Piotr Duchnowicz

Melatonin treatment improves blood pressure, lipid profile, and parameters of oxidative stress in patients with metabolic syndrome.

Abstract:u2002 Experimental studies have proven that melatonin has many beneficial pleiotropic actions. The aim of this study was to assess melatonin efficacy in patients with metabolic syndrome (MS). The study included 33 healthy volunteers (who were not treated with melatonin) and 30 patients with MS, who did not respond to 3‐month lifestyle modification. Patients with MS were treated with melatonin (5u2003mg/day, 2u2003hr before bedtime) for 2u2003months. The following parameters were studied: systolic and diastolic blood pressure (SBP, DBP), levels of glucose, serum lipids, C‐reactive protein, fibrinogen, activities of antioxidative enzymes: catalase (CAT), glutathione peroxidase (GSH‐Px), superoxide dismutase (SOD), thiobarbituric acid reactive substrates (TBARS). After 2‐month therapy in comparison with baseline, the following significant changes were measured: systolic blood pressure (132.8u2003±u20039.8 versus 120.5u2003±u200311.0u2003mmHg, Pu2003<u20030.001), DBP (81.7u2003±u20038.8 versus 75u2003±u20037.4u2003mmHg, Pu2003<u20030.01), low‐density lipoprotein cholesterol (LDL‐C) (149.7u2003±u200326.4 versus 139.9u2003±u200330.2u2003mg/dL, Pu2003<u20030.05), TBARS (0.5u2003±u20030.2 versus 0.4u2003±u20030.1u2003μm/gHb, Pu2003<u20030.01), and CAT (245.9u2003±u200346.9 versus 276.8u2003±u200339.4u2003U/gHb). Melatonin administered for 2u2003months significantly improved antioxidative defense (increase in CAT activity, decrease in TBARS level) and lipid profile (decrease in LDL‐C), and lowered blood pressure. We conclude that melatonin therapy may be of benefit for patients with MS, particularly with arterial hypertension. Further studies with higher doses of melatonin or prolonged supplementation are awaited.

Damage of erythrocyte by phenoxyacetic herbicides and their metabolites

The molecular background of toxic properties of phenoxy herbicides for humand and animals is insufficiently studied. In this study, damage parameters (hemolysis, hemoglobin oxidation, and lipid peroxidation) were measured in human erythrocytes exposed to several commonly used herbicides from this group (2,4-D, 2,4,5-T, and MCPA) and their phenolic metabolites. For all parameters studied the impact of herbicide metabolites was stronger than that of herbicides themselves. The extent of hemolysis was dose-dependent and also depended on the solvent used. Whereas compounds with methyl groups were more potent in the methemoglobin formation assay, compounds with chlorine substituents caused higher lipid peroxidation.

CATALASE ACTIVITY IN HUMAN ERYTHROCYTES: EFFECT OF PHENOXYHERBICIDES AND THEIR METABOLITES

The effects of exposure to different concentrations of phenoxyherbicides and their metabolites were studied in human erythrocytes, with particular attention to catalase (CAT—EC. 1.11.1.6— hydrogen peroxide: hydrogen peroxide oxidoreductase). 4‐chloro‐2‐methylphenoxyacetic acid (MCPA), 2,4‐dimethylphenol (2,4‐DMP) and 2,4‐dichlorophenoxyacetic acid (2,4‐D) did not affect CAT activity, but 2,4‐dichlorophenol (2,4‐DCP) and 2,4,5‐trichlorophenol (2,4,5‐TCP) decrease its activity, the latter being the more inhibitory.

Hypolipidemic and antioxidant effects of hydroxycinnamic acids, quercetin, and cyanidin 3-glucoside in hypercholesterolemic erythrocytes (in vitro study)

ObjectiveFour polyphenols: ferulic acid and p-coumaric acid (hydroxycinnamic acids), quercetin (flavonol) and cyanidin 3-glucoside (anthocyanin) were selected, and their antioxidant properties and their influence on cholesterol concentration in hypercholesterolemic and normal erythrocytes were investigated.MethodsTo determine the effect of phenolic compounds, we prospectively studied cholesterol concentration, lipid peroxidation and membranes fluidity. Whole-blood and isolated erythrocytes (2% hematocrit) were incubated for 24xa0h with selected compounds at concentration 1, 10 and 100xa0μmol/L. All investigated compounds decreased lipid peroxidation in whole blood. Cyanidin 3-glucoside and quercetin showed higher antioxidant properties than hydroxycinnamic acids (ferulic acid and p-coumaric acid).ResultsIncubation of whole blood of hypercholesterolemic patients with quercetin and cyanidin 3-glucoside resulted in statistically significant reduction of cholesterol concentration in erythrocytes down to 75% (at 10xa0μmol/L of polyphenols) and 69% (at 100xa0μmol/L of polyphenols) of initial values. The effect of both compounds on isolated erythrocytes was even more pronounced, reduction down to 70% (at 10xa0μmol/L of polyphenols) and 58% (at 100xa0μmol/L of polyphenols) of initial values. After incubation of isolated erythrocytes of hypercholesterolemic patients with quercetin and cyanidin 3-glucoside, increase of membrane fluidity was noticed. After incubation of isolated erythrocytes of healthy donors with investigated compounds, no changes in membrane fluidity were observed.ConclusionOur results indicate that flavonols and anthocyanins have higher antioxidant properties and higher influence on cholesterol concentration in erythrocytes membranes than simple hydroxycinnamic acids.

Effect of polyphenols extracts from Brassica vegetables on erythrocyte membranes (in vitro study)

The aim of this work was to estimate the in vitro effects of polyphenol extracts from Brassica vegetables (Brussels sprouts and red cabbage) on erythrocyte membranes with normal and high concentration of cholesterol. To determine the effect of phenolic compounds we prospectively studied cholesterol concentration, lipid peroxidation, membrane fluidity and ATPase activity. Polyphenol extracts from Brassica vegetables resulted in statistically significant reductions in cholesterol concentrations in hypercholesterolemic erythrocytes. For control erythrocytes, no significant reduction of cholesterol levels was observed for both extracts. Decreases in lipid peroxidation intensity were observed after incubation of hypercholesterolemic erythrocytes with the extracts. No changes in membrane fluidity for both extracts were noted for normal and hypercholesterolemic erythrocytes. The activity of ATPase decreased after incubation of normal and hypercholesterolemic erythrocytes with extract from Brassica vegetables. Our results indicate that polyphenols from red cabbage and Brussels sprout may directly influence erythrocyte membrane properties.

Oxidative damages in erythrocytes of patients with metabolic syndrome.

The aim of the study was to estimate the changes caused by oxidative stress in structure and function of membrane of erythrocytes from patients with metabolic syndrome (MS). The study involved 85 patients with MS before pharmacological treatment and 75 healthy volunteers as a control group. Cholesterol level, lipid peroxidation, glutathione level (GSH), and antioxidant enzyme activities in erythrocytes were investigated. The damage to erythrocyte proteins was also indicated by means of activity of ATPase (total and Na+,K+ ATPase) and thiol group level. The membrane fluidity of erythrocytes was estimated by the fluorescent method. The cholesterol concentration and the level of lipid peroxidation were significantly higher, whereas the concentration of proteins thiol groups decreased in the patient group. ATPase and GSH peroxidase activities diminished compared to those in the control group. There were no differences in either catalase or superoxide dismutase activities. The membrane fluidity was lower in erythrocytes from patients with MS than in the ones from control group. These results show changes in red blood cells of patients with MS as a consequence of a higher concentration of cholesterol in the membrane and an increased oxidative stress.

Anti-inflammatory and hypolipemic effects in vitro of simvastatin comparing to epicatechin in patients with type-2 hypercholesterolemia.

OBJECTIVEnThe study involved 25 patients with type-2 hypercholesterolemia (mean age 49.3+/-11.3). The control group consisted of 28 healthy individuals (mean age 50.7+/-7.2).nnnMETHODSnThe cholesterol concentrations in plasma membranes of erythrocytes were measured by means of Liebermann-Burchard reagent. The membrane lipid peroxidation in whole erythrocytes was determined. The membrane fluidity was estimated by spin labelled method.nnnRESULTSnThe in vitro study shows that the cholesterol concentration in membranes incubated with simvastatin and epicatechin decreases; in healthy donors there are no changes. Simvastatin does not lead to changes in the lipid peroxidation in the in vitro data. Epicatechin decreases the level of membrane lipid peroxidation in patients with hypercholesterolemia and in healthy donors. Simvastatin and epicatechin cause an increase in the fluidity of plasma membranes of erythrocytes.nnnCONCLUSIONSnSimvastatin causes the decrease in cholesterol concentration in erythrocytes membranes not only in the in vivo but also the in vitro experiments. Flavonoids have antioxidant properties in vitro. Simvastatin influences the lipid peroxidation only in vivo, not in vitro systems. This observation is an additional contribution to the statins pleiotropic effect.

In vivo influence of extract from Aronia melanocarpa on the erythrocyte membranes in patients with hypercholesterolemia

Summary Background Hypercholesterolemia increases cholesterol concentration in erythrocyte membranes, which results in decrease of membrane fluidity and decreases the deformability of red blood cells. The fruits of Arona melanocarpa contains many of polyphenols and other compounds that have beneficial health effects. Material/Methods The aim of the study was to estimate the influence of 2-month supplementation of extract from Aronia melanocarpa (100 mg Aronox, three times per day) on cholesterol concentration, lipid peroxidation, membrane fluidity, level of thiol groups and activity of ATPase in erythrocytes from patients with hypercholesterolemia. The study involved 25 patients with hypercholesterolemia without pharmacological treatment and 20 healthy individuals as a control group. Blood samples were collected before, and after 1 and 2 months of Aronia administration. Results The 2-month Aronia supplementation resulted in a decrease of cholesterol concentration (by 22%) and a decrease of lipid peroxidation (by 40%), and an increase of membrane fluidity. No statistically significant increase of the concentration of thiol groups and of ATPase activity were observed. Conclusions Our study shows that supplementation of extract from Aronia melanocarpa has a beneficial effect on rheological properties of erythrocytes.

Multivalent interacting glycodendrimer to prevent amyloid-peptide fibril formation induced by Cu(II): A multidisciplinary approach

Amyloid peptide fibrillogenesis induced by Cu(II) ions is a key event in the pathogenesis of Alzheimer’s disease. Dendrimers have been found to be active in preventing fibril formation. Therefore, they hold promise for the treatment of Alzheimer’s disease. In this study, the fibrillation mechanism of amyloid peptide Aβ 1-40 was studied by adding Cu(II) in the absence and presence of 4th generation poly(propyleneimine) glycodendrimer functionalized with sulfate groups, using dynamic light scattering (DLS), circular dichroism (CD), fluorescence, electron paramagnetic resonance (EPR) and molecular modeling (MD). The glycodendrimer was non-toxic to mHippoE-18 embryonic mouse hippocampal cells, selected as a nerve cell model, and decreased the toxicity of peptide aggregates formed after the addition of Cu(II). The binary systems of Cu(II)–glycodendrimer, Cu(II)–peptide, and glycodendrimer–peptide were first characterized. At the lowest Cu(II)/glycodendrimer molar ratios, Cu(II) was complexed by the internal-dendrimer nitrogen sites. After saturation of these sites, Cu(II) binding with sulfate groups occurred. Stable Cu(II)–peptide complexes formed within 5 min and were responsible for a transition from an α helix to a β-sheet conformation of Aβ 1-40. Glycodendrimer–peptide interactions provoked the stabilization of the α-helix, as demonstrated in the absence of Cu(II) by the Thioflavin T assay, and in the presence of Cu(II) by CD, EPR, and MD. Formation of fibrils is differentially modulated by glycodendrimer and Cu(II) concentrations for a fixed amount of Aβ 1-40. Therefore, this multidisciplinary study facilitated the recognition of optimal experimental conditions that allow the glycodendrimer to avoid the fibril formation induced by Cu(II).

Disorders of erythrocyte structure and function in hypertensive patients

Summary Background The prevalence of hypertension is growing at an alarming rate. Increasing attention is being focussed on the oxidative stress accompanying this disease. In this study we examined the impact of this disease on some parameters of erythrocytes and human blood plasma. Material/Methods We examined the impact of hypertension on some parameters of erythrocytes and human plasma. The study involved 13 patients with hypertension and 19 healthy subjects. We determined lipid peroxidation, SH groups concentration, antioxidants enzymes activity, ATPase activity, total antioxidant capacity, total cholesterol level and erythrocyte membrane fluidity. Results We found an increased level of lipid peroxidation and the concentration of SH groups in membrane proteins in patients with hypertension, and a decrease in the activity of catalase and superoxide dysmutase. No changes were observed in glutathione peroxidase and ATPase activity, level of total antioxidant capacity, total cholesterol level and fluidity of erythrocyte membranes. Conclusions These results suggest the existence of an impaired oxidative balance in hypertensive human erythrocytes.