Determination of polyphenols,tocopherols, and antioxidant capacity in virgin argan oil (Argania spinosa,Skeels)

This study establishes data on polyphenols, tocopherols, and antioxidant capacity (AC) of virgin argan oil. A total of 22 samples from Morocco were analyzed. Total polyphenol content ranged between 6.07 and 152.04 mg GAE/kg. Total tocopherols varied between 427.0 and 654.0 mg/kg, being γ‐tocopherol the major fraction (84.68%); α‐, β‐, and δ‐tocopherols represent 7.75, 0.33, and 7.29%, respectively. No influence of oil extraction method on total tocopherols was observed. The AC of argan virgin oils determined by the ABTS method in n‐hexane oils dilution ranged between 14.16 and 28.02 mmol Trolox/kg, and by the ABTS, DPPH, and FRAP methods in methanolic oil extracts between 2.31–14.15, 0.19–0.87, and 0.62–2.32 mmol Trolox/kg, respectively. A high correlation was found between ABTS and DPPH methods applied to a methanolic oil extract. Virgin argan oil presents a higher polyphenol and tocopherol content, and total AC than other edible vegetable oils.     

Antioxidant effect of mono‐ and dihydroxyphenols in sunflower oil with different levels of naturally present tocopherols

Antioxidant properties of mono‐ and dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially tocopherol‐stripped sunflower oil (total tocopherols 8.7 mg/kg) and distilled fatty acid methyl esters (FAME) as a tocopherol‐free medium. The chemical reaction of tocopherols with diazomethane tested for the purpose to eliminate their antioxidant activity failed due to the negligible degree of methylation of hydroxyl group in the tocopherol molecule. Caffeic acid and protocatechuic acid (3,4‐dihydroxyphenolic acids) and their alkyl esters were found to be more active antioxidants than monohydroxyphenolic acid (p‐hydroxybenzoic acid), 2,5‐dihydroxyphenolic acid (gentisic acid), 3‐methoxy‐4‐hydroxyphenolic acids (vanillic and ferulic acids) and their corresponding alkyl esters. Naturally present tocopherols in refined sunflower oil proved to have a synergistic effect on gentisic acid but not on its alkyl esters. In contrast, tocopherols showed an antagonistic effect on alkyl esters of caffeic acid, because their protection factors decreased with increasing level of tocopherols in the test medium. Moreover, the antioxidant activity of these alkyl esters decreased with increasing length of their alkyl chain in conformity with the polar paradox hypothesis. Practical applications: Tocopherols as naturally present antioxidants influence considerably the antioxidant activity of other antioxidants added to plant oils used as a test medium. Distilled fatty acid methyl esters prepared from refined sunflower oil may serve as an optimal tocopherol‐free test medium. Some alkyl esters of phenolic acids were evaluated to be applicable as natural more lipophilic antioxidants in comparison with phenolic acids.     

Antioxidant activity of the essential oil and methanolic extract of cumin seed (Cuminum cyminum)

The antioxidant activities of the essential oil and crude methanolic extract (CEx) of cumin seed (Cuminum cyminum) were evaluated. Total phenolics and tocopherols contents, reducing power, DPPH radical‐scavenging capacity (EC₅₀), and the oxidative/oil stability index were assessed. The contents of total phenolics and total tocopherols in the essential oil (18.47 and 0.11 mg/g, respectively) were significantly lower than those of the CEx (29.12 and 0.42 mg/g, respectively). The CEx had an EC₅₀ value (0.74 mg/mL) significantly lower than those of the essential oil and α‐tocopherol (1.20 and 32.50 mg/mL, respectively). The reducing power of the CEx (459.46 mmol Fe²⁺ per mass) was significantly higher than those of the essential oil (18.47 mmol/L) and α‐tocopherol (99.96 mmol/L). The addition of CEx to the purified sunflower oil significantly improved its oxidative stability at the levels of 800 ppm and higher whereas the essential oil indicated no antioxidant activity at the levels experimented (200–2000 ppm). The CEx was considered to be a useful antioxidative compound in bulk oil and emulsion systems but the essential oil showed no antioxidant activities. The CEx in the bulk oil system had higher antioxidant activities than in the emulsion system. The CEx concentration of 2000 ppm showed the highest antioxidant activity and reduced the formation of hydroperoxides and secondary products more than the other antioxidative compounds applied in this study.     

Tocopherol retention in physically refined rapeseed oil as a function of deodorization temperature

The effect of deodorization temperature (between 220 and 270 °C) on tocopherol retention in physically refined rapeseed oil during deodorization in a plant‐scale semi‐continuous tray‐type deodorizer was investigated. Among the three tocopherol homologues detected in the samples of rapeseed oils under study, the α‐ and γ‐tocopherol homologues, with the latter predominating, constituted the most abundant part of total tocopherols, accompanied by a small amount of δ‐tocopherol. The retention values calculated for both total and individual tocopherols decreased linearly with increasing deodorization temperature. The retention of total tocopherols decreased considerably from 91.5% at 220 °C to 54.7% at 270 °C, approaching a value of about 80% in the main area of concern between 230 and 240 °C. The retention values of individual tocopherols as well as the slopes resulting from the equations relating these retentions to deodorization temperature were observed to decrease in the same order as their molecular weights. Since the retention of α‐tocopherol is slightly higher than that of γ‐tocopherol, the average proportion of α‐tocopherol during deodorization slightly increases at the expense of γ‐tocopherol.     

Minimal effective dose on serum cholesterol concentration and the safety evaluation of dressing containing plant sterol in Japanese subjects

We examined the minimal effective dose on serum cholesterol concentration and the safety of dressing containing plant sterol in humans. EXP.1: Sixty-eight healthy Japanese males (total cholesterol (TC) > or = 170 mg/dL) were randomly divided into four groups, and were given 0, 400, 800 or 1200 mg/day of plant sterol in 15 g dressing for 4 weeks followed by the washout period of 4 weeks. Although there were no significant differences in serum TC and low-density lipoprotein cholesterol (LDL-C) concentrations among all groups after feeding plant sterol for 4 weeks, in 36 subjects with TC > or = 220 mg/dL, serum LDL-C concentration tended to reduce when received 800 or 1200 mg of plant sterol, and the difference between 0 and 1200 mg groups was statistically significant. The difference between 0 and 800 mg groups was near significant (p=0.053). Intake of 400 mg of plant sterol did not change serum LDL-C concentration. EXP.2: Twenty-one healthy Japanese subjects (TC > or = 180 mg/dL, 10 men, 11 women) were given 2400 mg/day of plant sterol in 45 g dressing for 4 weeks. Clinical data were all remained normal. These results indicated that minimal effective dose of the plant sterol on serum cholesterol concentration in healthy male subjects is around 800 mg/day, and intake of 2400 mg/day of plant sterol is regarded to be safe.     

Alpha- and gamma-tocopherol levels in lipoproteins fractionated by affinity chromatography

Alpha- and gamma-tocopherol levels of nine women were measured in whole serum and in serum lipoproteins separated by heparin affinity chromatography. Alphatocopherol levels (mean±SD) in whole serum, low density plus very low density lipoproteins and high density lipoproteins were 10.8±2.7, 6.4±1.6 and 4.6±1.4 (μg/ml), respectively. Corresponding values (μg/ml) for gamma-tocopherol were 1.2±0.5, 0.7±0.3 and 0.6±0.2. Recoveries of serum alpha- and gamma-tocopherol from the heparin columns were 102±5% and 105±7%, respectively. Serum alpha-tocopherol was linearly correlated with components of high density lipoprotein (apolipoproteins, high density lipoprotein cholesterol), but not with serum total lipids or indices of low density lipoprotein, even though high density lipoprotein carried less than half of the serum alpha-tocopherol. However, serum gamma-tocopherol was highly correlated with indices of serum lipids, such as serum cholesterol (r=0.92, p=0.005). The coefficient for the correlation of low density lipoprotein (+very low density lipoprotein) tocopherol with high density lipoprotein tocopherol was r=0.66 (p=0.06) for alpha-tocopherol and r=0.84 (p=0.004) for gamma-tocopherol. These differences in the relationships of the two tocopherols to lipids and lipoproteins support the view that when the two tocopherols are present at normal dietary levels, gamma-tocopherol partitions between lipoproteins based on their relative lipid content, but a portion of the alpha-tocopherol in high density lipoprotein is specifically bound.     

Performance of tocopherols as antioxidants in ABS

Mixed tocopherols, γ‐tocopherol, and δ‐tocopherol were evaluated for antioxidant performance in acrylonitrile–butadiene–styrene by using oxidative induction time as the response. Three commonly used phenolic antioxidants and vitamin E (α‐tocopherol) were used as controls. Mixed tocopherols were found to have a greater antioxidant effect than the hindered phenolic antioxidants or vitamin E in acrylonitrile–butadiene–styrene. γ‐tocopherol was found to be primarily responsible for the improved performance of mixed tocopherols. J. VINYL. ADDIT. TECHNOL. 12:66–72, 2006. © 2006 Society of Plastics Engineers     

The effect of various concentrations of tocopherols and tocopherol mixtures on the oxidative stability of a sample of lard

A comparison was made of α-, γ-, and δ-tocopherol at various concentrations and a mixture of these tocopherols representing the average tocopherol content of peanut oil on the oxidative stability of lard at 97C. Uptake of oxygen was used to indicate the length of the induction period. The antioxidant effectiveness of the tocopherols was found to increase in the order α, δ, γ. The antioxidant efficiency decreases with increasing concentrations of tocopherols such that addition of any single tocopherol above a concentration of 250 μg/g has little effect on oxidative stability. A mixture equivalent to that of an average peanut oil sample, containing 150 μg/g of α-tocopherol and 250 μg/g of γ-tocopherol and 15 μg/g of δ-tocopherol was found to be no more stable than one containing 250 μg/g of γ-tocopherol alone.     

Tocopherols and tocotrienols in Finnish foods: Oils and fats

The tocopherols and tocotrienols of vegetable oils, cod liver oil, margarines, butter and Voimariini dairy spread were analyzed by HPLC. The total tocopherol content varied from 4 (coconut oil) to 242 mg/100 g (wheat germ oil). α-tocopherol equivalents varied from 2 (coconut oil) to 225 mg/100 g (wheat germ oil). Semisoft and soft margarines had an average total tocopherol of 53 and 61 mg, and an average α-tocopherol equivalent of 17 and 27 mg/100 g, respectively. Hard margarines averaged 29 mg total tocopherol and 9 mg α-tocopherol equivalent/100 g. The average tocopherol content of butter and Voimariini was 2 and 15 mg/100 g, respectively, and the average α-tocopherol equivalent 2 and 6 mg/100 g.     

α- und γ-Tocopherol-Status und Fettsäurespektren in Seren von Vegetariern und Nichtvegetariern

α- and γ-Tocopherol Status and Fatty Acid Patterns in Serum Samples of Vegetarians and Non-Vegetarians A subsample (108 females, 70 males) of the Berlin vegetarian study was screened concerning the fatty acid patterns and the α- and γ-tocopherol levels of serum samples. Detailed diet-history (7-day-protocols) shows that vegetarians consume 35–40% more tocopherols than non-vegetarians. Concerning the fatty acids the uptake of polyunsaturated fatty acids (esp. linoleic acid) as well as the content of the serum is significantly higher in vegetarians than in age- and sex-matched controls. Despite the higher intake of tocopherols the serum levels of α-tocopherol show lower values for vegetarians (females: x = 11.01 mg/l, males: x = 8.91 mg/l) than for non-vegetarians (females: x? = 11.42 mg/l, males: x? = 10.55 mg/l). Possible causes for the differences observed could be the higher lipid status (total cholesterol, total glycerol) of non-vegetarians and/or the higher levels of linoleic acid in vegetarian sera.     

Lipid profile in Venezuelan preschoolers by socioeconomic status

Epidemiological studies have shown that unfavorable serum lipids levels in childhood are predictors of development of atherosclerosis lesions in adulthood. We assessed the lipid profile of 297 Venezuelan preschool children (4-7 years old) from two socioeconomic levels in order to compare them by this characteristic. Their social level was determined according to modified Graffar method, and two groups were obtained: high socioeconomic status (HSES, n=103) and low socioeconomic status (LSES, n=194). Nutritional anthropometric evaluation was performed by weight to height, and NCHS/OMS cut-off point was used. Lipid profile was determined by colorimetric biochemical methods and atherogenic risks factors were calculated. Underweight for HSES was 5.8% and for LSES: 14.9%, while normal status was 78.6% and 70.1%, and overweight was 15.5% and 14.9%, respectively. Mean values for triglycerides were 0.66 +/- 0.27and 0.76 +/- 0.31 mmol/L, total cholesterol (TC): 3.61 +/- 0.65 and 2.98 +/- 0.71 mmol/L, HDL-C: 1.04 +/- 0.18 and 0.62 +/- 0.16 mmol/L, LDL-C: 2.27 +/- 0.61 and 2.01 +/- 0.71 mmol/L, TC/HDL-C: 3.5 +/- 0.78 and 5.0 +/- 1.5; LDL-C/HDL-C: 2.0 +/- 0.71 and 3.4 +/- 1.4 with significant differences between HSES and LSES as shown respectively. A significant association was found (p < 0.01) between lipid values and socioeconomic status, being the LSES preschoolers those with the higher atherogenic risk. Its pattern was of lower HDL-C levels, and higher TC/HDL-C and LDL-C/HDL-C ratio. Comparisons of lipid profile by nutritional status or gender did not show significant differences. Findings indicate that children from low socioeconomic status are at a higher risk for cardiovascular disease and atherosclerosis than children from high socioeconomic status.     

Optimal tocopherol concentrations to inhibit soybean oil oxidation

The optimal concentration for tocopherols to inhibit soybean oil oxidation was determined for individual tocopherols (α-, γ-, and δ-tocopherol) and for the natural soybean oil tocopherol mixture (tocopherol ratio of 1∶13∶5 for α-, γ-, and δ-tocopherol, respectively). The concentration of the individual tocopherols influenced oil oxidation rates, and the optimal concentrations were unique for each tocopherol. For example, the optimal concentrations for α-tocopherol and γ-tocopherol were ∼100 and ∼300 ppm, respectively, whereas δ-tocopherol did not exhibit a distinct concentration optimum at the levels studied (P<0.05). The optimal concentration for the natural tocopherol mixture ranged between 340 and 660 ppm tocopherols (P<0.05). The antioxidant activity of the tocopherols diminished when the tocopherol levels exceeded their optimal concentrations. Above their optimal concentrations, the individual tocopherols and the tocopherol mixture exhibited prooxidation behavior that was more pronounced with increasing temperature from 40 to 60°C (P<0.05). A comparison of the antioxidant activity of the individual tocopherols at their optimal concentrations revealed that α-tocopherol (∼100 ppm) was 3–5 times more potent than γ-tocopherol (∼300 ppm) and 16–32 times more potent than δ-tocopherol (∼1900 ppm).     

The effect of temperature on the antioxidant activity of tocopherols

The effect of temperature on the antioxidant activity of α‐ and δ‐tocopherol (at 100 mg/kg level) was studied in pork lard, using the Oxipres apparatus, in the temperature range from 80 to 150 °C. The antioxidant activity of δ‐tocopherol decreased with increasing working temperature in the whole temperature range studied. The activity of α‐tocopherol was practically constant in the temperature range from 80 to 110 °C and decreased with increasing temperature at temperatures higher than 110 °C. Both tocopherols were ineffective at 150 °C (p <0.05). Due to different temperature effects on the antioxidant activities of α‐ and δ‐tocopherol, the δ‐tocopherol activity was approximately two times higher than the α‐tocopherol activity at 80 °C, but their activities were the same (p <0.05) at 130 °C.     

Effect of Agronomical Factors and Storage Conditions on the Tocopherol Content of Oblica and Leccino Virgin Olive Oils

The influence of agronomical factors (two growing areas and four harvest periods) and storage conditions of virgin olive oils (room temperature, +4 and ?20 °C) on tocopherols was investigated on two cultivars having significantly different tocopherol content (Oblica 269–443 mg/kg, Leccino 403–784 mg/kg). α‐Tocopherol accounted for 97 % of total tocopherols and its content decreased during ripening of both cultivars. In a warmer growing area both cultivars gained a higher γ‐tocopherol content while only Leccino showed a higher content of α‐tocopherol. After 12 months of storage α‐tocopherol content decreased by up to 27 %. Lower storage temperatures did not always contribute to the higher stability of α‐tocopherol compared to room temperature.     

Contents of Carotenoids, Tocopherols and Sterols in Acacia cyanophylla Seed Oils

Seeds from 12 Acacia cyanophylla ecotypes, harvested in Tunisia, were examined for their seed oil contents of carotenoids, tocopherols and phytosterols. The average carotenoid content (lutein and zeaxanthin) was ca. 102 mg kg^?1 of total extracted lipids. Lutein (ca. 97 mg kg^?1 of total extracted lipids) was usually more abundant than zeaxanthin (ca. 5 mg kg^?1 of total extracted lipids). The mean total tocopherol content was ca. 704 mg kg^?1 of total extracted lipids. The main isomer was α‐tocopherol, with more than 75 % of total tocopherols (ca. 528 mg kg^?1 of total extracted lipids), followed by γ‐tocopherol (ca. 168 mg kg^?1 of total extracted lipids) and δ‐tocopherol (ca. 86 mg kg^?1 of total lipids). High levels of phytosterols (ca. 7.8 g kg^?1 of total extracted lipids) were detected, among which β‐sitosterol was the most abundant (47 %). All these results highlight the richness of carotenoids, tocopherols and sterols in A. cyanophylla seed oil, and imply that this species might constitute a potential resource for the development of functional foods.     

Seed Oils of Five Black Tartary Buckwheat Cultivars with Biochemical Characterization and Antioxidant Properties

Black tartary buckwheat oils (BTBOs) were extracted from five major industrial tartary buckwheat cultivars grown under similar agronomical activities and environmental conditions. These oils were characterized for the bioactive compounds containing fatty acids, β‐carotene, lutein, α‐, β‐, δ‐ and γ‐tocopherol, and for their antioxidant properties. The total tocopherol contents that were obtained ranged from 704.66 to 1156.19 mg/kg, with γ‐tocopherol (588.98–977.91 mg/kg) as the main component. The concentration of lutein ranged from 253.14 to 429.63 mg/kg, which was almost ten times higher than that of β‐carotenoid (46.71–69.2 mg/kg), indicating that black tartary buckwheat seed oils were a good source of lutein. The predominant fatty acids were unsaturated oleic acid (C18:1) (35.27–40.61 %) and linoleic acid (C18:2) (38.25–42.90 %). Excellent values of 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH), diammonium salt (ABTS) radical scavenging activities were obtained and the highest oxygen radical absorbance capacity (ORAC) value of 13.89 mmol Trolox equiv/g oil was detected in the variety of Chuanqiao No. 1, which was clearly separated by principal component analysis (PCA) on the basis of the highest content of tocopherols and carotenoids. Moreover, the correlation analysis showed that tocopherols and carotenoids were the major contributors to the antioxidant activities of the BTBOs. This study demonstrates that lipophilic extraction in the tartary buckwheat seed contains many interesting bioactive compounds, which are beneficial for human health.     

Effects of tocopherols and their mixtures on the oxidative stability of olive oil and linseed oil under heating

The tested tocopherols (γ,δ,α) showed antioxidative activity at all levels of addition to the monounsaturated olive oil, the effects increased as a function of concentrations (maximum: +287% with 800 mg γ‐tocopherol/100 g oil compared to the control oil). In the highly unsaturated linseed oil, which contains 58 mg/100 g initial concentration of γ‐tocopherol, γ‐tocopherol showed antioxidative behavior up to the addition of 100 mg/ 100 g oil. Additions of more than the 100 mg/100 g affected the oil, resulting in a faster oxidation. Mixtures of γ/δ‐tocopherols in olive oil were found to protect more efficiently than both vitamins when added separately α‐tocopherol reduced effects of other tocopherols in both plant oils. The stabilizing effect of added tocopherols and their mixtures (100 mg/100 g oil each) in olive oil are γ/δ‐T>γ‐T>δ‐T>γ/α‐T>δ/α‐T>α‐T and in linseed oil γ‐T>γ/δ‐T>δ‐T>γ/α‐T>α‐T>α/δ‐T.     

Antioxidant Efficacy of a New Synergistic,Multicomponent Formulation for Fish Oil Omega-3 Concentrates

Today, tocopherols serve as the industrial standard antioxidant protection for fish oil omega-3 concentrates. Synergistic interactions between tocopherols, ascorbyl palmitate and natural polyphenols extracted from plant sources have been demonstrated in model systems. The main goal for this work was to develop a mix of such antioxidants with improved efficacy in the context of preserving industrial marine oil concentrates. The antioxidant formulation comprises tocopherols, ascorbyl palmitate, rosemary extract and green tea catechins. Part of the scope was to develop a method for dissolving green tea catechins in oil. The key element of the method is to introduce green tea on a lipid insoluble carrier when dissolving the extract in the oil, and thereafter remove the carrier by filtration. The antioxidant mix was tested against tocopherol in omega-3 concentrates of minimum 300 mg/g eicosapentaenoic acid (EPA) plus 200 mg/g docosahexaenoic acid (DHA) in the form of triacylglycerides and ethyl esters. The mix was superior compared to tocopherols in suppressing both primary- and secondary oxidation. Weight increase measurements of oil in contact with air correlated well with standard oxidation tests within individual samples and the method was considered simple and useful for monitoring oxidation in omega-3 concentrates.     

The effect of walnut intake on factors related to prostate and vascular health in older men

Background

Tocopherols may protect against prostate cancer and cardiovascular disease (CVD).

Methods

We assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). Subjects (n = 21) consumed (in random order) their usual diet +/- a walnut supplement (75 g/d) that was isocalorically incorporated in their habitual diets. Prior to the supplement study, 5 fasted subjects participated in an acute timecourse experiment and had blood taken at baseline and 1, 2, 4, and 8 h after consuming walnuts (75 g).

Results

During the timecourse experiment, triglycerides peaked at 4 h, and gamma-tocopherol (γ-T) increased from 4 to 8 h. Triglyceride – normalized γ-T was two-fold higher (P = 0.01) after 8 versus 4 h. In the supplement study, change from baseline was +0.83 ± 0.52 μmol/L for γ-T, -2.65 ± 1.30 μmol/L for alpha-tocopherol (α-T) and -3.49 ± 1.99 for the tocopherol ratio (α-T: γ-T). A linear mixed model showed that, although PSA did not change, the ratio of free PSA:total PSA increased and approached significance (P = 0.07). The α-T: γ-T ratio decreased significantly (P = 0.01), partly reflecting an increase in serum γ-T, which approached significance (P = 0.08).

Conclusion

The significant decrease in the α-T: γ-T ratio with an increase in serum γ-T and a trend towards an increase in the ratio of free PSA:total PSA following the 8-week supplement study suggest that walnuts may improve biomarkers of prostate and vascular status.