Antiaggregatory Activity Research Articles

Quinones bearing non-steroidal anti-inflammatory fragments as multitarget ligands for Alzheimer’s disease

The anti-amyloid properties shared by several quinones inspired the design of a new series of hybrids derived from the multi-target drug candidate memoquin (1). The hybrids consist of a central benzoquinone core and a fragment taken from non-steroidal anti-inflammatory drugs, connected through polyamine linkers. The new hybrids retain the potent anti-aggregating activity of the parent 1, while exhibiting micromolar AChE inhibitory activities. Remarkably, 2, 4, (R)-6 and (S)-6 were Aβ aggregation inhibitors even more potent than 1. The balanced amyloid/cholinesterase inhibitory profile is an added value that makes the present series of compounds promising leads against Alzheimer’s disease.

Antithrombogenic Activity of Antioxidant Compounds

Antithrombotic activities of enoxifol, a new antioxidant with antiaggregant activity demonstrated in vitro and in vivo, and antioxidant mexidol were compared on the rat model of arterial thrombosis induced by application of 50% ferric chloride. Acetylsalicylic acid (antiaggregant) served as the reference drug. All drugs exhibited dose-dependent antithrombotic activity. Enoxifol was more effective than mexidol, both drugs being more active than the reference drug (acetylsalicylic acid). Taking into account the pathogenesis of the thrombosis in this experimental model, we can hypothesize that the pronounced antithrombotic effect of enoxifol was due to its antiaggregant and antioxidant activities.

Effect of Tomato Industrial Processing on Phenolic Profile and Antiplatelet Activity

Background: Regular consumption of fruits and vegetables (e.g., tomatoes) has been shown to be beneficial in terms of reducing the incidence of cardiovascular diseases. The industrial processing of tomatoes into tomato-based products includes several thermal treatments. Very little is known on the effect of tomato industrial processing on antiaggregatory activity and phenolic profile. Methods: It was assessed the effect of tomato and by-products extracts on platelet aggregation induced by ADP, collagen, TRAP-6 and arachidonic acid. These in vitro antithrombotic properties were further supported in an in vivo model of thrombosis. A set of antiplatelet compounds has been selected for HPLC analysis in the different extracts. Results: Some natural compounds such as chlorogenic, caffeic, ferulic and p-coumaric acids were identified by HPLC in tomatoes and its products may inhibit platelet activation. Red tomatoes, tomato products (sauce, ketchup and juice) and by-products extracts inhibited platelet aggregation induced adenosine 5'-diphosphate, collagen, thrombin receptor activator peptide-6 and arachidonic acid, but to a different extent. Also, pomace extract presents antithrombotic activity. Conclusions: Processed tomatoes may have a higher content of health-benefiting compounds than fresh ones. Pomace even presents the best antiplatelet activity. Finally, tomato products may be used as a functional ingredient adding antiplatelet activities to processed foods.

Bioactive stilbenes from Vitis vinifera grapevine shoots extracts

Viticultural residues from commercial viticultural activities represent a potentially important source of bioactive stilbenes such as resveratrol. The main aim of the present study was therefore to isolate, identify and perform biological assays against amyloid-β peptide aggregation of original stilbenes from Vitis vinifera shoots. A new resveratrol oligomer, (Z)-cis-miyabenol C (3), was isolated from Vitis vinifera grapevine shoots together with two newly reported oligostilbenes from Vitis vinifera shoots, vitisinol C (1) and (E)-cis-miyabenol C (2), and six known compounds: piceatannol, resveratrol, (E)-ε-viniferin (trans-ε-viniferin), ω-viniferin, vitisinol C and (E)-miyabenol C. The structures of these resveratrol derivatives were established on the basis of detailed spectroscopic analysis including nuclear magnetic resonance experiments. All the newly reported compounds were tested for their anti-aggregative activity against amyloid-β fibril formation. Vitisinol C was found to exert a significant activity against amyloid-β aggregation. Vitis vinifera grapevine shoots are potentially interesting as a source of new bioactive stilbenes, such as vitisinol C.

Pharmacological and physicochemical properties of mechanochemically synthesized supramolecular complexes of acetylsalicylic acid and polysaccharide arabinogalactan from lrches Larix sibirica and Larix gmelinii

180 In effective complex therapy of cardiovascular dis� eases, a major role is played by antithrombotic drugs, the most popular of which are based on acetylsalicylic acid (ASA) medicines (1). Given the fact that the use of ASA for primary and secondary prevention of car� diovascular diseases is a lifetime measure, the risk of development of adverse side effects, inherent in almost every drug, increases. The most frequent clinically sig� nificant side effect of ASA is the irritation of gastric membranes of the gastrointestinal tract, including the formation of erosions and ulcers (the socalled ulcero� genic effect) (2). Special studies have shown that this effect depends on the dose of ASA. For this reason, in cardiology it is used in relatively low (75-150 mg) doses (3). Further dose decrease reduces the anti� thrombotic effect. Another method to improve the safety of ASA therapy is the use of socalled enterosol� uble or "buffered" pills; however, the opinions of phar� macists in this regard are contradictory (3). Therefore, the design of new effective antithrombotic drugs with the least side effects is a very relevant problem. Previously (4, 5), we have shown that the use of some drugs in the form of mechanochemically synthe� sized complexes with polysaccharides and glycyrrhizic acid makes it possible to reduce the effective doses of these drugs while retaining their therapeutic activity and to reduce the ulcerogenic and (in the case of NSAIDs). Therefore, in this study, we investigated the antiaggregating and ulcerogenic activity and physico� chemical properties of the complexes of ASA with the polysaccharide arabinogalactan (AG), which was iso� lated from the wood of larch

Water‐Soluble Nitric‐Oxide‐Releasing Acetylsalicylic Acid (ASA) Prodrugs

A series of water-soluble (benzoyloxy)methyl esters of acetylsalicylic acid (ASA), commonly known as aspirin, are described. The new derivatives each have alkyl chains containing a nitric oxide (NO)-releasing nitrooxy group and a solubilizing moiety bonded to the benzoyl ring. The compounds were synthesized and evaluated as ASA prodrugs. After conversion to the appropriate salt, most of the derivatives are solid at room temperature and all possess good water solubility. They are quite stable in acid solution (pH 1) and less stable at physiological pH. In human serum, these compounds are immediately metabolized by esterases, producing a mixture of ASA, salicylic acid (SA), and of the related NO-donor benzoic acids, along with other minor products. Due to ASA release, the prodrugs are capable of inhibiting collagen-induced platelet aggregation of human platelet-rich plasma. Simple NO-donor benzoic acids 3-hydroxy-4-(3-nitrooxypropoxy)benzoic acid (28) and 3-(morpholin-4-ylmethyl)-4-[3-(nitrooxy)propoxy]benzoic acid (48) were also studied as representative models of the whole class of benzoic acids formed following metabolism of the prodrugs in serum. These simplified derivatives did not trigger antiaggregatory activity when tested at 300 μM. Only 28 displays quite potent NO-dependent vasodilatatory action. Further in vivo evaluation of two selected prodrugs, {[2-(acetyloxy)benzoyl]oxy}methyl-3-[(3-[aminopropanoyl)oxy]-4-[3-(nitrooxy)propoxy]benzoate⋅HCl (38) and {[2-(acetyloxy)benzoyl]oxy}methyl 3-(morpholin-4-ylmethyl)-4-[3-(nitrooxy)propoxy]benzoate oxalate (49), revealed that their anti-inflammatory activities are similar to that of ASA when tested in the carrageenan-induced paw edema assay in rats. The gastrotoxicity of the two prodrugs was also determined to be lower than that of ASA in a lesion model in rats. Taken together, these results indicated that these NO-donor ASA prodrugs warrant further investigation for clinical application.

Synthesis and Antiaggregant Activity of 8-Substituted 1-Alkyl-3-methyl-7-(1-oxothietan-3-yl)xanthines

Oxidation of 1-ethyl- and 1-propyl-8-bromo-3-methyl-7-(thietan-3-yl)xanthines was used to synthesize 8-bromo-substituted 1-alkyl-3-methyl-7-(1-oxothietan-3-yl)xanthines, with yields of 49 – 52%; these were used to synthesize 8-amino-substituted 1-alkyl-3-methyl-7-(1-oxothietan-3-yl)xanthines, with yields of 14 – 87%. Piperidine, morpholine, monoethanolamine, and trisamine were used as reagents. The structures of the substances were established by IR and 1H NMR spectroscopy. The compounds synthesized here were found to have marked antiaggregant activity.

Synthesis and Pharmacological Activity of Amino Alcohols of the Indole Series

Opening of the oxirane ring in 1-oxiranylmethylindoles yielded new indole derivatives containing 1,2-amino alcohol residues at the nitrogen atom. Compounds were studied in vitro in relation to various types of pharmacological activity typical of this class of compounds, including receptor (5-HT2, 5-HT3, P2Y1-ergic, κ-opioid), antiaggregant, hemorheological, antiarrhythmic, and antioxidant activities.

Searching for an endogenous anti-Alzheimer molecule: identifying small molecules in the brain that slow Alzheimer disease progression by inhibition of β-amyloid aggregation

Alzheimer disease is a neurodegenerative disorder that progresses with marked interindividual clinical variability. We postulate the existence of endogenous molecules within the human brain exerting an antiaggregant activity that will prevent/slow Alzheimer disease progression. We performed in silico studies to determine if the small endogenous molecules L-phosphoserine (L-PS) and 3-hydroxyanthranilic acid (3-HAA) could bind to the target region of ß-amyloid responsible for protein misfolding. In vitro assays measured the antiaggregation effect of these molecules at varying concentrations. In silico studies demonstrated that L-PS and 3-HAA, both endogenous brain molecules, were capable of binding to the histidine(13)-histidine-glutamine-lysine(16) (HHQK) region of ß-amyloid involved in misfolding: these interactions were energetically favoured. The in vitro assays showed that both L-PS and 3-HAA were capable of inhibiting ß-amyloid aggregation in a dose-dependent manner, with 3-HAA being more potent than L-PS. Studies were performed in silico and in vitro but not in vivo. We successfully identified 2 endogenous brain molecules, L-PS and 3-HAA, that were capable of binding to the region of ß-amyloid that leads to protein misfolding and neurotoxicity. Both L-PS and 3-HAA were able to inhibit ß-amyloid aggregation in varying concentrations; levels of these compounds in the brain may impact their effectiveness in slowing/preventing ß-amyloid aggregation.

Synthesis, biological evaluation, X-ray molecular structure and molecular docking studies of RGD mimetics containing 6-amino-2,3-dihydroisoindolin-1-one fragment as ligands of integrin αIIbβ3

A series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born’s method was shown to be due to inhibition of fibrinogen binding to αIIbβ3. Molecular docking of RGD mimetics to αIIbβ3 receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores. The single crystal X-ray data were obtained for five mimetics.

Pyrazole derivatives as inhibitors of arachidonic acid-induced platelet aggregation

Antiplatelet drugs are promising therapeutics to intervene with platelet aggregation in arterial thrombosis, most prominently in myocardial infarction and ischemic stroke. Here, we describe the synthesis and structure–activity relationships of potent inhibitors of platelet aggregation based on the 1,5-diarylpyrazol-3-carboxamide scaffold. Analogs from this series demonstrated potent anti-aggregatory activities against arachidonic acid-induced platelet aggregation, as measured by turbidimetric method of Born. 1,5-Diarylpyrazole-3-carboxamides obtained with small-basic amines (7, 8, 50, 51, 61, 62) displayed the strongest activity with IC50 values in low nanomolar range (5.7–83 nM). On the basis of their high potency in cellular environment, these straightforward pyrazole derivatives may possess potential in the design of more potent compounds for intervention with cardiovascular diseases.

ГЕМОСТАТИЧЕСКИ ЗНАЧИМАЯ АКТИВНОСТЬ СОСУДОВ У ПОРОСЯТ ПРИ ПОТРЕБЛЕНИИ РАСТИТЕЛЬНЫХ КОРМОВ

The survey of 34 healthy piglets of the Large White breed at 41-240 days of life revealed the lowering in concentration of lipid peroxidation products in their blood serum against the background of the increasing the antioxidant potential activity in their plasma. It was shown, that low levels of endotheliazitemia with all tested inductors and their combinations result in raising the indices of antiaggregatory activity of the vascular wall. The piglets endotheliocytes were characterized by increased production, which provides the necessary antitrombin III level in their blood anticoagulants vascular origin. The secretion of tissue plasminogen activators identified when creating temporary cerebral venous wall in piglets of this age has grown.

Natural Dipeptides as Mini-Chaperones: Molecular Mechanism of Inhibition of Lens βL-Crystallin Aggregation

The effect of histidine-containing dipeptides-carnosine and N-acetylcarnosine-on preventing and treating of cataracts of various etiologic origins has been demonstrated in many studies in vivo, while the precise molecular mechanism of their action is actually obscure. Cataract has been recently attributed to conformational diseases due to the association of lens structure protein aggregation with cataract pathogenesis. In our study, effect of histidine-containing dipeptides-carnosine, N-acetylcarnosine, and anserine-on the UV induced βL-crystallin aggregation was studied in vitro. It was first demonstrated that N-acetylcarnosine and anserine (10-40 mM) considerably suppressed UV induced aggregation of βL-crystallin, while carnosine exerted no effect. Positive correlation between anti-aggregating activity of the compounds used and their hydrophobicity was obtained. It was revealed that N-acetylcarnosine and anserine inhibited the initial stages of the protein photochemical damage. A decrease in the size of protein aggregates was detected in the presence of N-acetylcarnosine and anserine. UV irradiation of βL-crystallin resulted in a significant increase in the number of protein carbonyl groups, and the dipeptides studied did not affect this process. We suppose that N-acetylcarnosine and anserine inhibit βL-crystallin aggregation via formation of a protein-dipeptide complex that prevents macromolecular conformational changes and ensuing protein aggregation.

Towards dual antithrombotic compounds – Balancing thrombin inhibitory and fibrinogen GPIIb/IIIa binding inhibitory activities of 2,3-dihydro-1,4-benzodioxine derivatives through regio- and stereoisomerism

Enantiomers of 2,3-dihydro-1,4-benzodioxine derivatives possessing both thrombin and fibrinogen GPIIb/IIIa binding inhibitory activities were prepared from (R)- and (S)-glycidol as potential dual antithrombotic compounds. The influence of chirality and substitution pattern on thrombin inhibition and on inhibition of fibrinogen binding to GPIIb/IIIa was analyzed. Docking studies were used in an attempt to rationalize the results. The (S)-isomers of both 2,3-dihydro-1,4-benzodioxine regioisomers at positions 6 and 7 were found to be better thrombin inhibitors than the corresponding (R)-enantiomers, whereas we observed that stereochemistry does not display a consistent influence on fibrinogen GPIIb/IIIa binding inhibitory activity. Compound 11b, the (S)-isomer of the 6-substituted regioisomer, possessed the best balanced dual activity, with Ki(thrombin) = 1.67 ± 0.27 μM and IC50(GPIIb/IIIa) = 0.665 ± 0.26 μM, raising the hope that merging anticoagulant and platelet antiaggregatory activities in the same molecule could lead to successful multitarget antithrombotic agents.

Synthesis and pharmacological activity of amides of 2-amino-3-indolylacrylic acid

Opening of the five-member ring of indolylmethyleneoxazolones with aliphatic amines was used to synthesize a series of amides of 2-amino-3-indolylacrylic acid. These compounds were studied in vitro in relation to the various types of pharmacological activity typical of this class, including receptor (5-HT2-, 5-HT3-, and P2Y1-ergic, K-opioid), antiaggregant, hemorheological, antiarrhythmic, and antioxidant activities.

Synthesis and study of 2-acetyl amino-3-[4-(2-amino-5-sulfo-phenylazo)-phenyl]-propionic acid: a new class of inhibitor for hen egg white lysozyme amyloidogenesis

The compounds capable of blocking the aggregation of amyloidogenic proteins may have therapeutic potentials. We report on the synthesis of 2-acetyl amino-3-[4-(2-amino-5-sulfo-phenylazo)-phenyl]-propionic acid as an HEWL (hen egg white lysozyme) amyloid inhibitor starting from phenylalanine. The compounds arrest the monomers and exhibit anti-aggregating activity. Moreover, the acetyl derivative 1 served as a better inhibitor than the trifluoroacetyl derivative 2 against in vitro amyloid fibrillogenesis of the HEWL model system.

Critique of the use of fluorescence‐based reporters in Escherichia coli as a screening tool for the identification of peptide inhibitors of Aβ42 aggregation

High-throughput screens that dispense with the need for expensive synthetic Aβ peptide would be invaluable for identifying novel anti-aggregants as potential treatments for Alzheimer's disease. A biosynthetic in vivo approach, using a recombinant fluorescent green fluorescent protein (GFP) reporter for the aggregation state of Aβ in Escherichia coli, has been reported by other workers. Here, inducible Aβ-GFP expression in E. coli was coupled to the concurrent constitutive production of a quasi-random peptide library to screen for anti-aggregant activity. To attempt to introduce greater robustness, mCherry was also co-expressed as an internal fluorescence standard to allow ratiometric comparison between samples. However, fluctuations in mCherry expression levels, as well as a low dynamic range of GFP output between positive and negative anti-aggregant peptides, highlighted limitations with the approach. Despite this, two novel peptides were identified that showed an equivalent in vitro anti-aggregant activity to that of epigallocatechin-3-gallate. Thus, although biosynthetic in vivo strategies show promise as screens for novel activities, unforeseen problems can arise because of the variability inherent in any biological system.

In silico search for an endogenous anti-Alzheimer’s molecule — Screening amino acid metabolic pathways

Alzheimer’s disease (AD) is a neurodegenerative disorder arising from abnormal aggregation of β-amyloid (Aβ) and progressing at different rates from person to person. There may exist endogenous compounds within the brain that play a role in inhibiting aggregation. We have devised a unique in silico screening strategy of endogenous molecules within the human brain, with special emphasis on amino acid metabolic pathways, to identify compounds with the potential to inhibit Aβ aggregation. Metabolites of tryptophan were computationally identified through this screening as potential therapeutics and were optimized via molecular modelling to determine their capacity to bind to Aβ. The most successful molecule identified was 3-hydroxyanthranilic acid (3-HAA). This endogenous molecule was then computationally explored to design novel analogues of 3-HAA with the goal of improving Aβ antiaggregant activity. These combined in silico methods of screening, identifying, and successfully “analoguing” an endogenous molecule of the brain as an AD therapeutic has yielded positive results and a novel approach to computer-aided drug design.

Diabetic CVD – Soluble Epoxide Hydrolase as A Target

The incidence of cardiovascular diseases remains high in diabetic patients despite the optimization of blood glucose control and the therapeutic management of risk factors. One emerging promising pharmacological approach that may help to prevent the development of diabetic cardiovascular complications is to improve endothelial function through the restoration of the bioavailability of epoxyeicosatrienoic acids (EETs). EETs are crucial eicosanoid signaling molecules synthesized by cytochrome P450 epoxygenases in the vascular endothelium and in pancreatic islets. EETs promote vasodilatation and display attractive anti-inflammatory and anti-aggregating actions together with potent effects on insulin release and sensitivity. In animal models of insulin-resistance and diabetes, a decrease in EET availability has been reported, and is a deleterious mechanism that probably contributes to multiple metabolic, cardiovascular and renal disorders in this setting. Moreover, increasing experimental evidence suggest that the use of soluble epoxide hydrolase (sEH) inhibitors, which prevent EET degradation, is a promising pharmacological approach to prevent endothelial dysfunction and to protect against target organ damage in metabolic diseases. This review presents evidence that the EET pathway is disturbed from the early stages of metabolic diseases, and analyzes the potential contribution of EETs impairment to the progression of cardiovascular diseases associated with diabetes. Pathophysiological and therapeutic perspectives are thereafter discussed, including the necessity to demonstrate the role of EET pathway alterations in endothelial dysfunction associated with diabetes in human, and the interest of sEH inhibitors to prevent the development of diabetic cardiovascular complications, with the expected result of improving patients' health.

Synthesis and preliminary biological profile of new NO-donor tolbutamide analogues

We describe a new class of NO-donor hypoglycemic products obtained by joining tolbutamide, a typical hypoglycemic sulfonylurea, with a NO-donor moiety through a hard link. As NO-donors we chose either furoxan (1,2,5-oxadiazole 2-oxide) derivatives or the classical nitrooxy function. A preliminary biological characterization of these compounds, including stimulation of insulin release from cultured rat pancreatic β-cells and in vitro vasodilator and anti-aggregatory activities, is reported.