Evaluation of the antioxidant capacity of lupin sprouts germinated in the presence of selenium

Antioxidant capacity of 5 DAS (days after seeding) lupin sprouts germinated in the presence of selenate or selenite was determined by cyclic voltammetry (CV), Folin-Ciocalteu reagent (FCR) application and photochemiluminescence (PCL) methods. The hydrophilic (80% methanol) and lipophillic (hexane/methanol) extracts of 5 DAS lupin sprouts germinated in the absence of selenium (control sprouts) showed higher antioxidant capacity than ungerminated seeds. Five DAS sprouts produced in the presence of higher concentration of selenate or selenite (6–8 mg/L) showed increased total antioxidant capacity formed by both hydrophilic and lipohillic antioxidants when evaluated by CV and FCR methods. The hydrophilic extracts from sprouts produced in the presence of low concentration of selenate (2–6 mg/L) showed a significantly higher antioxidant capacity of water-soluble compounds (PCL ACW) while no changes were noted in those germinated in the presence of the highest concentration in relation to the control sprouts. In contrast, the antioxidant capacity of lipid-soluble compounds (PCL ACL) lowered significantly in relation to the control sprouts. The similar changes in antioxidant capacity of sprouts produced in the presence of selenite were found by both PCL assays. Comparison of PCL with CV and FCR reducing capacity assays has shown that these methods yielded considerably different chemical information. Moreover, the changes in total antioxidant and total reducing capacity of sprouts germinated in the presence of either selenate or selenite provided by CV and FCR assays were higher than those obtained by photochemiluminesce measurements. It can be suggested to use 6–8 mg/L of selenite rather than selenate in order to obtain a lupin sprouts with high antioxidant capacity.     

Fluctuations in the phenolic content and antioxidant capacity of dark fruit juices in refrigerated storage

The changes in total phenol content and antioxidant capacity were monitored in six industrial dark fruit juices during 29-day refrigerated storage. The initial total phenol values ranged from 1302.1 mg/L GAE (strawberry) to 1919.8 mg/L GAE (black currant) with a mean of 1573.3 mg/L GAE. All juices exhibited fluctuations in TP values with a marked increase after 48 hours in refrigerated storage, and a greater overall TP content in 5/6 studied juices after 29 days. Antioxidant capacity was evaluated using the DPPH radical scavenging assay and cyclic voltammetry (CV) and expressed as Trolox equivalent antioxidant capacity (TEAC). Black currant juice exhibited the highest TEAC values according to both CV (2.42 mM Trolox) and the DPPH assay (5.68 mM Trolox), while cranberry juice antioxidants exhibited the greatest storage stability and the smallest antioxidant capacity decrease on day 29, 20% (CV) and 15% (DPPH assay). At the end of 29-day storage 5/6 juices exhibited a significant loss in antiradical activity and all 6 juices exhibited a significant loss in TEAC derived from CV measurements. Significant linear correlation was observed between the results of CV measurements and the DPPH antiradical activity (r² = 0.62).     

Anti-oxidant capacity of dietary polyphenols determined by ABTS assay: a kinetic expression of the results

The 2, 2^′‐Azino‐bis(3‐ethylbenz‐thiazoline‐6‐sulfonic acid) (ABTS)/Trolox equivalent anti oxidant capacity (TEAC) assay, which measures the ability of compounds to scavenge the ABTS radical cation (ABTS^?+) in relation to Trolox (TEAC) is one of the most widely used methods to determine anti oxidant capacity. Usually, the measurements are based on a fixed end‐point (4–6 min), which may not take into account the different kinetic behaviour of anti‐oxidants. The aim of this work was to propose a kinetic procedure for ABTS^?+ assay, by using the kinetic parameters ED₅₀, t_EC50 and AE [antiradical efficiency = 1/(ED₅₀ × t_EC50)], previously applied to the 2, 2‐Diphenyl‐1‐picrylhydrazyl (DPPH^?) assay. It was found that some polyphenols standards – ferulic acid, resveratrol and others‐have not yet completed their reaction at the fixed end‐point. The consideration of kinetic parameters in this method may provide a more thorough understanding of the behaviour of the anti‐oxidants. A comparison of the activity of anti‐oxidants measured by the scavenging of ABTS^?+ with that of DPPH^? was also carried out.     

Classification of eight pomegranate juices based on antioxidant capacity measured by four methods

The antioxidant capacity of pomegranate juices (PJs) obtained from eight cultivars were determined by the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and β-carotene-linoleate model system. Total phenolic content (TPC) and total anthocyanin content (TAC) were also determined and found to vary between the range of 208.3–343.6 mg catechin equivalents and 8.1–36.9 mg cyanidine-3-glucoside equivalents per 100 ml of PJ, respectively. Cultivar Izmir 8 showed the highest scores for trolox equivalent antioxidant capacity (TEAC) as 418.3 ± 5.2 mg/100 ml of PJ, anti-lipid peroxidative activity (ALPA) as 93.5 ± 1.8% and efficient concentration (EC₅₀) as 29.8 ± 2.9 ml of PJ/g of DPPH. The hierarchy of PJs for antioxidant capacity with respect to their TEAC and ALPA values was I8 > I1499 > I10 > I1264 > I1479 > I26 > I23 > Zivzik. Interrelationships among the analyzed parameters and PJs obtained from eight cultivars were investigated by principal component analysis (PCA). Dimension of data set was reduced to two components by PCA accounting for the 93% of the total variance. Eight PJs were classified into three groups by cluster analysis (CA).     

Ultrahigh pressure extraction as a tool to improve the antioxidant activities of green tea extracts

In this study, the effect of ultrahigh pressure extraction at pressures of 150 MPa, 250 MPa, 350 MPa and 450 MPa on the total phenolic contents, the extraction yields and the antioxidant activities of green tea were investigated. The antioxidant activities of these extracts were analyzed using DPPH radical scavenging activity and total antioxidant capacity. The results showed that the phenolic contents and the antioxidant activities of extracts were greatly influenced by high pressure. The total phenolic contents and the antioxidant activities of ultrahigh pressure extraction at 450 MPa were higher than those of other ultrahigh pressure extraction and conventional extraction. The high content of phenolic compounds in the green tea leaves could account for the antioxidant activity. This study indicated that this new technology can benefit the food and pharmaceutical industries.     

Antioxidant activity of minor components of tree nut oils

The antioxidative components of tree nut oils were extracted using a solvent stripping process. Tree nut oil extracts contained phospholipids, sphingolipids, sterols and tocopherols. The chloroform/methanol extracted oils had higher amounts of phenolic compounds than their hexane extracted counterparts. The antioxidant activity of tree nut oil minor component extracts were assessed using the 2,2-azino-bis (3-ethylbenzthiazoline sulphonate) (ABTS) radical scavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, β-carotene bleaching test, oxygen radical absorbance capacity (ORAC) and photochemiluminescence inhibition assays. Results of these studies demonstrated that extracts of chloroform/methanol extracted oils possessed higher antioxidant activities than extracts of their hexane extracted counterparts. Meanwhile the extract of chloroform/methanol extracted pecan oil possessed the highest antioxidant activity.     

Total phenolics,ascorbic acid,and antioxidant capacity of noni (Morinda citrifolia L.) juice and powder as affected by illumination during storage

Total phenolics, ascorbic acid, and antioxidant capacity of noni (Morinda citrifolia L.) juice and powder were determined during storage at 24 °C. After 2 weeks of storage, illuminated noni juice lost 32% of total phenolics, 89% of ascorbic acid, and 46–65% of antioxidant capacity—about 8%, 22%, and 9–15% more than unilluminated juice. Both illuminated and unilluminated juice lost 97% of ascorbic acid by 4 weeks. The difference in antioxidant characteristics between illuminated and unilluminated juice became insignificant at 12 weeks. After 12 weeks, illuminated noni powder lost 21% of total phenolics, 17% of ascorbic acid, and 23–36% of antioxidant capacity—about 13%, 4%, and 7–19% more than the unilluminated powder. Noni powder in brown bottles retained antioxidant characteristics significantly greater than that in clear bottles. Protection from light effectively reduced degradation of antioxidant characteristics of noni juice for only 2 weeks but those of noni powder for at least 3 months.     

Antioxidant and radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.     

Antioxidant capacity,total phenolic and ascorbate content as a function of the genetic diversity of leek (Allium ampeloprasum var. porrum)

Extracts of the white shaft and green leaves of 30 leek cultivars were investigated for their antioxidant properties, total phenolic (TP) and l-ascorbic acid (AA) content. The measured antioxidant properties included free radical scavenging activities against peroxyl (ORAC) and 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) and their Fe³⁺ reducing capacity (FRAP). The results from this study suggest that the green leek leaves generally have significantly stronger antioxidant properties than the white shaft. Correlation analysis between the TP and the AA content and the antioxidant activity showed that phenolics and ascorbic acid contribute significantly to the antioxidant activity of leek. The three antioxidant activity assays were all correlated for the extracts of the white shaft of the 30 leek cultivars. Principal component analysis (PCA) elucidated the influence of part and type of cultivar on the antioxidant capacity, TP, and l-ascorbic acid content, whilst the breeding strategy and seed company had no influence.     

Antioxidant capacity of medicinal plants from the Province of Córdoba (Argentina) and their in vitro testing in a model food system

The total phenols content (Folin–Ciocalteau assay) and antioxidant capacity (ferric reducing/antioxidant power – FRAP) of 41 plants from Córdoba (Argentina) were analyzed. Phenol content ranged from 8.2 to 100.2 mg GAE/g. FRAP ranged from 85.2 to 1862.0 μmol of Fe(II)/g. Capparis atamisguea had the lowest values of total phenols content and antioxidant capacity (8.2 mg GAE/g and 85.2 μmol of Fe(II)/g, respectively), while Ligaria cuneifolia exhibited the highest values (100.2 mg GAE/g and 1862.0 μmol of Fe(II)/g, respectively). A significant linear correlation (p < 0.05) was found (0.9125) between phenols content and antioxidant capacity. Results support the idea that these plants may be a good source of natural antioxidants for food applications. Plants from the Asteraceae family (the most representative of the Córdoba flora) were further tested for their DPPH radical scavenging activity. Some plant extracts were tested in a simple food system to investigate to their potential use in foods.