE during a model of hyperhomocysteinemia (induced by reduced form of homocysteine at final dose of 100 µM) and the most reactive form of Hcy--its cyclic thioester, homocysteine thiolactone (HTL, 1 µM). Moreover, the additional aim of our study was also to establish and compare the influence of the aronia extract, GSE and resveratrol (3,4',5-trihydroxystilben), a phenolic compound, which has been supposed to be beneficial for the prevention of cardiovascular events, on selected steps of platelet activation. METHODS: The effects of tested extracts on adhesion of blood platelets to collagen and fibrinogen were determined according to Tuszynski and Murphy. The platelet aggregation was determined by turbidimetry method using a Chrono-log Lumi-aggregometer. RESULTS: We have observed that HTL, like its precursor-Hcy stimulated the generation of O2⁻• (measured by the superoxide dismutase-inhibitable reduction of cytochrome c) in platelets and caused an augmentation of the platelet adhesion and aggregation induced by the strong physiological agonist-thrombin. Our present results in vitro also demonstrated that the aronia extract and grape seeds extract reduced the toxicity action of Hcy and HTL on blood platelet adhesion to collagen and fibrinogen, the platelet aggregation and superoxide anion radicals production in platelets, suggesting its potential protective effects on hemostasis during hyperhomocysteinemia. CONCLUSION: In the comparative studies, the aronia extract was found to be more effective antiplatelet factors, than GSE or resveratrol during a model of hyperhomocysteinemia. It gives hopes for development of diet supplements, which may be important during hyperhomocysteinemia.

Platelet-activating factor (PAF) antagonistic activity of a new biflavonoid from Garcinia nervosa var. pubescens King.

The methanol extract of the leaves of Garcinia nervosa var. pubescens King, which showed strong inhibitory effects on platelet-activating factor (PAF) receptor binding, was subjected to bioassay-guided isolation to obtain a new biflavonoid, II-3,I-5, II-5,II-7,I-4',II-4'-hexahydroxy-(I-3,II-8)-flavonylflavanonol together with two known flavonoids, 6-methyl-4'-methoxyflavone and acacetin. The structures of the compounds were elucidated by spectroscopic methods. The compounds were evaluated for their ability to inhibit PAF receptor binding to rabbit platelets using ³H-PAF as a ligand. The biflavonoid and acacetin showed strong inhibition with IC50 values of 28.0 and 20.4 µM, respectively. The results suggest that these compounds could be responsible for the strong PAF antagonistic activity of the plant.

Recent safety concerns with proton pump inhibitors.

There have been recent concerns about the safety of proton pump inhibitors (PPIs). We focus here on 3 specific concerns-the possible interaction between PPIs and clopidogrel, the postulated link between PPI use and fractures, and the possibility that long-term PPI use might lead to hypomagnesemia. There is evidence for an in vitro interaction between clopidogrel and at least some PPIs. The Food and Drug Administration (FDA) has warned against the use of certain PPIs by patients on clopidogrel. However, a randomized controlled trial that compared clopidogrel alone with the combination of clopidogrel and omeprazole found no increase in adverse cardiovascular outcomes and a reduction in the rate of adverse gastrointestinal outcomes attributable to omeprazole. PPI use may be a weak risk factor for certain fractures, but the quality of evidence is relatively poor and there is a strong possibility of confounding. The mechanism whereby PPI use might increase fracture risk is unknown. Currently, no additional measures concerning calcium supplementation or bone mineral density monitoring are recommended for patients on a PPI. The FDA has suggested monitoring serum magnesium levels in patients on PPI therapy. The mechanism and frequency of PPI-induced hypomagnesemia are unclear. PPI treatment should not be withheld from patients who genuinely require it, but the PPI should be taken in the lowest effective dose and only for as long as clinically indicated. The same is, of course, true for all medicines. The benefits of PPI therapy greatly outweigh the risks.