Production Of Thiobarbituric Acid Reactive Substances Research Articles

Effect of maternal protein restriction on liver metabolism in rat offspring.

Consequences of gestational protein restriction (GPR) on liver metabolism in rat offspring were investigated. Pregnant dams were divided into groups: normal (NP, 17% casein) or low-protein diet (LP, 6% casein). Livers were collected from 30-day-old offspring (d30) for analysis or isolation of mitochondria. At d30, hepatic and muscle glycogen was increased in LP group. Mitochondrial swelling and oxygen uptake (recorded with a Clark-type electrode) were significantly reduced in NP female and LP pups. Thiobarbituric acid reactive substances production was lower in females (NP or LP), suggesting significant inhibition of lipid peroxidation. Measurement of mitochondrial respiration (states 3 and 4 stimulated by succinate) showed a higher ADP/O ratio in LP pups, particularly females, suggesting higher phosphorylation efficiency. In the 1st month of life, under our experimental conditions, GPR protects liver mitochondria against oxidative stress and females seem to be more resistant or more suitable for survival.

Use of Red Blood Cell Membranes to Evaluate the Antioxidant Potential of Plant Extracts

Antioxidant phytochemicals in fruits and vegetables of a vegetarian diet may account for the reduced risk of aging and stress oxidative associated diseases. In this study, a simple, rapid and accurate new bioassay for the determination of the antioxidant activity of purified or crude plant extracts and thier interactions is described, based on the fluorimetric determination of thiobarbituric acid reactive substances (TBARS) released by UV-B radiated red blood cell (RBC) ghosts. Pure resveratrol, white and red wine and pomegranate juice (PJ) were used as antioxidant source to test the biological method. TBARS production is a function of radiation time, the number of RBC ghosts in the radiated sample and the loaded antioxidant. The antioxidant activity of resveratrol was detected at a submicromolar concentration range [0.02μg/mL-0.1μmol/L]. The activity of red wine was almost 10 times higher than that of white wine, and PJ juice had the highest activity. Submaximal protective effects of PJ and red wine were additive.

Extracts from Tribulus species may modulate platelet adhesion by interfering with arachidonic acid metabolism

The present work was designed to study the effects of crude extracts from Tribulus pterocarpus, T. pentandrus and T. parvispinus on selected biological functions of human blood platelets in vitro. Platelet suspensions were pre-incubated with extracts from aerial parts of T. pterocarpus, T. pentandrus and T. parvispinus, at the final concentrations of 0.5, 5 and 50 µg/ml. Then, for platelet activation thrombin, was used. The effects of crude extracts from T. pterocarpus, T. pentandrus and T. parvispinus on adhesion of blood platelets to collagen were determined by method according to Tuszynski and Murphy. Arachidonic acid metabolism was measured by the level of thiobarbituric acid reactive substances (TBARS). In these studies we also compared the action of tested crude plant extracts with the effects of the polyphenolic fraction isolated from aerial parts of T. pterocarpus, which has antiplatelet and antioxidative properties. The performed assays demonstrated that the tested crude extract from T. pterocarpus and the phenolic fraction from T. pterocarpus might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of this tested extract and its phenolic fraction on adhesion of resting platelets and thrombin – stimulated platelets to collagen was found. We also observed that the crude extract from T. pterocarpus, like the polyphenolic fraction from T. pterocarpus reduced TBARS production in blood platelets. In the comparative studies, the tested crude extract from T. pterocarpus was not found to be more effective antiplatelet factor, than the polyphenolic fraction from this plant. The results obtained suggest that T. pterocarpus may be a promising source of natural compounds, valuable in the prevention of the enhanced activity of blood platelets in numerous cardiovascular diseases.

Day/night patterns of melatonin and oxidative stress markers in the rat Harderian gland

The rodent Harderian gland (HG) is a highly porphyrinogenic organ that is vulnerable since free radicals elicited by excessive porphyrins lead to oxidative damage. We assessed the day/night HG oxidative stress status by assaying lipid peroxidation products thiobarbituric acid-reactive substances (TBARS) and antioxidant defence systems: glutathione peroxidase (GPx), Cu, Zn-superoxide dismutase (SOD), and melatonin in male Wistar rats acclimatized to light/dark cycles regimen of 12:12 for 3 weeks, before being sacrificed in the middle of the light phase or in the middle of the dark phase. Whereas TBARS concentrations were significantly higher during the photophase compared with scotophase (p < 0.05), no day/night differences were noted in the endogenous cytoprotective and antioxidant agents, such as melatonin, GPx and SOD, in these organs. We show here that increased lipid peroxidation mostly during the light phase, a probable consequence of photoreaction, is not counteracted by HG melatonin and antioxidant enzymes GPx and SOD contents.

Robustaside B and para-hydroxyphenol: Phenolic and antioxidant compounds purified from Cnestis ferruginea D.C induced membrane permeability transition in rat liver mitochondria

The antioxidant properties of robustaside B and para‑hydroxyphenol isolated from Cnestis ferruginea were measured as the rate of inhibition of thiobarbituric acid reactive substance (TBARS) production in the Fe2+/ascorbate system. The modulatory effects of the compounds on mitochondrial membrane permeability transition (MMPT) were monitored spectrophotometrically as decreases in light scattering at 540 nm. The varying concentrations of robustaside B and para‑hydroxyphenol (0.05, 0.1, 0.2, 0.25, 0.5, 0.75 and 1 mM) significantly reduced (P<0.05) the amount of TBARS generated by the Fe2+/ascorbate system by 85.3, 86.4, 86.0, 86.1, 86.0, 86.0 and 86.0% and 86.7, 81.3, 81.3, 80, 80, 82.6 and 83.1%, respectively. Similarly, quercetin, a standard antioxidant, was found to induce an 80% reduction in the amount of TBARS produced. The same IC50 value of 0.025 mM was observed for robustaside B, para‑hydroxyphenol and quercetin. Pre‑incubation of varying concentrations of robustaside B (0.125, 0.2, 0.5 and 1 mM) with succinate‑energized mitochondria induced MMPT pore opening by 0, ‑33.3, ‑59.3 and ‑218.5%, compared with control mitochondria. Para‑hydroxyphenol at 0.1, 0.2, 0.25 and 0.5 mM induced MMPT pore opening in a concentration‑dependent manner up to 0.25 mM by ‑21, ‑54.4 and ‑107.0%, respectively. Quercetin at 0.05, 0.1, 0.25, 0.5, 0.75 and 1 mM also induced MMPT pore opening in the absence of calcium in a concentration‑dependent manner by 5, 3.7, ‑42.6, ‑81.5, ‑187 and ‑161.1%, respectively. The current observations confirm the antioxidant properties of robustaside B and para‑hydroxyphenol, and indicate a potential therapeutic use of the compounds for the treatment of diseases requiring the induction of cell death, including cancer.

Effects of Plasma from Patients Affected by Mild Cognitive Impairment and Alzheimer's Disease on Cultured Endothelial Cells

There is accumulating evidence that Alzheimer's disease (AD) can have vascular contribution. In particular, endothelial dysfunction may impair nitric oxide (NO) production and cause cerebral hypoperfusion. Blood flow impairment can be provoked also by an increased production of reactive oxygen species (ROS). The present study was performed in order to investigate the effect of plasma from subjects affected by AD and mild cognitive impairment (MCI) on human aortic endothelial cells (HAECs) in vitro, since endothelial dysfunction has been suggested to be an early event in patients affected by AD. Plasma samples were obtained from 27 AD patients, 15 MCI subjects, and 19 age-and sex-matched healthy subjects. After a short incubation period the following parameters were evaluated: NO release, superoxide dismutase (SOD) and Na+/K+-ATPase activities, membrane fluidity, and thiobarbituric acid-reactive substance (TBARS) production. Exposure to MCI plasma provoked a decrease in NO release, more pronounced in the presence of AD plasma. Our data on SOD and Na+/K+-ATPase activities showed a similar trend, since the lowest values were recorded after incubation with AD plasma. Endothelial membrane fluidity was deeply affected by the exposure to MCI plasma, and even more following incubation with AD plasma. Finally, enhanced TBARS production after incubation with MCI and AD plasma was observed. In conclusion, our results showed that MCI and AD plasma affects endothelial cells, thus highlighting the need for early treatment aimed at protecting the endothelium.

Mammary gene expression and activity of antioxidant enzymes and oxidative indicators in the blood, milk, mammary tissue and ruminal fluid of dairy cows fed flax meal

The effects of flax meal (FM) on the activity of antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT)) in the blood, mammary tissue and ruminal fluid, and oxidative stress indicators (thiobarbituric acid-reactive substances(TBARS) and 1,1-diphenyl-2-picrylhydrazyl-scavenging activity) in the milk, plasma and ruminal fluid of dairy cows were determined.The mRNA abundance of the antioxidant enzymes and oxidative stress-related genes was assessed in mammary tissue. A total of eight Holstein cows were used in a double 4 x 4 Latin square design. There were four treatments in the diet: control with no FM(CON) or 5% FM (5FM), 10% FM (10FM) and 15% FM (15FM). There was an interaction between treatment and time for plasma GPx and CAT activities. Cows supplemented with FM had a linear reduction in TBARS at 2 h after feeding, and there was no treatment effect at 0, 4 and 6 h after feeding. TBARS production decreased in the milk of cows fed the 5FM and 10FM diets. There was a linear increase in nuclear factor (erythroid-derived 2)-like 2 (NFE2L2) mRNA abundance in mammary tissue with FM supplementation.A linear trend for increased mRNA abundance of the CAT gene was observed with higher concentrations of FM. The mRNA abundance of CAT, GPx1, GPx3, SOD1, SOD2, SOD3 and nuclear factor of k light polypeptide gene enhancer in B-cells (NFKB) genes was not affected by the treatment. These findings suggest that FM supplementation can improve the oxidative status of Holstein cows as suggested by decreased TBARS production in ruminal fluid 2 h post-feeding and increased NFE2L2/nuclear factor-E2-related factor 2 (Nrf2) mRNA abundance in mammary tissue.

Antioxidant properties of glutamine and its role in VEGF-Akt pathways in portal hypertension gastropathy.

To investigate the effects of glutamine on oxidative/nitrosative stress and the vascular endothelial growth factor (VEGF)-Akt-endothelial nitric oxide synthase (eNOS) signaling pathway in an experimental model of portal hypertension induced by partial portal vein ligation (PPVL). Portal hypertension was induced by PPVL. The PPVL model consists of a partial obstruction of the portal vein, performed using a 20 G blunt needle as a guide, which is gently removed after the procedure. PPVL model was performed for 14 d beginning treatment with glutamine on the seventh day. On the fifteenth day, the mesenteric vein pressure was checked and the stomach was removed to test immunoreactivity and oxidative stress markers. We evaluated the expression and the immunoreactivity of proteins involved in the VEGF-Akt-eNOS pathway by Western blotting and immunohistochemical analysis. Oxidative stress was measured by quantification of the cytosolic concentration of thiobarbituric acid reactive substances (TBARS) as well as the levels of total glutathione (GSH), superoxide dismutase (SOD) activity, nitric oxide (NO) production and nitrotyrosine immunoreactivity. All data are presented as the mean ± SE. The production of TBARS and NO was significantly increased in PPVL animals. A reduction of SOD activity was detected in PPVL + G group. In the immunohistochemical analyses of nitrotyrosine, Akt and eNOS, the PPVL group exhibited significant increases, whereas decreases were observed in the PPVL + G group, but no difference in VEGF was detected between these groups. Western blotting analysis detected increased expression of phosphatidylinositol-3-kinase (PI3K), P-Akt and eNOS in the PPVL group compared with the PPVL + G group, which was not observed for the expression of VEGF when comparing these groups. Glutamine administration markedly alleviated oxidative/nitrosative stress, normalized SOD activity, increased levels of total GSH and blocked NO overproduction as well as the formation of peroxynitrite. Glutamine treatment demonstrated to reduce oxidative damage but does not reduce angiogenesis induced by PH in gastric tissue, demonstrating a beneficial role for the PI3K-Akt-eNOS pathway.

Probucol Inhibited Nox2 Expression and Attenuated Podocyte Injury in Type 2 Diabetic Nephropathy of db/db Mice

The present study was conducted to investigate the effects of probucol on the progression of diabetic nephropathy and the underlying mechanism in type 2 diabetic db/db mice. Eight weeks db/db mice were treated with regular diet or probucol-containing diet (1%) for 12 weeks. Non-diabetic db/m mice were used as controls. We examined body weight, blood glucose, and urinary albumin. At 20 weeks, experimental mice were sacrificed and their blood and kidneys were extracted for the analysis of blood chemistry, kidney histology, oxidative stress marker, and podocyte marker. As a result, 24 h urinary albumin excretions were reduced after probucol treatment. There were improvements of extracellular matrix accumulation and fibronectin and collagen IV deposition in glomeruli in the probucol-treated db/db mice. The reduction of nephrin and the loss of podocytes were effectively prevented by probucol in db/db mice. Furthermore, probucol significantly decreased the production of thiobarbituric acid-reactive substances (TBARS), an index of reactive oxygen species (ROS) generation and down-regulated the expression of Nox2. Taken together, our findings support that probucol may have the potential to protect against type 2 diabetic nephropathy via amelioration of podocyte injury and reduction of oxidative stress.

5-lipoxygenase deficiency reduces acetaminophen-induced hepatotoxicity and lethality.

5-Lipoxygenase (5-LO) converts arachidonic acid into leukotrienes (LTs) and is involved in inflammation. At present, the participation of 5-LO in acetaminophen (APAP)-induced hepatotoxicity and liver damage has not been addressed. 5-LO deficient (5-LO−/−) mice and background wild type mice were challenged with APAP (0.3–6 g/kg) or saline. The lethality, liver damage, neutrophil and macrophage recruitment, LTB4, cytokine production, and oxidative stress were assessed. APAP induced a dose-dependent mortality, and the dose of 3 g/kg was selected for next experiments. APAP induced LTB4 production in the liver, the primary target organ in APAP toxicity. Histopathological analysis revealed that 5-LO−/− mice presented reduced APAP-induced liver necrosis and inflammation compared with WT mice. APAP-induced lethality, increase of plasma levels of aspartate aminotransferase and alanine aminotransferase, liver cytokine (IL-1β, TNF-α, IFN-γ, and IL-10), superoxide anion, and thiobarbituric acid reactive substances production, myeloperoxidase and N-acetyl-β-D-glucosaminidase activity, Nrf2 and gp91phox mRNA expression, and decrease of reduced glutathione and antioxidant capacity measured by 2,2′-azinobis(3-ethylbenzothiazoline 6-sulfonate) assay were prevented in 5-LO−/− mice compared to WT mice. Therefore, 5-LO deficiency resulted in reduced mortality due to reduced liver inflammatory and oxidative damage, suggesting 5-LO is a promising target to reduce APAP-induced lethality and liver inflammatory/oxidative damage.

Attenuation of hepatocellular carcinoma by naringenin is associated with modulation of circadian rhythms of redox status in rats

We evaluated the effect of naringenin on the circadian rhythms of circulatory lipid peroxidation and antioxidant status during N-Nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in rats. The characteristics of circadian rhythms (acrophase, amplitude and mesor) of lipid peroxidation products thiobarbituric acid reactive substances (TBARS) and antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST)) were markedly altered in NDEA-treated rats when compared to other groups. Pre- and post-treatment of naringenin to NDEA treated animals significantly increased the mesor and alter amplitude values of antioxidants and significantly decreased the mesor values of TBARS. Further delays in acrophase in NDEA-treated rats were reversed by naringenin administration. Our findings suggest that naringenin could alter the circadian characteristics of lipid peroxidation and antioxidant status, and further research is in process on the chronotherapeutic efficacy of naringenin.

Antioxidant and pro-oxidant activity of (−)-epigallocatechin-3-gallate in food emulsions: Influence of pH and phenolic concentration

Polyphenols have been observed to exert both antioxidant and pro-oxidant activity in lipid foods, and factors that influence that net effect include both polyphenol concentration and matrix pH. In this study, the effects of concentration (1–500μM) of a model polyphenol, (−)-epigallocatechin-3-gallate (EGCG), and matrix pH (2–7) on the net anti-/pro-oxidant activity of EGCG in flaxseed oil-in-water (o/w) emulsions were systematically evaluated. After 24h, EGCG (5–100μM) was observed to exhibit pro-oxidant activity in low pH (pH 2–4) emulsions, as determined by conjugated dienes (CDs) and thiobarbituric acid reactive substances (TBARSs) production. At the higher pH values studied (pH 5–7), lower CD and TBARS concentrations were detected in samples with 25–500μM EGCG at 24h. Overall, EGCG concentration and pH both played significant roles in determining net antioxidant or pro-oxidant effects, with the largest antioxidant and pro-oxidant effects observed at the higher EGCG concentrations (100–500μM) tested.

Synergist effects of n-acetylcysteine and deferoxamine treatment on behavioral and oxidative parameters induced by chronic mild stress in rats

A growing body of evidence has pointed to a relationship between oxidative stress and depression. Thus, the present study was aimed at evaluating the effects of the antioxidants n-acetylcysteine (NAC), deferoxamine (DFX) or their combination on sweet food consumption and oxidative stress parameters in rats submitted to 40days of exposure to chronic mild stress (CMS). Our results showed that in stressed rats treated with saline, there was a decrease in sweet food intake and treatment with NAC or NAC in combination with DFX reversed this effect. Treatment with NAC and DFX decreased the oxidative damage, which include superoxide and TBARS production in submitochondrial particles, and also thiobarbituric acid reactive substances (TBARS) levels and carbonyl proteins in the prefrontal cortex, amygdala and hippocampus. Treatment with NAC and DFX also increased the activity of the antioxidant enzymes, superoxide dismutase and catalase in the same brain areas. Even so, a combined treatment with NAC and DFX produced a stronger increase of antioxidant activities in the prefrontal cortex, amygdala and hippocampus. The results described here indicate that co-administration may induce a more pronounced antidepressant activity than each treatment alone. In conclusion, these results suggests that treatment with NAC or DFX alone or in combination on oxidative stress parameters could have positive effects against neuronal damage caused by oxidative stress in major depressive disorders.

Antioxidant capacity, antimicrobial activity and triterpenes isolated from Jatropha isabellei Müll Arg.

Jatropha isabellei Müll Arg. belongs to the family Euphorbiaceae. The antioxidant capacity of this plant was evaluated by the DPPH method and inhibition of thiobarbituric acid reactive substances (TBARS). Ethyl acetate fraction demonstrated the best antioxidant capacity against the DPPH free radical and its profile was similar to ascorbic acid. This fraction also presented the best results of phenolics, flavonoids and condensed tannins, showing a positive relation between the phenolic content and antioxidant activity. All fractions and the crude extract were able to inhibit significantly the TBARS production induced by Fe(II) for the two tested concentrations, reaching the basal levels. In this test, ethyl acetate and dichloromethane fraction showed good values for inhibitory concentration. The dichloromethane fraction showed the best results against the fungi Sporothrix schenckii and Fusarium proliferatum and the bacterium of Micrococcus genus. This fraction allowed the isolation of acetil aleuritolic acid and a mixture of sitosterol 3-O-β-D-glucoside and stigmasterol, described for the first time in this species.

Nitric oxide is involved in the regulation of trehalose accumulation under heat stress in Pleurotus eryngii var. tuoliensis

Little is known about the mechanism of how trehalose responds to various abiotic stresses although trehalose is considered as an important protectant in fungi. We investigated the role of nitric oxide (NO) in regulating trehalose accumulation during heat stress in Pleurotus eryngii var. tuoliensis. The addition of 100 or 200 g trehalose/l significantly inhibited the production of thiobarbituric acid-reactive substance under heat stress in mycelial cells. High temperature induced endogenous trehalose accumulation and sodium nitroprusside, a NO donor, further enhanced trehalose accumulation. Finally, heat-induced trehalose accumulation could be arrested by the NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-1-oxyl-3-oxide, at 250 μM by inhibiting the transcription of trehalose phosphate synthase gene. Thus NO plays an important role in the regulation of trehalose accumulation during abiotic stresses in P. eryngii var. tuoliensis.

Inhibition of Lipid Oxidation by MRP Antioxidant in Enriched Cooked Beef Patties with Polyunsaturated Fatty Acids

&lt;p&gt;The addition of n3 polyunsaturated fatty acids to foods is an emerging area of commercial and academic interest. However, the incorporation of n3 polyunsaturated fatty acids into food systems is potentially problematic due to their propensity to oxidize easily. The antioxidant capacity of MRP has mostly been studied in vitro, in fresh chicken, mutton and pork, and in precooked ground pork and beef patties and sausages. The aim of this study is to evaluate the antioxidant properties as well as the antioxidant effect of a preformed Maillard Reaction Product (MRP) from sarcoplasmic proteins/malondialdehyde, known for its antioxidant effect on water/oil emulsion and on lipid oxidation of beef patties when the level of n3 PUFA is improved. The MRP presented a high reducing power, a low phenolic compound content (9.2 mg gallic acid equivalent/g and 798.3 mg quercetin equivalent/g), and a minor DPPH and ABTS+ radicals scavenging activity (34 % and 23,5 %, respectively). All concentrations of MRP assayed inhibited hydroperoxide formation and thiobarbituric acid reactive substances (TBARS) production during refrigerated storage of enriched meat patties. The 3% concentration was the most efficient and exerted an 83 % and 85 % inhibition of peroxidation measured as peroxide value and TBARS, respectively.&lt;/p&gt;

Induction of Nrf2-dependent Antioxidation and Protection Against Carbon Tetrachloride-induced Liver Damage by Andrographis Herba (穿心蓮chuān xīn lián) Ethanolic Extract

Andrographis paniculata is a traditional Chinese herb and displays diverse biological activities including antioxidation, anti-tumorigenesis, anti-virus, and anti-atherogenesis. In this study, we investigated the up-regulation of ethanolic extract of A. paniculata (APE) on the antioxidant defense in rat livers and whether this enhancement protected against carbon tetrachloride (CCl4)-induced liver damage. Male Sprague-Dawley rats were orally administered (i.g.) 0, 0.75, or 2g/kg/d APE for 5 d. At d 6, rats were sacrificed and liver tissues were removed. Some animals (n=8) were intraperitoneally injected CCl4 (1mL/kg, 50% in olive oil) and blood was drawn 24h after CCl4 treatment. The results showed that APE increased hepatic glutathione (GSH) content and superoxide dismutase, GSH peroxidase, and GSH S-transferase activities in a dose-dependent manner (p<0.05). Results of immunoblotting and RT-PCR revealed that rats treated with APE had higher glutamate cysteine ligase catalytic and modifier subunits, heme oxygenase 1, superoxide dismutase 1, and GSH S-transferase Ya and Yb protein and mRNA expression than those of control rats. Moreover, APE increased Nrf2 nuclear translocation and Nrf2 binding to DNA in rat liver. In the presence of CCl4, APE decreased hepatic thiobarbituric acid-reactive substances production and plasma aspartate aminotransferase and alanine aminotransferase activities. These results suggest that APE protection against CCl4 insult is attributed, at least in part, to its up-regulation of antioxidant defense in rat liver.

Hypoxia-Induced Lipid Peroxidation in the Brain During Postnatal Ontogenesis

Reactive oxygen species (ROS) are common products of the physiological metabolic reactions, which are associated with cell signaling and with the pathogenesis of various nervous disorders. The brain tissue has the high rate of oxidative metabolic activity, high concentration of polyunsaturated fatty acids in membrane lipids, presence of iron ions and low capacity of antioxidant enzymes, which makes the brain very susceptible to ROS action and lipid peroxidation formation. Membranes of brain cortex show a higher production of thiobarbituric acid-reactive substances (TBARS) in prooxidant system (ADP.Fe(3+)/NADPH) than membranes from the heart or kidney. Lipid peroxidation influences numerous cellular functions through membrane-bound receptors or enzymes. The rate of brain cortex Na(+),K(+)-ATPase inhibition correlates well with the increase of TBARS or conjugated dienes and with changes of membrane fluidity. The experimental model of short-term hypoxia (simulating an altitude of 9000 m for 30 min) shows remarkable increase in TBARS in four different parts of the rat brain (cortex, subcortical structures, cerebellum and medulla oblongata) during the postnatal development of Wistar rat of both sexes. Young rats and males are more sensitive to oxygen changes than adult rats and females, respectively. Under normoxia or hypobaric hypoxia both ontogenetic aspects and sex differences play a major role in establishing the activity of erythrocyte catalase, which is an important part of the antioxidant defense of the organism. Rats pretreated with L-carnitine (and its derivatives) have lower TBARS levels after the exposure to hypobaric hypoxia. The protective effect of L-carnitine is comparable with the effect of tocopherol, well-known reactive species scavenger. Moreover, the plasma lactate increases after a short-term hypobaric hypoxia and decreases in L-carnitine pretreated rats. Acute hypobaric hypoxia and/or L-carnitine-pretreatment modify serum but not brain lactate dehydrogenase activity. The obtained data seem to be important because the variations in oxygen tension represent specific signals of regulating the activity of many specific systems in the organism.

Exogenous Arachidonate Restores the Dimethoate‐Induced Inhibition of Steroidogenesis in Rat Interstitial Cells

The present work studies the potential restorative effect of polyunsaturated fatty acids (PUFA, 5 μM/24 h) on the dimethoate (DMT)-induced inhibition of testosterone biosynthesis in Leydig cells isolated from rat testes. Various fatty acids (FA) from the n-6 (18:2, 20:3, 20:4, 22:4 and 22:5) and n-3 (18.3, 20:5, 22:5, 22:6) series were assayed in Leydig cells, alone (as delipidated BSA complexes) and in combination with DMT (1 ppm). The n-6 FA stimulated lipid peroxidation (LPO) and inhibited the activities of steroidogenic enzymes (3β- and 17β-hydroxysteroid dehydrogenases). The n-3 FA exerted an anti-oxidant effect, decreasing the production of thiobarbituric-acid reactive substances (TBARS) and inhibiting phospholipase A(2) activity. The biosynthesis of testosterone in DMT-treated cultures was completely normalized by ARA (20:4n-6) and partially restored by the addition of 20:3n-6, increasing ARA content inside the mitochondria. The other FA assayed failed to restore androgenesis. COX-2 protein and prostaglandin F2α and E2 production were stimulated by 20:3n-6, ARA, 18:3n-3 and 20:5 n-3. COX-2 protein decreased upon addition of 22:5n-3 and 22:6n-3. StAR protein was increased by ARA and partially increased by 20:3n-6, likely due to its metabolic conversion into ARA. Both FA increased the mitochondrial cholesterol pool available for testosterone biosynthesis. The rate of androgenesis is likely the result of various regulatory factors acting concomitantly on the physiology of Leydig cells.

Evaluation of polyphenolic fraction isolated from aerial parts of Tribulus pterocarpus on biological properties of blood platelets in vitro

The antiplatelet and antioxidative activity of polyphenolic fraction isolated from aerial parts of Tribulus pterocarpus in blood platelets stimulated by thrombin was studied. Thrombin as a strong physiological agonist induces the enzymatic peroxidation of endogenous arachidonic acid, the formation of different reactive oxygen species, including superoxide anion radicals (·) and the platelet aggregation. Therefore, the aim of our study was to assess if the polyphenolic fraction from aerial parts of T. pterocarpus may change the biological properties of blood platelets activated by thrombin. We used cytochrome c reduction method to test the ability of this fraction to change · generation in platelets. Arachidonic acid metabolism was measured by the level of thiobarbituric acid reactive substances (TBARS) and by the production of 8-epi-prostaglandin (8-EPI) F2. Moreover, we determined the effects of the fraction on blood platelet aggregation induced by thrombin. We observed that the polyphenolic fraction from T. pterocarpus reduced ·, 8-EPI and TBARS production in these cells. The ability of the fraction to decrease the · generation in blood platelets supports the importance of free radicals in platelet functions, including aggregation process. This study may suggest that the tested plant fraction might be a good candidate for protecting blood platelets against changes of their biological functions, which may be associated with the pathogenesis of different cardiovascular disorders.