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PubMed2001

Direct analysis of total antioxidant activity of olive oil and studies on the influence of heating.

Aim of this study was to evaluate the total antioxidant activity (TAA) of extra virgin olive oil (EVOO) and the effect of heating on the alpha-tocopherol content and TAA in relation to the presence of polyphenols, heating time, and temperature. Experiments included the measurement by ABTS decolorization assay of antioxidant capacity of alpha-tocopherol and 14 simple phenolic compounds present in EVOO, either dissolved in ethanol or added to refined olive oil, and the evaluation of TAA, total phenols, and alpha-tocopherol of six commercial EVOO and three olive oils. Finally, four experimental oils were prepared from refined olive oil containing a fixed amount (300 ppm) of alpha-tocopherol and increasing amounts of polyphenols (25, 125, 225, and 326 ppm) extracted from EVOO. The thermal stability of experimental oils under domestic heating conditions (heating time from 30 to 120 min, heating temperature from 160 to 190 degrees C) was studied by evaluating the loss of alpha-tocopherol and TAA according to a Latin square design. Results indicate that TAA of commercial oils is mainly due to their phenol and alpha-tocopherol content. Heating experiments suggest that polyphenols from EVOO are effective stabilizers of alpha-tocopherol during olive oil heating, thus contributing to the nutritional value of cooked foods.

Antioxidants↗
PubMed1984

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 12. Comparison of peanut and olive oils.

The atherogenicity of peanut oil is well established as is the fact that the structure of the component triglycerides of peanut oil influences its atherogenicity. This study was carried out to determine if the relative saturation of peanut oil was partly responsible for the observed effects. Rabbits were fed a semipurified, cholesterol-free diet containing 14% of North American peanut oil (iodine value, 100), South American peanut oil (iodine value, 110) or olive oil (iodine value, 83) for 8 months. Rabbits fed olive oil exhibited higher levels of serum and liver lipids than did the two peanut oil-fed groups but significantly lower levels of aortic atherosclerosis. The findings confirm earlier observations that the structure of a fat can have an affect on its atherosclerogenic potential that is independent of its level of unsaturation.

Animals↗
PubMed1995

Histological evaluation of the canine decidual reactions induced by intraluminal injection of olive oil.

The present study deals with histological changes of the canine decidual reactions of the endometrium stimulated by intraluminal injection of olive oil with or without scratching injury using a wire. Olive oil caused conspicuous proliferation of the superficial endometrial glands. When olive oil injection was carried out after the scratching, cystic hyperplasia of basal glands as well as proliferation of superficial glands occurred. The results suggest that olive oil stimulates only proliferation of the superficial endometrial glands and the occlusion of the glandular orifices by some stimuli such as the traumatical injury would be needed to induce cystic hyperplasia of the basal glands.

Animals↗
PubMed2000

Protective effect of topically applied olive oil against photocarcinogenesis following UVB exposure of mice.

Reactive oxygen species have been shown to play a role in ultraviolet light (UV)-induced skin carcinogenesis. Vitamin E and green tea polyphenols reduce experimental skin cancers in mice mainly because of their antioxidant properties. Since olive oil has also been reported to be a potent antioxidant, we examined its effect on UVB-induced skin carcinogenesis in hairless mice. Extra-virgin olive oil was applied topically before or after repeated exposure of mice to UVB. The onset of UVB-induced skin tumors was delayed in mice painted with olive oil compared with UVB control mice. However, with increasing numbers of UVB exposures, differences in the mean number of tumors between UVB control mice and mice pretreated with olive oil before UVB exposure (pre-UVB group) were lost. In contrast, mice that received olive oil after UVB exposure (post-UVB group) showed significantly lower numbers of tumors per mouse than those in the UVB control group throughout the experimental period. The mean number of tumors per mouse in the UVB control, pre-UVB and post-UVB groups was 7.33, 6.69 and 2.64, respectively, in the first experiment, and 8.53, 9.53 and 3.36 in the second experiment. Camellia oil was also applied, using the same experimental protocol, but did not have a suppressive effect. Immunohistochemical analysis of DNA damage in the form of cyclobutane pyrimidine dimers (CPD), (6-4) photoproducts and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in samples taken 30 min after a single exposure of UVB showed no significant difference between UVB-irradiated control mice and the pre-UVB group. In the post-UVB group, there were lower levels of 8-OHdG in epidermal nuclei, but the formation of CPD and (6-4) photoproducts did not differ. Exposure of olive oil to UVB before application abrogated the protective effect on 8-OHdG formation. These results indicate that olive oil topically applied after UVB exposure can effectively reduce UVB-induced murine skin tumors, possibly via its antioxidant effects in reducing DNA damage by reactive oxygen species, and that the effective component may be labile to UVB.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Comparison of natural polyphenol antioxidants from extra virgin olive oil with synthetic antioxidants in tuna lipids during thermal oxidation.

Polyphenols extracted from extra virgin olive oil (EVOO) were tested for their ability to inhibit lipid oxidation of canned tuna. Hydroperoxide formation during oxidation was monitored by measurement of peroxide value and decomposition of hydroperoxides by static headspace gas chromatographic analysis of volatiles. In tuna oxidized at 40 and 100 degrees C, 400 ppm of the EVOO polyphenols was an effective antioxidant as compared with 100 ppm of a 1:1 mixture of the synthetic antioxidants butylated hydroxytoluene and butylated hydroxyanisole. However, at concentrations <100 ppm, the EVOO phenolic compounds promoted hydroperoxide formation and decomposition. The EVOO polyphenols were effective antioxidants when added to heated tuna muscle in the presence of either brine or refined olive oil. The oxidation rate in tuna muscle packed in brine was higher than that of tuna packed in refined olive oil. The EVOO polyphenols had higher antioxidant activity in the brine samples than in the refined olive oil. The higher antioxidant activity of EVOO polyphenols in tuna packed in brine may be explained by their greater affinity toward the more polar interface between water and the fish oil system.

Animals↗
PubMed2003

A study to assess the effects of a new detergent-free, olive oil formulation dentifrice in vitro and in vivo.

OBJECTIVE: To determine the effects of a detergent-free dentifrice containing olive oil using in vitro microbiological tests and an in vivo plaque re-growth model. METHOD: A total of 20 subjects took part in a double blind, single-centre, crossover study in which slurry rinses were the only form of plaque control over a 5-day period. Following a washout and prophylaxis the subjects used 2x daily rinses in the absence of all other plaque control methods. Subjects returned to the clinic on the afternoon of day 5 when plaque was disclosed and assessed by plaque index and area. A further 9-day washout was carried out and the rinse period repeated to ensure that each subject had used both experimental and control slurries. In vitro microbiological experiments were conducted to examine the effects of olive oil alone and in the new dentifrice on bacterial growth and adhesion. RESULTS: 20 subjects completed the trial. The olive oil product showed a significant inhibition of plaque re-growth (17.2%) compared with a fluoride-matched control using the Turesky index (p<0.0001) and also using the planimetric technique (22.0%) (p<0.0001). Significant decreases in bacterial growth and adhesion (measured as total viable count) were detected in the presence of olive oil and the new dentifrice. CONCLUSION: The results suggest that the experimental olive oil containing paste has potential value in the inhibition of plaque.

Adult↗
PubMed1993

Dietary olive oil reduces low-density lipoprotein uptake by macrophages and decreases the susceptibility of the lipoprotein to undergo lipid peroxidation.

Low-density lipoprotein (LDL) oxidation and macrophage cholesterol accumulation are both involved in atherogenesis. Recently it was shown that feeding rabbits or humans with an oleic-acid-rich diet reduced the susceptibility of their LDL to in vitro oxidation. Since olive oil is highly enriched with oleic acid, we tested the effect of olive oil supplementation (50 g/day) to the diet of 10 healthy male subjects, during a 2-week period, on macrophage uptake of their LDL and on the propensity of their LDL to oxidation (with copper ions). Olive oil supplementation to the diet resulted in LDL enrichment with oleic acid (C18:1) and sitosterol. No effect on plasma cholesterol levels was found, but the LDL cholesteryl ester content was reduced (16%) whereas its unesterified cholesterol was increased (41%). Even after 1 week of the olive oil diet, the LDL susceptibility to in vitro oxidation was significantly reduced (p < 0.01). Macrophage uptake of LDL was studied by analysis of cellular cholesterol content and by analysis of the macrophage cholesterol esterification rates. LDL obtained after 1 and 2 weeks of the olive oil diet demonstrated reduced cellular uptake in comparison with LDL obtained before the supplementation of olive oil, by 50 and 61%, respectively. The LDL resistance to oxidation was shown by a reduction in its peroxide, malondialdehyde and conjugated diene content by 73, 28 and 32%, respectively. LDL incubation with oleic acid for the period of its oxidation with copper ions demonstrated a dose-dependent inhibition of lipoprotein oxidation by up to 72% as opposed to linoleic and arachidonic acids (50 microM) which increased LDL oxidation by 22 and 72%, respectively. Sitosterol, in a similar incubation system, inhibited LDL oxidation by up to 26%. We conclude that olive oil supplementation to the diet modifies LDL lipid composition and enriches the lipoprotein with oleic acid and sitosterol. The antiatherogenic properties of this modified lipoprotein may be related to its resistance to in vitro peroxidation and its reduced uptake by macrophages.

Adult↗
PubMed1996

Effect of microwave heating on the migration of dioctyladipate and acetyltributylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil and water.

Migration of dioctyladipate (DOA) and acetyltributylcitrate (ATBC) plasticizers from plasticized polyvinylchloride (PVC) and polyvinylidene chloride (PVDC)/PVC (Saran) films into both olive oil and distilled water during microwave heating has been studied. The plasticizer migrating into olive oil and water was determined using an indirect GC method after saponification of the ester-type plasticizer (DOA or ATBC) and subsequent collection of the alcohol component of the ester, namely: 2-ethyl-1-hexanol and 1-butanol, respectively. Migration was dependent on heating time, microwave power setting, the nature of the food simulant and the initial concentration of the plasticizer in the film. Migration of DOA into olive oil reached equilibrium after heating for 10 min at full power (604.6 mg DOA/l). Migration into distilled water was 74.1 mg/l after 8 min of microwave cooking at full power. The amount of ATBC migrating into olive oil reached equilibrium after heating for 10 min at full power (73.9 mg ATBC/l). Migration into distilled water was 4.1 mg/l after heating at full power for 8 min. Control samples containing olive oil gave DOA migration values which were significantly higher than the upper limit for global migration (60 mg/l) set by the European Community. It is proposed that PVC should not be used in direct contact with food in the microwave oven, while Saran may be used with caution in microwave heating and reheating applications, avoiding its direct contact with high fat foodstuffs.

Adipates↗
PubMed2003

Garlic attenuates hypercholesterolemic risk factors in olive oil fed rats and high cholesterol fed rats.

This study was undertaken to compare the effects of garlic (G) on hypercholesterolemic risk factors in rats fed with corn oil (C) or olive oil (O) with and without cholesterol (Ch) enrichment in the diet. Male Sprague-Dawley rats (n=6 per group) were fed semi-purified diets containing 5% oil with or without cholesterol (Ch) or garlic (G) for 21 days. In the C fed rats, addition of dietary Ch, there was a redistribution of Ch from HDL to LDL class. In contrast, 1% Ch added to O diets produced a 4-fold increase in serum Ch compared with levels in rats fed O without Ch. This was associated with a 14-fold increase in LDL Ch and a 7-fold decrease in HDL Ch levels. Addition of 2% G had no effect on the distribution of serum Ch between HDL and LDL Ch in C+Ch fed rats, but in O+Ch fed rats, G halved the increase in serum Ch and LDL and attenuated the decrease in serum HDL by 23%. The results suggest that the dietary O regulated the levels of serum in Ch loaded rats. G attenuated serum Ch in O fed rats and decreased serum risk factors, both total Ch and LDL-C ratio and LDL-Ch/HDL-Ch ratio.

Journal Article↗
PubMed2006

Daily consumption of a high-phenol extra-virgin olive oil reduces oxidative DNA damage in postmenopausal women.

Extra-virgin olive oils (EVOO), high in phenolic compounds with antioxidant properties, could be partly responsible for the lower mortality and incidence of cancer and CVD in the Mediterranean region. The present study aims to measure oxidative DNA damage in healthy human subjects consuming olive oils with different concentrations of natural phenols. A randomised cross-over trial of high-phenol EVOO (high-EVOO; 592 mg total phenols/kg) v. low-phenol EVOO (low-EVOO; 147 mg/kg) was conducted in ten postmenopausal women in Florence. Subjects were asked to substitute all types of fat and oils habitually consumed with the study oil (50 g/d) for 8 weeks in each period. Oxidative DNA damage was measured by the comet assay in peripheral blood lymphocytes, collected at each visit during the study period. Urine samples over 24 h were collected to measure the excretion of the olive oil phenols. The average of the four measurements of oxidative DNA damage during treatment with high-EVOO was 30 % lower than the average during the low-EVOO treatment (P=0.02). Urinary excretion of hydroxytyrosol and its metabolite homovanillyl alcohol were significantly increased in subjects consuming high-EVOO. Despite the small sample size, the present study showed a reduction of DNA damage by consumption of an EVOO rich in phenols, particularly hydroxytyrosol.

Aged↗
PubMed2004

Olive oil and its main phenolic micronutrient (oleuropein) prevent inflammation-induced bone loss in the ovariectomised rat.

The present study was designed to evaluate the effect of olive oil and its main polyphenol (oleuropein) in ovariectomised rats with or without inflammation. Rats (6 months old) were ovariectomised or sham-operated as control. Ovariectomised rats were separated into three groups receiving different diets for 3 months: a control diet with 25 g peanut oil and 25 g rapeseed oil/kg (OVX), the control diet with 50 g olive oil/kg or the control diet with 0.15 g oleuropein/kg. The sham-operated group was given the same control diet as OVX. Inflammation was induced 3 weeks before the end of the experiment by subcutaneous injections of talc (magnesium silicate) in one-half of each group. The success of ovariectomy was verified at necropsy by the atrophy of uterine horns. Inflammation, oleuropein or olive oil intakes did not have any uterotrophic activity, as they had had no effect on uterus weight. The plasma concentration of alpha-1-acid glycoprotein (an indicator of inflammation) was increased in OVX rats with inflammation. With regard to bone variables, osteopenia in OVX was exacerbated by inflammation, as shown by a decrease in metaphyseal and total femoral mineral density. Both oleuropein and olive oil prevented this bone loss in OVX rats with inflammation. At necropsy, oleuropein and olive oil consumption had had no effect on plasma osteocalcin concentrations (marker of bone formation) or on urinary deoxypyridinoline excretion (marker of bone resorption). In conclusion, oleuropein and olive-oil feeding can prevent inflammation-induced osteopenia in OVX rats.

Animals↗
PubMed2001

The in vivo fate of hydroxytyrosol and tyrosol, antioxidant phenolic constituents of olive oil, after intravenous and oral dosing of labeled compounds to rats.

In vitro studies have shown phenolics in olive oil to be strong radical scavengers. The absorption and elimination of two radiolabeled phenolic constituents of olive oil, hydroxytyrosol and tyrosol were studied in vivo using rats. Compounds were administered intravenously (in saline) and orally (in oil- and water-based solutions). For both compounds, the intravenously and orally administered oil-based dosings resulted in significantly greater elimination of the phenolics in urine within 24 h than the oral, aqueous dosing method. There was no significant difference in the amount of phenolic compounds eliminated in urine between the intravenous dosing method and the oral oil-based dosing method for either tyrosol or hydroxytyrosol. Oral bioavailability estimates of hydroxytyrosol when administered in an olive oil solution and when dosed as an aqueous solution were 99% and 75%, respectively. Oral bioavailability estimates of tyrosol, when orally administered in an olive oil solution and when dosed as an aqueous solution were 98% and 71%, respectively. This is the first study that has used a radiolabeled compound to study the in vivo biological fates of hydroxytyrosol and tyrosol.

Administration, Oral↗
PubMedDate not supplied

Gas to olive oil partition coefficients: a linear free energy analysis.

Literature values of gas to olive oil partition coefficients at 37 degrees C have been assembled for 218 compounds. Application of an Abraham linear free energy equation correlates 215 compounds with R2=0.981 and a standard deviation, SD, of 0.196 log units. One hundred and eight compounds were then used as a training set, and the resulting equation was used to predict the remaining 107 compounds with an average error of 0.025, an absolute average error of 0.150, and a standard deviation of 0.224 log units. The linear free energy equation shows that as a solvent olive oil is not very polar but is reasonably basic, although with a weaker hydrogen bond base than ethyl acetate or acetone, and has no hydrogen bond acidity. The coefficients for partition from the gas phase to biological phases such as blood and brain lie between those for water and olive oil, which explains why gas to biological phase partition can be described in an empirical way by a combination of gas to olive oil and gas to saline coefficients.

Journal Article↗
PubMed2003

Bioavailability of tyrosol, an antioxidant phenolic compound present in wine and olive oil, in humans.

Tyrosol is a phenolic compound present in two of the traditional components of the Mediterranean diet: wine and virgin olive oil. The presence of tyrosol has been described in red and white wines. Tyrosol is also present in vermouth and beer. Tyrosol has been shown to be able to exert antioxidant activity in in vitro studies. Oxidation of low-density lipoprotein (LDL) appears to occur predominantly in arterial intima in microdomains sequestered from antioxidants of plasma. The antioxidant content of the LDL particle is critical for its protection. Thus, phenolics, which are able to bind LDL, could be effective in preventing lipid peroxidation and atherosclerotic processes. The ability of tyrosol to bind human LDL has been reported. We have demonstrated the bioavailability of tyrosol in humans from virgin olive oil in its natural form. Urinary tyrosol increased, reaching a peak at 0-4 h after virgin olive oil administration. Men and women showed a different pattern of urinary excretion of tyrosol. Moreover, tyrosol is absorbed in a dose-dependent manner after sustained and moderate doses of virgin olive oil. In summary, our results suggest that tyrosol from wine or virgin olive oil could exert beneficial effects on human health in vivo if its biological properties are confirmed in in vivo studies.

Antioxidants↗
PubMed1985

Effectiveness and reliability of medium term treatment with a diet rich in olive oil of patients with vascular diseases.

In the present work we investigated the usefulness of olive oil in a standard hypolipidemic diet suitable for the secondary prevention of atherosclerosis. Some patients who had received a diet with a P/S value of 1.3 were turned to a diet, rich in olive oil, with a P/S ratio of 0.52; the same number of patients were fed on with the initial diet. The main differences we found were a decrease of LDL cholesterol parallel to an increase of HDL cholesterol in the patients fed on the diet rich in olive oil. No modifications were found in these patients as far as hemostatic function and liver functional tests are concerned.

Adult↗
PubMed2006

A simple high-performance liquid chromatography method for the determination of throat-burning oleocanthal with probated antiinflammatory activity in extra virgin olive oils.

A high-performance liquid chromatography (HPLC) method was developed to quantitatively analyze oleocanthal in extra virgin olive oils. Oleocanthal, a deacetoxy ligstroside aglycone, is known to be responsible for the back of the throat irritation of olive oils and to have probated antiinflamatory activity. Oleocanthal was isolated from small amounts of olive oil sample (1 g) by liquid-liquid extraction. Hexane-acetonitrile was found to be the best solvent system to extract oleocanthal from the oil matrix. The solvent extract was analyzed by reversed-phase HPLC with UV detection at 278 nm. Chromatogaphic separation of oleocanthal from other extracted compounds and of the two geometric isomers of oleocanthal was achieved by an elution gradient with acetonitrile and water. Both the external standard calibration curve and the internal standard calibration curve were established, and quantitation using both calibration curves gave essentially the same result. The reproducibility (RSD = 4.7%), recovery (> 95%), and limit of quantitation (< 1 microg/g) were also determined. Concentrations of oleacanthal in 10 selected throat-burning extra virgin olive oils were determined using the method (ranged from 22 to 190 microg/g) with external standard calibration.

Aldehydes↗
PubMed2002

Detection of adulterants in olive oil by headspace-mass spectrometry.

In the present work, we propose the use of direct coupling of a headspace sampler to a mass spectrometer for the detection of adulterants in olive oil. Samples of olive oils were mixed with different proportions of sunflower oil and olive-pomace oil, respectively, and patterns of the volatile compounds in the original and mixed samples were generated. Application of the linear discriminant analysis technique to the data from the signals was sufficient to differentiate the adulterated from the non-adulterated oils and to discriminate the type of adulteration. The results obtained revealed 100% success in classification and close to 100% in prediction. The main advantages of the proposed methodology are the speed of analysis (since no prior sample preparation steps are required), low cost, and the simplicity of the measuring process.

Discriminant Analysis↗
PubMed2006

Comparison of the amounts of volatile compounds in French protected designation of origin virgin olive oils.

Headspace solid-phase microextraction (HS-SPME) -gas chromatography using flame ionization detection and multivariate analysis were applied to the study of the specificity of protected designation of origin (PDO) virgin olive oils produced in a southern French region (Alpes-Maritimes) based on their volatile compounds. A total of 35 PDO olive oils from Nice, 6 commercial oils, and 12 other French PDO olive oils were analyzed. Recorded data were subjected to principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The method developed here was able to perfectly distinguish different qualities of olive oils. Representative samples from each class obtained by chemometric treatment were analyzed by HS-SPME and GC-MS. PCA and SIMCA of chromatographic data were related to sensory analysis and led to a better understanding of the chemical features and observed sensory effects of olive oils.

Chromatography, Gas↗