Lipid Peroxidation In Human Plasma Research Articles

Antioxidant action of persulfides and polysulfides against free radical-mediated lipid peroxidation

Hydrogen sulfide, hydropersulfides, and hydropolysulfides have been revealed to play important physiological roles such as cell signaling and protection against oxidative stress, but the underlying mechanisms and dynamics of action remain elusive. It is generally accepted that these species act by two-electron redox mechanisms, while the involvement of one-electron redox chemistry has received less attention. In this study, the radical-scavenging activity of hydrogen persulfide, hydrogen polysulfides (HSnH n = 2–4), and diallyl- or dialkyl-sulfides (RSnR, n = 1–4) was measured. Furthermore, their antioxidant effects against free radical-mediated human plasma lipid peroxidation were assessed by measuring lipid hydroperoxides. It was found that disodium disulfide, trisulfide, and tetrasulfide acted as potent peroxyl radical scavengers, the rate constant for scavenging peroxyl radical being 3.5 × 105, 4.0 × 105, and 6.0 × 105 M−1 s−1 in PBS pH 7.4 at 37 °C respectively and that they inhibited plasma lipid peroxidation efficiently, the efficacy is increased with the catenation number. Disodium tetrasulfide was 1.5 times as reactive as Trolox toward peroxyl radical and inhibited plasma lipid peroxidation more efficiently than ascorbate and Trolox. On the other hand, diallyl- and dialkyl-sulfides did not exert significant radical-scavenging activity, nor did they inhibit lipid peroxidation efficiently, except for diallyl tetrasulfide, which suppressed plasma lipid peroxidation, despite less significantly than disodium tetrasulfide. Collectively, this study shows that hydrogen persulfide and hydrogen polysulfides act as potent radical-scavenging antioxidants and that, in addition to two-electron redox mechanisms, one electron redox reaction may also play important role in the in vivo defense against deleterious oxidative stress.

Giffonins, Antioxidant Diarylheptanoids from Corylus avellana, and Their Ability to Prevent Oxidative Changes in Human Plasma Proteins.

With the aim to explore the ability of diarylheptanoids to reduce oxidative changes in human plasma proteins, a phytochemical investigation of the MeOH extract of Corylus avellana leaves was perfomed. Analysis by LC-ESI/LTQOrbitrap/MS/MSn guided the isolation of two new diarylheptanoid derivatives, giffonins W (1) and X (2). The structures 1 and 2 were assigned by analysis of NMR data combined with a QM (quantum mechanical)/NMR approach. The absolute configurations of 1 and 2 were established by analysis of electronic circular dichroism (ECD) spectra compared with the TDDFT-simulated curves. The antioxidant activity of the new and known giffonins was evaluated by inhibition of human plasma lipid peroxidation. Giffonins with the highest inhibitory activity were tested for their ability to reduce oxidation of thiol groups and carbonylation in plasma proteins, and some of them exhibited higher antioxidant activity than curcumin.

Hypoglycemic and antioxidant properties of konjac (Amorphophallus konjac) in vitro and in vivo.

The aim of this study was to evaluate the hypoglycemic and antioxidant potential of konjac in vitro and in vivo. Glucose diffusion and enzymatic starch digestion of konjac were assayed using α-amylase and α-glucosidase. Oral glucose tolerance test (OGTT) and oral starch tolerance test (OSTT) were performed at dose of 102mg/Kg of body weight (equivalent to 1g/meal in humans). Additionally, the antioxidant activity of konjac was evaluated through inhibition of lipid peroxidation. The konjac decreased glucose diffusion by 36% and 19% compared with the negative and positive controls, respectively. Additionally, konjac inhibited α-amylase and α-glucosidase activities by 14% and 90%, respectively. After OSTT, group treated with konjac showed significant lower glucose levels compared with control group (p=.03). Finally, konjac reduced lipid peroxidation in human plasma (93%) compared with the negative control. Our results suggest that konjac exhibits hypoglycemic and antioxidant activities in vitro and in vivo. PRACTICAL APPLICATIONS: Because the use of herbal products have emerged as an attractive therapeutic option for chronic diseases, konjac administration may be an adjuvant for the treatment of type 2 diabetes.

In Vitro Study of Antioxidant Activity of Carboxymethyl Chitosan derived from Silkworm (Bombyx mori L.) Pupa against Human Plasma Lipid Peroxidation

The study was aimed to evaluate the lipid peroxides blockage capability of carboxymethyl chitosan (CMCTS) from silkworm pupa. It was an experimental study. CMCTS was produced from silkworm pupa. CMCTS of silkworm pupa was subjected to be analysed the toxicity through Brine Shrimp Lethality (BSL) assay, antioxidant activity through DPPH assay, and lipid peroxides inhibitory capacity in human plasma through TBARS assay. The result of our screening indicated that 24 h of treatment of CMCTS had a low impact on the percentage of Artemia salina L. nauplii lethality. CMCTS of silkworm pupa provided a moderate antioxidant activity and a significant inhibitory effect on the lipid peroxide level of human plasma at a concentration of more than or equal to 10 mM. These results proved that CMCTS of silkworm pupa was non-toxic substance also can be used as an alternative antioxidant source.

Biological properties of Elaeagnus rhamnoides (L.) A. Nelson twig and leaf extracts

BackgroundSea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson, SBT) is a valuable plant because of its medical and therapeutic potential. Different bioactive compounds in SBT berries are of special interest to various researchers. However, not only sea buckthorn berries, but also leaves of this plant (both fresh and dried) contain a lot of nutrients and bioactive compounds, including phenolic compounds. The present study was carried out in order to investigate antioxidant and anticoagulant properties of sea buckthorn twig and leaf extracts (0.5–50 μg/mL) by using various in vitro models. Moreover, the aim of present experiments was to compare the biological activity of SBT leaf extract and SBT twig extract with selected berry extracts (a rich source of phenolic compounds): SBT berry extract (flavonoids being the dominant components), a commercial extract from the berries of Aronia melanocarpa (Aronox®), and a grape seed extract.MethodsWe determined the effect of plant extracts on the oxidative stress using selected markers of this process, i.e. the level of carbonyl groups in proteins. Additionally, we analysed the potential mechanism of modulation of hemostatic properties of human plasma (using selected coagulation times).ResultsSBT twig and leaf extracts were observed to exhibit an antioxidant activity against two strong biological oxidants: hydrogen peroxide (H2O2) and H2O2/Fe (the donor of hydroxyl radicals), which induced human plasma lipid peroxidation and protein carbonylation. Both extracts also showed anticoagulant properties.ConclusionsOur present results have demonstrated that extracts from different parts of SBT, especially berries and twigs, in comparison to well-known berries (aronia and grape), may also be viewed as a good source of active substances – antioxidants for pharmacological or cosmetic applications. Moreover, it is very important from an economic point of view to know that there is a possibility of obtaining phenolic compounds not only from the berries or leaves, but also from twigs, which constitute a production waste.

A comparative study on the radioprotective potential of the polyphenolic glycoconjugates from medicinal plants of Rosaceae and Asteraceae families versus their aglycones

Radioprotective potential of the polyphenolic glycoconjugates, isolated from flowers of Sanguisorba officinalis L. (So) and Erigeron canadensis L. (Ec), and from leaves of Fragaria vesca L. (Fv) and Rubus plicatus Whe. Et N. E. (Rp) as well as their aglycones (SoA, EcA, FvA and RpA, respectively), against γ-radiation-induced lipid peroxidation in human plasma and DNA damage in lymphocytes, were investigated in vitro. These properties were assessed by measuring the concentration of thiobarbituric acid reactive substances (TBARS) and using the alkaline comet assay, and were compared to the protective effects of rutin (R) and quercetin (Q). Cytotoxicity of the glycoconjugates/aglycones towards L929 mouse fibroblasts and human lymphocytes were also measured. Plant products from S. officinalis, similar to Q, were able to reduce the most radiation-induced lipid peroxidation as well as DNA damage and extent of oxidative damage to the DNA basis. Contrary to the pure flavonoids, where Q was shown to be significantly more effective than its glycoside R, the results did not show more benefit with application of SoA/EcA over So/Ec in terms of lipid peroxidation inhibition. Moreover, glycoconjugates Ec and So showed much higher capacity in protecting lymphocytes against radiation-induced genotoxicity which may suggest that between the polyphenolic and polysaccharide parts exist some synergistic effects. There were no significant differences between Fv versus FvA or Rp versus RpA in terms of the provided radioprotection. Summarizing, plant glycoconjugates isolated by the multi-step method offered sufficient radioprotection. In addition, they possess many advantages, compared to the synthetic polyphenolic compounds or the plant extracts, such as water-solubility and minor toxicity.

Quali-quantitative analysis of the phenolic fraction of the flowers of Corylus avellana, source of the Italian PGI product “Nocciola di Giffoni”: Isolation of antioxidant diarylheptanoids

There is only limited information available on the chemical composition of the non-edible parts of Corylus avellana, source of the Italian PGI product “Nocciola di Giffoni” (hazelnut). An initial LC-MS profile of the methanolic extract of the male flowers of C. avellana, cultivar ‘Tonda di Giffoni’ led to the isolation of 12 compounds, of which the structures were elucidated by NMR spectroscopy. These were identified as three previously undescribed diarylheptanoids, named giffonins Q-S, along with nine known compounds. Furthermore, the quantitative determination of the main compounds occurring in the methanolic extract of C. avellana flowers was carried out by an analytical approach based on LC-ESI(QqQ)MS, using the Multiple Reaction Monitoring (MRM) experiment. In order to explore the antioxidant ability of C. avellana flowers, the methanolic extract and the isolated compounds were evaluated for their inhibitory effects on human plasma lipid peroxidation induced by H2O2 and H2O2/Fe2+, by measuring the concentration of TBARS.

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.

Studies on the antioxidant properties of extracts from the roots and shoots of two Scutellaria species in human blood plasma.

We determined the in vitro antioxidant activity of methanolic extracts from the shoots and roots of Scutellaria species (S. altissima and S. alpina) against the action of strong oxidants: hydrogen peroxide (H2O2) and H2O2+Fe(2+) (donor of hydroxyl radicals) on plasma proteins and lipids. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). Protein oxidation was measured by quantitation of thiol group. We observed that the extracts (5-50 µg ml(-1)) containing phenolic compounds from both Scutellaria species distinctly reduced oxidation of lipids and proteins in human plasma treated with H2O2. These results also indicated that the extracts have a protective effect against oxidative damage to the human plasma lipids and proteins by induced hydroxyl radical. The main components of the plant materials analysed were flavonoids, present as aglycones (luteolin) or glycosides (cynaroside, baicalin, wogonoside). In all of the extracts, the phenylethanoid verbascoside was also found. The properties of the tested plant extracts were also compared with the action of a well characterised commercial antioxidative polyphenolic extract from the berries of Aronia melanocarpa (Aronox(®)). The comparative studies indicated that the analysed plant extracts were comparable to or even more effective in reducing the oxidation processes than the A. melanocarpa extract. The present study suggests that natural extracts from S. altissima and S. alpina have antioxidant activities and, therefore, may be beneficial in the prevention of diseases related to oxidant stress, such as cancer, cardiovascular, and inflammatory diseases.

Giffonins A-I, antioxidant cyclized diarylheptanoids from the leaves of the hazelnut tree (Corylus avellana), source of the Italian PGI product "Nocciola di Giffoni".

Eight new diaryl ether heptanoids, giffonins A-H (1-8), and one diaryl heptanoid, giffonin I (9), were isolated from the methanol extract of the leaves of Corylus avellana. Its hazelnut is the PGI product of the Campania region (Italy) known as "Nocciola di Giffoni". The MeOH extract of C. avellana leaves and giffonins A-I (1-9) were evaluated for their inhibitory effects on human plasma lipid peroxidation induced by H2O2 and H2O2/Fe(2+), by measuring the concentration of TBARS (thiobarbituric acid reactive substances). Compounds 4 and 8 at 10 μM reduced both H2O2- and H2O2/Fe(2+)-induced lipid peroxidation by more than 60% and 50%, respectively, indicating higher activity than curcumin used as reference compound.

Recrystallization of Dihydromyricetin fromAmpelopsis grossedentataand Its Anti-Oxidant Activity Evaluation

A fast and efficient method for purification of dihydromyricetin (3,5,7,3',4',5'-six hydroxy-2,3-dihydro flavonol; DMY) from Ampelopsis grossedentata was created by crystallization eight times at 25°C, and a purity of 98% was finally achieved. The purified DMY exhibited high oxygen radical absorbance capacity (ORAC) (30.21 μmol Trolox equiv/mg) and strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (half-maximal inhibitory concentration [IC50]=0.235 μg/mL). The addition of DMY could also effectively attenuate 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced human erythrocyte hemolysis and cupric chloride (CuCl2)-induced human plasma lipid peroxidation via inhibition of intracellular reactive oxygen species (ROS) generation. It was also found that DMY (>12 μg/mL) treatment significantly inhibited intracellular malondialdehyde (MDA) formation. Meanwhile, DMY treatment significantly inhibited the obvious increase of anti-oxidant enzymes levels (superoxide dismutase [SOD]; glutathione peroxidase [GPX], and catalase [CAT]) induced by AAPH radicals, suggesting that stress defense mechanisms are associated with protection of DMY against intracellular oxidation.

The Effects of Ziprasidone, Clozapine and Haloperidol on Lipid Peroxidation in Human Plasma (in vitro): Comparison

Oxidative injury in schizophrenia can be caused by the disease itself and probably by antipsychotics treatment. The aim of the study was to establish whether there is a difference between ziprasidone, clozapine and haloperidol effect on lipid peroxidation in human plasma, measured by the level of thiobarbituric acid reactive substances (TBARS). The samples of plasma from healthy subjects were incubated with the drugs (1 and 24 h) and compared with control samples. The levels of TBARS were measured spectrophotometrically, according to the Rice-Evans method. The multifactorial variance analysis ANOVA II test showed that the differences in TBARS levels significantly depended on the studied drugs (ziprasidone 40 ng/ml, haloperidol 4 ng/ml and clozapine 350 ng/ml) (F = 3.248 p = 0.047) and (ziprasidone 139 ng/ml, haloperidol 20 ng/ml and clozapine 420 ng/ml) (F = 2.248, p = 2.9 × 10(-5)). Statistically increased levels of TBARS after 24 h incubation of plasma with ziprasidone 139 ng/ml and haloperidol 20 ng/ml (p < 0.001, p < 0.05 respectively) in comparison with control samples were observed. Clozapine did not significantly (p > 0.05) increase TBARS level in plasma in comparison with control samples. The results obtained in the study showed that ziprasidone and haloperidol contrary to clozapine induced a significant increase in plasma lipid peroxidation.

Epicatechin Inhibits Human Plasma Lipid Peroxidation Caused by Haloperidol In Vitro

Epicatechin belongs to flavonoids protecting cells against oxidative/nitrative stress. Oxidative/nitrative stress observed in schizophrenia may be caused partially by the treatment of patients with various antipsychotics. The aim of our study was to establish the effects of epicatechin and antipsychotics action (the first generation antipsychotic (FGA)--haloperidol and the second generation antipsychotic (SGA)--amisulpride) on peroxidation of plasma lipids in vitro. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). The properties of epicatechin were also compared with the action of a well characterized antioxidative commercial polyphenol-resveratrol (3,4',5-trihydroxystilbene) and quercetin (3,5,7,3',4'-pentahydroxyflavone). Amisulpride, contrary to haloperidol (after 1 and 24 h) does not significantly influence the increase of plasma TBARS level in comparison with control samples (P > 0.05). After incubation (1 and 24 h) of plasma with haloperidol in the presence of epicatechin we observed a significantly decreases the level of TBARS (P < 0.001, P < 0.001, respectively). In our other experiments, we found that epicatechin also decreased the amount of TBARS in human plasma treated with amisulpride. In conclusion, the presented results indicate that epicatechin-the major polyphenolic component of green tea reduced significantly human plasma lipid peroxidation caused by haloperidol. Moreover, epicatechin was found to be a more effective antioxidant, than the solution of pure resveratrol or quercetin.

Beta-glucan from Saccharomyces cerevisiae reduces plasma lipid peroxidation induced by haloperidol

Since oxidative stress observed in schizophrenia may be caused partially by the treatment of patients with various antipsychotics, the aim of the study was to establish the effects of beta-d-glucan, polysaccharide derived from the yeast cell walls of species such as Saccharomyces cerevisiae, and the antipsychotics (the first generation antipsychotic (FGA) – haloperidol and the second generation antipsychotic (SGA) – amisulpride) action on plasma lipid peroxidation in vitro. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with haloperidol or amisulpride in the presence of beta-glucan (4μg/ml). The action of beta-d-glucan was also compared with the properties of a well characterized commercial monomeric polyphenol – resveratrol (3,4′,5-trihydroxystilbene, the final concentration – 4μg/ml). The two-way analysis variance showed that the differences in TBARS levels were depended on the type of tested drugs (p=7.9×10−6). We observed a statistically increase of the level of biomarker of lipid peroxidation such as TBARS after 1 and 24h incubation of plasma with haloperidol compared to the control samples (p<0.01, p<0.02, respectively). Amisulpride, contrary to haloperidol (after 1 and 24h) did not cause plasma lipid peroxidation (p>0.05). We showed that in the presence of beta-glucan, lipid peroxidation in plasma samples treated with haloperidol was significantly decreased. Moreover, we did not observe the synergistic action of beta-glucan and amisulpride on the inhibition of plasma lipid peroxidation. However, the beta-d-glucan was found to be more effective antioxidant, than the solution of pure resveratrol. The presented results indicate that beta-glucan seems to have distinctly protective effects against the impairment of plasma lipid molecules induced by haloperidol.

Inhibitory effects of polyphenol compounds on lipid peroxidation caused by antipsychotics (haloperidol and amisulpride) in human plasma in vitro

Objective. Plant antioxidants protect cells against oxidative stress. Since oxidative stress observed in schizophrenia may be caused partially by the treatment of patients with various antipsychotics, the aim of the study was to assess whether there is a difference between a first-generation antipsychotic (FGA; haloperidol) and a second-generation antipsychotic (SGA; amisulpride (4-amino-N-[(1-ethylpyrrolidin-2-yl)methyl]-5-ethysufonyl-2-methoxy-benzamide)) action on peroxidation of plasma lipids, and to establish the effects of polyphenol compounds (resveratrol (3,4′,5-trihydroxystilbene) and quercetin (3,5,7,3′,4′- pentahydroxyflavone)) and the antipsychotics action on this process in vitro. Methods. Lipid peroxidation in human plasma was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with haloperidol or amisulpride in the presence of polyphenols: resveratrol and quercetin. Results. The two-way analysis variance (ANOVA II test) showed that the differences in TBARS levels were depended on the type of tested drugs (P=8.35×10−6). We observed a statistically increase of the level of biomarker of lipid peroxidation such as TBARS after 1 and 24 h incubation of plasma with haloperidol compared to the control samples (P<0.03, P<0.0002, respectively). Amisulpride, contrary to haloperidol (after 1 h) does not significantly influence the increase of plasma TBARS level in comparison with control samples. Amisulpride induced significantly decrease of plasma TBARS level after 24 h (P=0.03). We showed that in the presence of polyphenols: resveratrol and quercetin, lipid peroxidation in plasma samples treated with tested drugs was significantly decreased. After incubation (24 h) of plasma with haloperidol in the presence of resveratrol or quercetin we observed a significantly decreased the level of TBARS (P=3.9×10−4, P=2.1×10−3, respectively). Conclusion. Considering the data presented in this study, we showed that haloperidol, contrary to amisulpride caused a distinct increase of lipid peroxidation. Polyphenols reduced significantly lipid peroxidation caused by haloperidol.

Antioxidant action of sugar-pendant C 60 fullerenes

The action of C 60 fullerene and its derivatives as a radical-scavenging antioxidant has received much attention, but their reactivity toward free radicals and antioxidant capacity have not been well elucidated yet. In the present study, the reactivity of the two types of water-soluble, sugar-pendant C 60 fullerenes, C 60-1S and C 60-2S, toward peroxyl radical and their effect against human plasma lipid peroxidation were measured. The rate constants for the reaction of C 60-1S and C 60-2S with peroxyl radicals were obtained from their effect on the bleaching of β-carotene in lipid-SDS micelle system as 4.6 × 10 3 and 8.0 × 10 3 M −1 s −1 at 37 °C, respectively. They inhibited the free radical-induced lipid peroxidation in human plasma in a concentration-dependent manner. These results suggest that the sugar-pendant fullerenes C 60-1S and C 60-2S act as a radical-scavenging antioxidant with the activity similar to the phenolic antioxidants.

P.3.d.023 The effects of quetiapine and haloperidol on human plasma lipid peroxidation in vitro

P.3.d.023 The effects of quetiapine and haloperidol on human plasma lipid peroxidation in vitro

Levels of Lipid Peroxidation in Human Plasma and Erythrocytes: Comparison between Fatty Acids and Cholesterol

Lipid peroxidation has gained renewed attention with increasing evidence showing its biological role in producing toxic compounds and cellular signaling mediators. The assessment of lipid peroxidation levels in vivo is difficult partly because lipids are oxidized by different oxidants by different mechanisms to give versatile types of products, which may undergo metabolism and secondary reactions. In the present study, total hydroxyoctadecadienoic acids (tHODE) and 7alpha- and 7beta-hydroxycholesterol (t7-OHCh) from 44 healthy human subjects were assessed as biomarkers after reduction with sodium borohydride followed by saponification with potassium hydroxide comparing with the prevailing standard 8-isoprostaglandin F(2alpha) (t8-iso-PGF(2alpha)). The average concentrations of tHODE, total 8-isoprostaglandin F(2alpha) (t8-iso-PGF(2alpha)), t7alpha-OHCh, and t7beta-OHCh were 203, 0.727, 87.1, and 156 nmol/l plasma and 1,917, 12.8, 1,372, and 3,854 nmol/l packed erythrocytes, respectively. The ratios of tHODE and t7-OHCh to the parent substrates were 194 and 3,519 micromol tHODE/mol linoleates and 40.9 and 686 micromol t7-OHCh/mol cholesterol in plasma and erythrocytes, respectively. It was found that (1) t7-OHCh in blood was unexpectedly high, as high as or even higher than tHODE, (2) the amounts of tHODE was more than 100 fold higher than t8-iso-PGF(2alpha) (3) the level of lipid oxidation products in erythrocytes was higher than that in plasma, and (4) lipid peroxidation products level tended to increase while antioxidant level decrease with age. These products may be used as potential biomarker for assessment of lipid peroxidation and oxidative stress in vivo.

Major Phytochemicals in Apple Cultivars: Contribution to Peroxyl Radical Trapping Efficiency

Forty-one samples of apples (peel plus pulp), obtained from eight cultivars, were examined for concentration of some important phytochemicals and for antioxidant activity expressed as peroxyl radical trapping efficiency. Five major polyphenolic groups plus ascorbate were identified and quantified by HPLC in the apple varieties. Oligomeric and polymeric proanthocyanidins were found to be about two-thirds of total polyphenols. The antioxidant efficiency of the apple extracts and of representative pure compounds for each group of phytochemicals was measured in a micellar system mimicking lipid peroxidation in human plasma. Although the amount of polyphenols measured by HPLC is similar to that measured by standard methods, the antioxidant efficiency calculated on the basis of the contribution of the pure compounds was lower than the antioxidant efficiency of the apple extracts. The higher efficiency of apples appears to be strictly related to the overwhelming presence of oligomeric proanthocyanidins.

P.3.092 A comparative study of haloperidol and clozapine on lipid peroxidation in human plasma ( in vitro)

P.3.092 A comparative study of haloperidol and clozapine on lipid peroxidation in human plasma ( in vitro)