Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180-200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg x day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.     

Dietary oils high in oleic acid, but with different non-glyceride contents, have different effects on lipid profiles and peroxidation in rabbit hepatic mitochondria

The influence on the lipid profile and lipid peroxidation in rabbit-liver mitochondria exerted by different edible oils high in oleic acid but different non-glyceride phenolic fractions was studied. High-phenolic virgin olive oil from the variety "Picual", the same oil submitted to an exhaustive process of washing to eliminate the phenolic fraction without altering the lipid profile and high-oleic sunflower oil (poor in phenolic compounds) were added to rabbit diets. The results reveal the importance of the different oleic: linoleic ratio of the lipid sources on the lipid profile of mitochondrial membranes. This is highlighted by the greater proportion of saturated fatty acids and the lower content in oleic acid (p < 0.05) shown by the rabbits fed on high-oleic sunflower oil. The group fed on the fat rich in phenolics exhibited the highest level of antioxidants (alpha-tocopherol, ubiquinone 10) and the highest activity of glutathione peroxidase as well as the lowest content in hydroperoxides and TBARS. The study provides evidences in vivo about the considerable antioxidant capacity of the phenolic fraction of virgin olive oil in rabbit-liver mitochondria and the important role that this non-glyceride fraction can play in the overall antioxidant benefits attributed to this oil.     

Arabica coffee and olive oils mitigate malathion-induced nephrotoxicity in rat: In silico,immunohistochemical and biochemical evaluation

Malathion (MAL) is an organophosphate insecticide that disrupts the body's antioxidant system; it is one of the earliest organophosphate insecticides extensively used as dust, emulsion, and vapor control a wide variety of insect pests under different conditions. This experimentation aims to evaluate the influence of Arabica coffee oil and olive oil on MAL-induced nephrotoxicity in male rat. 6 sets bearing the same number of animals were applied to this experiment. Each set comprised 10 rats. The first set of rats was used as the control group; rats in the second set were exposed to MAL measured at 100 mg/kg body weight for 7 weeks. Animals in the third and fourth set were treated with 400 mg/kg body weight of Arabica coffee oil and olive oil, and 100 mg/kg body weight of MAL. The fifth, together with the sixth set, were fed with a similar proportion of Arabica coffee oil and olive oil as administered to the third set of rats. After the experimental duration, rats of group 2 showed severe biochemical alterations, including significant increases of creatinine, uric acids, and urea nitrogen (BUN), resulting in marked decreases in serum albumin values and total protein (TP). Severe histopathological and immunohistochemical alterations of kidney tissues were observed in exposed MAL-intoxicated rats. Administration of these oils reduced the detected biochemical, histopathological modifications caused by MAL intoxication. Two active ingredients in Arabica coffee oil (oleic acid) and olive oil (hydroxytyrosol) showed good cyclooxygenase-2 (COX 2) interaction. Moreover, oleic acid from coffee oil and olive oil exhibited impressive association with xanthine oxidase (XO). The current finding showed that coffee oil and olive oil could be appraised as possible and a likely deterrence component against nephrotoxicity brought about by MAL.     

Olive oil polyphenols enhance the expression of cholesterol efflux related genes in vivo in humans. A randomized controlled trial

Both oleic acid and polyphenols have been shown to increase high-density lipoprotein (HDL) cholesterol and to protect HDL from oxidation, a phenomenon associated with a low cholesterol efflux from cells. Our goal was to determine whether polyphenols from olive oil could exert an in vivo nutrigenomic effect on genes related to cholesterol efflux in humans. In a randomized, controlled, cross-over trial, 13 pre/hypertensive patients were assigned 30 ml of two similar olive oils with high (961 mg/kg) and moderate (289 mg/kg) polyphenol content. We found an increase in ATP binding cassette transporter-A1, scavenger receptor class B type 1, peroxisome proliferator-activated receptor (PPAR)BP, PPARα, PPARγ, PPARδ and CD36 gene expression in white blood cells at postprandial after high polyphenol olive oil when compared with moderate polyphenol olive oil intervention (P<.017), with COX-1 reaching borderline significance (P=.024). Linear regression analyses showed that changes in gene expression were related to a decrease in oxidized low-density lipoproteins and with an increase in oxygen radical absorbance capacity and olive oil polyphenols (P<.05). Our results indicate a significant role of olive oil polyphenols in the up-regulation of genes involved in the cholesterol efflux from cells to HDL in vivo in humans. These results are in agreement with previous ones concerning the fact that benefits associated with polyphenol-rich olive oil consumption on cardiovascular risk could be mediated through an in vivo nutrigenomic effect in humans.     

Antioxidant effect of hydroxytyrosol (DPE) and Mn2+ in liver of cadmium-intoxicated rats

Liver TBARS formation in cadmium-intoxicated rats was completely reduced by administering a low amount of MnCl(2) (2 mg/kg b.w.) 1 h before intoxication. A similar antioxidant effect was first shown by hydroxytyrosol (2-(3,4-dihydroxyphenyl)ethanol, (DPE), a phenolic compound present in olive oil, given twice to rats (9 mg/kg b.w.) after cadmium administration. The antioxidant properties shown in vivo by both Mn(2+) and DPE were also active in vitro when rat liver microsomes were subjected to lipid peroxidation by cadmium or other prooxidant systems. The increase in liver glutathione concentrations occurring in cadmium-intoxicated rats, was also found, for the first time, 24 h after MnCl(2) administration. Unlike cadmium intoxication, which caused a higher formation of both glutathione and TBARS, Mn(2+) induced glutathione synthesis without any TBARS formation. The same situation was also observed when cadmium plus Mn(2+) or cadmium plus DPE was given to rats. Our data show that: (a). both DPE and low Mn(2+) concentrations may have an antioxidant effect in the livers of cadmium-intoxicated rats and (b). Mn(2+), like cadmium, induces liver glutathione synthesis and this effect is probably independent of TBARS formation.     

Influence of olive oil and its components on mesenchymal stem cell biology

Extra virgin olive oil is characterized by its high content of unsaturated fatty acid residues in triglycerides, mainly oleic acid, and the presence of bioactive and antioxidant compounds. Its consumption is associated with lower risk of suffering chronic diseases and unwanted processes linked to aging, due to the antioxidant capacity and capability of its components to modulate cellular signaling pathways. Consumption of olive oil can alter the physiology of mesenchymal stem cells(MSCs). This may explain part of the healthy effects of olive oil consumption, such as prevention of unwanted aging processes. To date,there are no specific studies on the action of olive oil on MSCs, but effects of many components of such food on cell viability and differentiation have been evaluated. The objective of this article is to review existing literature on how different compounds of extra virgin olive oil, including residues of fatty acids,vitamins, squalene, triterpenes, pigments and phenols, affect MSC maintenance and differentiation, in order to provide a better understanding of the healthy effects of this food. Interestingly, most studies have shown a positive effect of these compounds on MSCs. The collective findings support the hypothesis that at least part of the beneficial effects of extra virgin olive oil consumption on health may be mediated by its effects on MSCs.     

黔产毛蒟挥发油对油酸致大鼠急性肺损伤的影响及其机制

为研究黔产毛蒟挥发油在油酸诱导的大鼠急性肺损伤中的作用及其机制。实验将雄性成年清洁级SD大鼠按照体重随机分为对照组、油酸模型组和毛蒟挥发油组(0.125、0.25、0.5 mL/kg)。油酸模型组大鼠采用右侧颈静脉注射油酸0.2 mL/kg形成急性肺损伤模型;毛蒟挥发油组大鼠在油酸造模前30分钟静脉注射毛蒟挥发油;建模4 h后处死,留取标本。观察各组肺组织病理学形态并进行肺损伤评分,同时测定血气分析值、右下肺湿干重、肺通透指数以及肺泡灌洗液中TNF-α、IL-6和IL-1β炎症因子的含量,最后采用免疫组化和Western Blot检测p38MAPK和p-p38MAPK蛋白的表达量。结果表明大鼠PaO_2和PaO_2/FiO_2在油酸模型组明显低于对照组,同时右下肺湿干重、肺通透指数以及肺泡灌洗液中TNF-α、IL-6和IL-1β炎症因子的含量在油酸模型组明显高于对照组。油酸模型组肺组织病理学显示肺损伤明显;毛蒟挥发油组上述指标较油酸模型组明显减轻。p-p38MAPK蛋白表达量在油酸模型组中明显高于对照组,而p-p38MAPK蛋白表达量在毛蒟挥发油组中明显低于油酸模型组。实验证明黔产毛蒟挥发油能够通过抑制p38MAPK通路减少急性肺损伤炎症因子的产生,对急性肺损伤具有较好的保护作用。     

Postprandial LDL phenolic content and LDL oxidation are modulated by olive oil phenolic compounds in humans

Olive oil phenolic compounds are potent antioxidants in vitro, but evidence for antioxidant action in vivo is controversial. We examined the role of the phenolic compounds from olive oil on postprandial oxidative stress and LDL antioxidant content. Oral fat loads of 40 mL of similar olive oils, but with high (366 mg/kg), moderate (164 mg/kg), and low (2.7 mg/kg) phenolic content, were administered to 12 healthy male volunteers in a cross-over study design after a washout period in which a strict antioxidant diet was followed. Tyrosol and hydroxytyrosol, phenolic compounds of olive oil, were dose-dependently absorbed (p<0.001). Total phenolic compounds in LDL increased at postprandial state in a direct relationship with the phenolic compounds content of the olive oil ingested (p<0.05). Plasma concentrations of tyrosol, hydroxytyrosol, and 3-O-methyl-hydroxytyrosol directly correlated with changes in the total phenolic compounds content of the LDL after the high phenolic compounds content olive oil ingestion. A 40 mL dose of olive oil promoted a postprandial oxidative stress, the degree of LDL oxidation being lower as the phenolic content of the olive oil administered increases. In conclusion, olive oil phenolic content seems to modulate the LDL phenolic content and the postprandial oxidative stress promoted by 40 mL olive oil ingestion in humans.     

Hydroxytyrosol, a natural molecule occurring in olive oil, induces cytochrome c-dependent apoptosis

2-(3,4-Dihydroxyphenyl)ethanol (DPE), a naturally occurring phenolic antioxidant molecule found in olive oil, has been reported to exert several biological and pharmacological activities. We studied the effect of this compound on the proliferation and survival of HL60 cell line. Concentrations from 50 to 100 microM DPE, comparable to its olive oil content, caused a complete arrest of HL60 cell proliferation and the induction of apoptosis. This was demonstrated by flow cytometric analyses, poly(ADP-ribose) polymerase cleavage, and caspase 3 activation. The apoptotic effect requires the presence of two ortho-hydroxyl groups on the phenyl ring, since tyrosol, 2-(4-hydroxyphenyl)ethanol, did not induce either cell growth arrest or apoptosis. DPE-dependent apoptosis is associated with an early release of cytochrome c from mitochondria which precedes caspase 8 activation, thus ruling out the engagement of cell death receptors in the apoptotic process. 2-(3,4-Dihydroxyphenyl)ethanol induced cell death in quiescent and differentiated HL60 cells, as well as in resting and activated peripheral blood lymphocytes, while did not cause cell death in two colorectal cell lines (HT-29 and CaCo2). These results suggest that DPE down-regulates the immunological response, thus explaining the well-known antinflammatory and chemopreventive effects of olive oil at the intestinal level.     

Lipid composition of liver microsomes in rats fed a high monounsaturated fatty acid diet

The fatty acid and cholesterol contents of tissue membranes are the determinants of membrane stability and functionality. This study was designed to evaluate the influence of a high monounsaturated fatty acid diet on the fatty acid composition of rat liver microsomes and on their cholesterol and lipid phosphorus content. Weanling animals were fed for 5 weeks with high fat diets containing olive oil or corn oil. Saturated fatty acids were increased and oleic acid decreased in microsomal total phospholipids and in the three major phosphoglycerides, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI), of rats fed corn oil as compared to the olive oil group. The percentage of linoleic acid was higher in the corn oil group, but only for total phospholipids and PC. Linoleic and alpha-linolenic metabolites were significantly increased in total phospholipids of olive oil-fed animals with respect to those fed corn oil. These changes were responsible for the low unsaturation index found in microsomal phospholipids of the corn oil group. The diet did not affect the microsome cholesterol or the lipid phosphorus content. These results show that, in olive oil-fed rats, the cholesterol content and the degree of unsaturation of liver microsomes was similar to that observed in weanling animals; this probably suggests an adequate maintenance of functionality of membranes in olive oil-fed animals.     

Physicochemical properties of cold pressed sunflower,peanut, rapeseed,mustard and olive oils grown in the Eastern Mediterranean region

Fatty acid composition and stability of vegetable oils have taken more attention as an essential source of biologically active compounds in a good balanced diet. The purpose of the study was to determine peroxide value, free fatty acids, unsaponifiable matter, total carotenoid content, iodine value and fatty acid composition of sunflower, rapeseed, mustard, peanut and olive oils. Rapeseed and peanut oils had the highest peroxide values, while sunflower oil had the lowest peroxide values. The free fatty acid value of the tested oils varied between 0.43 and 1.36% oleic. The peanut oil had the highest free acid value and the mustard oil had the lowest one. Total carotenoid contents of mustard and rape seed oil were higher than those of the other oils tested. Palmitic acid (C16:0), oleic acid (C18:1) and stearic acid (C18:0) were the common main fatty acid components of the vegetable oils tested. Followed by linoleic acid, the amount of oleic acid was the highest among other fatty acid components. Mustard oil had the highest erucic acid (C22:1) with the amount of 11.38%, indicating that it cannot be used for human consumption. Among the oils investigated, sunflower and mustard oils were more stable than rapeseed, peanut and olive oils.     

Modeling of olive oil degradation and oleic acid inhibition during chemostat and batch cultivation of Bacillus thermoleovorans IHI-91

Olive oil degradation by the thermophilic lipolytic strain Bacillus thermoleovorans IHI-91 in chemostat and batch culture was modeled to obtain a general understanding of the underlying principles and limitations of the process and to quantify its stoichiometry. Chemostat experiments with olive oil as the sole carbon source were successfully described using the Monod chemostat model extended by terms for maintenance requirements and wall growth. Maintenance requirements and biomass yield coefficients were in the range reported for mesophiles. For a chemostat experiment at D = 0.3 h(-1) the model was validated up to an olive oil feed concentration of about 3.0 g L(-1) above which an inhibitory effect occurred. Further analysis showed that the liberated oleic acid is the main cause for this inhibition. Using steady-state oleic acid concentrations measured in chemostat experiments with olive oil as substrate it was possible to derive a kinetic expression for oleic acid utilization, showing that a concentration of 430 mg L(-1) leads to a complete growth inhibition. Oleic acid accumulation observed during batch fermentations can be predicted using a model involving growth-associated lipase production and olive oil hydrolysis. Simulations confirmed that this accumulation is the cause for the sudden growth cessation occurring in batch fermentations with higher olive oil start concentrations. Further, an oscillatory behavior, as observed in some chemostat experiments, can also be predicted using the latter model. This work clearly demonstrates that thermophilic lipid degradation by Bacillus thermoleovorans IHI-91 is limited by long-chain fatty acid beta-oxidation rather than oil hydrolysis.     

Transport mechanism and metabolism of olive oil hydroxytyrosol in Caco-2 cells

3,4-dihydroxyphenylethanol (hydroxytyrosol; DPE) is the major phenolic antioxidant present in extra virgin olive oil, either in a free or esterified form. Despite its relevant biological effects, no data are available on its bioavailability and metabolism. The aim of the present study is to examine the molecular mechanism of DPE intestinal transport, using differentiated Caco-2 cell monolayers as the model system. The kinetic data demonstrate that [(14)C]DPE transport occurs via a passive diffusion mechanism and is bidirectional; the calculated apparent permeability coefficient indicates that the molecule is quantitatively absorbed at the intestinal level. The only labelled DPE metabolite detectable in the culture medium by HPLC (10% conversion) is 3-hydroxy-4-methoxyphenylethanol, the product of catechol-O-methyltransferase; when DPE is assayed in vitro with the purified enzyme a K(m) value of 40 microM has been calculated.     

Olive oil supplemented with Coenzyme Q(10): effect on plasma and lipoprotein oxidative status

Olive oil consumption is associated with protective cardiovascular properties, including some beneficial modifications in lipoprotein profile and composition. Coenzyme Q(10) (CoQ(10)) exerts a protective effect on plasma lipoproteins. Aim of the study was to investigate whether extra virgin (EV) olive oil enriched with CoQ(10) affects CoQ(10) levels and oxidative status in plasma and in isolated lipoproteins. Twelve subjects were administered 20 mL olive oil per day for 2 weeks, followed by 2 weeks of olive oil enriched with 20 mg and 2 more weeks with 40 mg of CoQ(10). Plasma and isolated lipoproteins were collected in each phase of the study and subsequently analyzed to assess lipid profile, CoQ10 levels, ORAC assay, resistance of lipoproteins to peroxidation and paroxonase 1 activity. Plasma CoQ(10) levels significantly increased with the 20 mg (+73%) and 40 mg dose (+170%), while the percentage of oxidized CoQ(10) decreased. A significant inverse correlation was found in plasma between percentage of oxidized CoQ(10) and total antioxidant capacity. A lower susceptibility of LDL to peroxidation was also found. Finally, a positive correlation was observed between concentration of CoQ(10) in HDL and paraoxonase-1 activity. EV olive oil enriched with both doses of CoQ(10) significantly affects its bioavailability and plasma redox status. These changes are associated with a decreased susceptibility of plasma lipoproteins to peroxidation associated with a chain-breaking antioxidant activity of the formulation.     

Lipid components of olive oil from Tunisian Cv. Sayali: Characterization and authenticity

The analysis of the total lipid fraction from the Sayali variety of olive oil was accomplished in the present investigation. Glyceridic, unsaponifiable and flavour fractions of the oil were isolated and identified using several analytical methods. Chromatographic techniques have proven to be suitable for these determinations, especially capillary gas chromatography. Gas chromatography coupled to mass spectrometry was successfully used to identify sterols, triterpenes alcohols, 4-monomethylsterols, aliphatic alcohols and aroma compounds in our samples. Furthermore, solid phase microextraction was used to isolate volatiles from the total lipid fraction. Results from the quantitative characterization of Sayali olive oil showed that oleic acid (77.4%) and triolein (47.4%) were the dominant glyceridic components. However, the main compounds of the unsaponifiable fraction were β-sitosterol (147.5 mg/100 g oil), 24-methylene cycloartenol (146.4 mg/100 g oil) and hexacosanol (49.3 mg/100 g oil). Moreover, results showed that the aldehydic compounds were the major flavours present in Sayali olive oil.     

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.     

Effects of Two Highly Monounsaturated Oils on Lipid Composition and Enzyme Activities in Rat Jejunum

The effects of two monounsaturated fatty acid (MUFA) oils, olive oil (OO)and high-oleic sunflower oil (HOSO), with high content in oleic acid butdiffering in their non-fatty acid fraction, on brush-border membrane(BBM) lipid composition and fluidity and on mucosal enzyme activitiesof rat jejunum were studied. Animals were given semipurified diet withlinoleic acid to prevent essential fatty acid deficiency (control group)or semipurified diet containing 10% of either OO or HOSO for 12weeks. There was a significant decrease in the content of jejunalBBM phospholipids together with an increase in the level of freecholesterol in both oil-fed rats, when compared to controlgroup. Although the increase in the BBM free cholesterol levelwas not statistically significant in HOSO-fed rats, a significantdecrease in the phospholipid/free cholesterol ratio was found inboth OO and HOSO-fed animals compared to control group. Rat jejunalBBM had a high level of free fatty acids which was increased in BBMisolated from OO and HOSO-fed animals. There was no statisticalsignificant difference in the phospholipid distribution between thecontrol and the OO group. However, HOSO-fed animals showed the lowestlevel of phosphatidylethanolamine together with the highestphosphatidylcholine content and the phosphatidylcholine/sphingomyelinratio. The fatty acid pattern of jejunal BBM lipids was modifiedaccording to the major fatty acids in the oils. There was a decreasein both stearic acid (18:0) and linoleic acid (18:2 n-6), togetherwith an increase in oleic acid (18:1 n-9) in jenunal BBM isolatedfrom both oil experimental groups. All these results were accompaniedby a significant increase in the BBM fluidity (as assessed bysteady-state fluorescence polarization of diphenylhexatriene) isolatedfrom oil-fed rat, when compared to control group. OO and HOSO-fedanimals had the lowest activities of sucrase and maltase, whilealkaline phosphatase activity only was decreased in HOSO-fedanimals. The specific activity of maltase was not modified in anyexperimental rats. In summary, both MUFA oils induced similar effectson jejunal BBM lipid composition, fluidity, sucrase, maltase andlactase activities. Furthermore, HOSO intake resulted in a lowestalkaline phosphatase activity which was accompanied by changes inindividual phospholipid composition. All these results suggest thateffects of MUFA oils on jejunal BBM lipid composition and hydrolaseactivities are most likely due to the presence of high content ofoleic acid rather than other components contained in the non-fattyacid of olive oil.     

Effect of dietary oils on lipid peroxidation and on antioxidant parameters of rat plasma and lipoprotein fractions.

In order to investigate the influence of fatty acid pattern and antioxidants other than vitamin E on lipid peroxidation and antioxidant levels of plasma very low density and low density lipoproteins (VLDL + LDL), the effects of three diets (equalized for vitamin E) containing soybean oil, olive oil, or an oleate-rich mixture of triglycerides (triolein) were studied in rats. A significantly lower concentration of thiobarbituric acid-reactive substances (TBA-RS) in plasma and lipoproteins was found after the olive oil diet (soybean oil, 3.7 +/- 0.4 nmol/ml; triolein, 2.1 +/- 0.5 nmol/ml; olive oil, 1.5 +/- 0.3 nmol/ml, in plasma) (soybean oil, 0.99 +/- 0.16 nmol/ml; triolein, 0.96 +/- 0.13 nmol/ml; olive oil, 0.38 +/- 0.12 nmol/ml, in the VLDL + LDL fraction). Furthermore, the results from in vitro copper-induced lipid peroxidation, expressed in terms of conjugated dienes, lipid hydroperoxides, and TBA-RS content, showed that VLDL + LDL particles from olive olive oil-fed rats were remarkably resistant to oxidative modification. The results suggest that the fatty acid unsaturation of dietary oils is not the only determining factor of the antioxidant capacity of lipoproteins in this animal model. The maximal protection observed after the olive oil diet may be explained by the presence of other unidentified antioxidants in addition to vitamin E, derived from oil intake. Therefore, the optimal balance between the content of unsaturated fatty acids and natural antioxidants in dietary oils appears to be of major importance.     

Liver Lipid Composition and Antioxidant Enzyme Activities of Spontaneously Hypertensive Rats After Ingestion of Dietary Fats (Fish, Olive and High-Oleic Sunflower Oils)

Hypertension is associated with greater than normal lipoperoxidation and an imbalance in antioxidant status, suggesting that oxidative stress is important in the pathogenesis of this disease. Although many studies have examined the effect of antioxidants in the diet on hypertensión and other disorders, less attention has been given to the evaluation of the role of specific dietary lipids in modulating endogenous antioxidant enzyme status. Previously, we have described that liver antioxidant enzyme activities may be modulated by consumption of different oils in normotensive rats. The purpose of the present study was to examine the effects of feeding different lipidic diets (olive oil, OO, high-oleic-acid sunflower oil, HOSO, and fish oil, FO) on liver antioxidant enzyme activities of spontaneously hypertensive rats (SHR). Plasma and liver lipid composition was also studied. Total triacylglycerol concentration increases in plasma and liver of animals fed on the HOSO and OO diets and decreases in those fed on the FO diet, relative to rats fed the control diet. The animals fed on the oil-enriched diet show similar hepatic cholesterol and phospholipid contents, which are higher than the control group. Consumption of the FO diet results in a decrease in the total cholesterol and phospholipid concentration in plasma, compared with the high-oleic-acid diets. In liver, the FO group show higher levels of polyunsaturated fatty acids (PUFA) of the (n-3) series, in relation to the animals fed on the diets enriched in oleic acid. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (i) significantly higher activities of catalase, glutathione peroxidase and Cu/Zn superoxide dismutase; (ii) no differences in the NADPH-cytochrome c reductase activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the efficiency of the antioxidant defence system and may yield a benefit in the hypertension status. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid, but different content of natural antioxidants, had similar effects on the antioxidant enzyme activities studied.