Constantinos Demopoulos

National and Kapodistrian University of Athens | uoa · Division of Faculty of Chemistry II

Since 2000s, we have outlined the multifaceted role of inflammation in several aspects of cancer, via specific inflammatory mediators, including the platelet activating factor (PAF) and PAF-receptor (PAFR) related signaling, which affect important inflammatory junctions and cellular interactions that are associated with tumor-related inflammatory m...

Inflammation and thrombosis are implicated in several chronic disorders. Recent studies have outlined the way in which several compounds can offer protection against inflammation. Within this comprehensive review the so-far reported anti-inflammatory health-promoting effects of several metal-based complexes, both in vitro and in vivo, are thoroughl...

Inflammatory mediators constitute a recently coined term in the field of metal-based complexes with antiplatelet activities. Our strategy targets Platelet-Activating Factor (PAF) and its receptor, which is the most potent lipid mediator of inflammation. Thus, the antiplatelet (anti-PAF) potency of any substance could be exerted by inhibiting the PA...

Atherosclerosis is a progressive vascular multifactorial process. The mechanisms underlining the initiating event of atheromatous plaque formation are inflammation and oxidation. Among the modifiable risk factors for cardiovascular diseases, diet and especially the Mediterranean diet (MedDiet), has been widely recognized as one of the healthiest di...

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit pl...

Previous publications have reported a potent effect of COVID‐19 on platelet function and that the Spike protein enhances washed human platelet aggregation induced by various agonists. This study aims to evaluate whether mRNA vaccination for COVID‐19 affects human platelet‐rich plasma (hPRP) aggregation response, whether a recombinant Spike protein...

In the present work the entomopathogenic fungus B. bassiana lipids were studied against the potent pro-inflammatory and thrombotic mediators implicated in several disorders, platelet-activating factor (PAF) and thrombin. Bioactivities of lipid extracts from B. bassiana cells and culture supernatants and of their lipid fractions separated by a one-s...

Lipids are a very heterogeneous class of biomolecules with distinct structures and functions. Total lipids (TLs) obtained from natural sources are regularly further separated into lipid subclasses, with the two major ones being the polar lipids (PLs) and neutral lipids (NLs). Traditional analytical methods for fractionating TLs into NLs, PLs, and t...

The new coronavirus disease 2019 (COVID-19) pandemic is an emerging situation with high rates of morbidity and mortality, in the pathophysiology of which inflammation and thrombosis are implicated. The disease is directly connected to the nutritional status of patients and a well-balanced diet is recommended by official sources. Recently, the role...

The new coronavirus disease 2019 (COVID-19) pandemic is an emerging situation with high rates of morbidity and mortality, in the pathophysiology of which inflammation and thrombosis are implicated. The disease is directly connected to the nutritional status of patients and a well-balanced diet is recommended by official sources. Recently, the role...

Recent articles report elevated markers of coagulation, endothelial injury, and microthromboses in lungs from deceased COVID-19 patients. However, there has been no discussion of what may induce intravascular coagulation. Platelets are critical in the formation of thrombi and their most potent trigger is platelet activating factor (PAF), first char...

Recent papers report elevated markers of coagulation, endothelial injury and microthromboses in lungs from deceased CoVid-19 patients. Platelets are critical in the formation of thrombi and their most potent trigger is platelet activating factor (PAF), the structure of which was elucidated by Demopoulos and colleagues, who also described its semisy...

Spirulina (Arthrospira maxima) components have shown several health-benefits, including immunomodulatory and anti-inflammatory properties. Even though a few studies have examined the effects of some Spirulina-derived ingredients on platelets, none studied the effects on platelet aggregation induced by inflammatory and thrombotic mediators, namely p...

Purpose of this article is to project from the point of view of the scientific data concerning PAF and as a new approach by involving PAF, in order to contribute to clarification and proposal a possible mechanism of action of the coronavirus SARS-CoV-2 and to give a possible explanation for its observed side effects-complications of Covid-19 diseas...

The Friedländer condensation reaction was employed to synthesize the new bidentate ligands namely 6-bromo-4-phenyl-2-pyridin-2-yl-quinoline (1) and 4-(4-phenyl-2-(pyridin-2-yl)quinolin-6-yl)phenol (2). These compounds were fully characterized including the X-ray structures of 1 and the protonated form of 2, i.e. 2·HCl·H2O. We also report the synthe...

In the late 1960s, Barbaro and Zvaifler described a substance that caused antigen induced histamine release from rabbit platelets producing antibodies in passive cutaneous anaphylaxis. Henson described a 'soluble factor' released from leukocytes that induced vasoactive amine release in platelets. Later observations by Siraganuan and Osler observed...

The introduction of the term “French Paradox” motivated an extensive and in-depth research into health benefits of moderate wine consumption. The superiority of wine is thought to be attributed to its micro-constituents and consequent effort was made to isolate and identify these bioactive compounds as well as to elucidate the mechanisms of their a...

In this minireview, we refer to recent results as far as the Platelet Activating Factor (PAF) inhibitors are concerned. At first, results of organic compounds (natural and synthetic ones and specific and nonspecific) as inhibitors of PAF are reported. Emphasis is given on recent results about a new class of the so-called metal-based inhibitors of P...

Platelet Activating factor (PAF) is a potent inflammatory mediator that is involved in the initiation and the prolongation of atherosclerosis. The purpose of the study was to investigate the effect of wine consumption on the activity of PAF metabolic enzymes and on IL-6 levels as a cytokine inflammatory marker. Healthy men participated in 4 daily t...

Antiretroviral therapy (ΑRT) has successfully decreased AIDS morbidity and mortality and increased the lifespan of HIV patients to several decades. However, numerous factors contribute with unknown mechanisms to chronic immune activation and inflammation leading to severe “non-AIDS morbidities’’. Platelet Activating Factor (PAF) is a potent lipid i...

Chemical structures of PAF antagonists isolated from wines and oils.

Aim The aim of this study was to investigate the effect of different prostaglandin analogs on platelet-activating factor (PAF) levels. Methods Three prostaglandin analogs were selected: bimatoprost 0.3 mg/mL, latanoprost 50 μg/mL, and tafluprost 15 μg/mL. Each drug sample was tested for its ability to cause platelet aggregation, which was measured...

The aim of the current study was to compare the biological activities of total polar lipids (TPL) and thin-layer chromatography (TLC) polar lipid fractions of sardine fillet and cod liver oil against atherogenesis. TPL and TLC polar lipid fractions obtained from these two sources were assessed for their ability to inhibit the platelet-activating-fa...

The purpose of this study is to determine the effect of various commonly used antiglaucoma eye drops on inflammatory mediators such as the platelet activating factor (PAF). Various intraocular pressure (IOP) lowering drops were tested to examine their inhibitory effect on PAF. Multiple eye drops were tested in washed rabbit platelets (WRPs) in orde...

About the antiplatelet, antithrombotic activities of Ru(II) and Ru(III) metal complexes.

A number of studies support the anti-atherogenic effect of wine compounds. The scope of this study was to examine the effect of a red (Cabernet Sauvignon–CS) and a white (Robola–R) wine, as well as resveratrol and quercetin, on the platelet activating factor (PAF) biosynthetic enzymes, acetyl-CoA:lyso-PAF acetyltransferase (lyso-PAF-AT) and DTT-ins...

Platelet Activating Factor (PAF), the most potent inflammatory mediator, is involved in a wide range of pathophysiological actions. PAF signal transduction is mediated through PAF receptors (PAFR) that are coupled with several isoforms of G-proteins. PAF hydrolysis is mediated through specific enzymes clustered as PAF acetylhydrolases (PAF-AH). The...

In this chapter emphasis is given to the investigation of the biological action of rhodium coordination compounds. More precisely the antiinflammatory behavior of a series of Rh(I) and Rh(III) complexes incorporating bifunctional organic compounds (ligands) is reported. The anti-inflammatory action of these compounds was exerted by their potency to...

Age-related macular degeneration (ARMD) is the leading cause of severe vision loss and blindness worldwide, mainly affecting people over 65 years old. Dry and wet ARDM are the main types of the disease, which seem to have a multifactorial background. The aim of this review is to summarize the mechanisms of ARMD pathogenesis and exhibit the role of...

The separation and identification of glyceryl ether (G E ) derivatives from pollen neutral lipids of Pine tree Pinus halepensis (Miller) is described. The separation and purification of GE derivatives from the other lipid classes, especially from monoglycerides and diglycerides, was done by thin layer chromatography. The purified GE derivatives wer...

The purpose of this study was to evaluate the sensory (using descriptive analysis) and cardioprotective properties - studying the biological activity against atheromatosis based on the in vitro inhibition of Platelet Activating Factor (PAF) induced platelet aggregation - of two types of gilthead sea bream (Sparus aurata): the first was the conventi...

Background Persistent immune activation and inflammation are lying behind HIV-infection even in the setting of ART mediated viral suppression. The purpose of this study is to define the in vivo effect of two first-line ART regimens on certain inflammatory mediators in male HIV patients. Methods Male, naive, HIV-infected volunteers were assigned ei...

Given that platelet activating factor (PAF) is a crucial inflammatory phospholipid mediator that is implicated in the mechanism of atherogenesis, the presence of PAF inhibitors in food reinforces their nutritional value in terms of protection against cardiovascular diseases. The aim of the present study was to evaluate the anti-atherogenic (anti-in...

Olive oil is an important lipid source of the Mediterranean diet which has been associated with lower incidence of cardiovascular diseases whereas olive pomace (OP), a natural by-product of olive oil production, has been found to contain micro constituents with antioxidant, antithrombotic and antiatherogenic activities. The evaluation of OP in orde...

Objective: The purpose of our study was to investigate for the first time a series of vitamin supplements used for age-related macular degeneration (AMD) as potential inhibitors of platelet-activating factor (PAF). Materials and methods: Various vitamin supplements were tested in washed rabbit platelets (WRPs), in order to investigate the intera...

Given the pivotal role of Platelet-Activating-Factor (PAF) in atherosclerosis and the cardio-protective role of PAF-inhibitors derived from olive pomace, the inclusion of olive pomace in fish feed has been studied for gilthead sea bream (Sparus aurata). The aim of the current research was to elucidate the anti-atherogenic properties of specific HPL...

The aim of this study was to investigate the effect of grilling and brining on the sensory properties, the fillet fatty acid composition and the cardio-protective activity of sardine (Sardina pilchardus), studying the in vitro activity against Platelet-Activating-Factor (PAF) induced platelet aggregation. Sensory evaluation of grilled and brined sa...

Interleukin-1beta (IL-1β) is a potent agonist of platelet-activating factor (PAF) synthesis. The monocyte-derived PAF may amplify the inflammatory and thrombotic processes. The IL-1β-induced enzymatic alterations leading to increased PAF synthesis are ill-defined. In the present study the last enzymatic activities of the remodeling (acetyl-CoA:lyso...

Background: Vitamin D is beneficial in human and experimental chronic kidney disease, the leading cause of which is diabetic nephropathy. Vitamin D through its receptor, VDR, provides renal protection in diabetic nephropathy, but limited data exist about its effect on podocytes. Renal podocytes form the main filtration barrier possessing a unique...

Three different types of hen egg yolk, cage-free, organic and daily fresh, were tested for their antiatherogenic properties. Total lipids (TL) of all hen egg yolk samples were extracted by the method of Bligh and Dyer and further separated into total polar lipids (TPL) and total neutral lipids (TNL) by counter current distribution chromatography. T...

Purpose: Paricalcitol improves the inflammatory status of hemodialysis patients. PAF is a strong inflammatory mediator which is produced during hemodialysis. We studied the effects of paricalcitol on PAF and other inflammatory mediators implicated in chronic kidney disease (CKD). Methods: We examined the in vitro effects of paricalcitol on PAF/t...

Background Tangier disease (TD) is a phenotypic expression of rare familial syndrome with mutations in the ABCA1 transporter. The risk of coronary artery disease in patients with TD is variable. On the other hand the pivotal role of Platelet-Activating Factor (PAF) mediator in atheromatosis was found. Plasma lipoproteins are transporters of the PAF...

Freezing is an efficient method of fish preservation. The aim of the present work was to examine the impact of freezing in fatty acid composition and in the in vitro inhibitory activity of sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) fillet lipids against platelet activating factor (PAF). The Bligh and Dyer extraction meth...

Human Immunodeficiency Virus (HIV)-infected patients are at increased risk for cardiovascular diseases partly due to chronic inflammation. Some antiretroviral drugs and Highly Active Anti-Retroviral Therapy (HAART) regimens seem to be related and amplify this increased risk, especially the ones containing abacavir. Platelet-Activating-Factor (PAF)...

Gilthead sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were fed with two experimental diets: olive pomace diet and olive pomace oil diet, in order to examine whether fish oil substitution in fish feeds by olive oil production wastes, such as olive pomace and olive pomace oil, has an influence on growth performance, fatty acid compos...

Platelet activating factor (PAF) has been proposed as a key factor and initial trigger in atherosclerosis. Recently, a modulation of PAF metabolism by bioactive food constituents has been suggested. In this study we investigated the effect of fish polar lipid consumption on PAF metabolism. The specific activities of four PAF metabolic enzymes; in l...

Platelet-activating factor (PAF) is implicated in human immunodeficiency virus (HIV)-related manifestations. Increased PAF synthesis has been recently detected in HIV-infected patients. In this study, we examined in naive HIV-infected patients the in vivo effects of a highly active antiretroviral therapy (HAART) regimen, containing tenofovir-DF/emt...

The Zn[(OPPh2)(SePPh2)N]2 complex was prepared by a metathetical reaction between a Zn(II) salt and the deprotonated form of the dichalcogenoimidodiphosphinato ligand [(OPPh2)(SePPh2)N]−. X-ray crystallography revealed a pseudo-tetrahedral MO2Se2 coordination sphere, owed to the asymmetric (O,Se) nature of the chelating ligand. A comparison between...

Platelet-activating factor (PAF), a mediator of proatherosclerotic inflammatory processes, is also implicated in endothelial dysfunction during human immunodeficiency virus (HIV) infection. We examined PAF metabolism in blood of naive male patients, 8 with early HIV infection (group A) and 17 just before treatment initiation (group B), versus 18 he...

Leishmania spp are obligate intracellular protozoan parasites of the mononuclear phagocyte system that cause a spectrum of diseases known as leishmaniasis. Platelet Activating Factor (PAF) and some PAF-antagonists seem to play a key role in Leishmania infection. In this article we detected for the first time the specific activities of PAF basic met...

To study the effects of PAF, in comparison with oxLDL and IL-1β on MCP-1 and IL-6 secretion from U-937 monocytes and to investigate the mechanism of its action. U-937 cell line was cultured in the presence or absence of PAF or oxLDL or IL-1β. Secretion of IL-6 and MCP-1 was measured by ELISA method, mRNA levels of MCP-1 and PAFR was measured using...

Platelet-Activating-Factor (PAF) is a potent inflammatory mediator implicated in several pathological situations including atherosclerosis, cardiovascular and renal diseases. Mediterranean Diet contains foods that exhibit protective effects against these pathologies. We have previously described that micro-constituents existing in polar-lipids of o...

Sepsis is characterized as a systemic inflammatory response that results from the inability of the immune system to limit bacterial spread during an ongoing infection. In this condition the significant mediator of inflammation Platelet Activating Factor (PAF) and the coagulant factor thrombin are implicated. In animal models, treatment with PAF-ant...

Ginkgo biloba products seem to protect from several pathological conditions, including HIV manifestations, where Platelet Activating Factor (PAF) is implicated. In the present study, we examined for the first time the in vivo effects of a standardized formulation of Ginkgo biloba extract (150 mg daily, per os) on PAF metabolism in blood cells and p...

The ATP-binding cassette transporter A1 (ABCA1) is essential protein involved in lipid metabolism. The present study was undertaken to detect the possible association of polymorphisms in the ABCA1 gene [rs2230806 (R219K) and rs2230808 (R1587K)] and lipid profile in Greek young nurses. The study population consisted of 308 unrelated nurses who were...

Platelet activating factor (PAF) is implicated in cardiovascular disease (CVD). Statins are widely used in these situations. Therefore, we assessed their effect on the biological activities and metabolism of PAF. Several statins, including simvastatin, exhibited an inhibitory effect against PAF, comparable with that of PAF-inhibitors. Simvastatin a...

Metal complexes bearing dichalcogenated imidodiphosphinate [R(2)P(E)NP(E)R(2)'](-) ligands (E = O, S, Se, Te), which act as (E,E) chelates, exhibit a remarkable variety of three-dimensional structures. A series of such complexes, namely, square-planar [Cu{(OPPh(2))(OPPh(2))N-O, O}(2)], tetrahedral [Zn{(EPPh(2))(EPPh(2))N-E,E}(2)], E = O, S, and oct...

The aim of this study was to investigate whether the fish lipid extracts have in vivo anti-atherogenic properties in hypercholesterolaemic rabbits. Fish oil extracts were obtained from cultured gilthead sea bream (Sparus aurata) and, for the in vivo experiment, 12 healthy male New Zealand rabbits of specific weight and age were used, which were ran...

Recognition and uptake of oxidized LDL (oxLDL) by scavenger receptors of macrophages and foam cell formation are mediated by the oxidatively modified apolipoprotein B (ApoB) and lipid moiety of oxLDL. A great amount of oxidized phosphatidylcholine (oxPC) of oxLDL is hydrolyzed at the sn-2 position by lipoprotein associated phospholipase A(2) (Lp-PL...

The reaction of RhCl3·3H2O with the ligand L=2-(2′-pyridyl)quinoxaline (pqo) in a 1:2 molar ratio formed the mononuclear complex cis-[RhL2Cl2]Cl (1), which has been characterized by elemental analysis, FT-IR, FT-Raman, 1H, 13C NMR, electronic absorption spectroscopy and by electrospray mass spectrometry. The molecular structure of 1 (needle like an...

Olive mill waste water (OMWW) is a major environmental issue in the Mediterranean. We address this problem by investigating the wastes for the presence of biologically active compounds already detected in both olive oil and pomace. Two initial OMWW samples were filtered using two microporous filtering media: (a) clayey diatomite and (b) zeolitic vo...

Cancer is one of the leading causes of death in Europe and United States. New blood vessel formation penetrating into solid tumors seems to be required for their growth and metastasis. Several protein growth factors can induce endothelial cell proliferation and angiogenesis, through signal transduction cascades that result in the production of seve...

Virgin olive oil polar lipid extract (OOPL) and olive pomace polar lipid extract (PPL) have similar antiatherosclerotic effects in cholesterol-fed rabbits. Our aim was to compare the effect of PPL with that of simvastatin on the progression of atherogenesis. Rabbits were fed an atherogenic diet for 6 weeks in order to develop dyslipidemia and ather...

Apart from being the main energy reserves of the human body, triacylglycerols take part in metabolic processes that determine the rate of fatty acid oxidation, the plasma levels of free fatty acids, the biosynthesis of other lipid molecules and the metabolic fate of lipoproteins. Allosteric, hormonal, nutritional and transcriptional signals activat...

We evaluated the effects of propofol on oxidative stress and acute liver injury and regeneration produced by acetaminophen administration in rats. Acetaminophen (3.5 g kg(-1)) was administered by gastric tube to 50 adult male Wistar rats. One minute before acetaminophen, propofol was administered intraperitoneally (60 mg kg(-1)) to 25 rats and diet...

Platelet-activating factor (PAF) is a potent lipid inflammatory mediator acting on cells through its specific receptor. Plasma PAF-acetylhydrolase (PAF-AH) is the main enzyme that inactivates PAF in blood, participating in its homeostasis. The objective of this study was to investigate the involvement of PAF in the liver fibrotic process using an e...

E Fragopoulou1, C A Demopoulos2, S Antonopoulou11Department of Science of Nutrition-Dietetics, Harokopio University, Athens, Greece; 2Faculty of Chemistry, National and Kapodistrian University of Athens, Athens, GreeceAbstract: The “French paradox” is the observation that the French suffer a relatively low incidence of coronary heart disease, despi...

The anti-PAF and the antibacterial activities of lipid extracts obtained from cultured sea bass (Dicentrarchus labrax) and cultured gilthead sea bream (Sparus aurata) were evaluated. Total lipids of sea bass and gilthead sea bream exerted PAF-like activity while, in higher amounts they inhibited this PAF activity. Neutral lipids of both sea bass an...