lignans and 3-4-dihydroxyphenylethanol

Olive fruit and leaves have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers. The present research was achieved on Tunisian olive flowers. It aimed at studying the effects of flower development on phenolic compounds and antioxidant activity. The extracts were analyzed using high performance liquid chromatography coupled to diode array detection (HPLC/DAD) and coupled to mass spectrometry (LC-MS/MS). The HPLC/DAD analysis indicated that oleuropein aglycon (from 1.158 to 3.746 g/kg), followed by hydroxytyrosol (from 0.168 to 1.581 g/kg) and oleoside (from 0.143 to 1.325 g/kg) were the predominant phenolics in olive flowers extracts during development stages. Twenty compounds have been identified, revealing the complex profile of olive flowers, composed, in order of abundance, by secoiridoids, phenolic alcohols, lignans, flavonoids and phenolic acids. Total phenolic contents increased from 2.455 to 8.541 g/kg Gallic acid equivalent per kg of fresh flowers during all steps of the flower development. A correlation between antioxidant activity and total phenolic contents was determined.

Topics: Acetates; Antioxidants; Chromatography, High Pressure Liquid; Cyclopentane Monoterpenes; Flavonoids; Flowers; Fruit; Hydroxybenzoates; Iridoids; Lignans; Olea; Phenols; Phenylethyl Alcohol; Plant Leaves; Pyrans; Tandem Mass Spectrometry

The effect of the composition of twelve varieties of extra virgin olive oils (EVOOs) on their differentiation based in agronomic criteria and on the antioxidant capacity was studied. Principal component analysis permitted an overview of the samples and their compositions, showing evidence of grouping and correlation between antioxidant capacity, oleuropein and ligstroside derivatives (OLD) and specific extinction at 270. Oleic and linoleic acids, 3,4-DHPEA-EA and p-HPEA-EDA (OLD), unsaturated/saturated ratio and induction time (IT) allowed the correct classification of samples according to year of harvest, ripening stage and variety. The antioxidant capacity of EVOOs was satisfactory predicted through a partial least square model based on ΔK, hydroxytyrosol, pinoresinol, oleuropein derivate and IT. Validation of the model gave a correlation R>0.83 and an error of 7% for independent samples. This model could be a useful tool for the olive industry to highlight the nutritional quality of EVOOs and improve their marketing.

Topics: Agriculture; Antioxidants; Chile; Food Analysis; Furans; Glucosides; Iridoid Glucosides; Iridoids; Least-Squares Analysis; Lignans; Olive Oil; Phenylethyl Alcohol; Principal Component Analysis; Pyrans

Enriching oils, such as olive oil, could be one solution to tackle the worldwide epidemic of vitamin D deficiency and to better fit with omega 3 (DHA) recommendations. However, data regarding the interactions occurring at the intestinal level between vitamin D and phenols from olive oil are scarce. We first determined the effect of polyphenols from a virgin olive oil, and a virgin olive oil enriched with DHA, on vitamin D absorption in rats. We then investigated the effects of 3 main olive oil phenols (oleuropein, hydroxytyrosol and pinoresinol) on vitamin D uptake by Caco-2 cells. The presence of polyphenols in the olive oil supplemented with DHA inhibited vitamin D postprandial response in rats (-25%, p<0.05). Similar results were obtained with a mix of the 3 polyphenols delivered to Caco-2 cells. However, this inhibitory effect was due to the presence of pinoresinol only. As the pinoresinol content can highly vary between olive oils, the present results should be taken into account to formulate an appropriate oil product enriched in vitamin D.

Topics: Animals; Caco-2 Cells; Docosahexaenoic Acids; Female; Furans; Humans; Intestinal Absorption; Iridoid Glucosides; Iridoids; Lignans; Olive Oil; Phenylethyl Alcohol; Polyphenols; Rats; Rats, Wistar; Vitamin D

Potato, tomato, eggplant and pumpkin were deep fried, sautéed and boiled in Mediterranean extra virgin olive oil (EVOO), water, and a water/oil mixture (W/O). We determined the contents of fat, moisture, total phenols (TPC) and eighteen phenolic compounds, as well as antioxidant capacity in the raw vegetables and compared these with contents measured after cooking. Deep frying and sautéing led to increased fat contents and TPC, whereas both types of boiling (in water and W/O) reduced the same. The presence of EVOO in cooking increased the phenolics identified in the raw foods as oleuropein, pinoresinol, hydroxytyrosol and tyrosol, and the contents of vegetable phenolics such as chlorogenic acid and rutin. All the cooking methods conserved or increased the antioxidant capacity measured by DPPH, FRAP and ABTS. Multivariate analyses showed that each cooked vegetable developed specific phenolic and antioxidant activity profiles resulting from the characteristics of the raw vegetables and the cooking techniques.

Topics: Antioxidants; Benzothiazoles; Chlorogenic Acid; Chromatography, High Pressure Liquid; Cluster Analysis; Cooking; Cucurbita; Dietary Fats; Furans; Iridoid Glucosides; Iridoids; Lignans; Multivariate Analysis; Olive Oil; Phenols; Phenylethyl Alcohol; Rutin; Solanum lycopersicum; Solanum melongena; Solanum tuberosum; Sulfonic Acids; Vegetables

Refined edible oils (viz., oils from maize, soya, high-oleic sunflower, sunflower, olive, and rapeseed) enriched at two concentration levels (200 and 400 μg/mL total phenolic content) with phenolic extracts isolated from olive pomace and leaves have been characterized and compared with nonenriched oils and extra virgin olive oil (EVOO). Enriched oils were analyzed by LC-TOF/MS to generate representative fingerprints and compared with nonenriched oils and EVOO by unsupervised principal component analysis (PCA). The two raw materials reported enriched oils with profiles which were compared with those provided by EVOOs. Correlation analysis enabled us to establish the enriched oils with a composition more similar to EVOO. Discrimination according to the enrichment level depended on the raw material for extracts, and a global discussion about the enrichment on relevant phenolic compounds present in EVOO has reported quantitative results concerning the enrichment level for those significant compounds with known nutraceutical properties.

Topics: Antioxidants; Flavonoids; Furans; Iridoids; Lignans; Mass Spectrometry; Olea; Olive Oil; Phenols; Phenylethyl Alcohol; Plant Extracts; Plant Leaves; Plant Oils; Principal Component Analysis

Virgin olive oils were subjected to simulated common domestic processing, including frying, microwave heating, and boiling with water in a pressure cooker. The impact of these processes on polyphenol content and physicochemical characteristics of oils was assessed. Thermal oxidation of oils at 180 degrees C caused a significant decrease in hydroxytyrosol- and tyrosol-like substances. In contrast, oils heated for 25 h still retained a high proportion of the lignans 1-acetoxypinoresinol and pinoresinol. Thermal oxidation also resulted in a rapid degradation of alpha-tocopherol and the glyceridic fraction of oils. Microwave heating of oils for 10 min caused only minor losses in polyphenols, and the oil degradation was lower than that in thermoxidation assays. Again, lignans were the least affected polyphenols and did not change during microwave heating. Boiling a mixture of virgin olive oil and water in a pressure cooker for 30 min provoked the hydrolysis of the secoiridoid aglycons and the diffusion of the free phenolics hydroxytyrosol and tyrosol from the oil to the water phase. Losses of polyphenols were detected only at pH lower than 6. Moreover, alpha-tocopherol and the glyceridic fraction of oils were not modified during this process. It is worth noting that all the heating methods assayed resulted in more severe polyphenols losses and oil degradation for Arbequina than for Picual oil, which could be related to the lower content in polyunsaturated fatty acids of the latter olive cultivar. These findings may be relevant to the choice of cooking method and olive oil cultivar to increase the intake of olive polyphenols.

Topics: alpha-Tocopherol; Chemical Phenomena; Chemistry, Physical; Chromatography, High Pressure Liquid; Flavonoids; Food Handling; Glycerides; Hot Temperature; Lignans; Microwaves; Olive Oil; Oxidation-Reduction; Phenols; Phenylethyl Alcohol; Plant Oils; Polymers; Polyphenols; Pressure