Madiha Dhibi

The intake of high fat diet with different trans fatty acid levels differentially induces oxidative stress and non alcoholic fatty liver disease (NAFLD) in rats

BackgroundTrans-fatty acids (TFA) are known as a risk factor for coronary artery diseases, insulin resistance and obesity accompanied by systemic inflammation, the features of metabolic syndrome. Little is known about the effects on the liver induced by lipids and also few studies are focused on the effect of foods rich in TFAs on hepatic functions and oxidative stress. This study investigates whether high-fat diets with different TFA levels induce oxidative stress and liver dysfunction in rats.MethodsMale Wistar rats were divided randomly into four groups (n = 12/group): C receiving standard-chow; Experimental groups that were fed high-fat diet included 20% fresh soybean oil diet (FSO), 20% oxidized soybean oil diet (OSO) and 20% margarine diet (MG). Each group was kept on the treatment for 4 weeks.ResultsA liver damage was observed in rats fed with high-fat diet via increase of liver lipid peroxidation and decreased hepatic antioxidant enzyme activities (superoxide dismutase, catalase and glutathione peroxidase). The intake of oxidized oil led to higher levels of lipid peroxidation and a lower concentration of plasma antioxidants in comparison to rats fed with FSO. The higher inflammatory response in the liver was induced by MG diet. Liver histopathology from OSO and MG groups showed respectively moderate to severe cytoplasm vacuolation, hypatocyte hypertrophy, hepatocyte ballooning, and necroinflammation.ConclusionIt seems that a strong relationship exists between the consumption of TFA in the oxidized oils and lipid peroxidation and non alcoholic fatty liver disease (NAFLD). The extent of the peroxidative events in liver was also different depending on the fat source suggesting that feeding margarine with higher TFA levels may represent a direct source of oxidative stress for the organism. The present study provides evidence for a direct effect of TFA on NAFLD.

Chemical composition and biological activities of volatile fractions from three Tunisian cultivars of olive leaves

The chemical composition, antibacterial, and antifungal activities of the volatile fractions from fresh and dried leaves of three Olea europaea L. cultivars from Tunisia (Neb jemel, Chemchali and Chemlali) have been studied. The volatile components were obtained via hydrodistillation and analyzed by GC–MS. The major constituents were (E)-3-hexenol, 3-ethenylpyridine, (E)-β-damascenone and phenylethyl alcohol, but their percentages varied according to the treatment of the leaves. Antioxidant activities were determined applying DPPH and ABTS+ radical-scavenging assays. In general, antioxidant activity of the volatile fraction obtained from fresh leaves was superior to that obtained from dried leaves. The antibacterial and antifungal activities of the volatile fractions from fresh and dried leaves were evaluated against four bacterial and four fungal strains. The volatile fractions showed significant antibacterial and antifungal effects. However, some differences were observed in the response for several microorganisms, because of the variability of the composition. This work gives further knowledge for extensive development of this medicinal plant.

Nutritional Fatty Acid Quality of Raw and Cooked Farmed and Wild Sea Bream (Sparus aurata)

The effects of steaming, grilling, and frying in corn and sunflower oils, respectively, on the fatty acid compositions of farmed and wild sea bream were evaluated. The lipid content increased with frying in both oil types. The maximum moisture value was found in steamed fish (P<0.05). Fried sea bream in corn and sunflower oils contained a lower content of n-3 polyunsaturated fatty acids (P<0.05) (3.87 and 5.32% of total fatty acids (TFA) in farmed fish and 2.96 and 2.14% TFA in wild fish). The n-3/n-6 ratio decreased significantly after cooking, particularly after frying in corn and sunflower oils, respectively: from 2.51 to 0.08 and 0.12 in farmed fish and from 0.94 to 0.06 and 0.04 in wild fish. The trans fatty acid levels remain stable after steaming and grilling, but they were significantly affected by frying. Our results reveal that the cooking process has considerable effect on the fatty acid compositions of farmed and wild sea bream.

trans-Fatty acid isomers in two sesame (Sesamum indicum L.) seed byproducts under processing.

The present study has been inspired by the growing need for rigorously controlling the nutritional quality and safety of food products. The impact of application in the food industry on fatty acids composition, trans-fatty acids (TFAs), and conjugated linoleic acid (CLA) profiles were investigated in a highly consumed candy byproduct of sesame seed (chamia) in comparison to fresh sesame seed oil (SSO) and heated SSO under simulated frying experiments. The effect of treatment on SSO was studied by determining the TFA and CLA changes. Results showed significant differences between the two byproducts in TFA and CLA amounts. Total TFAs were found to be significantly higher in chamia than fresh SSO (1.31 versus 0.066%, respectively; p < 0.05) and even higher than all heated SSO from 2 to 10 h at 180 °C (1.31 versus 0.33%, respectively; p < 0.05). A significant linear relationship was found between trans-monounsaturated fatty acid (MUFA), trans-polyunsaturated fatty acid (PUFA), and total TFA and the time of processing, with a correlation coefficient (R(2)) greater than 0.9 for TFA and PUFA, with a higher correlation assigned to PUFA (r = 0.988; p < 0.001), followed by TFA (r = 0.959; p < 0.01) and MUFA (r = 0.844; p < 0.05). Principal component analysis of the fatty acid (FA) profiles showed discrimination between chamia and both fresh and heated SSO. A high stability of SSO against isomerization reactions as compared to their chamia sample counterpart has been noted. These findings suggest that the food industry engenders relatively higher changes in fatty acid configurations than the frying process.

Consumption of Oxidized and Partially Hydrogenated Oils Differentially Induces Trans-Fatty Acids Incorporation in Rats' Heart and Dyslipidemia

Objectives: A direct effect of process-induced trans-fatty acids (TFAs) on nonalcoholic fatty liver disease (NAFLD) as a cardiovascular disease (CVD) risk factor has previously been shown. We hypothesized that TFAs directly induced CVD. This article describes an investigation of the association between TFAs, provided by the consumption of oxidized soybean oil and margarine, and plasma lipid profiles, coronary artery lesions, and coronary fatty acids distribution in rats. Male rats were fed a standard chow or high-fat diet containing different TFA levels ranging from <1%, <2%, and >2% of total fat in fresh soybean oil, oxidized soybean oil, and margarine, respectively, for 4 weeks. Results: The results indicated that the high-fat diets differently changed the plasma lipid profiles by significantlt increasing triglycerides, total cholesterol, low-density lipoprotein cholesterol, and the ratio of low-density to high-density lipoprotein cholesterol compared to control rats. Compared to fresh soybean oil, oxidized oil further increased plasma lipid markers. The strongest inflammatory effect was induced by margarine, which contains the highest level of TFAs, or 2% of total fat. Total TFAs in the heart of the margarine-fed group were increased by 4.7 regarding to control and by 2.17 and 2.6 relative to groups receiving oxidized and fresh oil, respectively. Increased TFAs consumption was associated with increased histological aspects of atherosclerotic lesions in a dose-dependent manner. Conclusion: In conclusion, process-induced TFAs cause changes including proatherogenic plasma lipid markers, heart fatty acid profiles, and coronary artery histology depending on the TFA level in the supplemented fat and therefore on the type of technological process used.

Antioxidant Activity of the Leaf Volatile Oil and Extracts of Olea europaea L.cv. Chetoui fromNorthern Tunisia

Antioxidant Activity of the Leaf Volatile Oil and Extracts of Olea europaea L.cv. Chetoui from Northern Tunisia This study is designed to examine the chemical composition and the in vitro antioxidant activity of the volatile oil and the extracts (polar and non-polar sub-fractions) of the methanol extract of Olea europea L. (cv) chetoui. GC and GC–MS analyses of the volatile oil from the dried leaves of the variety chetoui resulted in the identification of 32 compounds, representing 92.1% of the oil; alcohols (39.5%), aldehydes (19.1%) and ketones (12.2%) were the main groups of volatiles in the studied cultivar, comprising 70.8% of the total oil. Antioxidant activities of the samples were determined by the test system namely DPPH. The weakest radical scavenging activity was exhibited by the volatile oil (49.92%). Antioxidant activity of the non-polar sub-fraction of methanol extract was superior to the all samples tested with an inhibition of the free radical DPPH value of 64.31%. Total phenolic content of the polar and non-polar sub-fractions was 65.35 and 69.17 mg/100 g DW, respectively. In fact, the results showed no significant differences in the levels of polyphenols between sub-fractions of the methanol extract of Olea europea L. Furthermore, the amount of the total orthodiphenols was highest in the non-polar sub-fraction (219.66 mg /100 g DW).