Reactive oxygen scavenging effect of enzymatic extracts from Sargassum thunbergii

The free radical scavenging activity of water soluble natural antioxidants from Sargassum thunbergii, which is a brown marine alga, was evaluated by examining the radical scavenging activities of the extracts of hydrolyzates from S. thunbergii on hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and alkyl radicals. A spin-trapping electron spin resonance (ESR) spectrometer was employed, and the results were compared for their ESR signal intensity. S. thunbergii was enzymatically hydrolyzed to prepare water soluble extracts by five carbohydrases (AMG, Celluclast, Termamyl, Ultraflo, and Viscozyme) and proteases (Alcalase, Flavorzyme, Kojizyme, Neutrase, and Protamex). The scavenging activity of the radicals increased with increased concentrations of the extracts. The scavenging results were higher for hydroxyl and alkyl radicals and lower for DPPH radical as compared with vitamin C as a reference. The hydrogen peroxide scavenging activity of the extracts was also investigated; the Alcalase extract showed the highest scavenging activity among the extracts prepared with the five proteases and five carbohydrates. In addition, the DNA damage was determined by using the comet assay with alkaline electrophoresis and was quantified by measuring the tail length. The preventive effect of Alcalase extract from S. thunbergii against DNA damage increased with increments of concentration of the enzymatic extracts.     

Novel low-density lipoprotein (LDL) oxidation model: antioxidant capacity for the inhibition of LDL oxidation

A novel model of peroxyl radical initiated low-density lipoprotein (LDL) oxidation (LDL oxidation model for antioxidant capacity, or LOMAC) was developed to assess the free radical scavenging capacity of antioxidants and the extracts of natural products. A water-soluble free radical initiator, 2,2'-azobis(amidinopropane) dihydrochloride, was used at physiological temperature (37 degrees C) to generate peroxyl radicals to catalyze lipid oxidation of LDL isolated from human plasma samples. Headspace hexanal, a major decomposition product of LDL oxidation, was measured by a headspace gas chromatograph as an indicator of antioxidant capacity of different concentrations of pure antioxidants (vitamins C and E) and the extracts of natural products (fresh apple phytochemical extracts). All vitamin C and E and apple extract concentrations tested resulted in increasing partial suppression and delay of LDL oxidation. On the basis of the median effective dose (EC(50)) calculated for each compound or extract tested, the LOMAC value of 100 g of apple against LDL oxidation was equivalent to 1470 mg of vitamin E or to 402 mg of vitamin C. This study shows that the LOMAC assay can be routinely used to analyze or screen antioxidants or phytochemical extracts against LDL oxidation to prevent cardiovascular disease. The food-specific LOMAC values will be very useful as a new alternative biomarker for future epidemiological studies of cardiovascular disease.     

Antioxidant activity and inhibition of lipid peroxidation in germinating seeds of transgenic soybean expressing OsHGGT

Tocochromanols are potent lipid-soluble antioxidants and essential nutrients for human health. Genetic engineering techniques were used to develop soybeans with enhanced vitamin E levels, including tocotrienols, which are not found in soybean. The gene encoding rice homogentisate geranylgeranyl transferase (HGGT) was overexpressed in soybeans using seed-specific and constitutive promoters. The association between abundance of vitamin E isomers and antioxidant activity was investigated during seed germination. With the exception of β-tocotrienol, all vitamin E isomers were detected in germinating seeds expressing OsHGGT. The antioxidant properties of germinating seed extracts were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radicals and lipid peroxidation (TBARS). Compared with intact wild-type seeds, transgenic seeds showed increases in radical scavenging of 5.4-17 and 23.2-35.3% in the DPPH and ABTS assays, respectively. Furthermore, the lipid peroxidation levels were 2.0-4.5-fold lower in germinating seeds from transgenic lines than in wild-type seeds. Therefore, it appears that the antioxidant potential of transgenic oil-producing plants such as soybean, sunflower, and corn may be enhanced by overexpressing OsHGGT during seed germination.     

Free radical scavenging properties of conjugated linoleic acids.

Conjugated linoleic acids (CLA) were investigated for free radical scavenging properties against the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH.) by electron spin resonance (ESR) spectrometry and spectrophotometric methods. ESR results demonstrated that CLA directly reacted and quenched free DPPH radicals in benzene, while spectrophotometric analysis showed the radical scavenging capacity of CLA in ethanol. Dose and time effects of CLA-DPPH. reactions were observed in both tests. The ED(50) of CLA was 18 mg/mL under experimental conditions. CLA are much weaker radical scavengers as compared to vitamin E, vitamin C, and BHT. Kinetics of CLA-DPPH. reactions was different to that of linoleic acid (LA)-DPPH. reactions. CLA reacted and quenched DPPH radicals at all tested levels without a lag phase, while LA had a lag phase and showed no radical quenching activity at levels of 5-80 mg/mL in 30 min. These data indicated that CLA can provide immediate protection against free radicals, but LA cannot.     

Antioxidant activities of extracts from Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae)

Various extracts of the aerial parts of Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae) have been used in folk medicine to treat many ailments, particularly inflammation and migraine. Neither the bioactive components responsible nor the mechanisms involved have been evaluated. Here are reported antioxidant activities of their methanol, dichloromethane, and ethyl acetate extracts. Samples were evaluated for oxygen radical absorption capacity (ORAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging, and inhibition of the formation of thiobarbituric acid reactive species (TBARS), a measure of lipid peroxidation. Antioxidant activities were strongly correlated with total polyphenol content. The most active extracts from P. gentianoides in scavenging DPPH radicals and inhibiting TBARS formation were the methanol extract (A) and a further ethyl acetate extract of this (E). Partition E was further divided into eight fractions, and both E and the fractions were compared for activity against butylated hydroxytoluene, quercetin, and tocopherol. Partition E and the most active fractions, 5 and 6, were found to have I(50) values of 14.1, 38.6, and 41.8 ppm, respectively, against DPPH and 18.5, 26.0, and 12.7 ppm, respectively, against TBARS formation. Consistent with this finding, partition E and fractions 4-6 had the greatest ORAC and FRAP values. These results show that these plants could be useful antioxidant sources.     

Effect of heat treatment of camelina (Camelina sativa) seeds on the antioxidant potential of their extracts

The effect of different heat treatments of camelina (Camelina sativa) seeds on the phenolic profile and antioxidant activity of their hydrolyzed extracts was investigated. The results showed that total phenol contents increased in thermally treated seeds. Heat treatment affected also the quantities of individual phenolic compounds in extracts. Phenolics in unheated camelina seeds existed in bound rather than in free form. A temperature of 160 °C was required for release of insoluble bound phenolics, whereas lower temperatures were found to be optimal to liberate those present as soluble conjugates. The best reducing power and alkyl peroxyl radical scavenging activity in the emulsion was expressed by phenolics which were bound to the cell wall, whereas the best iron chelators and 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical scavengers were found to be those present in free form. The heat treatment of seeds up to 120 °C increased the reducing power and DPPH? radical scavenging ability of extracts, but negatively affected iron chelating ability and their activity in an emulsion against alkyl peroxyl radicals.     

Total antioxidant capacity of arginine-conjugated linoleic acid (CLA) complex

Conjugated linoleic acids (CLA) have shown diverse biological activities, including anti-carcinogenic, anti-atherosclerotic, anti-adipogenic, and anti-diabetogenic effects. Recent reports also showed that CLA has free radical scavenging capacity, which may give health benefits to human beings. However, the application of CLA as a bioactive ingredient has been limited due to its insolubility in water. To overcome this problem, we investigated antioxidant activities of arginine (Arg)-CLA, a water-soluble CLA salt, using both 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. CLA, Arg, and Arg-CLA all exerted radical scavenging activities in a dose-dependent manner in both assays. Arg-CLA at 20 mM scavenged 89 and 55% of ABTS and DPPH radicals in 3 h, respectively, whereas CLA alone quenched only 48 and 26% of them under the same conditions. The antioxidant activity of the Arg-CLA complex was found to be synergistic in ABTS assay and comparable to that of vitamin E in DPPH assay.     

In vitro antioxidant activities of edible artichoke (Cynara scolymus L.) and effect on biomarkers of antioxidants in rats

Artichoke (Cynara scolymus L.), an edible vegetable from the Mediterranean area, is a good source of natural antioxidants such as vitamin C, hydroxycinnamic acids, and flavones. The antioxidant activity of aqueous-organic extracts of artichoke were determined using three methods: (a) free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) scavenging, (b) ferric-reducing antioxidant power (FRAP), and (c) inhibition of copper(II)-catalyzed in vitro human low-density lipoprotein (LDL) oxidation. In addition, the present study was performed to investigate the ability of the edible portion of artichoke to alter in vivo antioxidative defense in male rats using selected biomarkers of antioxidant status. One gram (dry matter) had a DPPH(*) activity and a FRAP value in vitro equivalent to those of 29.2 and 62.6 mg of vitamin C and to those of 77.9 and 159 mg of vitamin E, respectively. Artichoke extracts showed good efficiency in the inhibition in vitro of LDL oxidation. Neither ferric-reducing ability nor 2,2'-azinobis(3-ethylbenzothiazolin-6-sulfonate) radical scavenging activity was modified in the plasma of the artichoke group with respect to the control group. Among different antioxidant enzymes measured (superoxide dismutase, gluthatione peroxidase, gluthatione reductase, and catalase) in erythrocytes, only gluthatione peroxidase activity was elevated in the artichoke group compared to the control group. 2-Aminoadipic semialdehyde, a protein oxidation biomarker, was decreased in plasma proteins and hemoglobin in the artichoke-fed group versus the control group. In conclusion, the in vitro protective activity of artichoke was confirmed in a rat model.     

Free radical scavenging properties of wheat extracts

Three hard winter wheat varieties (Akron, Trego, and Platte) were examined and compared for their free radical scavenging properties and total phenolic contents (TPC). Free radical scavenging properties of wheat grain extracts were evaluated by spectrophotometric and electron spin resonance (ESR) spectrometry methods against stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH*) and radical cation ABTS*+ (2,2'-azino-di[3-ethylbenzthiazoline sulfonate]). The results showed that the three wheat extracts differed in their capacities to quench or inhibit DPPH* and ABTS*+. Akron showed the greatest activity to quench DPPH radicals, while Platte had the highest capacity against ABTS*+. The ED50 values of wheat extracts against DPPH radicals were 0.60 mg/mL for Akron, 7.1 mg/mL for Trego, and 0.95 mg/mL for Platte under the experimental conditions. The trolox equivalents against ABTS*+ were 1.31 +/- 0.44, 1.08 +/- 0.05, and 1.91 +/- 0.06 micromol/g of grain for Akron, Trego, and Platte wheat, respectively. ESR results confirmed that wheat extracts directly reacted with and quenched free radicals. The TPC were 487.9 +/- 927.8 microg gallic acid equivalents/g of grain. No correlation was observed between TPC and radical scavenging capacities for DPPH* and ABTS*+ (p = 0.15 and p > 0.5, respectively).     

Effects of genotype and environment on the antioxidant properties of hard winter wheat bran

Recent consumer interest in controlling and preventing chronic diseases through improved diet has promoted research on the bioactive components of agricultural products. Wheat is an important agricultural and dietary commodity worldwide with known antioxidant properties concentrated mostly in the bran fraction. The objective of this study was to determine the relative contributions of genotype (G) and growing environment (E) to hard winter wheat bran antioxidant properties, as well as correlations of these properties to growing conditions. Bran samples of 20 hard winter wheat varieties grown in two locations were examined for their free radical scavenging capacities against DPPH, ABTS cation, peroxyl (ORAC), and superoxide anion radicals and chelating properties, as well as their total phenolics and phenolic acid compositions. Results showed significant differences for all antioxidant properties tested and multiple significant correlations between these properties. A factorial designed analysis of variance for these data and pooled previously published data showed similar results for four of the six antioxidant properties, indicating that G effects were considerably larger than E effects for chelating capacity and DPPH radical scavenging properties, whereas E was much stronger than G for ABTS cation radical scavenging capacity and total phenolics, although small interaction effects (GxE) were significant for all antioxidant properties analyzed. Results also showed significant correlations between temperature stress or solar radiation and some antioxidant properties. These results indicate that each antioxidant property of hard winter wheat bran is influenced differently by genotype and growing conditions.     

Antioxidant properties of various solvent extracts of total phenolic constituents from three different agroclimatic origins of drumstick tree (Moringa oleifera Lam.) leaves

Water, aqueous methanol, and aqueous ethanol extracts of freeze-dried leaves of Moringa oleifera Lam. from different agroclimatic regions were examined for radical scavenging capacities and antioxidant activities. All leaf extracts were capable of scavenging peroxyl and superoxyl radicals. Similar scavenging activities for different solvent extracts of each collection were found for the stable 1,1-diphenyl 2-picrylhydrazyl (DPPH(*)) radical. Among the three different moringa samples, both methanol and ethanol extracts of Indian origins showed the highest antioxidant activities, 65.1 and 66.8%, respectively, in the beta-carotene-linoleic acid system. Nonetheless, increasing concentration of all the extracts had significantly (P < 0.05) increased reducing power, which may in part be responsible for their antioxidant activity. The major bioactive compounds of phenolics were found to be flavonoid groups such as quercetin and kaempferol. On the basis of the results obtained, moringa leaves are found to be a potential source of natural antioxidants due to their marked antioxidant activity. This is the first report on the antioxidant properties of the extracts from freeze-dried moringa leaves. Overall, both methanol (80%) and ethanol (70%) were found to be the best solvents for the extraction of antioxidant compounds from moringa leaves.     

Effect of foliar application of selenium on the antioxidant activity of aqueous and ethanolic extracts of selenium-enriched rice

Selenium fertilizer was foliar applied to determine the effects of antioxidant activity of selenium-enriched rice assessed by alpha,alpha-diphenyl-beta-picylhydrazyl (DPPH) radical scavenging and the ferric thiocyanate (FTC) method. Results showed that selenium concentration in rice was significantly enhanced dose dependently. Aqueous or ethanolic extracts of rice displayed significantly higher antioxidant activity against lipid peroxidation. The activities of aqueous extracts were significantly higher than those of ethanolic extracts and increased with the increasing selenium concentration in rice. The DPPH assay showed that the kinetic behaviors of aqueous extracts were complex and slow, while ethanolic extracts reacted quickly with DPPH radical. Aqueous extracts of rice exhibited higher antiradical efficiencies than ethanolic extracts, and rice (1.275 mg Se kg(-)(1)) presented the lowest EC(50) values of 533.46 +/- 0.58 microg mL(-)(1). As compared to rice extracts, all of the reference antioxidants showed more than 4-fold antiradical efficiencies than rice extracts. This radical scavenging activity was significantly correlated with selenium concentrations in rice (R = 0.862, p < 0.05), while ethanolic extracts were inversely correlated with selenium concentration in rice.     

In vitro activity of almond skin polyphenols for scavenging free radicals and inducing quinone reductase

Observational studies and clinical trials suggest nut intake, including almonds, is associated with an enhancement in antioxidant defense and a reduction in the risk of cancer and cardiovascular disease. Almond skins are rich in polyphenols (ASP) that may contribute to these putative benefits. To assess their potential mechanisms of action, we tested the in vitro effect of ASP extracted with methanol (M) or a gastrointestinal juice mimic (GI) alone or in combination with vitamins C (VC) or E (VE) (1-10 micromol/L) on scavenging free radicals and inducing quinone reductase (QR). Flavonoid profiles from ASP-M and -GI extracts were different from one another. ASP-GI was more potent in scavenging HOCl and ONOO (-) radicals than ASP-M. In contrast, ASP-M increased and ASP-GI decreased QR activity in Hepa1c1c7 cells. Adding VC or VE to ASP produced a combination- and dose-dependent action on radical scavenging and QR induction. In comparison to their independent actions, ASP-M plus VC were less potent in scavenging DPPH, HOCl, ONOO (-), and O 2 (-) (*). However, the interaction between ASP-GI plus VC promoted their radical scavenging activity. Combining ASP-M plus VC resulted in a synergistic interaction, inducing QR activity, but ASP-GI plus VC had an antagonistic effect. On the basis of their total phenolic content, the measures of total antioxidant activity of ASP-M and -GI were comparable. Thus, in vitro, ASP act as antioxidants and induce QR activity, but these actions are dependent upon their dose, method of extraction, and interaction with antioxidant vitamins.     

Antioxidant properties of bran extracts from Trego wheat grown at different locations

The effects of growing conditions during the grain-filling period, including high temperature stress, total solar radiation, and average daily solar radiation, on the antioxidant properties of Trego wheat were evaluated. Bran extracts were prepared from Trego wheat, grown at four nonirrigated and one irrigated location in Colorado, and compared for their radical scavenging activities against ABTS*+ and DPPH*, Fe(2+) chelating capacities, and total phenolic contents. Significant differences in radical scavenging activities, chelating capacities, and total phenolic contents were detected among Trego bran samples grown at different locations, suggesting that growing conditions may influence the antioxidant properties of wheat. The bran sample obtained from Fort Collins had the strongest scavenging activity against either ABTS*+ or DPPH* radicals and the greatest chelating activity, whereas the highest total phenolic content was detected in bran samples from Walsh, indicating that each antioxidant activity may respond to the environmental changes differently. Positive correlations were detected between the DPPH* scavenging activity and either total solar radiation (r = 0.97, p = 0.03) or average daily solar radiation (r = 0.97, p = 0.03). In addition, HPLC analysis detected the presence of ferulic, syringic, vanillic, p-hydroxybenzoic, and coumaric acids in wheat bran. Additional research is needed to further investigate the effects of environmental conditions and the interactions between genotype and environmental factors on the antioxidant properties of wheat to promote the production of wheat with improved antioxidant properties by optimizing the growing conditions for a selected genotype.     

Antioxidant activity of extracts of black sesame seed (Sesamum indicum L.) by supercritical carbon dioxide extraction

Antioxidant activities of extracts derived from sesame seed by supercritical carbon dioxide (SC-CO(2)) extraction and by n-hexane were determined using alpha,alpha-diphenyl-beta-picylhydrazyl (DPPH) radical scavenging and linoleic acid system methods. The highest extracted yield was given at 35 degrees C, 40 MPa, and a CO(2) flow rate of 2.5 mL min(-1) by an orthogonal experiment. The yields of extracts increased with increasing pressure, and yields at 40 and 30 MPa were higher than that by solvent extraction at 46.50%. Results from the linoleic acid system showed that the antioxidant activity follows the order: extract at 35 degrees C, 20 MPa > BHT > extract at 55 degrees C, 40 MPa > extract at 55 degrees C, 30 MPa > Trolox > solvent extraction > alpha-tocopherol. The SC-CO(2) extracts exhibited significantly higher antioxidant activities comparable to that by n-hexane extraction. The extracts at 30 MPa presented the highest antioxidant activities assessed in the DPPH method. At 20 MPa, the EC(50) increased with temperature, which indicated that the antioxidant activity was decreased in a temperature-dependent manner. The significant differences of antioxidant activities were found between the extracts by SC-CO(2) extraction and n-hexane. However, no significant differences were exhibited among the extracts by SC-CO(2) extraction. The vitamin E concentrations were also significantly higher in SC-CO(2) extracts than in n-hexane extracts, and its concentrations in extracts corresponded with the antioxidant activity of extracts.     

Correlation between some nutritional components and the total antioxidant capacity measured with six different assays in eight horticultural crops

The contents of antioxidant nutritional compounds, total soluble phenolics (TSP), vitamin C, vitamin E, beta-carotene, and total carotenoids (TC), were correlated with the total antioxidant capacity (AOC) of hydrophilic (HPE) and lipophilic extracts (LPE) from eight horticultural crops, namely, guava, avocado, black sapote, mango, papaya, prickly pear fruit, cladodes, and strawberry. AOC was measured using six different assays: 2,2'-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), ferric-ion-reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and total oxidant scavenging capacity (TOSC). AOC values from HPE were about 95 times higher than LPE values. HPE of guava had the highest AOC value when evaluated with DMPD, DPPH, FRAP, TEAC, and TOSC assays, whereas with ORAC assay, black sapote had the highest value. HPE of papaya and prickly pear fruit presented the lowest AOC values with all assays. From HPE, vitamin C and TSP contents were highly correlated with AOC for all assays, while from LPE, TC and beta-carotene contents possessed a high correlation with AOC only in the DMPD assay.     

Effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley (Hordeum vulgare L.)

Four kinds of solvent extracts from three Chinese barley varieties (Ken-3, KA4B, and Gan-3) were used to examine the effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley through free radical scavenging activity, reducing power and metal chelating activity, and individual and total phenolic contents. Results showed that extraction solvent mixtures had significant impacts on antioxidant activity estimation, as well as different extraction capacity and selectivity for free phenolic compounds in barley. The highest DPPH* and ABTS*+ scavenging activities and reducing power were found in 80% acetone extracts, whereas the strongest *OH scavenging activity, O2*- scavenging activity, and metal chelating activity were found in 80% ethanol, 80% methanol, and water extracts, respectively. Additionally, 80% acetone showed the highest extraction capacity for (+)-catechin and ferulic, caffeic, vanillic, and p-coumaric acids, 80% methanol for (-)-epicatechin and syringic acid, and water for protocatechuic and gallic acids. Furthermore, correlations analysis revealed that TPC, reducing power, DPPH* and ABTS*+ scavenging activities were well positively correlated with each other (p < 0.01). Thus, for routine screening of barley varieties with higher antioxidant activity, 80% acetone was recommended to extract free phenolic compounds from barley. DPPH* scavenging activity and ABTS*+ scavenging activity or reducing power could be used to assess barley antioxidant activity.     

Antioxidant and antimelanogenic activities of polyamine conjugates from corn bran and related hydroxycinnamic acids

The antioxidant activity of three major polyamine conjugates, N,N'-dicoumaroyl-putrescine (DCP), N-p-coumaroyl-N'-feruloylputrescine (CFP), and N,N'-diferuloyl-putrescine (DFP) isolated from corn bran, and their related hydroxycinnamic acids, p-coumaric acid and ferulic acid, were evaluated by three antioxidant in vitro assay systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide and hydroxyl radicals generated by enzymatic and nonenzymatic reactions. Additionally, five phenolic compounds were evaluated for melanogenesis inhibitory activity using mushroom tyrosinase and B16 melanoma cells. Most of the phenolic compounds significantly scavenged DPPH, superoxide, and hydroxyl radicals in a dose-dependent manner. Particularly, DFP showed potent DPPH (IC50 = 38.46 microM) and superoxide (IC50 = 291.62 microM) radical scavenging activities, while DCP exhibited the strongest hydroxyl radical scavenging activity (IC50 = 120.55 microM). CFP also exerted moderate DPPH, superoxide, and hydroxyl radical scavenging activities. Meanwhile, DCP (IC50 = 181.73 microM) showed potent tyrosinase inhibitory activity toward l-tyrosine as the substrate, whereas DFP (IC50 = 733.64 microM) significantly inhibited melanin synthesis in B16 melanoma cells. These current results indicate that these three polyamine conjugates from corn bran may be useful potential sources of natural antioxidants and skin-whitening agents.     

Comparison of the radical scavenging potential of polar and lipidic fractions of olive oil and other vegetable oils under normal conditions and after thermal treatment

The antioxidant activity (IC(50)) of extra virgin olive oil (EVOO), commercial olive oil, and other vegetable oils (soybean, sunflower, and corn oil) was determined by UV-vis and by electron paramagnetic resonance (EPR) spectroscopy of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Also, we studied the antioxidant activity of the methanol soluble phase (methanolic, MF) and the nonsoluble phase (lipidic, LF) of oils by the same methods. Similarly, we studied the effect of heating on the antioxidant activity at 160 and 190 degrees C. Also, the MF, containing the polyphenolic substances, was used for measurements of the radical scavenging capacity toward the most important oxygen free radicals, superoxide anion (O(2)(*)(-)) and hydroxyl (HO(*)) radicals. Results showed that soybean oil and EVOO had the highest antioxidant potential and thermal stability. In the case of soybean oil, the antioxidant capacity is the result of its high content of gamma- and delta-tocopherols (with the highest antioxidant capacity and thermostabilities), whereas in EVOO, the antioxidant potential is the result of the combination of specific antioxidant polyphenols, which are acting additionally as effective stabilizers of alpha-tocopherol. The high content of EVOO in tyrosol, hydrotyrosol, and oleuropein and other polyphenolics with radical scavenging abilities toward superoxide anion and hydroxyl radical suggests that olive oil possesses biological properties that could partially account for the observed beneficial health effects of the Mediterranean diet.     

Antioxidant contents and antioxidative properties of traditional rye breads

The purpose of this research was to find out the effect of flour extraction rate on the antioxidative properties of traditional rye bread and then to compare the bioactive compounds content and antioxidant properties of rye breads with commercial wheat roll. Four types of rye flour with different extraction rates of 100 (whole meal dark flour), 95 (brown flour), 90 (brown flour), and 70% (light flour) originated from Warko rye cultivar were used for traditional bread baking with sourdough fermentation. Four types of the respective rye breads were analyzed for their potentially beneficial components, including tocopherols and tocotrienols, total phenolics and flavonoids, reduced glutathione, and inositol hexaphosphates. Moreover, the phenolic acids profile was provided. The Trolox equivalent antioxidant capacity (TEAC) of the breads was evaluated using free radical scavenging activities of 80% methanol extracts against ABTS*+ radical cation (ABTS radical cation decolorization method) whereas radical scavenging activity (RSA) was determined against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*). The superoxide dismutase-like activity (SOD-like activity) was evaluated as free radical scavenging activities of PBS extracts against superoxide anion radicals (O2*-). The results were compared to whole meal rye bread as well as to wheat roll taken as representative example of wheat based bakery product. The studies showed that flour extraction rates strongly affected the content of bioactive compounds and antioxidative properties of traditionally baked rye breads. The incorporation of the rye flours with extraction rates from 100 down to 70% in the formulation caused decrease in tocopherol (T), tocotrienol (T3), inositol hexaphosphate (IP6), and phenolic compound (TPC) contents in rye breads. No changes in reduced glutathione (GSH) contents were noted between each type of rye bread. A significant decrease in Trolox equivalent antioxidant capacity and radical DDPH scavenging activity was also found in bread formulated on flour with an extraction rate of 70% in comparison to the breads formulated on flour with extraction rates from 100 to 90%. The highest SOD-like activity was noted for rye bread formulated on flour with an extraction rate of 70%. The four types of rye breads showed better antioxidative properties and higher antioxidant contents when compared to wheat roll with one exception made to tocopherols and tocotrienols.