Bogdan Kontek

Lipid peroxidation in patients with schizophrenia

Aims:  There is evidence that dysregulation of free radicals metabolism associated with abnormal activities of antioxidative enzymes in schizophrenia can lead to lipid peroxidation in plasma, erythrocytes, blood platelets and cerebrospinal fluid. Injury to neurons in schizophrenia may affect their function, i.e. membrane transport, impairment of energy production in mitochondria, changes in membrane phospholipid composition, alteration of receptors and transporters as well as neurotransmission. The purpose of the present study was to assess the total antioxidant capacity (TAC) and lipid peroxidation (expressed as the level of thiobarbituric acid reactive substances [TBARS]) in plasma from schizophrenic patients taking olanzapine or risperidone. The level of TBARS estimated according to the Rice–Evans method and TAC ([ABTS; 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical cation decolorization assay]) in plasma from schizophrenic patients (DSM‐IV criteria for schizophrenia, n = 30, age 18–36) taking olanzapine or risperidone and from healthy volunteers (n = 30) were measured.

Quetiapine, olanzapine and haloperidol affect human plasma lipid peroxidation in vitro.

Objective: Oxidative injury in schizophrenia may be caused not only by pathophysiological processes but partly also by treatment with antipsychotics. The purpose of the present study was to examine and to compare the effects of quetiapine (QUE), olanzapine (OLA) and haloperidol (HAL), at final concentrations corresponding to doses used for treatment of acute episodes of schizophrenia, on plasma lipid peroxidation in vitro, measured by the level of thiobarbituric acid-reactive substances (TBARS). Methods: Blood from 30 healthy volunteers was collected into ACD (citric acid/citrate/dextrose) solution. The drugs in form of active substances were dissolved in 0.01% dimethyl sulfoxide, added to plasma at the final concentrations [QUE (175 and 275 ng/ml), OLA (20 and 40 ng/ml), HAL (4 and 20 ng/ml)] and incubated for 1 and 24 h at 37°C. The level of TBARS was measured spectrophotometrically (according to the Rice-Evans method, 1991). Results: The comparative study in vitro showed that QUE causes a decrease in the TBARS level in plasma, whereas HAL increases the plasma TBARS level. After 24 h of incubation of plasma with QUE or HAL (at lower and higher concentrations),thedifferences in TBARS levels between the drugs were significant (p = 5.9 × 10–4, p = 2.2 × 10–5, respectively). Conclusion: QUE and OLA, contrary to the prooxidative action of HAL, did not induce oxidative stress; moreover, QUE has antioxidant properties.

The first- and second-generation antipsychotic drugs affect ADP-induced platelet aggregation

Objective. Blood platelets play an important role in haemostasis and their hyperaggregability may lead to thrombosis and cardiovascular diseases. Increased incidence of mortality, caused by cardiovascular disease, and the increased risk of thrombotic complication in schizophrenic patients treated with antipsychotics have been reported. The effects of antipsychotic drugs on blood platelet function are not fully explained, therefore the purpose of the present study was to examine and compare the effects of the second-generation antipsychotic drugs used in schizophrenia (clozapine, risperidone and olanzapine), with the effects of the first generation antipsychotic, haloperidol, on the platelet aggregation induced by ADP in vitro. Methods. Blood obtained from healthy volunteers (n=25) collected into sodium citrate was centrifuged (250×g, 10 min) at room temperature to obtain platelet-rich plasma. Aggregation of blood platelets (10 µM ADP) was recorded (Chrono-log aggregometer) in platelet-rich plasma preincubated with antipsychotic drugs (final concentration: clozapine 420 ng/ml, risperidone 65 ng/ml, olanzapine 40 ng/ml, haloperidol 20 ng/ml) for 30 min. Results. Our results showed that all tested drugs inhibit platelet aggregation induced by ADP in vitro. Among studied antipsychotic drugs clozapine and olanzapine significantly reduced platelet aggregability in vitro. In comparison with control platelets (without the drug), clozapine inhibited ADP-induced platelet aggregation by 21% (P=3.7×10−6) and olanzapine by 18% (P=2.8×10−4), respectively. Conclusion. The obtained results indicate that antipsychotic drugs, especially clozapine and olanzapine, contrary to haloperidol, reduced response of blood platelets to ADP measured as platelet aggregation. This suggests that therapy with such antipsychotics, particularly with second-generation antipsychotics, may partly reduce prothrombotic events associated with the increased platelet activation observed in schizophrenic patients. The mechanism of antiaggregatory influence of antipsychotics requires further studies.

Chemotherapy modulates the biological activity of breast cancer patients plasma: The protective properties of black chokeberry extract

In breast cancer patients (before and during anti-cancer therapy) oxidative/nitrative damage to various molecules is observed. Furthermore, anti-cancer treatments may also influence the hemostatic properties of blood platelets and plasma. The aim of our study was to assess the effect of oxidative/nitrative stress (estimated by measurements of the levels of carbonyl groups and 3-nitrotyrosine in proteins--ELISA and C-ELISA methods, respectively; lipid peroxidation and total antioxidant level--TAS) on the selected parameters of hemostatic activity of plasma (the process of fibrin polymerization and lysis) collected from breast cancer patients after surgery and after various phases of chemotherapy (doxorubicin and cyclophosphamide). Subsequently, we also evaluated the level of oxidative/nitrative stress and hemostatic activity in plasma from these patients in the presence of the commercial extract of Aronia melanocarpa (Aronox®) in vitro. Patients were hospitalized in Department of Oncological Surgery and Department of Chemotherapy in Medical University of Lodz, Poland. We observed increased levels of biomarkers of oxidative/nitrative stress in plasma from patients with breast cancer (before or after surgery and after various phases of chemotherapy) in comparison to healthy group. Our further experiments demonstrated the hemostatic activity of plasma from the investigated patients differs from hemostatic properties of plasma obtained from healthy volunteers. We also recognize the existence of a relationship between oxidative stress (measured by the level of carbonyl groups) and changes of hemostasis in breast cancer patients after I and IV phases of chemotherapy. Moreover, the obtained results showed that the commercial extract from A. melanocarpa berries significantly reduced, in in vitro system, the oxidative/nitrative stress and hemostasis changes in plasma from breast cancer patients, after surgery and different phases of chemotherapy. Considering the data presented in this study, we suggest that the oxidative/nitrative stress in plasma obtained from breast cancer patients (not only before or after the surgery, but also after various phases of doxorubicin and cyclophosphamide chemotherapy) may induce changes of hemostatic activity, which may contribute to thrombosis in these patients. Our results also suggest that the commercial extract of A. melanocarpa may be regarded as a promising new source of bioactive antioxidant natural compounds for breast cancer patients.

Hippophae rhamnoides L. Fruits Reduce the Oxidative Stress in Human Blood Platelets and Plasma

Effects of the phenolic fraction from Hippophae rhamnoides fruits on the production of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation) and the generation of superoxide anion (O2 −∙) in human blood platelets (resting platelets and platelets stimulated by a strong physiological agonist, thrombin) were studied in vitro. We also examined antioxidant properties of this fraction against human plasma lipid peroxidation and protein carbonylation induced by a strong biological oxidant, hydrogen peroxide (H2O2) or H2O2/Fe (a donor of hydroxyl radicals). The tested fraction of H. rhamnoides (0.5– 50 µg/mL; the incubation time: 15 and 60 min) inhibited lipid peroxidation induced by H2O2 or H2O2/Fe. The H. rhamnoides phenolic fraction inhibited not only plasma lipid peroxidation, but also plasma protein carbonylation stimulated by H2O2 or H2O2/Fe. Moreover, the level of O2 −∙ in platelets significantly decreased. In comparative experiments, the H. rhamnoides fraction was a more effective antioxidant than aronia extract or grape seed extract (at the highest tested concentration, 50 µg/mL). The obtained results suggest that H. rhamnoides fruits may be a new, promising source of natural compounds with antioxidant and antiplatelet activity beneficial not only for healthy people, but also for those with oxidative stress-associated diseases.

The possible role of hydrogen sulfide as a modulator of hemostatic parameters of plasma

Hydrogen sulfide (H2S) is a well known toxic gas at high levels. However, at physiological levels, H2S may play a role in the pathogenesis of various cardiovascular diseases. The objective was to study the effects of exogenous H2S on the hemostatic parameters (coagulation and fibrinolytic activity) of human plasma. Human plasma was incubated (5, 15 and 30 min) with NaHS as a H2S donor at the final concentration of 0.01-100 μM. Hemostatic factors, such as maximum velocity of clot formation, fibrin lysis half-time, the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) were estimated. Moreover, the aim of our study was to establish the influence of NaHS (10 μM; 5, 15 and 30 min) on the clot formation using the purified fibrinogen. We demonstrated that coagulation/fibrinolytic properties of human plasma incubated with NaHS were changed. APPT, PT and TT of plasma treated with NaHS at tested concentrations--0.01-100 μM were prolonged. We observed that NaHS (0.01-100 μM) reduced fibrin polymerization in whole plasma and 10 μM NaHS also reduced polymerization of purified fibrinogen. In the presence of NaHS (at the low tested concentration--1 μM) the decrease was about 18% (in plasma, p<0.05). Our experiments also showed that NaHS (0.01-100 μM) stimulated the fibrin lysis in whole plasma. However, the time-dependent (5, 15 and 30 min) reduction of fibrin/fibrinogen polymerization and stimulation of fibrin lysis by NaHS (10 μM) was not observed. In conclusion, the present study demonstrates the anticoagulant properties of exogenous H2S in vitro.

LC–ESI-MS/MS profile of phenolic and glucosinolate compounds in samh flour (Mesembryanthemum forsskalei Hochst. ex Boiss) and the inhibition of oxidative stress by these compounds in human plasma

Samh flour (Mesembryanthemum forsskalei) is a foodstuff with high protein content, which can be used as a replacement for wheat flour. It is often consumed by Bedouin tribes of northern Saudi Arabia. Very little is known about bioactive molecules present in samh flour, therefore we analyzed its extracts to evaluate the contents of secondary metabolites. A total of 43 secondary metabolites present in 60% MeOH extract of samh flour were tentatively identified using LC-ESI-MS/MS. These compounds represented five major categories: glucosinolates, sinapic acid and sinapoylglycosides, acylated flavonoids, flavonoids, and amide derivatives. Their effect on oxidative damage of proteins and lipids was determined in vitro by assessing levels of protein thiol groups and concentrations of thiobarbituric acid reactive species (TBARS) in human plasma. Obtained results indicated that samh flour is a rich source of compounds with antioxidant activity.

Vitamin C modulates DNA damage induced by hydrogen peroxide in human colorectal adenocarcinoma cell lines (HT29) estimated by comet assay in vitro

Introduction Cancer cells, compared to normal cells, are under increased oxidative stress associated with oncogenic transformation, alterations in metabolic activity, and increased generation of reactive oxygen species. Material and methods We investigated the ability of vitamin C to reduce the damage induced by hydrogen peroxide, in human colorectal adenocarcinoma cells in vitro by the comet assay. Additionally, we measured the kinetics and efficacy of the repair of DNA damage after incubation with vitamin C in the presence of H2O2. Results The obtained results showed that 1 h pre-incubation with vitamin C and exposure to H2O2 for the last 10 min of incubation caused a statistically significant (p < 0.05) increase in DNA migration in comet tails in all experimental series. For the 10 µM, 25 µM, 50 µM, 100 µM vitamin C concentrations the levels of DNA damage were as follows: 18.6%, 21.1%, 25.3% and 27.2%, respectively, as compared to the untreated cells (3.26%). However, in comparison with H2O2 alone (29.1%), we observed a statistically significant (p < 0.05) decrease of the genotoxic effect in HT29 cells induced by H2O2 for the two lowest of concentrations of vitamin C: 10 µM and 25 µM. The HT29 cells were able to achieve effective repair of the damaged DNA within 60 and 120 min after incubation with the tested compounds. All the values obtained in the test were statistically significant (p < 0.05). Conclusions Vitamin C caused a weaker DNA damaging effect of hydrogen peroxide and positively influences the level of oxidative DNA damage in HT29 cells (decrease ∼ 30%). We noted that DNA damage was effectively repaired during 120 min postincubation in the tested cells and that oxidative damage was the major type of damage.

Comparative chemical composition, antioxidant and anticoagulant properties of phenolic fraction (a rich in non-acylated and acylated flavonoids and non-polar compounds) and non-polar fraction from Elaeagnus rhamnoides (L.) A. Nelson fruits

This study focuses on two fractions from sea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson) fruits: the phenolic fraction (rich in non-acylated and acylated flavonoids and non-polar compounds) and the non-polar fraction. The objective was to investigate both the chemical composition of these fractions, as well as their biological activities in vitro. The tested fractions of sea buckthorn inhibited lipid peroxidation induced by H2O2, however, the non-polar fraction reduced more powerfully the process induced by H2O2/Fe as compared to the phenolic fraction. The tested fractions of sea buckthorn fruits also inhibited carbonylation stimulated by H2O2/Fe. Moreover, the action of the phenolic fraction and non-polar fraction on hemostatic parameters of plasma was also compared to activities of other phenolic fraction, in which flavonoids were the dominant compounds. Our results indicate that sea buckthorn fruits are a rich source of different secondary metabolites, i.e. triterpenes and their derivates, which possess not only antioxidant properties, but may also display anticoagulant attributes.

Polyphenols from Berries of Aronia melanocarpa Reduce the Plasma Lipid Peroxidation Induced by Ziprasidone.

Background. Oxidative stress in schizophrenia may be caused partially by the treatment of patients with antipsychotics. The aim of the study was to establish the effects of polyphenol compounds derived from berries of Aronia melanocarpa (Aronox) on the plasma lipid peroxidation induced by ziprasidone in vitro. Methods. Lipid peroxidation was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) alone and with Aronox (5 ug/ml; 50 ug/ml). Results. We observed a statistically significant increase of TBARS level after incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) (after 24 h incubation: P = 7.0 × 10−4, P = 1.6 × 10−3, and P = 2.7 × 10−3, resp.) and Aronox lipid peroxidation caused by ziprasidone was significantly reduced. After 24-hour incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) in the presence of 50 ug/ml Aronox, the level of TBARS was significantly decreased: P = 6.5 × 10−8, P = 7.0 × 10−6, and P = 3.0 × 10−5, respectively. Conclusion. Aronox causes a distinct reduction of lipid peroxidation induced by ziprasidone.