Broccoli seed extracts but not sulforaphane have strong free radical scavenging activities

The abilities of broccoli seed extracts and purified sulforaphane (SF) to scavenge 2,2′‐azinobis [3‐ethylbenzothiazoline‐6‐sulphonate] (ABTS^?+), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) and superoxide anions were studied. The free radical scavenging activities of broccoli seed extracts had no exact correlation with SF content, indicating that SF was not the main antioxidant component. The broccoli seed extracts were separated by high‐speed countercurrent chromatography to obtain purified SF, which showed dose‐dependent free radical scavenging activities in the DPPH^? and ABTS^?+ assays, but its activities were weaker to those of ascorbic acid. The same trend was observed in the chemiluminescence assay. The results showed that broccoli seed extracts had strong free radical scavenging activities that were not attributable to SF.     

Pomological features, nutritional quality, polyphenol content analysis, and antioxidant properties of domesticated and 3 wild ecotype forms of raspberries (Rubus idaeus L.)

Abstract: The raspberry (Rubus idaeus L.) is an economically important berry crop that contains many phenolic compounds with potential health benefits. In this study, important pomological features, including nutrient content and antioxidant properties, of a domesticated and 3 wild (Yayla, Yavuzlar, and Yedigöl) raspberry fruits were evaluated. Also, the amount of total phenolics and flavonoids in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were calculated as gallic acid equivalents (GAEs) and quercetin equivalents (QE). The highest phenolic compounds were found in wild Yayla ecotype (26.66 ± 3.26 GAE/mg extract). Whilst, the highest flavonoids were determined in wild Yedigöl ecotype (6.09 ± 1.21 QA/mg extract). The antioxidant activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were investigated as trolox equivalents using different in vitro assays including DPPH^?, ABTS^?+, DMPD^?+, and O^??₂ radical scavenging activities, H₂O₂ scavenging activity, ferric (Fe³⁺) and cupric ions (Cu²⁺) reducing abilities, ferrous ions (Fe²⁺) chelating activity. In addition, quantitative amounts of caffeic acid, ferulic acid, syringic acid, ellagic acid, quercetin, α‐tocopherol, pyrogallol, p‐hydroxybenzoic acid, vanillin, p‐coumaric acid, gallic acid, and ascorbic acid in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were detected by high‐performance liquid chromatography and tandem mass spectrometry (LC‐MS‐MS). The results clearly show that p‐coumaric acid is the main phenolic acid responsible for the antioxidant and radical scavenging activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits.     

Identification and in vitro biological activities of flavonols in garlic leaf and shoot: inhibition of soybean lipoxygenase and hyaluronidase activities and scavenging of free radicals

We isolated four flavonols from garlic (Allium sativum L) leaf and shoot and measured the in vitro antioxidant activity of the isolated flavonols and their aglycones. The chemical structures of the compounds were shown to be quercetin 3‐O‐β‐D ‐glucopyranoside (isoquercitrin), quercetin 3‐O‐β‐D ‐xylopyranoside (reynoutrin), kaempferol 3‐O‐β‐D ‐glucopyranoside (astragalin) and isorhamnetin 3‐O‐β‐D ‐glucopyranoside based on FAB‐MS and NMR analyses. Assays of DPPH (1,1‐diphenyl‐β‐picryl hydrazyl) and hydroxyl radical scavenging, inhibition of linoleic acid peroxidation, and soybean lipoxygenase (LO) and hyaluronidase (HYA) inhibition were used to evaluate the antioxidant activity. Quercetin and its glycosides showed the highest antioxidant activity among the compounds. In the LO assay, the IC₅₀ values of quercetin, isoquercitrin and reynoutrin were 16.9, 40.1 and 32.9 µM respectively. Quercetin was the most effective among the flavonols. In the HYA assay the IC₅₀ values of quercetin, isoquercitrin and reynoutrin were 23.0, 20.9 and 22.1 mM respectively. Isoquercitrin had the most potent inhibitory activity on HYA. The inhibition patterns of the flavonols on LO and HYA were elucidated as mixed types of competitive and non‐competitive inhibition according to Lineweaver–Burk plot results. Although most garlic shoots and leaves are discarded and not used at present, our results suggest that ancillary garlic parts could be utilised as functional foods or ingredients. Copyright © 2004 Society of Chemical Industry     

The phenolic constituents and free radical scavenging activities of Gynura formosana Kiamnra

Gynura formosana Kiamnra (Compositae) is a herbal folk medicine that is a popular vegetable in Taiwan. The free‐radical scavenging activities of a 70% aqueous acetone extract from the herb G formosana were evaluated. Bioassay‐guided fractionation, column separation on Diaion, Toyopearl HW 40(C), Sephadex LH‐20 and MCI CHP20P, and high‐performance liquid chromatography (HPLC) were used to isolate for the first time in G formosana four potent phenolics [caffeic acid ( I ), quercetin 3‐O‐rutinoside ( II ), kaempferol 3‐O‐rutinoside ( III ) and kaempferol 3‐O‐robinobioside ( IV )]. The IC₅₀ values of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity for compounds I – IV were 6.7, 7.7, 300.3 and 286.7 µM , respectively, and, for superoxide radical scavenging activity, they were 187.3, 25.8, 55.3 and 87.4 µM , respectively. Using a spin trapping electron spin resonance (ESR) method, caffeic acid ( I ) and quercetin 3‐O‐rutinoside ( II ) exhibited good hydroxyl radical activity. The free radical scavenging activity of G formosana phenolics may improve the economic value of this herb and assist in its development as a health food. Copyright © 2004 Society of Chemical Industry     

Antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.) as affected by processing methods

This research investigated the effects of processing by dry heating, boiling, and steaming on the antioxidant activity and DNA protection against oxidative damage of bambara groundnut seeds (Vigna subterranea (L.) Verdc.). Comparing raw and processed samples of bambara groundnut seeds, dry heating caused a significant (P < 0.05) reduction of ferric-reducing antioxidant power (FRAP), metal chelating activity, DPPH^? and ABTS^?+ radical scavenging activity. The boiling process did not cause a significant difference in FRAP and metal chelating activity and caused smaller losses in DPPH^? and ABTS^?+ radical scavenging activity than the dry heating and steaming processes. The steaming process caused a significant (P < 0.05) reduction of FRAP, DPPH^? and ABTS^?+ radical scavenging activity. For DNA protection against oxidative damage, boiled and steamed bambara groundnut seed samples were more effective with a lower minimum concentration (50 µg/mL) than raw and dry heated samples. These results indicated that the boiling process caused smaller losses antioxidant activity than dry heating and steaming. Therefore, boiling was recommended as processing method for bambara groundnut seeds to preserve antioxidant components and antioxidant activity.     

Nutritional composition and antioxidant activity in hazelnut shells from US‐grown cultivars

The hard shell of a hazelnut is a major waste of the hazelnut industry. The chemical composition, phenolic compounds (total phenolics, tannins and condensed tannins), antioxidant activity (DPPH and ABTS free‐radical scavenging assays), and the relationships between phenolic compounds and antioxidant activities of the hazelnut shells from twelve US grown cultivars were investigated to for potential commercial development. Crude fibre accounted for over 85% of total carbohydrate. The shells contained high concentrations of phenolic compounds. Concentrations of phenolic constituents and ABTS^?+ ‐scavenging capacities were significantly higher (P > 0.05) in the Oregon cultivars than their Nebraska counterparts. There were significant positive correlations between ABTS^?+ scavenging capacities and the phenolic compounds, whereas DPPH^? ‐scavenging capacity demonstrated a weak negative correlation with ABTS^?+ scavenging capacity and the phenolics. The results suggest that hazelnut hard shell may serve as a potential source of natural antioxidants for food applications.     

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.     

Identification of bioactive compounds in Phyllenthus emblica L. fruit and their free radical scavenging activities

Emblica has been used as an important traditional herbal medicine in southeast Asia since ancient times. In this study, the air-dried hulls of emblica fruit were extracted with 95% ethanol, and then the extract was partitioned by diethyl ether and ethyl acetate (EA). The EA fraction was purified by silica gel column and thin layer chromatography (TLC) to obtain six compounds. They were identified as cinnamic acid (C1), quercetin (C2), 5-hydroxymethylfurfural (C3), gallic acid (C4), β-daucosterol (C5) and ellagic acid (C6) using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Cinnamic acid and 5-hydroxymethylfurfural were identified as components of emblica fruit for the first time. The DPPH and ABTS⁺ radical scavenging activities of components were evaluated. All the compounds showed significant DPPH and ABTS⁺ radical scavenging activity except for cinnamic acid. Gallic acid showed the highest DPPH radical scavenging activity while ellagic acid showed the highest ABTS⁺ scavenging activity amongst all the compounds tested.     

A Comparative Study Between Labeling and Reality: The Case of Phytochemical Composition of Commercial Pomegranate‐Based Products

Manufacturers are deeply involved in the development of new pomegranate‐based products, which have acquired great prestige due to many studies proving their potential health benefits. Commercial pomegranate products including capsules and supplements and juices and nectars were assayed. The contents of the key phytochemical compounds (punicalagin, ellagic acid, and total polyphenolic content) and the associated antioxidant capacity (DPPH^?, ABTS^?+, and FRAP) were analyzed. The experimental ranges of punicalagin and ellagic acid contents were 0.96 to 308 mg/g and 0.09 to 13.1 mg/g, respectively. Punicalagin content was positively correlated (P < 0.001) with DPPH^? and total polyphenolic content values. No significant (P > 0.05) correlation was observed among ellagic acid with the antioxidant capacity. The labeling standardization of these products is necessary due to the wide variability among “theoretically” similar pomegranate‐based products.     

Natural volatile treatments increase free‐radical scavenging capacity of strawberries and blackberries

Free‐radical scavenging capacities of strawberries and blackberries treated with methyl jasmonate (MJ), allyl isothiocyanate (AITC), essential oil of Melaleuca alternifolia (tea‐tree oil or TTO), and ethanol (EtOH) were investigated. All of these natural volatiles tested reduced the severity of decay in both strawberries and blackberries during storage at 10 °C as compared to the control. Most of these compounds enhanced antioxidant capacity and free‐radical scavenging capacity, except the AITC treatment. The MJ treatment for strawberries and blackberries had the highest antioxidant capacity, expressed as oxygen radical absorbance capacity (ORAC) values, after 7 days of storage. Moreover, the MJ treatment promoted the antioxidant capacity in strawberries and blackberries as measured by the radical 2,2‐di (4‐tert‐octylphenyl) ‐1‐picrylhydrazyl (DPPH) and the radical cation 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS^?+) scavenging activity in both 7 and 14 days after storage. The MJ treatment also increased scavenging capacities on the superoxide radical (O₂^??), hydrogen peroxide (H₂O₂), hydroxyl radical (^?OH), and singlet oxygen (¹O₂) in strawberries and blackberries. Treatment with TTO or EtOH enhanced most of these free‐radical scavenging capacities, except for H₂O₂ in strawberries, and for O₂^?? and ¹O₂ in blackberries. These results indicated that all of the natural volatile compounds tested in this study, except AITC, promoted the antioxidant capacity and scavenging capacity of most major free radicals and, thus, helped to improve the physiology of berry fruits and enhanced their resistance to decay. While AITC was also very effective in reducing decay, its effect on free‐radical scavenging capacity was inconsistent, suggesting that additional mechanisms may be involved in its inhibition of fungal growth. Copyright © 2007 Society of Chemical Industry     

Kinetics of fructose on the Maillard brown colour development,pH change and antioxidative activity development in model fructose/glycine systems

Model fructose/glycine systems with fructose concentration between 0.035 and 0.28 m were incubated at temperature 45–90 °C for investigating the effects of fructose and temperature on the brown colour development, pH change and the antioxidative activity developments of Maillard reaction. The result showed that effects of fructose followed logarithm‐order kinetics on brown colour and DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) radical scavenging activity (S_DPPH) development, and first‐order kinetics on system pH decrease. However, the effect of fructose on ABTS·⁺ (2,2′‐azino‐bis[3‐ethylbenzthiazoline‐6‐sulphonic acid]) radical scavenging activity (S_ABTS) development was first order at 60–90 °C and logarithm order at 45 °C, which revealed the mutual synergistic interaction of concentration with temperature on S_ABTS development. Activation energy for S_DPPH development was lower than that for S_ABTS development, revealing that DPPH radical was more vulnerable than ABTS·⁺ radical to fructose/glycine MRPs at low temperature. But the relative vulnerability would invert at high temperature, as the Q₁₀ value for S_DPPH development was lower than that for S_ABTS development.     

Antioxidative principals of Jussiaea repens: an edible medicinal plant

Jussiaea repens L. (JRL) is an edible medicinal plant and is also used as a vegetable by the local people in southwestern China. The crude extract and its four fractions derived from JRL were evaluated for the 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging ability, hydroxyl radical‐scavenging capacity and the potassium ferricyanide reduction property. The ethyl acetate‐soluble fraction (EAF) and EAF6 (a subfraction derived from EAF) were the most valuable fraction and subfraction, respectively. Furthermore, bioactivity‐guided chromatographic fractionation revealed that three pure compounds greatly contributed to the antioxidant activities. Qualitative and quantitative analyses of the major antioxidant constituents in the extract were systematically conducted by NMR, mass spectral analyses and RP‐HPLC. The result demonstrated that rosmarinic acid (2.00 mg g^?1 JRL dry weight) quercetin 3‐O‐β‐d ‐glucopyranoside (9.88 mg g^?1 JRL dry weight), and kaempferol 3‐O‐β‐d ‐glucopyranoside (1.85 mg g^?1 JRL dry weight) were the major antioxidative constituents in JRL. These compounds are reported for the first time from this plant.     

Radical‐scavenging properties of extracts from the white button mushroom,Agaricus bisporus

BACKGROUND: Agaricus bisporus is the premier cultivated edible mushroom but is usually considered to be of lesser value nutritionally and medicinally compared with other cultivated mushrooms. The objective of this study was to investigate the radical‐scavenging properties of methanolic extracts and the free radical‐processing enzyme activities of water extracts from A. bisporus fruit bodies. Analyses were performed on total fruit bodies from three strains and on separated stipe, cap and gills from one strain, all cultivated experimentally under the same conditions. RESULTS: EC₅₀ values of scavenging ability on 1,1‐diphenyl‐2‐picrylhydrazyl radicals (DPPH^?), scavenging ability on 2,2‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical cations (ABTS^?+) and reducing power of methanolic extracts from total fruit bodies ranged between 1.7 and 5.0 and were 1.1–1.9 times higher in a white hybrid than in two wild strains, cream and brown. The gills exhibited higher antioxidant activities relative to the stipe and cap. In water extracts, glutathione peroxidase activities were up to eight times higher than glutathione reductase activities and no difference was observed between strains. Catalase activity was highest in the brown wild strain. The only significant differences in free radical‐processing enzymes between the three parts of the mushroom were higher catalase activity in the gills and lower glutathione reductase activity in the stipe. CONCLUSION: The radical‐scavenging properties of the button mushroom are comparable to those of other edible mushrooms and dependent on the strain and on the section of the fruit body. Copyright © 2008 Society of Chemical Industry     

Comparison between Supercritical CO2 Extraction and Hydrodistillation for Two Species of Eucalyptus: Yield,Chemical Composition,and Antioxidant Activity

In this work, 2 Eucalyptus species extracts (Eucalyptus cinerea and Eucalyptus camaldulensis) were prepared by hydrodistillation (HD) and supercritical carbon dioxide extraction (SCE) techniques. The best yields of E. cinerea and E. camaldulensis (27.5 and 8.8 g/kg, respectively) were obtained using SCE at 90 bar, 40 °C compared to HD (23 and 6.2 g/kg, respectively). Extracts were quantified by gas chromatography‐flame ionization detection and identified by gas chromatography‐mass spectrometry. 1,8‐cineole and p‐menth‐1‐en‐8‐ol were the major compounds of E. cinerea essential oil obtained by HD (64.89% and 8.15%, respectively) or by SCE (16.1% and 31.87%, respectively). Whereas, in case of E. camaldulensis, 1,8‐cineole (45.71%) and p‐cymene (17.14%) were the major compounds obtained by HD, and 8,14‐cedranoxide (43.79%) and elemol (6.3%) by SCE. Their antioxidant activity was assessed using 2 methods: 2,2‐azino‐di‐3‐ethylbenzothialozine‐sulphonic acid radical cation (ABTS^?+) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH^?). In the SCE extracts from both E. cinerea and E. camaldulensis, a promising radical scavenging activity was observed with ABTS^?+, (65 and 128 mg/L, respectively). The total phenolics composition of the extracts was measured and the range was 2 to 60 mg of gallic acid equivalent/g dry plant material. The SCE method was superior to HD, regarding shorter extraction times (30 min for SCE compared with 4 h for HD), a low environmental impact, allows production of nondegraded compounds and being part of green chemistry.     

Antioxidant properties of garden strawberry leaf extract and its effect on fish oil oxidation

The present study characterises garden strawberry leaf extract and reports its effect on shelf life and quality characteristics of fish oil. Radical scavenging capacity of the extract in DPPH^? and ABTS^?+ assays was equivalent to 1207 and 1579 μmol g^?1 of trolox equivalents, respectively, total phenolic content was 257 mg g^?1 of gallic acid equivalents. Phenolic and volatile constituents were analysed by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). The extract was added to fish oil and its oxidation was followed during 42 days: peroxide, p‐anisidine values and hexanal concentration were lower in the samples with extract, particularly at the end of storage. The effect of extract on fatty acid composition was not significant, however the changes in the percentages of some individual acids were observed. Fish oil containing 5% of extract had lower levels of lipid oxidation in comparison to other samples. The results indicate that strawberry leaves could be a potential source of natural antioxidants.     

Change in Flavonoid Composition and Antioxidative Activity during Fermentation of Onion (Allium cepa L.) by Leuconostoc mesenteroides with Different Salt Concentrations

The aim of this study is to investigate the change in flavonoid composition and antioxidative activity during fermentation of onion (Allium cepa L.) by Leuconostoc mesenteroides with different NaCl concentrations. In order to qualify and quantify the flavonoids during fermentation of onion, 7 flavonoids, [quercetin 3,7‐O‐β‐d ‐diglucopyranoside (Q3,7G), quercetin 3,4′‐O‐β‐d ‐diglucopyranoside (Q3,4′G), quercetin 3‐O‐β‐d ‐glucopyranoside (Q3G), quercetin 4′‐O‐β‐d ‐glucopyranoside (Q4′G), isorhamnetin 3‐O‐β‐d ‐glucopyranoside (IR3G), quercetin (Q), and isorhamnetin (IR)], were isolated and identified from onion. During fermentation, the contents of flavonoid glucosides (Q3,7G, Q3,4′G, Q3G, Q4′G, and IR3G) gradually decreased, whereas the contents of flavonoid aglycones (Q, IR) gradually increased. Decline rates of the flavonoid glucosides increased with the addition of L. mesenteroides. Furthermore, the activity of β‐glucosidase, which is produced by L. mesenteroides, is dose‐dependently inhibited with different NaCl concentrations during fermentation. The presence of L. mesenteroides enhanced the antioxidative activity of onion as demonstrated using the 1,1‐diphenyl‐2‐picrylhydrazyl, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid), and reducing power assays. The enhancement of antioxidative activity was considered because the content of flavonoid aglycones increased during fermentation. However, the addition of NaCl may decrease the antioxidative activity; we surmise that this phenomenon occurs because of the inhibition of β‐glucosidase by NaCl. Therefore, we conclude that the addition of NaCl may be useful for the regulation of antioxidative activity via the control of β‐glucosidase action, during the fermentation of flavonoid glucoside‐rich foods.     

Antioxidant properties and polyphenolics composition of common hedge hyssop (Gratiola officinalis L.)

The antioxidant potential of Gratiola officinalis was evaluated by the off-line and on-line HPLC/UV/DPPH radical scavenging assays, phytochemical composition was analyzed by LC/MS. On-line method was validated by using reference antioxidants and linear dependence was found between their concentration and radical scavenging peak area. Radical scavenging capacity (RSC) of methanol and acetone extracts expressed in their concentration required to scavenge 50% of DPPH^? was 0.10% and 0.13%, respectively; the RSC in ABTS^?+ assay was 1093 ± 104 and 746 ± 18 μM of trolox equivalents in 1 g, respectively. Good correlation was observed between total amount of phenolic compounds and RSC. Preliminary HPLC/UV/MS analysis revealed that the main compounds possessing antioxidant activity in the extracts might be phenylpropanoid glycosides; UPLC/UV/ESI-QTOF-MS analysis suggested 15 structures: 2,5-dihydroxy-p-benzenediacetic and caffeic acids, apigenin 6,8-di-C-β-d-glucopyranoside (vicenin-2), apigenin 8-C-α-l-arabinoside 6-C-β-d-glucoside, (shaftoside), forsythoside B, arenarioside, verbascoside (acteoside), amioside, quercetin-6-O-(2-O-acetyl-glucopyranosyl)-glucopyranoside, isoverbascoside, quercetin glucuronide, linariifolioside, methoxy luteolin-7-O-(6-O-acetyl-glucopyranosyl)-glucopyranoside, methoxy luteolin-glucuronide and luteolin glucuronide.     

Antioxidative activities of grape (Vitis vinifera) seed extracts obtained from different varieties grown in Turkey

In this study, total phenolic contents and antioxidant activities of grape seed extracts obtained from twelve different grape seeds from common varieties grown in Turkey were determined. Grape seeds were extracted with 70% acetone and extraction yield of grape seed were calculated. The total phenolic content of grape seed extracts were determined by the Folin‐Ciocalteu procedure and ranged from 33 945 to 58 730 mg per 100 g extract as gallic acid equivalent. Antioxidant activities of grape seed extracts with two different free radical scavenging methods, ABTS [2,2/‐azinobis (3‐ethylbenzothiazoneline‐6‐sulfonic acid)] and DPPH (2,2‐diphenyl‐picrylhydrazyl) assays, using Trolox equivalent as standards, were investigated. Grape seed extracts exhibited antioxidant activities 2.46–4.14 and 3.55–5.76 [Trolox equivalent antioxidant capacities (TEAC) mg^?1 extracts] in ABTS and DPPH assays, respectively. Compared with varieties, Muskule extracts exhibited the lowest total phenolic content, TEAC_ABTS and TEAC_DPPH value while Narince extracts had the highest total phenolic content and TEAC_DPPH value, and Alphonse Lavalleé had the highest TEAC_ABTS value. Total phenolic content showed that there is a significant correlation with TEAC_DPPH (r = 0.7974, P ≤ 0.001) and TEAC_ABTS values (r = 0.4860, P ≤ 0.05).     

Antioxidant and antimicrobial potentials of Serbian red wines produced from international Vitis vinifera grape varieties

BACKGROUND: Antioxidant and antimicrobial potentials of Serbian red wines produced from different international Vitis vinifera grape varieties and their correlation with contents of phenolic compounds were studied by spectrophotometric and chromatographic methods. The antioxidant activity of red wines was estimated through their ability to scavenge 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^?). The red wines, gallic acid, (+)‐catechin and quercetin were screened in vitro for antimicrobial activity against Gram‐positive and Gram‐negative strains using microdilution and disc diffusion techniques. RESULTS: Excellent correlations between the contents of quercetin‐3‐glucoside (R² = 0.9463) and quercetin (R² = 0.9337) and DPPH^?‐scavenging ability of the red wines were found. Serbian red wines exhibited significant activity against Staphylococcus aureus, Listeria inocua, Micrococcus flavus, Sarcina lutea, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella sonnei strains, which was in correlation with their phenolic composition and antioxidant activity. The compounds gallic acid, quercetin and (+)‐catechin showed high activity against B. subtilis, S. aureus, S. lutea and M. flavus Gram‐positive and S. enteritidis and P. aeruginosa Gram‐negative strains. CONCLUSION: The results show that quercetin‐3‐glucoside and quercetin concentrations can be used as markers for the determination of antioxidant and antimicrobial potentials of red wines. Copyright © 2012 Society of Chemical Industry     

Antioxidative activity of<Emphasis Type="Italic"> Geranium macrorrhizum</Emphasis>

The composition of radical-scavenging compounds from Geranium macrorrhizum leaves was analyzed and the antioxidative activities of various extracts was determined. Seven compounds, namely gallic acid, ellagic acid, 4-galloyl quinic acid, the flavonoid quercetin and three of its glycosides, quercetin-3--glucopyranoside, quercetin-3--galactopyranoside and quercetin-4--glucopyranoside were isolated and identified in the various fractions. The radical-scavenging activity of the isolated compounds was measured using DPPH^· and ABTS^·+ scavenging assays and compared with the activity of rosmarinic acid. Quercetin-3-glucopyranoside and quercetin-3-galactopyranoside showed the highest antioxidative capacities. Antioxidative activities of all plant fractions were assessed by model system tests (superoxide anion and hydrogen peroxide scavenging) and by oxidation tests (-carotene bleaching, peroxide value, UV absorbance and headspace-gas chromatography hexanal determination). The ethanol-butanol fraction of the plant possessed the highest activity in most of the tests.