Oxygen Radical Antioxidant Capacity Assays Research Articles

An in vitro analysis of an innovative standardized phospholipid carrier-based Melissa officinalis L. extract as a potential neuromodulator for emotional distress and related conditions.

Background: Melissa officinalis L. (MO), commonly known as lemon balm, a member of the mint family, is considered a calming herb. In various traditional medicines, it has been utilized to reduce stress and anxiety and promote sleep. A growing body of clinical evidence suggests that MO leaf extract supplementation possesses considerable neuropharmacological properties. However, its possible mechanism of action largely remains unknown. Objective: In the present in vitro studies, we comparatively investigated the central nervous system (CNS)-calming and antioxidative stress properties of an innovative standardized phospholipid carrier-based (Phytosome™) MO extract (Relissa™) vs. an unformulated dry MO extract. Methods: The neuropharmacological effect of the extract was studied in the anti-depressant enzymes γ-aminobutyrate transaminase (GABA-T) and monoamine oxidase A (MAO-A) assays and SH-SY5Y cells brain-derived neurotrophic factor (BDNF) expression assay. The neuroprotective effect of the extract against oxidative stress was assessed in SH-SY5Y cell-based (H2O2-exposed) Total Antioxidant Status (TAS) and Total Reactive Oxygen Species (ROS) assays. The cytotoxic effect of the extract was evaluated using MTT and LDH assays. The extract antioxidant effect was also evaluated in cell-free chemical tests, including TEAC-ABTS, DPPH, Ferric Reducing Antioxidant Power (FRAP), Oxygen Radical Antioxidant Capacity (ORAC), and Hydroxyl Radical Antioxidant Capacity (HORAC) assays. Results: Relissa™ exhibited high GABA-T inhibitory activity, IC50 (mg/mL) = 0.064 vs. unformulated dry MO extract, IC50 (mg/mL) = 0.27. Similar inhibitory effects were also observed for MAO-A. Relissa™ demonstrated an improved neuroprotective antioxidant effect on SH-SY5Y cells against H2O2-induced oxidative stress. Compared to unformulated dry MO extract, Relissa™ exerted high protective effect on H2O2-exposed SH-SY5Y cells, leading to higher cells BDNF expression levels. Moreover, cell-free chemical tests, including TEAC-ABTS, DPPH radical scavenging, FRAP, ORAC, and HORAC assays, validated the improved antioxidant effect of Relissa™ vs. unformulated dry MO extract. Conclusion: The results of the present study support the neuromodulating and neuroprotective properties of Relissa™, and its supplementation may help in the amelioration of emotional distress and related conditions.

The key phytochemistry of rosemary (Salvia rosmarinus) contributing to hair protection against UV.

The objective of this work was to correlate the phytochemistry of rosemary (Salvia rosmarinus), a botanical with known antioxidant properties, to a UV protection benefit in hair. These data will give insights into mechanisms of UV damage, the ROS formed and their reactivity. LC-MS was used to compare the compounds in 10 commercial extracts of rosemary. ORAC (oxygen radical antioxidant capacity) and FRAP (ferric reducing antioxidant power) were used to measure the antioxidant capacity of the rosemary extracts. The ORAC assay measures ability of an antioxidant to react with a peroxyl radical via hydrogen atom extraction and FRAP measures electron transfer through reduction of ferric iron (Fe3+ ) to ferrous iron (Fe2+ ) by antioxidants present in the samples. Correlation of extract composition with antioxidant measures was performed using principal component analysis. Selected extracts were assessed for their ability to protect hair from UV damage in a model peptide system and on hair. In addition, the same methods were used to test rosmarinic acid and carnosic acid, key phytochemistries in the rosemary extracts. The model system was a peptide and its decomposition on exposure to UV was monitored by LC-MS in the absence and presence of the rosemary extracts. Hair degradation in the presence of UV was measured by exposure of UV in an Atlas weatherometer followed by extraction of degraded protein in water. A fragment of the S100A3 protein was used as a marker of UV damage (m/z = 1278) and quantified via LC-MS. Ten rosemary extracts were assessed for antioxidant performance and correlated with their compositions. The phytochemistry in each extract varied widely with a total of 33 individual compounds identified. The differences were most likely driven by the solvent and extraction method used by the supplier with extracts varying in the proportion of polar or non-polar compounds. This did influence their reactivity in the ORAC and FRAP assays and their efficacy in preventing protein damage. Two of the key compounds identified were rosmarinic acid and carnosic acid, with rosmarinic acid dominating in extracts with mainly polar compounds and carnosic acid dominating in extracts with mainly nonpolar compounds. Extracts with higher rosmarinic acid correlated with ORAC and FRAP scores, with UV protection on hair and in the peptide model system. The extracts chosen for hair experiments showed hair protection. UV protection was also measured for rosmarinic and carnosic acid. Despite the variation in the profile of phytochemistries in the 10 rosemary extracts, likely driven by the chosen extraction method, all rosemary extracts had antioxidant activity measured. This study suggests that the polyphenols (e.g. rosmarinic acid, glycosides of selgin) and abietane diterpenes (e.g. carnosic acid) are the principal compounds which enables the extracts to protect hair from UV.

Enzyme-Digested Edible Bird's Nest (EBND) Prevents UV and Arid Environment-Induced Cellular Oxidative Stress, Cell Death and DNA Damage in Human Skin Keratinocytes and Three-Dimensional Epithelium Equivalents.

The aim of this study is to investigate the repressive effects of enzyme-digested edible bird's nest (EBND) on the combination of arid environment and UV-induced intracellular oxidative stress, cell death, DNA double-strand breaks (DSBs) and inflammatory responses in human HaCaT keratinocytes and three-dimensional (3D) epithelium equivalents. An oxygen radical antioxidant capacity assay showed that EBND exhibited excellent peroxyl radical scavenging activity and significantly increased cellular antioxidant capacity in HaCaT cells. When EBND was administered to HaCaT cells and 3D epitheliums, it exhibited significant preventive effects on air-drying and UVA (Dry-UVA)-induced cell death and apoptosis. Dry-UVA markedly induced intracellular reactive oxygen species (ROS) generation in HaCaT cells and 3D epitheliums as quantified by CellROX® Green/Orange reagents. Once HaCaT cells and 3D epitheliums were pretreated with EBND, Dry-UVA-induced intracellular ROS were significantly reduced. The results from anti-γ-H2A.X antibody-based immunostaining showed that EBND significantly inhibited Dry-UVA-induced DSBs in HaCaT keratinocytes. Compared with sialic acid, EBND showed significantly better protection for both keratinocytes and 3D epitheliums against Dry-UVA-induced injuries. ELISA showed that EBND significantly suppressed UVB-induced IL-6 and TNF-α secretion. In conclusion, EBND could decrease arid environments and UV-induced harmful effects and inflammatory responses in human keratinocytes and 3D epithelium equivalents partially through its antioxidant capacity.

Enhancement of Antioxidant Potential, Phytochemicals, Nutritional Properties, and Growth of Siphonochilus aethiopicus (Schweinf.) B.L.Burtt with Different Dosages of Compost Tea

The wild population of Siphonochilus aethiopicus (Zingiberaceae) is being eroded due to several pharmacological benefits and the hidden economy credited to its ethnobotanical uses in Southern Africa. This has called for the adoption of sustainable ways of cultivating the species without compromising its bioactive constituents. In this study, compost tea was brewed and applied at different dosages to potted S. aethiopicus to enhance its growth quality, phytochemical content, and elemental compositions. Treatments comprised 0.25, 0.50, 0.75 and 1.00 (vv) graded concentrations of compost tea, while water and undiluted compost tea were the control treatments. Results showed that dosages of compost tea had no significant effect on chlorophyl content or fresh and dry weights of rhizomes of S. aethiopicus. The longest leaves were recorded in plants irrigated with water only, while the shortest leaves were recorded in plants irrigated by 50% compost tea. A similar trend was observed in leaf width, except that equivalent values were recorded in all compost tea treatments while plants irrigated with undiluted compost tea were tallest. The highest and lowest flavanols were respectively recorded in 0.50 and 0.25 compost tea-treated plant samples, while undiluted compost tea yielded the highest flavonol and phenolic acids. The highest antioxidant contents were produced by the 0.25 compost tea-treated samples in the ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (Ferric Reducing Antioxidant Power) and ORAC (Oxygen Radical Antioxidant Capacity) assays, while the lowest were observed in plants irrigated with water only, although all compost tea-treated plants had equivalent effects on the ORAC content. The highest N, P, K, and Mn contents were produced in the 0.25-treated samples, while the minerals were least accumulated in samples treated with water only. All treatments had equivalent effects on Ca, Zn, and B yield, whereas the highest and equivalent accumulations of Mg and Na were recorded in the control treatments. Iron (Fe) and Cu were most influenced significantly by water whereas P, Ca and Zn tissue concentration was not significantly influenced by treatments. These results indicate that compost tea can optimize growth, mineral accumulation, phytochemicals, and antioxidants in S. aethiopicus. This approach serves as a greener and sustainable way of conserving overexploited indigenous medicinal plants such as S. aethiopicus to mitigate overexploitation of its wild relatives and preserve its genome from imminent extinction.

Salmon (Salmo salar) Side Streams as a Bioresource to Obtain Potential Antioxidant Peptides after Applying Pressurized Liquid Extraction (PLE).

The pressurized liquid extraction (PLE) technique was used to obtain protein extracts with antioxidant capacity from salmon muscle remains, heads, viscera, skin, and tailfins. A protein recovery percentage ≈28% was obtained for all samples except for viscera, which was ≈92%. These values represented an increase of 1.5–4.8-fold compared to stirring extraction (control). Different SDS-PAGE profiles in control and PLE extracts revealed that extraction conditions affected the protein molecular weight distribution of the obtained extracts. Both TEAC (Trolox equivalent antioxidant capacity) and ORAC (oxygen radical antioxidant capacity) assays showed an outstanding antioxidant activity for viscera PLE extract. Through liquid chromatography coupled with electrospray ionization triple time-of-flight (nanoESI qQTOF) mass spectrometry, 137 and 67 peptides were identified in control and PLE extracts from salmon viscera, respectively None of these peptides was found among the antioxidant peptides inputted in the BIOPEP-UMP database. However, bioinformatics analysis showed several antioxidant small peptides encrypted in amino acid sequences of viscera extracts, especially GPP (glycine-proline-proline) and GAA (glycine-alanine-alanine) for PLE extracts. Further research on the relationship between antioxidant activity and specific peptides from salmon viscera PLE extracts is required. In addition, the salmon side streams studied presented non-toxic levels of As, Hg, Cd, and Pb, as well as the absence of mycotoxins or related metabolites. Overall, these results confirm the feasible use of farmed salmon processing side streams as alternative sources of protein and bioactive compounds for human consumption.

Ex Vivo Antioxidant Capacities of Fruit and Vegetable Juices. Potential In Vivo Extrapolation.

Background: In support of claims that their products have antioxidant properties, the food industry and dietary supplement manufacturers rely solely on the in vitro determination of the ORAC (oxygen radical antioxidant capacity) value, despite its acknowledged lack of any in vivo relevance. It thus appears necessary to use tests exploiting biological materials (blood, white blood cells) capable of producing physiological free radicals, in order to evaluate more adequately the antioxidant capacities of foods such as fruit and vegetable juices. Materials: Two approaches to assessing the antioxidant capacities of 21 commercial fruit and vegetable juices were compared: the ORAC assay and the “PMA–whole blood assay,” which uses whole blood stimulated by phorbol myristate acetate to produce the superoxide anion. We described in another paper the total polyphenol contents (TPCs) and individual phenolic compound contents of all the juices were investigated. Results: Ranking of the juices from highest to lowest antioxidant capacity differed considerably according to the test used, so there was no correlation (r = 0.33, p = 0.13) between the two assays when considering all juices. Although the results of the ORAC assay correlated positively with TPC (r = 0.50, p = 0.02), a much stronger correlation (r = 0.70, p = 0.004) emerged between TPC and % superoxide anion inhibition. In the PMA–whole blood assay, peonidin-3-O-glucoside, epigallocatechin gallate, catechin, and quercetin present in juices were found to inhibit superoxide anion production at concentrations below 1 µM, with a strong positive correlation. Conclusions: Associated with the determination of total and individual phenolic compounds contained in fruit and vegetable juices, the PMA–whole blood assay appears better than the ORAC assay for evaluating juice antioxidant capacity.

Impact of in vitro gastrointestinal digestion on peptide profile and bioactivity of cooked and non-cooked oat protein concentrates

Oat (Avena sativa) is one of the most cultivated and consumed cereals worldwide. Recognized among cereals for its high protein content (12%–24%), it makes it an excellent source of bioactive peptides, which could be modified during processes such as heating and gastrointestinal digestion (GID). This work aims to evaluate the impact of heat treatment on the proteolysis of oat proteins and on the evolution of antioxidant peptide released during in vitro static GID, in terms of comparative analysis between cooked oat protein concentrate (COPC) and non-heated oat protein concentrate (OPC) samples. The protein extraction method and cooking procedure used showed no detrimental effects on protein quality. After GID, the proportion of free amino acids/dipeptides (<0.2 ​kDa) reached >40% for both samples (OPC and COPC), thus producing peptides with low molecular weight and enhanced bioactivity. Furthermore, during GID, the amino acid profile showed an increase in essential, positively-charged, hydrophobic and aromatic amino acids. At the end of GID, the reducing power of OPC and COPC increased >0.3 and 8-fold, respectively, in comparison to the non-digested samples; while ABTS•+ and DPPH• showed a >20-fold increase. Fe2+ chelating capacity of OPC and COPC was enhanced >4 times; similarly, Cu2+ chelation showed a >19-fold enhancement for OPC and >10 for COPC. β-carotene bleaching activity was improved 0.8 times in OPC and >9 times in COPC; the oxygen radical antioxidant capacity assay increased 2 times in OPC and >4.7 times in COPC, respectively. This study suggests that OPC after cooking and GID positively influenced the nutritional and bioactive properties of oat peptides. Thus, COPC could be used as a functional food ingredient with health-promoting effects, as hydrothermal treatment is frequently used for this type of cereals.

Combined Extract of Vitis vinifera L. and Centella asiatica Synergistically Attenuates Oxidative Damage Induced by Hydrogen Peroxide in Human Umbilical Vein Endothelial Cells.

Endothelial cell injury caused by oxidative stress is a critical factor in the initial stage of vascular diseases. Thus, identification of more effective antioxidants is a promising strategy to protect against endothelial cell injury. Recently, synergistic effects between phytochemicals have received renewed attention for their role in the treatment of various diseases. Vitis vinifera L. and Centella asiatica are well-known medicinal plants with various biological effects. However, the combination of the two has not previously been studied. Here, we investigated the effects of V. vinifera L. leaf and C. asiatica extract combination (VCEC), a standardized herbal blend comprising V. vinifera L. leaf extract (VE) and C. asiatica extract (CE), for its antioxidant activity and for the protection of endothelial cells against hydrogen peroxide (H2O2)-mediated oxidative damage in human umbilical vein endothelial cells (HUVECs). VCEC showed higher antioxidant activity than VE or CE in oxygen radical antioxidant capacity assays. In HUVECs, VCEC significantly suppressed increases in the production of intracellular reactive oxygen species, decreased levels of nitric oxide and vascular endothelial-cadherin, and increased endothelial hyperpermeability triggered by H2O2. Treatment with VE or CE alone ameliorated HUVEC injury in a pattern similar to VCEC, although their effects were significantly weaker than VCEC. Overall, VCEC exhibited a substantial synergistic effect on protecting endothelial cells against oxidative damage through its antioxidant activity. Therefore, VCEC could be developed as a potential agent for reducing the risk of vascular diseases related to oxidative stress.

Antioxidant Effects and Suppression of Nitric Oxide Production in LPS-stimulated Macrophages by Fractions of Vaccinium leschenaultii Wight

ABSTRACTSolvent fractions from leaf and bark extracts of Vaccinium leschenaultii were screened for their antioxidant, cell viability, and nitric oxide (NO) inhibitory potential. Antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant activity (TAC) and Oxygen Radical Antioxidant Capacity (ORAC) assays. Sulforhodamine B assay was used to estimate the cell viability of RAW 264.7 cells. Griess reagent was used to measure the NO production, which was induced by lipopolysaccharide (LPS) on RAW 264.7 cells. Higher antioxidant activity was observed in the fraction of V. leschenaultii bark ethyl acetate: methanol extract (VBEM, 60/40, v/v) in DPPH (IC50 = 20.80 µg mL−1), TAC (14.90 mmol uric acid equivalents/mg extract) and ORAC (454.58 µmol trolox equivalents/mg extract) assays compared to the leaf extracts. Similarly, VBEM (60/40) fraction also showed 83.87% of RAW 264.7 cell viability. V. leschenaultii leaf ethyl acetate: methanol extract (VLCE, 70/30, v/v) inhibited the NO production (90.06%, IC50 = 1.61 µg mL−1) and showed dose-dependent activity without inhibiting the macrophages. V. leschenaultii leaf and bark fractions from the methanol extract inhibited the free radicals including NO by modulating the macrophage-mediated inflammatory functions in the in vitro system.

Investigation of epigallocatechin-3-O-caffeoate and epigallocatechin-3-O-p-coumaroate in tea leaves by LC/MS-MS analysis

(−)-Epigallocatechin-3-O-gallate (EGCG), the major catechin present in green tea, exhibits potent antioxidant activity. We thereby investigated the presence of unknown components bearing the (−)-epigallocatechin (EGC) moiety in fresh tea leaf samples. Initially, liquid chromatography tandem mass spectrometry (LC-MS/MS) was employed to examine fresh tea leaves of the Yabukita, the most popular tea cultivar in Japan, which suggested the presence of the EGC phenylpropanoid derivatives, (−)-epigallocatechin-3-O-p-coumaroate (EGCpCA) and (−)-epigallocatechin-3-O-caffeoate (EGCCA). The structures of the detected EGCpCA and EGCCA were then confirmed by LC-MS/MS using synthesized EGCpCA and EGCCA as standards. In addition, EGCpCA and EGCCA were evaluated for their antioxidant activity in the ORAC (oxygen radical antioxidant capacity) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays, where EGCCA (8.60μmolTE/μmol, TE=Trolox equivalents) exhibited a stronger antioxidant activity than EGCG (5.52μmolTE/μmol) in the ORAC assay. Finally, EGCpCA and EGCCA were quantitated in several tea leaf samples using LC-MS/MS, and it was found that these compounds were present in lower quantities (EGCpCA, 16.8–345.8μg/g, EGCCA, 4.3–75.1μg/g in the dry tea leaves) than the major catechins. In this study, we found the potent antioxidant EGCCA using LC-MS/MS and revealed its wide existence in various tea leaves.

Polyphenolic compounds, antioxidant and anti-inflammatory effects of Abeliophyllum distichum Nakai extract

The present study was conducted to evaluate the antioxidant and anti-inflammatory activities of crude methanolic extract of Abeliophyllum distichum Nakai, and those of its partitioned fractions, including hexane, ethyl acetate, n-butanol, and aqueous. The antioxidant activities were analyzed by DPPH free radical scavenging and oxygen radical antioxidant capacity assay. Results showed that the BuOH fraction possessed a strong antioxidant activity through a hydrogen atom transfer reaction-based mechanism and a single electron transfer reaction-based mechanism. In lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, the BuOH fraction of A. distichum methanol extract exhibited a strong inhibitory effect on the nitric oxide production and inhibited the expression of pro-inflammatory mediators, including COX-2, TNF-α, and IL-6, through the inhibition of the MEK/ERK signaling pathway. In addition, the BuOH fraction inhibited the LPS-induced ROS level through the NADPH oxidase-independent mechanism. Furthermore, HPLC analysis identified chlorogenic acid, caffeic acid, gentisic acid, rutin, ferulic acid, and quercetin, and suggested that the antioxidant and anti-inflammatory activities of the BuOH fraction should be mediated by the presence of higher amounts of caffeic acid, rutin, and ferulic acid than other fractions. Taken together, these results suggest that A. distichum extract is a source of antioxidant and anti-inflammatory compounds, and could be developed as a potential source for functional food and dietary health supplement.

In Vitro Antioxidant-Activity Evaluation of Gallic-Acid-Grafted Chitosan Conjugate Synthesized by Free-Radical-Induced Grafting Method.

The major objective of this work was to develop a green and facile process to prepare gallic acid-chitosan conjugate and comprehensively evaluate the physicochemical properties and biological activities of an as-prepared water-soluble chitosan derivative. A free-radical-induced grafting approach using an ascorbic acid-hydrogen peroxide redox pair was adopted. The obtained conjugate was characterized by Fourier transform infrared spectroscopy, UV-vis, X-ray diffraction, and pKa analysis. The antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6)-sulphonic acid (ABTS), reducing power, and oxygen-radical antioxidant-capacity assays. The results showed that the mass ratio of gallic acid to chitosan played a vital role in determining the grafting degree and ζ potential of the conjugates, with the ratio of 0.5:1 being the optimal ratio that resulted in the highest grafting degree. The antioxidant assays demonstrated that conjugation significantly improved the antioxidant activities, being dramatically higher than that of free chitosan. It was notable that the DPPH- and ABTS-scavenging activities of conjugate at 0.4 mg/mL reached the same level as the free gallic acid at the equivalent concentration. Our study demonstrated a green and facile synthesis approach to preparing a novel water-soluble chitosan derivative that may have promising potentials in the food industry.

Pineapple Waste Extract for Preventing Oxidation in Model Food Systems.

Pineapple (Ananas comosus) is consumed in the form of chunks (canned), cubes, fruit salad, and also in juices, concentrates, and jams. In the processes to produce these products, the waste generated represents a high percentage of the total fruit. Some studies have shown that residues of certain fruits, such as pineapple, have the same antioxidant activity as the fruit pulp. So although these residues are discarded, they could be used as an alternative source of polyphenols, as natural antioxidants. This study is focused on the antioxidant activity of wastes obtained in the production of pineapple products and their application. The polyphenols' scavenging activity was determined by the oxygen radical antioxidant capacity assay. The antioxidant potential was determined in emulsions (o/w) and in muffins, where the primary oxidation products (by peroxide value, PV) and the secondary oxidation products (by thiobarbituric acid reactive substances) were analyzed. In addition the muffins were analyzed by means of a triangular sensory test. The PV method showed that pineapple waste extracts caused a reduction in oxidation products of 59% in emulsions and 91% in the muffins. The reduction in TBARs values for emulsions were 27% and for muffins were 51%. The triangular sensory test showed that the samples containing the extract were not distinguished from the control (α = 0.05).

Quantitative and antioxidative behavior of Trolox in rats' blood and brain by HPLC-UV and SMFIA-CL methods.

Trolox, a water-soluble vitamin E analogue has been used as a positive control in Trolox equivalent antioxidant capacity and oxygen radical antioxidant capacity assays due to its high antioxidative effect. In this study, the ex vivo antioxidative effects of Trolox and its concentration in blood and brain microdialysates from rat after administration were evaluated by newly established semi-microflow injection analysis, chemiluminescence detection and HPLC-UV. In the administration test, the antioxidative effect of Trolox in blood and brain microdialysates after a single administration of 200 mg/kg of Trolox to rats could be monitored. The antioxidative effects in blood (12.0 ± 2.1) and brain (8.4 ± 2.1, × 10(3) antioxidative effect % × min) also increased. Additionally, the areas under the curve (AUC)s0-360 (n = 3) for blood and brain calculated with quantitative data were 10.5 ± 1.2 and 9.7 ± 2.5 mg/mL × min, respectively. This result indicates that Trolox transferability through the blood-brain barrier is high. The increase in the antioxidative effects caused by Trolox in the blood and brain could be confirmed because good correlations between concentration and antioxidative effects (r ≥ 0.702) were obtained. The fact that Trolox can produce an antioxidative effect in rat brain was clarified.

Serum melatonin levels and antioxidant capacities after consumption of pineapple, orange, or banana by healthy male volunteers

Melatonin is a naturally occurring molecule biosynthesized by the pineal gland of vertebrates; it also has been identified in many plants. It is considered an important antioxidant and may retard the development of some neurodegenerative diseases and cancer. Previous studies in humans have measured melatonin metabolites in urine and have indicated that melatonin-containing foods may provide dietary melatonin. This study tested whether the consumption of fruits or fruit juice containing melatonin would influence the serum melatonin concentration and antioxidant status. In this crossover study, 12 healthy male volunteers took either juice extracted from one kilogram of orange or pineapple or two whole bananas, with a 1-wk washout period between the fruit or fruit juices. An enzyme-linked immunosorbent (ELISA) assay was used to determine the serum melatonin concentration. Serum antioxidant capacity was determined by ferric reducing antioxidant power (FRAP) assay and oxygen radical antioxidant capacity (ORAC) assay. The highest serum melatonin concentration was observed at 120min after fruit consumption, and compared with before consumption levels, their values were significantly increased for pineapple (146 versus 48pg/mL P=0.002), orange (151 versus 40pg/mL, P=0.005), and banana (140 versus 32pg/mL, P=0.008), respectively. Serum antioxidant capacity following fruit consumption also significantly increased in both the FRAP (7-14% increase, P≤0.004) and ORAC (6-9% increase, P=0.002) assays. Both the serum FRAP and ORAC values strongly correlated with serum melatonin concentration for all three fruits. These findings suggest that tropical fruit consumption increases the serum melatonin concentrations and also raises the antioxidant capacity in the serum of healthy volunteers in proportion to serum melatonin levels.

Influence of ultra-high pressure homogenisation on antioxidant capacity, polyphenol and vitamin content of clear apple juice

Ultra-high pressure homogenisation (UHPH) is a recently developed technology and is still under study to evaluate its effect on different aspects of its application to food products. The aim of this research work was to evaluate the effect of UHPH treatments on quality characteristics of apple juice such as antioxidant capacity, polyphenol composition, vitamin C and provitamin A contents, in comparison with raw (R) and pasteurised (PA) apple juice. Several UHPH treatments that include combinations of pressure (100, 200 and 300MPa) and inlet temperatures (4 and 20°C) were assayed. Apple juice was pasteurised at 90°C for 4min. Antioxidant capacity was analysed using the oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) assay while total phenolic content was determined by the Folin–Ciocalteau assay. According to the FRAP and DPPH assays, UHPH processing did not change apple juice antioxidant capacity. However, significant differences were detected between samples analysed by TEAC and ORAC assays. In spite of these differences, high correlation values were found between the four antioxidant capacity assays, and also with total polyphenol content. The analysis and quantification of individual phenols by HPLC/DAD analytical technique reflects that UHPH-treatment prevented degradation of these compounds. Vitamin C concentrations did not change in UHPH treated samples, retaining the same value as in raw juice. However, significant losses were observed for provitamin A content, but lower than in PA samples.UHPH-treatments at 300MPa can be an alternative to thermal treatment in order to preserve apple juice quality.

Antioxidant Capacities and Total Quercetin Content of Several Species of Polygonaceae in Mongolia

Antioxidant capacities (AOCs) and total phenolic (TP) content of 11 species of Polygonaceae from Mongolia were evaluated using diphenyl picrylhydrazyl radical (DPPH), oxygen radical antioxidant capacity (ORAC) and Folin-Ciocalteu (F-C) assays. Additionally, total quercetin content was determined by high performance liquid chromatography (HPLC) after acid hydrolysis. These plant extracts showed high AOCs using both DPPH (111.9-950.5 μmol Trolox equivalent (TE) /g.dw) and ORAC assays (770.7-2307.9 μmol TE/g.dw), and high TP contents (20.84-113.86 mg Gallic acid equivalent (GAE)/g.dw). AOCs were positively correlated with TP content (DPPH: r = 0.98; ORAC: r = 0.83). Moderate correlations were observed between AOCs and total quercetin content (DPPH: r = 0.58; ORAC: r = 0.51). These results suggest that quercetin glycosides may be one of the important contributors to AOCs of Mongolian Polygonaceae species.

Methods for evaluating the potency and efficacy of antioxidants

The aim of this article is to present a brief panorama of the most widely used methods and of new analytical approaches for evaluating antioxidant capacity and to discuss them in terms of advantages and drawbacks. To date, many in-vitro tests are available from the chemical assay performed in a homogenous solution such as oxygen radical antioxidant capacity assay to more complex cell-based methods using exogenic probes to detect oxidation. In complement to these existing methods, novel approaches have recently been developed such as the conjugated autoxidizable triene assay implemented in emulsions and using tung oil as ultraviolet probe. The complexity and diverse range of research topics investigated have led to the development of a multitude of tests, but unfortunately none of them are universal. Thus, one of the major challenges is to know which method is best suited for a particular application.

ORAC and TEAC assays comparison to measure the antioxidant capacity of food products

Oxygen radical antioxidant capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) assays were compared to estimate the total antioxidant capacity (TAC) of orange juice, milk, and an orange juice-milk beverage. When the TEAC method was used with this beverage, an increase in the concentration of orange juice corresponded to an increase in TAC, but increasing the percentage of milk did not increase the TAC value. When the ORAC method was applied, it was seen that increased concentrations of juice or milk corresponded to greater antioxidant capacity. An evaluation was also made of the influence of certain compounds (ascorbic acid, gallic acid, β-carotene, lutein, zeaxanthin and albumin) with antioxidant capacity that were present in the samples studied. Although the TEAC method is simpler and cheaper than the ORAC method, it gives an underestimate of the antioxidant capacity of foods or beverages of a more complex nature.