Olive oil polyphenols reduce oxysterols -induced redox imbalance and pro-inflammatory response in intestinal cells.

Dietary habits may strongly influence intestinal homeostasis. Oxysterols, the oxidized products of cholesterol present in cholesterol-containing foodstuffs, have been shown to exert pro-oxidant and pro-inflammatory effects, altering intestinal epithelial layer and thus contributing to the pathogenesis of human inflammatory bowel diseases and colon cancer. Extra virgin olive oil polyphenols possess antioxidant and anti-inflammatory properties, and concentrate in the intestinal lumen, where may help in preventing intestinal diseases. In the present study we evaluated the ability of an extra virgin olive oil phenolic extract to counteract the pro-oxidant and pro-inflammatory action of a representative mixture of dietary oxysterols in the human colon adenocarcinoma cell line (Caco-2) undergoing full differentiation into enterocyte-like cells. Oxysterols treatment significantly altered differentiated Caco-2 cells redox status, leading to oxidant species production and a decrease of GSH levels, after 1 h exposure, followed by an increase of cytokines production, IL-6 and IL-8, after 24 h. Oxysterol cell treatment also induced after 48 h an increase of NO release, due to the induction of iNOS. Pretreatment with the phenolic extract counteracted oxysterols effects, at least in part by modulating one of the main pathways activated in the cellular response to the action of oxysterols, the MAPK-NF-kB pathway. We demonstrated the ability of the phenolic extract to directly modulate p38 and JNK1/2 phosphorylation and activation of NF-kB, following its inhibitor IkB phosphorylation. The phenolic extract also inhibited iNOS induction, keeping NO concentration at the control level. Our results suggest a protective effect at intestinal level of extra virgin olive oil polyphenols, able to prevent or limit redox unbalance and the onset and progression of chronic intestinal inflammation.

Hydroxytyrosol and tyrosol sulfate metabolites protect against the oxidized cholesterol pro-oxidant effect in Caco-2 human enterocyte-like cells.

The aim of this study was to investigate the ability of the sulfate metabolites of hydroxytyrosol (HT) and tyrosol (TYR) to act as antioxidants counteracting the pro-oxidant effect of oxidized cholesterol in intestinal cells. For this purpose, we synthesized sulfate metabolites of HT and TYR using a chemical methodology and examined their antioxidant activity in Caco-2 monolayers in comparison with the parent compounds. Exposure to oxidized cholesterol led to ROS production, oxidative damage, as indicated by the MDA increase, a decrease of reduced glutathione concentration and an enhancement of glutathione peroxidase activity. All the tested compounds were able to counteract the oxidizing action of oxidized cholesterol; HT and TYR sulfate metabolites showed an efficiency in protecting intestinal cells comparable to that of the parent compounds, strengthening the assumption that the potential beneficial effect of the parent compounds is retained, although extensive metabolisation occurs, the resulting metabolites being able to exert a biological action themselves.

Effect of aqueous and lipophilic mullet (Mugil cephalus) Bottarga extracts on the growth and lipid profile of intestinal Caco-2 cells.

The importance of n-3 polyunsaturated fatty acid (n-3 PUFA) intake has long been recognized in human nutrition. Although health benefits, n-3 PUFA are subject to rapid and/or extensive oxidation during processing and storage, resulting in potential alteration in nutritional composition and quality of food. Bottarga, a salted and semi-dried mullet ( Mugil cephalus ) ovary product, is proposed as an important source of n-3 PUFA, having high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In this work, we investigated the extent of lipid oxidation of grated bottarga samples during 7 months of storage at -20 °C and room temperature under light exposure. Cell viability, lipid composition, and lipid peroxidation were measured in intestinal differentiated Caco-2 cell monolayers after 6-48 h of incubation with lipid and hydrophilic extracts obtained from bottarga samples at different storage conditions. The storage of bottarga did not affect the n-3 PUFA level, but differences were observed in hydroperoxide levels in samples from different storage conditions. All tested bottarga extracts did not show a toxic effect on cell viability of differentiated Caco-2 cells. Epithelial cells incubated with bottarga oil had significant changes in fatty acid composition but not in cholesterol levels with an accumulation of EPA, DHA, and 22:5. Cell hydroperoxides were higher in treated cells, in relation to the oxidative status of bottarga oil. Moreover, the bottarga lipid extract showed an in vitro inhibitory effect on the growth of a colon cancer cell line (undifferentiated Caco-2 cells).

Protective role of arzanol against lipid peroxidation in biological systems.

This study examines the protective effect of arzanol, a pyrone-phloroglucinol etherodimer from Helichrysum italicum subsp. microphyllum, against the oxidative modification of lipid components induced by Cu(2+) ions in human low density lipoprotein (LDL) and by tert-butyl hydroperoxide (TBH) in cell membranes. LDL pre-treatment with arzanol significantly preserved lipoproteins from oxidative damage at 2h of oxidation, and showed a remarkable protective effect on the reduction of polyunsaturated fatty acids and cholesterol levels, inhibiting the increase of oxidative products (conjugated dienes fatty acids hydroperoxides, 7ß-hydroxycholesterol, and 7-ketocholesterol). Arzanol, at non-cytotoxic concentrations, exerted a noteworthy protection on TBH-induced oxidative damage in a line of fibroblasts derived from monkey kidney (Vero cells) and in human intestinal epithelial cells (Caco-2), decreasing, in both cell lines, the formation of oxidative products (hydroperoxides and 7-ketocholesterol) from the degradation of unsaturated fatty acids and cholesterol. The cellular uptake and transepithelial transport of the compound were also investigated in Caco-2 cell monolayers. Arzanol appeared to accumulate in Caco-2 epithelial cells. This phenol was able to pass through the intestinal Caco-2 monolayers, the apparent permeability coefficients (P(app)) in the apical-to-basolateral and basolateral-to-apical direction at 2h were 1.93±0.36×10(-5) and 2.20±0.004×10(-5)cm/s, respectively, suggesting a passive diffusion pathway. The results of the work qualify arzanol as a potent natural antioxidant with a protective effect against lipid oxidation in biological systems.

Protective effect and relation structure-activity of nonivamide and iododerivatives in several models of lipid oxidation.

The introduction of an iodine atom on the vanillyl moiety of nonivamide causes a switch in the vanilloid activity (TRPV1 antagonism versus TRPV1 desensitization) and nullifies the aversive properties of capsaicinoids. In the present study we investigated the effect of iodination in the vanillyl moiety on the antioxidant activity of capsaicinoids. To this aim, we have compared the protective effects of nonivamide and three iododerivatives, 2-iodononivamide (2IN), 5-iodononivamide (5IN), and 6-iodononivamide (6IN) in a series of in vitro models of lipid oxidation, namely the autoxidation and the FeCl(3)-mediated oxidation of linoleic acid at 37 degrees C and the thermal (140 degrees C), solvent-free oxidation of cholesterol. All tested compounds could protect linoleic acid and cholesterol against oxidative degradation, the order of potency being: nonivamide>5IN>6IN approximately 2IN. Our results show that, in general, the introduction of an iodine atom on the vanillyl moiety of nonivamide causes a decrease in the antioxidant activity, and this effect is sensitive to the position of iodine on the aromatic ring, with 5IN substantially retaining the efficacy of nonivamide to protect linoleic and cholesterol against free radical attack. Moreover, the pre-treatment with 5IN, at noncytotoxic concentrations, significantly preserved LDL from Cu(2+)-induced oxidative damage at 37 degrees C for 2h, inhibiting the reduction of polyunsaturated fatty acids and cholesterol and the increase of their oxidative products. The results of the present work suggest that 5IN exerts useful antioxidant properties in different in vitro systems of lipid peroxidation. This, coupled to its lacks of pungency and TRPV1 inhibiting properties, qualifies this phenolic compound as an attractive candidate for further investigations in vivo.

Protective effect of the oligomeric acylphloroglucinols from Myrtus communis on cholesterol and human low density lipoprotein oxidation.

Myrtle (Myrtus communis L.), a culinary spice and flavouring agent for alcoholic beverages widespread in the Mediterranean area and especially in Sardinia, contains the structurally unique oligomeric non-prenylated acylphloroglucinols, semimyrtucommulone and myrtucommulone A, whose antioxidant activity was investigated during the oxidative modification of lipid molecules implicated in the onset of cardiovascular diseases. Both acylphloroglucinols showed powerful antioxidant properties during the thermal (140 degrees C), solvent-free degradation of cholesterol. Moreover, the pre-treatment with semimyrtucommulone and myrtucommulone A significantly preserved LDL from oxidative damage induced by Cu(2+) ions at 2h of oxidation, and showed remarkable protective effect on the reduction of polyunsaturated fatty acids and cholesterol, inhibiting the increase of their oxidative products (conjugated dienes fatty acids hydroperoxides, 7beta-hydroxycholesterol, and 7-ketocholesterol). Taking into account the widespread culinary use of myrtle leaves, the results of the present work qualify the natural compounds semimyrtucommulone and myrtucommulone A as interesting dietary antioxidants with potential antiatherogenicity.

Protective effect of vanilloids against tert-butyl hydroperoxide-induced oxidative stress in vero cells culture.

This study investigated the effect of synthetic capsiate, a simplified analogue of capsiate, and vanillyl alcohol on the oxidative stress induced by tert-butyl hydroperoxide (TBH) in a line of fibroblasts derived from monkey kidney (Vero cells). In response to the TBH-mediated oxidative stress, a reduction of the levels of total unsaturated fatty acids and cholesterol was observed, and a rise in the concentrations of conjugated dienes fatty acids hydroperoxides and 7-ketocholesterol. Pretreatment with both synthetic capsiate and vanillyl alcohol preserved Vero cells from oxidative damage and showed a remarkable protective effect on the reduction of the levels of total unsaturated fatty acids and cholesterol, inhibiting the increase of MDA, conjugated dienes fatty acids hydroperoxides, and 7-ketocholesterol. Both compounds were effective against peroxidation of cell membrane lipids induced by TBH, with synthetic capsiate essentially acting as a pro-drug of vanillyl alcohol, its hydrophilic hydrolytic derivative.

Evaluation of the antioxidant and cytotoxic activity of arzanol, a prenylated alpha-pyrone-phloroglucinol etherodimer from Helichrysum italicum subsp.microphyllum.

Various phenolics and (mero)terpenoids from Helichrysum italicum subsp. microphyllum, a plant endemic to Sardinia, were investigated for their capacity to inhibit non-enzymatic lipid peroxidation. These compounds were studied in simple in vitro systems, under conditions of autoxidation and of iron (EDTA)-mediated oxidation of linoleic acid at 37 degrees C. Arzanol, a pyrone-phloroglucinol etherodimer, and helipyrone, a dimeric pyrone, showed antioxidant activity, and could protect linoleic acid against free radical attack in assays of autoxidation and EDTA-mediated oxidation. Methylarzanol, as well as the sesquiterpene alcohol rosifoliol, showed a decreased, but still significant, protective effect against linoleic acid oxidation. Arzanol and helipyrone were also tested in an assay of thermal (140 degrees C) autoxidation of cholesterol, where arzanol showed significant antioxidant activity. The cytotoxicity of arzanol was further evaluated in VERO cells, a line of fibroblasts derived from monkey kidney. Arzanol, at non-cytotoxic concentrations, showed a strong inhibition of TBH-induced oxidative stress in VERO cells. The results of the present work suggest that the natural compound arzanol exerts useful antioxidant properties in different in vitro systems of lipid peroxidation.