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Simplification of the DPPH assay for estimating the antioxidant activity of wine and wine by-products

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Abstract

The DPPH assay is one of the most commonly employed methods for measuring antioxidant activity. Even though this method is considered very simple and efficient, it does present various limitations which make it complicated to perform. The range of linearity between the DPPH inhibition percentage and sample concentration has been studied with a view to simplifying the method for characterising samples of wine origin. It has been concluded that all the samples are linear in a range of inhibition below 40%, which allows the analysis to be simplified. A new parameter more appropriate for the simplification, the EC20, has been proposed to express the assay results. Additionally, the reaction time was analysed with the object of avoiding the need for kinetic studies in the method. The simplifications considered offer a more functional method, without significant errors, which could be used for routine analysis.

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... Antioxidant activity of wine was measured, as EC20 values, after the end of fermentation (racking) and at seven months of aging. EC20 value expresses the quantity of sample (mL) necessary to reduce 1 mg of DPPH by 20% according to Carmona-Jiménez and collaborators [12]. At the racking, after three and after seven months of aging the wines were evaluated for their contents in major volatile and in oak compounds while sensory analysis of the wines was assessed only after seven months of aging. ...
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In winemaking, wood products alternative to barrels are used to achieve various oenological goals, including rapid release of desirable volatile and polyphenolic compounds, color stabilization, and economic benefits. In this research study, oak wood formats (staves, cubes, and chips) were added to red Nebbiolo wines at two vinification stages: during and after alcoholic fermentation. Aromatic composition was analyzed at racking, after three and seven months of aging. Samples were analyzed by gas chromatography–mass spectrometry (GC–MS) and gas chromatography-flame ionization detector (GC-FID). After seven months, a trained panel assessed the sensory profiles of the wines who varied significantly based on the timing of wood addition and the type of wood used. Higher levels of vanillin and furan compounds were found in wines with wood added after fermentation and in those treated with staves. Wines treated with cubes had elevated benzoic aldehyde levels, while those with chips showed higher levels of whisky lactone, a key molecule for “boisé” notes. Sensory analysis revealed greater intensity of vanilla and oak wood descriptors in wines treated with cubes and chips. Cubes particularly enhanced spicy aromas like cloves and pepper, offering a more balanced aroma and sensory profile compared to staves and chips.
... Additionally, total indexes of anthocyanin, avonoids and polyphenols were measured at the end of fermentation and after seven months [10]. Antioxidant activity of wine was measured as EC20 values the quantity of sample (mL) necessary to reduce 1 mg of DPPH by 20% after the end of fermentation (racking off) and at seven months of aging according to Carmona-Jiménez and collaborators [11]. At the racking off, after three and after seven months of aging the wines were evaluated for their contents in oak compounds while sensory analysis of the wines was assessed only after seven months of aging. ...
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Full-text available
In winemaking, wood products alternative to barrels are used to achieve various oenological goals, including rapid release of desirable volatile and polyphenolic compounds, color stabilization, and economic benefits. In this research study, oak wood formats (staves, cubes, and chips) were added to red Nebbiolo wines at two vinification stages: during and after alcoholic fermentation. Aromatic composition was analyzed at racking off, after three and seven months of aging. Samples were analyzed by gas chromatography–mass spectrometry (GC–MS) and gas chromatography-flame ionization detector (GC-FID). After seven months, a trained panel assessed the sensory profiles of the wines who varied significantly based on the timing of wood addition and the type of wood used. Higher levels of vanillin and furan compounds were found in wines with wood added after fermentation and in those treated with staves. Wines treated with cubes had elevated benzoic aldehyde levels, while those with chips showed higher levels of whisky lactone, a key molecule for " boisé " notes. Sensory analysis revealed greater intensity of vanilla and oak wood descriptors in wines treated with cubes and chips. Cubes particularly enhanced spicy aromas like cloves and pepper, offering a more balanced aroma and sensory profile compared to staves and chips.
... The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was used to assess antioxidant capacity as described (Carmona-Jiménez et al., 2014). The mechanism is based on electron transfer indicated by a colour change from violet to light yellow in ethanol. ...
... Tis may be due to the low polarity and capacity of acetone to dissolve and extract the phenolic compounds present in this residual biomass. It has been reported that the antioxidant capacity is directly associated with the content of total polyphenols in the biomass-based extract [72][73][74][75]. It was also observed a direct relationship between TPC and antioxidant capacity in the diferent extracts obtained from rice husks with tested solvents. ...
Article
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In the present study, the experimental intensification and modeling of the extraction process of antioxidants from rice husks using different organic solvents (ethanol, methanol, and acetone, and their mixtures with water) were analyzed and discussed. The best experimental extraction conditions to recover polyphenols from rice husks were identified, and the extraction kinetic data were modeled using the mechanistic and pseudo–second-order models. The experimental results showed that the solvent-based extraction of polyphenols from rice husks was endothermic where the ethanol and methanol offered the best separation performance. The polyphenol extraction process using ethanol and acetone was mainly influenced by the percentage of water contained in the solvent mixture used as separation medium, whereas the extraction temperature significantly affected the polyphenol extraction with methanol. The rice husk-based extracts obtained with methanol and ethanol showed the highest total content of polyphenols (66.72 and 60.68 of gallic acid equivalent/g of biomass) and antioxidant capacity (71.93% and 72.02% 2,2-diphenyl-1-picrylhydrazyl [DPPH] inhibition). The mechanistic model offered the best performance to describe the experimental polyphenol extraction, and its results were used to discuss and analyze the mass transfer parameters associated with the intraparticle diffusion of this extraction process. These results contribute to the valorization of rice husk residues as a potential feedstock to be incorporated in the biorefinery context for obtaining value-added products.
... A recent study described the DPPH assay as a method for measuring radical scavenging activity (Fig. 3) (Comuzzo et al. 2015). This assay is often chosen because its radical form accepts electrons and hydrogen atoms from antioxidant scavenger molecules, which occurs in the presence of compounds with antioxidant activity (Carmona-Jiménez et al. 2014). Results revealed yeast lees as the ones with the highest activity. ...
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The wine industry is responsible for a considerable amount of waste produced by agricultural activities worldwide, which impacts both the economic sector and the environment through pollution and ecosystem imbalance. There are several examples of by-products generated during the winemaking process, such as grape pomace, vine leaves, grape stalks, or wine lees. These can be recovered and reused by the cosmetic industry, which is actively seeking natural and greener products. There are active ingredients that come from by-products that have relevant bioactive properties such as antioxidant, antiaging, anti-hyperpigmentation, or cellular protection. Therefore, the use of by-products from the wine industry as a source of active ingredients for topical application has attracted attention from the scientific community, overcoming some of the drawbacks of the winemaking process. Further research into extraction processes and methods is essential, as they directly influence the quality and quantity of recovered active ingredients. While current cosmetic products on the market undergo safety and cytotoxicity testing, it is important to evaluate the effects of pesticide treatments applied before pruning and the toxicity of the by-products to ensure the safety of future formulations. This review addresses a critical discussion on this subject, assessing the potential benefits of their use in topical formulations. Graphical Abstract
... Antiradical activity was measured with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (Carmona-Jiménez et al., 2014). Briefly, tannin stock solutions were prepared in model wine at 1 g/L. ...
... These compounds are: MS, as well as 1D and 2D-NMR. In addition, a high-quality isostevioside crystal was crystallized in methanol and its structure was determined by X-ray diffraction (38,134,139,140). ...
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Georgia is a small country, therefore, the effective use of the special possibilities of natural and climatic conditions for growing local or introduced plants is especially important for the country. Today, unfortunately, in many cases, the soil is not used properly. It is cultivated with plants that are not studied or not suitable for environmental conditions. Crop production (leaf, fruit, etc.) is cost-effective when studying its chemical composition using modern physicochemical methods. The research is particularly relevant when it comes to plants containing biologically active compounds. Therefore, there’ should be established qualitative and quantitative content, as well as the chemical structure and biological activity of a plant. There’ should also be studied the optimal period of accumulation of these compounds and, accordingly, the harvest time of raw material. It is important to adapt the most optimal (chemical composition, yield and other) varieties in this region. It is necessary to develop processing technology and pay attention to monitoring of biologically active compounds during the processing and in the obtained product. Early studies have shown that the Stevia plant of South American origin is particularly effective for soil and climatic conditions of western Georgia.
... The stable DPPH nitrogencentered radical exhibits a characteristic absorption pattern that diminishes in the presence of antioxidants [31]. By reacting with hydrogen-donating functionalities, the color of the DPPH changes from purple to yellow, and the intensity of the color change is related to the number of electrons captured [32]. ...
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The present article describes the synthesis of an isonicotinate-derived meso-arylporphyrin, that has been fully characterized by spectroscopic methods (including fluorescence spectroscopy), as well as elemental analysis and HR-MS. The structure of an n-hexane monosolvate has been determined by single-crystal X-ray diffraction analysis. The radical scavenging activity of this new porphyrin against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical has been measured. Its antifungal activity against three yeast strains (C. albicans ATCC 90028, C. glabrata ATCC 64677, and C. tropicalis ATCC 64677) has been tested using the disk diffusion and microdilution methods. Whereas the measured antioxidant activity was low, the porphyrin showed moderate but encouraging antifungal activity. Finally, a study of its effect on the germination of lentil seeds revealed interesting allelopathic properties.
... The stable DPPH nitrogen-centered radical exhibits a characteristic absorption pattern that diminishes in the presence of antioxidants [31]. By reacting with hydrogen-donating functionalities, the color of the DPPH changes from purple to yellow and the intensity of the color change is related to the number of electrons captured [32]. ...
Preprint
Full-text available
The present article describes the synthesis of an isonicotinate-derived meso-arylporphyrin, that has been fully characterized by spectroscopic methods (including fluorescence spectroscopy), as well as by elemental analysis and by HR-MS. The structure of a n-hexane monosolvate has been determined by single crystal X-ray diffraction analysis. The radical scavenging activity of this new porphyrin against the 2,2-diphenyl-1-picrylhydrazyl (DDPH) radical has been measured. Its antifungal activity against three yeast strains (C. albicans ATCC 90028, C. glabrata ATCC 64677 and C. tropicalis ATCC 64677) has been tested, using the disk diffusion and the microdilution methods. Whereas the measured antioxidant activity was low, the porphyrin showed moderate but encouraging antifungal activity. Finally, a study of its effect on the germination of lentil seeds revealed interesting allelopathic properties.
... The DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay is considered one of the most frequently proposed method used for evaluating and measuring antioxidant activity. It is simple, efficient, inexpensive method and can be run in the most laboratories, hence, it has been broad utilizations (25,26). The DPPH assay is a useful indicator of the typical antioxidant profile since most natural antioxidants have reactive hydrogen atoms that act as reductants. ...
Article
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Antitumor, antiviral, antimicrobial and antioxidant activities were reported for Euphorbia helioscopia usage in traditional medicine. Therefore, minimum inhibitory and bactericidal concentrations (MIC, MBC) of E. helioscopia aqueous leaf and stem extracts were evaluated by broth microdilution assay. As well as their antioxidant activity was carried out using DPPH assay. Obtained results showed that MIC values of leaf extract ranged from 0.78±0.0 mg/mL to 12.5±0.0 mg/mL and stem extract ranged from 3.125±0.0 mg/mL to 25±0.0 mg/mL. While, MBC of leaf and stem extracts had a range from 6.25±0.0 mg/mL to 50±0.0 mg/mL and 25±0.0 mg/mL to 50±0.0 mg/mL, respectively. The current study demonstrated that E. helioscopia leaf and stem extracts had antioxidant activity. One-way ANOVA test, the P values for the leaf and stem aqueous extracts were equal to 0.997 and 0.058, respectively. Consequently, both extracts showed no significant difference relative to the standard ascorbic acid (P value > 0.01). In addition, statistical analyses showed no significant differences between the tested concentrations of leaf extract and tested concentrations of ascorbic acid at P value > 0.01. The same thing was obtained for tested concentrations of stem aqueous extract, except at concentrations 7.81 and 3.91 µg/mL which showed DPPH inhibition percent 4.30±0.63 and 0.59±0.10, respectively. This indicates that E. helioscopia has potential to serve as a natural antioxidant, which makes it a promising candidate for therapeutic applications. Moreover, the positive antibacterial recorded data could potentially be used to develop potent drugs that improve the management and treatment of variety bacterial illnesses.
... The antioxidant capacity of the extract is evaluated by DPPH scavenging activity. The volume of sample or alcohol (blank) was 0.4 mL mixed with 0.8 mL of 0.1 mM DPPH solution in alcohol solvent (Carmona-Jiménez et al., 2014). Concentrations of extraction in mixed solution were from 400 to 60 µg/mL (ppm). ...
Article
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Many components in Crotalaria assamica benth composition make this plant a potential antioxidant and antibacterial herbal material, which can find many applications in medicine and biochemistry. In this study, Crotalaria assamica benth seed powder was extracted with aqueous alcohol solutions by an ultrasound-assisted leaching method. The ultrasound wave was 37 kHz, and the extraction was carried out at 30 °C for 10 mins. An alcohol content of 54.78 vol% and a mass ratio of solid to liquid (RSL) of 1/55 are suitable conditions according to the reaction surface method (RSM) developed by the Box-Beknen approach to design matrix experiments. With the above conditions, the actual result was that the TPC was 12.02 ± 0.24 mg GAE/g DW and the TFC was 7.68 ± 0.34 mg RE/g DW). Crotalaria assamica confers antioxidant activity of the extract with an IC50 value of 644 g/mL, and antibacterial activity against P. aeruginosa strain, with an average antibacterial ring diameter of 13.5 mm.
... A sample of 150 μL of (0.095-mM DPPH reagent was incubated in 15 μL of wine. The absorbance was measured for 10 min at 505 nm, and the output ratio was calculated as a difference between the absorbance values measured in the 10th minute and 2nd minute of the test (Carmona-Jimenez et al., 2014;Sochor et al., 2014). Antioxidant activity was determined in three repetitions immediately after sampling. ...
Article
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The lees produced during fermentation are known for their ability to consume oxygen. During wine aging, it has a positive effect on the antioxidant and sensory properties of wine. This study focuses on the effects of different doses of fermentation lees on the oxygen consumption and antioxidant activity of wine, which are important for the quality of the final product as well as consumer. The effect on oxygen consumption after bottling, antioxidant activity and phenolic composition was studied for wines of the variety Grüner Veltliner with different proportions of yeast lees. The rate of dissolved oxygen consumption increased with increasing dosages of fermentation lees. The first significant decrease was observed as early as the second day after bottling for all variants above 20 g of fermentation lees in 0.75 L of wine. Total polyphenol content and antioxidant activity also increased with the dose of yeast lees. The major negative parameter for the highest addition of lees was the concentration of volatile acids, which increased from a baseline value of 0.34 g L–1 to 0.45 g L–1.
... The superoxide anion radical (·O 2 -) scavenging ability was determined according to autoxidation with the pyrogallol method (Guo et al., 2008b). The 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) free radical (DPPH·) scavenging ability was determined according to a method devised by Yolanda et al. (2014), with ascorbic acid as the control, and was calculated according to the standard curve of ascorbic acid. ...
... [62] It reacts with hydrogen donating functions resulting in a colour change from purple to yellow. The intensity of this phenomena is related to the number of electrons captured [63] i.e., the greater the free radical scavenging capacity of an antioxidant compounds, the more reduction of DPPH and the less purple colour of the sample. Moreover, DPPH radical is related with known inflammatory results and have been often used to investigate the potential antioxidant activity of compounds, [64] which may bear also a potential anticancer and anti-inflammatory activity. ...
Article
Benzodiazepines, a well-studied class of seven-membered aromatic heterocycles containing two nitrogen atoms, have shown great promise as therapeutic agents. Efficient protocols have been developed to synthesize a variety of functionalized benzodiazepines. This study focuses on the synthesis of three derivatives of 1,5-benzodiazepin-2-one through regioselective acetylation using acetyl chloride under various conditions. One of the derivatives was characterized for its molecular and crystal structure using X-ray crystallography, Hirshfeld surfaces, and density functional theory computations (at wB97X-D/aug-cc-pVTZ level). The synthesized compounds were then subjected to in vitro evaluation to assess their antibacterial and antifungal activities against multiple strains. Additionally, their antioxidant and anti-inflammatory properties were examined. The results showed different levels of inhibitory effects on the growth of microorganisms, with all compounds displaying moderate to significant biological activities. Furthermore, molecular docking simulations were conducted to investigate the binding interactions of the compounds with bacterial and fungal targets. This research enhances our understanding of the chemistry of benzodiazepine derivatives and further highlights their therapeutic potential.
... Plant extracts demonstrated significant antioxidant properties. When antioxidant molecules are present, DPPH, ABTS+, or GOR may donate the antioxidant component's hydrogen atom can thus be transformed into more stable molecules [51]. CUPRAC findings suggested that in the presence of neocuproine, Cu +2 was reduced to Cu + . ...
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Since antiquity, phytomedicine played a crucial role and many comprehensive texts documenting the medicinal impact of plants were discovered during many civilization eras, suggesting folk medicine is the foundation of modern medicine. This work look into the phytochemical composition, as well as the pharmacological properties, of Tamarix Africana stems organic fractions. The phytochemical study was carried out using phytochemical screening method while phenolic, flavonoids, condensed and hydrolysable tannins contents by spectrophotometric approach. The antioxidant assay was measured using five approaches. Anti-diabetic capacity was investigated with two assays. Furthermore, the cytotoxicity of the extracts was tested against Artemia Salina nauplii and the photoprotective test was assessed using sun protection factor measurement (SPF). Data revealed that both extracts contained phenolic substances, the EA fraction had the highest proportion of phenolics, flavonoids, condensed and hydrolysable tannins (825.47±2.34 μ g GAE/mg), (238.4±2.11 μ g QE/mg), (8.44±1.05 μ g CE/mg), (508.23±3.65 μ g TAE/mg) respectively. The antioxidant, antidiabetic, and cytotoxicity of these extracts evolved in dose-dependent manner. EA activity was higher than MeOH extract in antioxidant tests. A moderate antidiabetic effect was expressed by EA extract, while this effect was higher for MeOH extract. A significant cytotoxic and photoprotective effects was observed for both MeOH and EA extracts when compared to the corresponding standards. This study suggests that Tamarix Africana stems has certain pharmacological effects, especially to cure disorders linked to oxidative stress, glycemia perturbation, dermatopathology and some cancers.
... Grape meal had the highest concentrations of total phenolic compounds and carotenoids and the best antioxidant capacity by both methods (ABTS and DPPH) ( Table 2). Since EC50 means the amount of the fruit meal necessary to reduce the concentration of the DPPH radical by 50%, the lower this value, the higher the antioxidant activity [51]. ...
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By-products from fruit industrialization retain nutritional and functional components; thus, they may find use in animal feeding. This study aimed to assess the effects of dietary fruit industrial by-products on the tilapias blood biochemical and oxidative parameters and on the composition and lipid peroxidation of their fillets. Four diets were supplied to the tilapias: a C-control diet, with no fruit meal, and three diets containing 5% of either acerola (ACM), apple (APM) or grape (GRM) meal. The phenolic compounds and the carotenoids in the meals and their antioxidant capacities were measured. Fish were weighed and measured for the calculation of the growth performance data, their blood was analyzed for health and oxidative status biomarkers and their fillets were analyzed for proximal composition and lipid peroxidation. Grape meal had the highest concentration of phenolics and carotenoids and the highest antioxidant activity, followed by acerola and apple meals. The productive performance was similar among the treatments. The fruit by-product diets either maintained or improved the biochemical biomarkers of health and improved the oxidative status of the fish. The fruit by-product diets increased the concentration of lipids in the fillets and slowed down the onset of the lipid peroxidation during frozen storage.
... 1,1-Diphenyl-2-picrylhydrazyl (DPPH) is a powerful oxidizing agent with rich purple color and a prominent absorption band. The radical scavenging capacity of the nanoparticles is defined by the reduction of the DPPH [88]. The prepared DPPH solution initially has a deep violet color that is altered and becomes purple and less purple as the increasing reactivity of the test sample, which according to the definition, shows the scavenging ability of these nanoparticles [89]. ...
... Our data are in the line of those reported that Tamarix species contained several phenolic acids and a considerable amount of flavonoids. 38 Also, our findings were in accordance with those results presented by Carmona-jiménez et al, 39 which demonstrated that Tamarix articulata extracts were wealthy in phenolics and flavonoids contents, and might potentially be a source of various phyto-compounds. The quantities of total phenolic components in the two extracts of Tamarix africana L. the ethyl acetate extract had a higher concentration (500-546 mg/g) while the aqueous extract had a total phenolic of (140-170 mg/g). ...
Article
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Objective: To characterize the chemical profile of methanolic crude extract and its fractions (Ethyl acetate, n-butanol and aqueous) using liquid chromatography-mass spectrometry (LC-MS) analysis, to evaluate their biological and pharmacological properties: antioxidant (1, 1-diphenyl-2-pycrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic) (ABTS), galvinoxyle free radical scavenging, reducing power, phenanthroline and β carotene-linoleic acid bleaching assays), enzymes inhibitory ability against several enzymes [acetyl-cholinesterase (AChE), buthyrylcholinesterase (BChE), urease and tyrosinase]. Methods: Secondary metabolites were extracted from Tamarix africana air-dried powdered leaves by maceration, the crude extract was fractionated using different solvents with different polarities (Ethyl acetate, n-butanol and aqueous). The amount of polyphenols, flavonoids and tannins (hydrolysable and condensed) were determined using colorimetric assays. A variety of biochemical tests were carried out to assess antioxidant and oxygen radical scavenging properties using DPPH, ABTS, galvinoxyle free radical scavenging, reducing power, phenanthroline and β carotene-linoleic acid bleaching methods. Neuroprotective effect was examined against acetylcholinesterase and buthy-rylcholinesterase enzymes. The anti-urease and anti-tyrosinase activities were performed against urease and tyrosinase enzymes respectively. The extract's components were identified using LC-MS and compared to reference substances. Results: The results indicated that Tamarix africana extracts presented a powerful antioxidant activity in all assays and exhibited a potent inhibitory effect against AChE and BChE as well as urease and tyrosinase enzymes. LC-MS analysis identified amount of eight phenolic compounds were revealed in this analysis; Apigenin, Diosmin, Quercetin, Quercetine-3-glycoside, Apigenin 7-O glycoside, Rutin, Neohesperidin and Wogonin in methanolic extract and its different fractions of Tamarix africana from leaves. Conclusions: Based on these findings, it is reasonable to assume that Tamarix africana could be considered as a potential candidate for pharmaceutical, cosmetics, and food industries to create innovative health-promoting drugs.
... The DPPH assay for the evaluation of antioxidant activity is a simple, cheap and effective method, one of the most commonly used to determine the antioxidant capacity of a compound, an extract or other biological matrices (plants, fruit, wine, honey) [52][53][54]. In its initial radical form, DPPH has an intense purple color, which changes to yellow when found in reduced form ( Figure S1). ...
Article
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The classification of olive oils and the authentication of their biological or geographic origin are important issues for public health and for the olive oil market and related industries. The development of techniques for olive oil classification that are fast, easy to use, and suitable for online, in situ and remote operation is of high interest. In this study, the possibility of discriminating and classifying vegetable oils according to different criteria related to biological or geographical origin was assessed using cyclic voltammograms (CVs) as input data, obtained with electrochemical sensors based on carbonaceous nanomaterials and gold nanoparticles. In this context, 44 vegetable oil samples of different categories were analyzed and the capacity of the sensor array coupled with multivariate analysis was evaluated. The characteristics highlighted in voltammograms are related to the redox properties of the electroactive compounds, mainly phenolics, existing in the oils. Moreover, the antioxidant activity of the oils’ hydrophilic fraction was also estimated by conventional spectrophotometric methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and galvinoxyl) and correlated with the voltammetric responses of the sensors. The percentage of DPPH and galvinoxyl inhibition was accurately predicted from the voltammetric data, with a correlation coefficients greater than 0.97 both in calibration and in validation. The results indicate that this method allows for a clear discrimination of oils from different biological or geographic origins.
... It reacts with hydrogen donating function leading a color shift from purple to yellow. The intensity of this phenomenon is related to the number of electrons captured [80], i.e., the further the free radical scavenging capability of an antioxidant composite, the more DPPH is reduced, and the sample becomes less purple in color. The scavenging activities of our four porphyrinic compounds were evaluated against DPPH. ...
Article
The reactions of the (triflato)(meso-tetra(para-methoxyphenyl)porphyrinato)manganese(III) ([MnIII(TMPP)(SO3CF3)] complex with an excess of 4-dimethylaminopyridine (DMAP) and hexamethylenetetramine (HMTA) have been examined. These reactions yield crystalline [MnIII(TMPP)(DMAP)2](0.1Cl)(0.9SO3CF3)•2CHCl3 (I) and [MnIII(TMPP)(HMTA)2](SO3CF3)•2CH2Cl2 (II) complexes, respectively. The hyper d-type electronic spectra of I-II are characteristic for high-spin (S = 2) Mn(III) metalloporphyrins with very redshifted Soret bands. A cyclic voltammetry investigation was carried out on these two Mn(III) coordination compounds. The crystal structures of the solid complexes I-II were determined by X-ray single-crystal diffraction and elucidated by Hirshfeld surface approach. Furthermore, bioactivity of the H2TMPP free base, the [MnIII(TMPP)(SO3CF3)] starting material and complexes I-II, was assessed by a set of in vitro tests checking for antioxidant, antibacterial and antifungal (against several strains) effects.
... Aktivitas antioksidan direpresentasikan dengan nilai IC 50 yaitu konsentrasi sampel yang mampu menghambat sebesar 50% radikal DPPH • yang dihitung menggunakan persamaan kurva regresi linier. Semakin kecil nilai IC 50 , aktivitas antioksidannya semakin efektif (Mishra et al. 2012;Carmona-Jiménez et al. 2014;Pisoschi et al. 2016). ...
Thesis
Diabetes mellitus (DM) is a disease caused by lacking of insulin production or by the inability of cells to respond to insulin (insulin resistance). According to the International Diabetes Federation, diabetes cases in the world reach 425 millions and are predicted to increase to 625 millions by 2045. The trend of increasing cases and death rates due to diabetes needs a special attention, especially in the pattern of it’s treatment. Diabetes treatment using natural ingredients is one of the most researched fields in the world because it is effective and safe. Curculigo latifolia Dryand. ex W.T. Aiton and Curculigo orchioides Gaertn. belonging to the family Hypoxidaceae, annual herbs with lanceolate-shaped leaves or parallel lanceolate arranged in a rosette, with yellow flowers, very short stems, and have a long cylindrical rhizome. A total of 39 species of this genus are accepted in the World Checklist of Selected Plant Families (WCSP 2020), including these two species. Both species are known as traditional medicinal plants in various tropical regions. Rhizome of Curculigo spp. is one of the raw material sources for traditional medicine to treat DM; this pharmacological effect comes from secondary metabolites. Those compounds are distributed and accumulated in certain secretory structures within the plant. However, the activities of the active compounds in such diverse plant organs are very difficult to be determined in a short time, as well as its pharmacokinetic and pharmacodynamics parameters. In addition, compounds produced under normal conditions in the nature are very low. Therefore, this study aimed to determine the distribution of secretory structures and the producing and/or accumulating sites of the bioactive compounds through histochemical tests, to determine which bioactive compounds contribute the most to diabetes mellitus, especially in antioxidant activity and α-glucosidase inhibition, and to determine their pharmacokinetics and pharmacodynamics parameters. In addition, this research was also carried out to produce callus and micropropagate the plants, as well as to ensure the existence of those bioactive compounds in in vitro cultured callus. Determination of secretory structure using cross sections of fresh samples according to plant anatomical procedures and histochemical analysis using several reagents were performed to detect groups of metabolites. Determination of bioactive compounds was done using an analysis combination on biological activities (antioxidants and α-glucosidase inhibition) with metabolite fingerprint using FTIR and metabolite profiling with UHPLC-Q-Orbitrap HRMS-based metabolomic and chemometric techniques using partial least squares regression analysis (PLSR). Pharmacokinetics and pharmacodynamics parameters were determined using Lipinski's rule of five, pharmacological networks using Cytoscape, and molecular docking with PyRx, PyMOL, and BIOVIA Discovery Studio. Callus production and micropropagation began with explant sterilization using environmental-friendly sterilants. Callus initiation and organogenesis were induced by various concentrations of auxins and cytokinin. Metabolomic analysis based on metabolite profiling using UHPLC-Q-Orbitrap HRMS and chemometric techniques using principal component analysis (PCA) were carried out to identify the compounds in the callus and plantlet’s leaves. The anatomical and histochemical analysis of fresh tissues showed that all organs contained secretory structures that accumulated various metabolites. The secretory structures identified in the roots, rhizomes, petiole, and leaves of these two species were secretory cavities and idioblasts. The group of compounds identified were phenols, alkaloids, terpenes, essential oils, and lipophilic. They were also spread over some common tissues of the organs. Based on metabolomic and chemometric analysis the main compounds contributing in antioxidant and α-glucosidase inhibition activities were notified from the phenol group, such as curculigoside B, orchioside B; 2,4-Dichloro-5-methoxy-3-methylphenol, orcinol glucoside; 1,1-Bis-(3,4-dihydroxyphenyl)-1-(2-furan)-methane; from the terpene group, such as: curculigosaponin G, H, and I; from the norlignan group, (1S,2R)-O-Methylnyacoside; and from the aldehyde group, 5-hydroxymethylfural, while the functional groups included O–H, C=O, C–O, C–H. These compounds were accumulated more abundantly in the leaves of C. latifolia (DLSP) from Sinjai-Palangka and C. orchioides (DOGM) from Gowa-Malakaji. Pharmacokinetic parameters showed that 33 out of the 79 compounds were able to be absorbed properly, while some compounds did not meet the requirements. The latter compounds must be converted into aglycones if they will be used as medicinal substances. The cynanuriculoside ligand A_qt based on pharmacological network analysis and molecular docking was able to interact pharmacodynamically with hydroxysteroid (11-beta) dehydrogenase 1 (HSD11B1) target via 6NJ7 receptor, resulting an affinity of –12.0 (kcal mol–1), with amino acid residues in the form of Ala 226, Leu 126, Val 180, Tyr 183, Leu 215, Ser 170, Ile 121, and Val 168. The sterilization of explants with the lowest concentrations of sterilizing agents and a short contact time with the explants produced 90% sterile cultures. The best combination of plant growth regulators (PGRs) for callus induction in C. latifolia and C. orchioides were BAP : IBA at 3 : 5 and 5 : 3 mg L–1, respectively. The callus were green and white, with a compact consistency. Those combinations of PGRs also regenerated shoots and roots in both species. The secretory structures found in the callus were secretory cavities and idioblast cells. In the callus of C. latifolia, phenol was identified in the organogenic parts and epithelium cells of the secretory cavities, and the essential oils were in idioblast cells; while C. orchioides’ callus contained phenol in the organogenic parts only. The compounds that had contribution in antioxidant and α-glucosidase inhibition activities, such as 1,1-Bis-(3,4-dihydroxyphenyl)-1-(2-furan)-methane, (1S,2R)-O-Methylnyacoside; 2,4-Dichloro-5-methoxy-3-methylphenol, curculigoside B, curculigosaponin G, H, and I; orchioside B, and orcinol glucoside were also identified in the callus and plantlet’s leaves. Most of them belong to the phenol group. The general conclusion of this study is that histochemical techniques revealed that there were differences in the accumulation sites of compounds among organs of Curculigo spp. Histochemically, phenolic compounds were identified in the rhizome, petiole, and leaves of C. latifolia, while in C. orchioides they were only identified in the rhizome. Phenolics were also found in the organogenic callus of these two species. From the metabolomic-chemometric analysis, compounds that contributed greatly to the antioxidant and α-glucosidase inhibition activities were accumulated in the leaves of both species. From the pharmacological network and molecular docking approaches, cynanuriculoside A_qt, curculigosaponin L_qt, and curculigenin B were confirmed to have potential for the treatment of diabetes mellitus. The compounds found in the plant’s organs of C. latifolia and C. orchioides that contribute greatly in antioxidant and α-glucosidase inhibition activities were also identified in the callus and plantlet’s leaves resulted from in vitro cultures. Some of which even demonstrated higher concentration (peak area) than those of the original plant organs.
... The reaction time depends on the constituents of the investigated sample, according to Carmona-Jimenez et al. (14) the standard polyphenols present fast kinetics and reaction time between 30 and 240 min. A reaction time of 1 h was determined in preliminary tests and based on previous work (15)(16)(17), with the final absorbance of each concentration being read at 515 nm in a spectrophotometer (Shimadzu 1601). ...
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This work aimed to obtain and investigate the properties and composition of extracts from flowers of Acacia mearnsii; this tree is widely cultivated because the bark is used as a raw material for various industry segments, but the flowers are not yet explored. The essential oil was evaluated by GC/FID, GC/MS, and GC/O. The antioxidant activity (DPPH and phosphomolybdenum methods) and chemical composition were investigated for a water-soluble extract, a by-product of the extraction process. 85.8% of the compounds present in the essential oil were identified, 8-heptadecene being the major compound. The main scents detected by the olfactory analysis were roast nutty, coffee, sweet, and floral. The water-soluble extract showed antioxidant activity that may be related to phenolic compounds. Results obtained from the LC-qTOF/MS analysis have shown that 25 likely flavonoids, such as naringenin, myricetin, quercetin, and rutin are present in the extract.
... The EC 50 is proposed as the amount of sample (antioxidant compound) needed to decrease the initial concentration of DPPH by 50%. That is, the lower the EC 50 value, the higher the antioxidant activity (Carmona-Jiménez, García-Moreno, Igartuburu, & Garcia Barroso, 2014). Maluf et al. (2018) also observed that grape pomace extract obtained from the winemaking process had a lower EC 50 value compared to BHT. ...
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... The antioxidant activity (AA / %) was calculated as: 11 ...
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In this study, an agricultural waste product was used to prepare a green corrosion inhibitor based on olive leaves (Olea Europaea Syslvestris). Firstly, an optimization study of antioxidant activity of Olea Europaea Syslvestris leaves monitored by the DPPH free radical trapping method, was carried out using full factorial design. In the second step, the extract obtained under optimal conditions was tested as a green corrosion inhibitor for steel in 0.5 mol dm?3 HCl, using gravimetric and electrochemical methods. The results obtained by various tech-niques showed that the extract acted as a mixed-type inhibitor. The adsorption of the inhibitor was spontaneous (?Gads = ?12.443kJ mol?1), through the mechanism of physical adsorption, and it obeyed the Langmuir adsorption isotherm. The highest corrosion inhibition efficiency of 92 % was obtained for 2.8 10?3 g cm?3of inhibitor, as measured by gravimetric method.
... The antioxidant activity levels of the prickly pear juice, the wine and the different vinegars were determined by DPPH (1,1-diphenyl-2-picrylhydrazyl) according to the method reported by Carmona-Jiménez et al. [37]. A total of 200 µL of sample or ethanol (blank) were added into vials containing 3.3 mL of a 50 µM solution of DPPH in ethanol prepared daily (0.069 ppm of the initial DPPH). ...
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This work intends to determine the effect on the aroma profile, phenolic content and antioxidant activity of prickly pear vinegars produced by the surface culture at two different fermentation temperatures and using different acetic acid bacteria (AAB) inocula. Prickly pear wine was fermented at two temperature levels (30 and 37 ºC) by using bacteria inocula containing Acetobacter, Gluconobacter or a mixture of bacteria isolated from Sherry vinegars. Eighty-five individual volatile compounds from different families and sixteen polyphenolic compounds have been identified. It was confirmed that the highest temperature tested (37 ºC) resulted in a lower concentration of volatile compounds, while no significant effect on the vinegars’ volatile composition could be associated with the AAB inoculum used. Contrariwise, the highest content of polyphenolic compounds was detected in those vinegars produced at 37 ºC and their concentration was also affected by the type of AAB inoculum used. Prickly pear wine displayed greater antioxidant activity than juices or vinegars, while the vinegars obtained through the mixture of AAB from Sherry vinegar showed higher antiradical activity than those obtained through either of the two AAB genera used in this study. It can be therefore concluded that, although the volatile content of vinegars decreased when fermented at a higher temperature, vinegars with a higher content in polyphenols could be obtained by means of partial fermentations at 37 ºC, as long as thermotolerant bacteria were employed.
... As the reduced form of DPPH is pale yellow, it is possible to determine the antioxidant activity by studying the change of color spectrophotometrically. The greater the free radical scavenging capacity of an antioxidant compound, the more reduction of DPPH and the less purple color there is in the sample [21]. reporting substantial antioxidant activity plant parts from this species. ...
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Background Uncaria tomentosa is a traditional medicinal herb with antiviral, antioxidant, immunostimulating, anti-inflammatory, and anticancer effects. Objective The present study was conducted to evaluate the antioxidant capacity in vitro and in vivo and the phytochemical analysis of Uncaria tomentosa . Materials and Methods The plant extract was screened for phytochemical compounds and antioxidant capacity in vitro using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and in vivo using acetic acid-induced colitis. Colitis was induced in rats by transrectal administration (5 mL/kg) of 4% (v/v) acetic acid. Forty adult albino rats were divided into four groups: control group, acetic acid group, acetic acid + sulfasalazine (100 mg/kg/day) group, and acetic acid + Uncaria tomentosa extract (250 mg/kg/day) group. After inducing colitis, sulfasalazine and Uncaria tomentosa extract were given orally for 10 days. Data were statistically analyzed, and P < 0.05 was considered statistically significant throughout the study. Results Preliminary phytochemical study showed that Uncaria tomentosa extract contains flavonoids, phenols alkaloids, saponin, and terpenoids. In the DPPH assay, the extract exhibited considerable antioxidant capacity in a dose-dependent manner. Also, Uncaria tomentosa extract dramatically decreased oxidative stress parameters, such as myeloperoxidase enzyme activity and malondialdehyde in colonic tissue. Moreover, Uncaria tomentosa treatment attenuated macroscopic colonic scores and histopathological changes induced by acetic acid. Conclusion The findings of this study show that Uncaria tomentosa extract could be a source of natural antioxidants and may have a therapeutic effect on ulcerative colitis.
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The method of ultrasound-assisted extraction (UAE) was utilized to extract polyphenols from Jerusalem artichokes tuber (JAT). To determine the ideal values for ultrasound power (UP), extraction time (ET), and temperature (TP), a response surface methodology was utilized. JAT extracts were prepared using UAE and their content of total flavonoids (TFC), total polyphenols (TPC), ferric reducing-antioxidant activity (FRAP), and 2, 2′-diphenyl-1-picrylhydrazyl (DPPH) were determined. Accordingly, optimal settings were obtained where TP = 80.0 °C, ET = 14.99 min, and UP = 99.2 °C. These conditions caused TPC, TFC, FRAP, and % DPPH values to reach 4163.6 mg GAE/kg, 2731.6 mg RE/kg, 2.16 mmol/L, and 85.2% respectively, with general-desirability values of 1.00. In addition, DPPH (R = 0.950) and FRAP (R = 0.962) correlated with TPC, indicating that TPC contributed significantly to antioxidant activity. It was found that UAE extraction yields were higher than conventional extraction yields.
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This study addressed the formation of co‐crystals from Quercetin and Curcumin by mechanochemical treatment employing ball mill grinding. The binary system was initially studied using molecular complementarity and hydrogen bond propensity analysis structural tools available in Mercury software. This study was performed from CCDC reported structural data for Curcumin and Quercetin dihydrate used as starting reagents. Reaction conditions, such as Quercetin: Curcumin molar ratio, grinding time, and solvent‐assisted variables, were optimised to synthesise a new solid phase from the binary system. The synthesised product was characterised by differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and powder X‐ray diffraction techniques. Finally, to compare the anti‐oxidant capacities from the pure components, eutectic mixtures previously reported and the new crystalline phase was evaluated in vitro using the 1,1‐diphenyl‐2‐pycril‐hydrazylhydrate radical inhibition method. The co‐crystal phase and eutectic mixtures present higher anti‐oxidant activity with values around 5.0 mg/L compared to pure Quercetin (3,444 mg/L) and Curcumin (9,141 mg/L), using only half of the molecules. These results indicate Quercetin molecule is synergically active with the Curcumin molecule in the binary mixtures.
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Background Rhus vulgaris is rich in various polyphenols and flavonoids that act as free radical scavengers, reduce oxidative stress, and cure various harmful human diseases. Traditionally, the plant is used to treat various diseases including cancer. Methods This study involved extraction using the solvents hexane, acetone, and 80% aqueous methanol, phytochemical screening, and antimicrobial testing. Using the spectrophotometric techniques of Folin-Ciocalteu and aluminum chloride, respectively, the plant's total phenolic and flavonoid contents were determined. The extracts' activity was assessed with the help of the (DPPH) radical scavenging assay. Results The extracts mostly contain alkaloids, phenols, flavonoids, glycosides, tannins, steroids, carbohydrates, and anthraquinones. Compared to the standard, the methanol extracts showed better inhibitory zones. Results revealed that total polyphenols and flavonoid contents were in the range of 5.82 ± 0.6–83.23 ± 0.6 mg GAE/100 g and 2.21 ± 0.34–23.47 ± 0.87 mg CE/100 g, respectively. Leaves extracts of R.vulgaris was found to have higher antioxidant activities ranging from 0.756 ± 0.8 to 131.56 ± 0.6 mg AAE/g sample. Conclusion The R. vulgaris 80% methanolic extract displayed the highest phenolic and flavonoid concentrations as well as a powerful antioxidant capacity. It could be used as an antibiotic for different curable and incurable diseases.
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Abstract This study aims to add value to a common wine industry waste by preserving bioactive compounds in cold‐hardy grape pomace (GP) and preventing any microbial growth under the proper drying conditions. Effects of infrared (IR) and hot air (HA) drying on the microbial and physicochemical properties such as color, phenolic compounds, and antioxidant activity of white (Edelweiss) and red (Marquette) GP were studied. The IR heating rapidly reduced the moisture content of GP from 55% wet basis (w.b.) to less than 10%, which resulted in a drying time reduction of 71.9% to 80.2% compared to HA drying. There were no significant differences in color parameters among the IR‐ and HA‐dried pomaces (p > .05). The phenolic content of ‘Edelweiss’ pomace was not significantly affected by both IR and HA drying, whereas the phenolic content of ‘Marquette’ pomace was substantially reduced from 274 mg/g dry extract in raw pomace to 127 mg/g dry extract after HA drying and to 141.9 mg/g dry extract after IR drying. Overall, the microbial load on the fresh pomace samples was dramatically reduced by IR heating, with a reduction of more than 99.9% when the pomaces were dried using IR at a temperature higher than 130°C. However, this high temperature of IR led to a significant reduction of DPPH antiradical scavenge activity for ‘Edelweiss’ pomace (p
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Plectranthus amboinicus is an herb which possesses antimicrobial, antioxidant, anticancer and antiepileptic properties and used as a traditional medicine in Southern parts of India. The study is intended to assess the antioxidant potential of the methanolic extracts of Plectranthus amboinicus leaves using different radical scavenging assays namely DPPH, ABTS, nitric oxide, hydrogen peroxide and superoxide at different concentrations (20-100 μg/ml). The results signified that the methanolic extract exhibited increased scavenging activity in the above tested assays in a dose dependent manner. Hence, Plectranthus amboinicus offers persuasive antioxidant components which might lead to the exclusion of Reactive Oxygen Species mediated ailments by scavenging free radicals or preventing the oxidation of biomolecules.
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Introduction Red wines are characterized of a high number of phenolic compounds. These amounts (e.g., Flavonoids and polyphenols) reduce oxidative stress. Tea (especially green) is one of the most frequently consumed plant-based drinks worldwide due to its unique aroma. Besides that, tea as red wines are also characterized by health-promoting properties due to its phenolic amount. Addition of tea leaves to a quantity of wine leads to extraction of chemical compounds which leads to changes in phenolic profile. In this study antiradical activity (AAR) of red wines was measured before and after addition of tea leaves (by using DPPH free radical method).
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This is my Habilitation thesis, in order to have the right to coordinate PhD students.
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α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method offers the first approach for evaluating the antioxidant potential of a compound, an extract or other biological sources. This is the simplest method, wherein the prospective compound or extract is mixed with DPPH solution and absorbance is recorded after a defined period. However, with the advancement and sophistication in instrumental techniques, the method has undergone various modifications to suit the requirements, even though the basic approach remains same in all of them. This article presents a critical review on various developments to the DPPH method.
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Applications of antioxidants are increasing due to their multiple roles in minimising harmful effects of oxidative stress. 2,2-diphenyl-1-picrylhydrazyl (DPPH�) radical scavenging assay is routinely practiced for the assessment of antiradical properties of different compounds. A detailed literature survey revealed use of different materials and methods for DPPH� assay by different investigators resulted in variation in the values of reference standards and measured parameters of new antioxidants. In the present work a detailed kinetic study of antioxidants has been performed and comprehensive results in terms of effective concentration which scavenges 50% radical (EC50), antioxidant reducing power (ARP), stoichiometry and second order rate constant (k2) values have been reported with DPPH� assay. Importance of selection of appropriate reference compounds and kinetic calculations are suggested. Few case studies of standard antioxidants have been discussed to emphasise the utilisation of appropriate methodology and reference compounds.
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The use of the stable free radical diphenylpicrylhydrazyl (DPPH) to estimate the activity of antioxidants is reviewed. Current applications of the method are examined, particularly the use of the parameter EC50 (substrate concentration to produce 50% reduction of the DPPH). Some recommendations are made as to the most suitable ways of carrying out this assay and evaluating the data produced.
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Red wine is a rich source of polyphenols, which exhibit a number of biological effects in different in vitro and in vivo systems. The bioavailability of polyphenols is poor and the plasma concentrations of major red wine polyphenols are usually low after consumption of dietary relevant amounts of red wine. In contrast to most organ systems, the gastrointestinal tract (particularly the epithelial cells of this organ system) is exposed to high concentrations of polyphenols. Here, we show that the total polyphenol pool isolated from a red wine (varity Lemberger, vintage 1998) at micromolar concentrations inhibited the proliferation of transformed colon epithelial cells HT 29 clone 19A induced by epidermal growth factor (EGF). Inhibition of proliferation was also associated with modulation of activation of mitogen-activated protein kinases (MAPK). Stress activated c-Jun N-terminal kinases 1/2 (JNK) and p38 MAPK were significantly activated by red wine polyphenols (6 mmol/L). Maximum phosphorylation of both MAPK was observed after a 1-h treatment with red wine polyphenols. In contrast, activation of extracellular signal regulated kinase (ERK) 1/2 by EGF (1 nmol/L) was significantly inhibited by red wine polyphenols (6 mmol/L). This signaling pattern, activation of JNK 1/2 and p38 MAPK and inhibition of ERK 1/2, is typical for antiproliferative compounds, indicating that red wine polyphenols may inhibit the proliferation of colon carcinoma cells by modulating MAPK intracellular signal transduction pathways.
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A high-throughput relative 2,2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging capacity (RDSC) assay was developed and validated in the present study. This RDSC assay is easy to perform and has acceptable accuracy (90-110% recovery), precision [3.9-7.0% pooled relative standard deviation (RSD)], and reproducibility (2.2 and 3.5% interday and intraday RSD). This assay reports the RDSC values for antioxidant samples, which make it possible to compare the DPPH radical scavenging capacities of antioxidants determined in different laboratories. The RDSC assay may be conducted in aqueous alcohol and acetone for hydrophilic antioxidants or in the organic solvents for lipophilic antioxidants without solubilizing agents, which makes it possible to directly compare the radical scavenging capacities of hydrophilic and lipophilic antioxidants. In addition, the high-throughput RDSC assay could be utilized for EC50 value estimation. The high-throughput RDSC assay may be used for screening and investigating potential natural antioxidants.
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The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•). After addi‐tion of different standard concentrations to DPPH· (0·025 g litre⁻¹), the percentage of remaining DPPH• was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH• against reaction time followed a multiplicative model equation: ln [DPPHREM•]=b ln t+ln a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH• concentration (EC50). This parameter, EC50, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC50 (TEC50) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE=1/EC50TEC50. It was shown that AE is more discriminatory than EC50. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (×10⁻³) in the compounds tested was: ascorbic acid (11·44)>caffeic acid (2·75)⩾gallic acid (2·62)>tannic acid (0·57)⩾DL‐α‐tocopherol (0·52)>rutin (0·21)⩾quercetin (0·19)>ferulic acid (0·12)⩾3‐tert‐butyl‐4‐hydroxyanisole, BHA (0·10)>resveratrol (0·05). © 1998 SCI.
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The protective effect of moderate alcohol consumption on the risk of cardiovascular disease has been consistently shown in many epidemiological studies. Antiatherogenic alterations in plasma lipoproteins, particularly increase in high density lipoprotein (HDL) cholesterol, are considered as the most plausible mechanism of the protective effect of alcohol consumption on coronary artery disease (CHD). Other potential mechanisms contributing to the cardioprotective effect of moderate alcohol consumption include antithrombotic alterations of blood platelet function, as well as of the coagulation and fibrinolysis balance. Since early observations suggested that consuming alcohol in the form of wine might confer a protection against CHD above that expected from its alcohol content, the topic "wine and health" has become more and more popular. Many epidemiological studies have explored this possibility, by comparing specific alcoholic beverage types in respect to their relative capacity to reduce the risk of CHD. In parallel, experimental studies have been done, in which wine and wine-derived products have been tested for their capacity to interfere with molecular and cellular mechanisms relevant to the pathogenesis of CHD. Wine might indeed conceivably nave other non-ethanol related beneficial effects. The biological rationale for such a hypothesis has been linked to the enrichment in grape-derived, non-alcoholic components, that possibly make it peculiar in respect to other alcoholic beverages. In fact, while the mechanisms underlying the effects of alcohol on cardiovascular disease have oeen limited to lipid metabolism and the haemostatic system, those related to wine consumption have also been extended to specific antioxidant and vasorelaxant properties of its polyphenolic constituents. The purpose of this mini-review is to summarize: 1) the epidemiological studies reporting comparisons between wine and other alcoholic beverages and the relative risk of CHD; 2) the experimental and interventional studies with wine or wine-derived products aimed at finding biological explanations for the possible superior cardioprotective effects of wine consumption.
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Several of the most commonly used methods for in vitro determination of antioxidant capacity are reviewed in the present paper. The chemical principles of methods based either on biological oxidants (peroxyl radical, superoxide radical anion, hydrogen peroxide, hydroxyl radical, hypochlorous acid, singlet oxygen, nitric oxide radical, and peroxynitrite) or on non-biological assays (scavenging of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (TEAC assay), scavenging of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH assay), ferric reducing antioxidant power (FRAP assay), Folin-Ciocalteu reducing capacity (FC assay), electrochemical total reducing capacity) are outlined and critically discussed. The scope of application, the advantages and shortcomings of each method are also highlighted.
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Subcritical water extraction of phenolic compounds from grape pomace was performed. The combined effects of extraction temperature (100, 120 and 140 °C) and pressure (8 MPa, 11.5 MPa and 15 MPa) were investigated using a 32 full factorial design and response surface methodology. Extractions with significantly higher polyphenols, flavonoids and antioxidant activity were achieved when using subcritical water extraction compared to conventional methods. The optimum extraction conditions and the desirability of model were at 140 °C and 11.6 MPa (0.9550). At this operating condition, 31.69 mgGAE/gDP and 15.28 mgCE/gDP of total polyphenols and flavonoids were recovered, respectively. The extracts showed antiradical power of 13.40 μgDPPH/μlextract. Subcritical water extraction was more efficient than using water and ethanol at atmospheric pressure for the extraction of these compounds.
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Regular moderate wine consumption is often associated with reduced morbidity and mortality from a variety of chronic diseases in which inflammation is the root cause. This review is focused on three of the numerous bioactive compounds present in wine: resveratrol, hydroxytyrosol and melatonin. Resveratrol and hydroxytyrosol are polyphenols. Melatonin, recently described in wine, is an indoleamine. Their structures, concentrations in wine, bioavailability, pharmacokinetic and health promoting properties are reviewed. Resveratrol seems to be one of the most promising compounds due to its bioactivity, with wine being the main source of resveratrol in diet. Hydroxytyrosol, which its main source in diet is olive oil has been also found in both red and white wine in considerable amounts. Melatonin has been found in wine in low amounts. However, both high bioactivity and bioavailability have been attributed to it. They show antioxidant, cardioprotective, anticancer, antidiabetic, neuroprotective and antiaging activities. However, human studies are still in the initial stages and therefore further studies are needed.
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Cold-pressed chardonnay, muscadine, ruby red, and concord grape seed oils and their defatted flours were studied for their fatty acid composition, oxidative stability and antioxidant and antiproliferative activities. The phenolic profiles of the seed flours were also measured. The most abundant fatty acid in the oils was linoleic acid, ranging from 66.0g/100g of total fatty acids in ruby red seed oil to 75.3g/100g of total fatty acids in concord seed oil. The oils were also high in oleic acid and low in saturated fat. Ruby red grape seed oil recorded the highest oxidative stability index of 40h under the accelerated conditions. Total phenolic content (TPC) was up to 100 times lower in the oils than in the flours. Lutein, zeaxanthin, cryptoxanthin, β-carotene, and α-tocopherol levels were also measured. DPPH radical-scavenging capacity ranged from 0.07 to 2.22mmol trolox equivalents (TE)/g of oil and 11.8 to 15.0mmol TE/g of flour. Oxidative stability of menhaden fish oil containing extracts of the seed flours was extended by up to 137%. HPLC analysis was conducted to determine the levels of free soluble, soluble conjugated and insoluble bound phenolics in the seed flours. The phenolic compounds analyzed included catechin, epicatechin, epicatechin gallate, quercetin, gallic acid, and procyanidins B1 and B2. Antiproliferative activity was tested against HT-29 colon cancer cells. All of the seed flours and muscadine seed oil registered significant (P
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Free radical generation is directly related with oxidation in foods and biological systems. Therefore, the search for methods to determine free radical scavenging is important. In this work are described the methods used for this purpose in both substrates as well as in specific cases of their application. The main methods comprise superoxide radicals scavenging (O2·-); hydrogen peroxide scavenging (H2O2); hypochlorous acid scavenging (HOCl); hydroxyl radical scavenging (HO.); peroxyl radical scavenging (ROO.), among them are the methods that use azo-compounds to generate peroxyl radicals, such as the ``TRAP'' method (Total Radical-Trapping Antioxidant Parameter) and the ``ORAC'' method (Oxygen-Radical Absorbance Capacity); the scavenging of radical cation 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) or the ABTS or the ``TEAC'' method (Trolox Equivalent Antioxidant Capacity); the scavenging of stable radical 2,2-diphenyl-1-picrylhydrazyl or DPPH . method and the scavenging of radical cation N,N-dimethyl-p-phenylenediamine or DMPD method. At present, in spite of the diversity of methods, there is a great need to standardize measurements of antioxidant activity. The search for more specific assays, giving us chemical information that could be related directly to oxidative deterioration of foods and biological systems could be the objective of future research.
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The anthocyanic composition of must and different types of Port wine (Ruby, LBV and Tawny from nine producers) was evaluated by HPLC. In addition, the radical scavenging activity of these Port wines was evaluated by using DPPH radical microassay. Musts, Ruby and LBV Port wines presented similar qualitative profiles of anthocyanins and quantitative differences, ranging from 382–601, 92–156 and 32–78 mg of malvidin-3-O-glucoside equivalent/l, respectively. Anthocyanins in Tawny Port wines ranged between not detected and 51 mg of malvidin-3-O-glucoside equivalent/l. Principal component analysis was applied to the percentage (in weight) of each compound in relation with the total content of anthocyanins. PCA yielded two components explaining 90.9% of the total variance. The first PC correlates positively with the glucoside derivatives of delphinidin, cyanidin, petunidin and malvidin. The second PC correlates positively with pyruvic acid adducts of anthocyanins that resulted from vinification process. Ruby and LBV presented low amounts of glucoside derivatives and variable amounts of pyruvic acid adducts of anthocyanins. Acid hydrolysis allowed the identification of five anthocyanidins. Malvidin was the most abundant one. LBV Port wine showed the strongest antiradical activity, while Tawny Port wines revealed the lowest ones, with these wines presenting lower amounts of anthocyanic compounds owing to their ‘‘oxidative’’ aging in wooden barrels. These results suggest that aging process is an important factor influencing the antioxidant activity of Port wines.
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METHODS for measuring antioxidants and appraising antioxidant activity appear to be of two general types. If the chemical nature of the antioxidant is known, one may strive for a test specific for the compound or group of interest; for example, the nitroprusside test for sulphydryl groups. Alternatively one may observe the inhibition of some natural oxidative process such as the β-oxidation of fats, as a function of the added antioxidant.
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Grape skin extracts from pinot noir and pinot gris exhibited significant in vitro antiviral (influenza virus) activity. Five tea infusions from grape skins (Vitis vinifera var. pinot noir and pinot gris) without any additives (control pinot noir and control pinot gris) or by adding variable amounts of green tea and hibiscus were investigated as a means to utilise wine wastes. The antioxidant activities (DPPH scavenging capacity and superoxide anion radical scavenging capacity), total phenolics, the polyphenolics profile and objective colour measurements (CIELab) were determined on freeze-dried water extracts of all five tea infusions, hibiscus and green tea. The colour parameters, L∗ and a∗ values, varied widely (P < 0.05) for all the infusions as a result of having different levels and variety of pigments. The tea infusions exhibited weak antioxidant activity and the antiviral activity in grape skin appears not related to phenolics contents.Highlights► New antiviral activity (influenza virus) for hot-water grape skin extracts. ► Antiviral activity of grape skin may not be dependent on total phenolic content. ► Grape skin tea infusions could be used in functional beverages.
Article
A novel method for measuring the antioxidant activity using N,N-dimethyl-p-phenylenediamine (DMPD) was developed. The radical cation of this compound gives a stable colored solution and a linear inhibition of color formation can be observed in the presence of 0.2−11 μg of TROLOX. The experimental protocol, which is rapid and inexpensive, ensures sensitivity and reproducibility in the measure of antioxidant activity of hydrophilic compounds. The effectiveness of the DMPD method on real foods was verified by evaluating the antioxidant ability of wine samples coming from different areas of Campania, Italy. Antioxidant capacity of wines is strictly related to the amount of phenolic compounds. The results obtained by the DMPD method are very similar to those obtained on the same samples when the radical cation of 2,2‘-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (Miller et al., 1996) was used. Keywords: Antioxidant activity; DMPD; radical cation; ABTS; wine
Article
The concentrations of phenolics of three grape varieties and two red wines were determined. The red grape variety and the red wines contain phenolics at concentrations of 920 mg/kg and 1800 and 3200 mg/L, respectively. The antioxidative effects of wine phenolics on the catalysis of lipid peroxidation by biological catalysts such as myoglobin, cytochrome c, iron ascorbate, and copper ions were estimated. Lipid peroxidation catalyzed by myoglobin, cytochrome c, and iron ascorbate was inhibited (I-50) by wine phenolics at concentrations of 0.2, 0.35, and 0.9 mu g of phenolics/mL. The antioxidative effects of wine phenolics were determined also in a system containing low-density lipoproteins (LDL) oxidized ex vivo by CU2+ ions. The inhibition of LDL oxidation by wine phenolics was compared with that by alpha-tocopherol. The results show I-50 inhibitions of less than 1 mu M for wine phenolics and 2 mu M for alpha-tocopherol, respectively. The nutritional implications of natural antioxidants at high concentration in grapes, wines, and byproducts, and their utilization in foods, are discussed.
Article
The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH•). After addi-tion of different standard concentrations to DPPH· (0·025 g litre−1), the percentage of remaining DPPH• was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH• against reaction time followed a multiplicative model equation: ln [DPPHREM•]=b ln t+ln a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH• concentration (EC50). This parameter, EC50, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC50 (TEC50) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE=1/EC50TEC50. It was shown that AE is more discriminatory than EC50. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (×10−3) in the compounds tested was: ascorbic acid (11·44)>caffeic acid (2·75)⩾gallic acid (2·62)>tannic acid (0·57)⩾DL-α-tocopherol (0·52)>rutin (0·21)⩾quercetin (0·19)>ferulic acid (0·12)⩾3-tert-butyl-4-hydroxyanisole, BHA (0·10)>resveratrol (0·05). © 1998 SCI.
Article
In this study, 73 South American red wines (Vitis vinifera) from 5 varietals were classified based on sensory quality, retail price and antioxidant activity and characterised in relation to their phenolic composition. ORAC and DPPH assays were assessed to determine the antioxidant activity, and sensory analysis was conducted by seven professional tasters using the Wine & Spirits Education Trust’s structured scales. The use of multivariate statistical techniques allowed the identification of wines with the best combination of sensory characteristics, price and antioxidant activity. The most favourable varieties were Malbec, Cabernet Sauvignon, and Syrah produced in Chile and Argentina. Conversely, Pinot Noir wines displayed the lowest sensory characteristics and antioxidant activity. These results suggest that the volatile compounds may be the main substances responsible for differentiating red wines on the basis of sensory evaluation.Highlights► Red wine’s price does not correlate to antioxidant activity. ► We found 3 red wine varieties with best sensory properties and antioxidant activity. ► Gallic acid, quercetin and myricetin associated with the antioxidant activity.
Article
Free radical scavenging capacity of the extracts from red and white grape pomace peels (RGPP, WGPP) and as a reference for two commonly used antioxidants (BHA (synthetic) and DL-R-tocopherol (natural) heated at processing temperatures (80, 100, and 120 °C) was evaluated using the 2,2-diphenyl-1-picrylhidrazyl (DPPH •) reagent. Kinetic behavior of the sample extracts did not change when they were heated, following a general multiplicative model in which remaining DPPH • was more affected by temperature than the time needed to reach the steady state. The reduction of this property in the sample extracts heated at 120 °C as compared to those at 20 °C followed an increasing order: BHA (15.3%) < WGPP (22.9%) < RGPP (28.3%) < DL-R-tocopherol (69.8%). Color losses were also measured by a tristimulus colorimeter HunterLab and two parameters were used to express the sample extract color: hue angle (tan b*/a*) -1 and a*/b* ratio. The higher red color losses in RGPP extracts (12.9 times in hue angle) as compared to the yellow color losses in the WGPP extracts (1.5 times in a*/b* ratio) during heating may explain their differences in the free radical scavenging capacity.
Article
Synopsis Many analytical methods are used to measure the antioxidative activity of substances yet little is known about the comparability of the test results between laboratories. After an initial evaluation of a broad range of methods conducted by one laboratory, the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay, the trolox equivalent antioxidant capacity (TEAC) assay, the lipid assay (or 2,2′‐azobis(2‐aminepropane) (ABAP) assay) and the thiobarbituric acid (TBA) assay were selected to be evaluated in the interlaboratory study. The antioxidative potentials of trolox, tocopherol, lipochroman‐6, ascorbic acid, 4‐methyl‐brenzcatechin, and/or 3,5‐di‐tert‐butyl‐4‐hydroxytoluene (BHT) were assessed using each of the methods. These methods were then evaluated in respect of their reproducibility and classification properties. Based on the results of this study, the DPPH assay followed by the TEAC assay yielded the best results based on reproducibility and sensitivity both within one laboratory and between laboratories. The results of the interlaboratory study were then compared with the single center results obtained from the commercially available photochemolumiescence (PCL) kit. To assess the transferability of chemical data to biological systems, they were also compared with the single center results obtained using the cell‐based Dichlorodihydrofluoresceine (DCFH) assay.
Article
Antioxidants are important because they prevent lipid oxidation in food, and decrease the adverse effects of reactive species on normal physiological functions in humans. A wide variety of in vitro chemical models have been developed to assess the ability to prevent oxidative damages; amongst the chemical tests that measure radical scavenging capacity, the DPPH assay is one of the most widely employed method. EC50 (concentration required to obtain a 50% antioxidant capacity) is typically employed to express the antioxidant activity and to compare the antioxidant capacity of various samples; however its measurement requires some care, because of the non-linear relation between antioxidant concentration and antiradical activity. In this work a statistical software was developed in order to apply different linearising transformations in the study of DPPH-scavenging properties of antioxidants. The software was also implemented to perform the determination of outliers, the calculation of the EC50 values and the comparison of the curves, and of their corresponding straight lines, obtained from the regression analysis of the data. First, the analysis of the DPPH-scavenging activity was performed on standard molecules and then applied to different food extracts. The regression models employed in this work (probit, logit and angular regressions) appeared to be equivalent and to fit well the antiradical activity curves obtained for both standard molecules and food extracts; probit regression was finally chosen to discuss the results and to introduce a new parameter characterising these curves.
Article
A comparative study of the antioxidant activity of wine phenolics has been performed. Standards of phenolic compounds, including benzoic and cinnamic acids, flavanols, flavonols and resveratrol, as well as some of their metabolites have been analysed for their antioxidant activity. Antioxidant assays included the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods and the Oxygen Radical Absorbance Capacity method (ORAC).We compared the reactivity of standard phenolic compounds under selected tests and obtained a ranking order for each one. Both ABTS and DPPH methods were well correlated. Several new structure–activity relationships were observed. As the number of phenoxyl groups increases, the antioxidant capacity, determined by DPPH and ABTS tests, improves. In the case of the ORAC assay, the ortho-position of phenoxyl groups clearly determines the activity. The metabolites of phenolic compounds present antioxidant activity and their values are similar to those of the phenolic compounds themselves.The choice of solvent, the effect of concentration and the information provided by the three tests under study are considered.
Article
The antiradical activities of various antioxidants were determined using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH*). In its radical form. DPPH* has an absorption band at 515 nm which dissappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPH* and shown to follow one of three possible reaction kinetic types. Ascorbic acid, isoascorbic acid and isoeugenol reacted quickly with the DPPH* reaching a steady state immediately. Rosmarinic acid and δ-tocopherol reacted a little slower and reached a steady state within 30 min. The remaining compounds reacted more progressively with the DPPH* reaching a steady state from 1 to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometry of 4 to 6 reduced DPPH* molecules per molecule of antioxidant. Vanillin, phenol, γ-resorcylic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry for the other 13 phenolic compounds varied from one to three reduced DPPH* molecules per molecule of antioxidant. Possible mechanisms are proposed to explain the experimental results.
Article
Winery waste (from red winemaking, variety Agiorgitiko) was extracted under various conditions using different solvents. The minimum time required for ensuring maximum extraction of phenols was 180 min at a solvent to sample ratio 9:1 v/w and at pH 1.5. The antioxidant activity of solvent extracts was investigated by DPPH radical scavenging method, by determination of peroxide value on virgin olive oil and by the Rancimat method on sunflower oil. Ethanol extract exhibited the highest antioxidant activity compared to the other solvent extracts, to synthetic food antioxidants BHT, ascorbyl palmitate and to the natural food antioxidant, vitamin E. No correlation was found between antioxidant activity and total phenol content. HPLC analysis of the extracts showed that gallic acid, catechin and epicatechin were the major phenolic compounds in winery waste. Hydroxytyrosol, tyrosol, cyanidin glycosides and various phenolic acids such as caffeic, syringic, vanillic, p-coumaric and o-coumaric acids were also identified.
Article
The reaction mechanisms of three antioxidants are proposed in order to explain experimental results obtained from a kinetic study using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH.) method, previously adapted in our laboratory. In its radical form, DPPH.shows an absorbance maximum at 515 nm which disappears upon reduction by an antiradical compound. BHT, a synthetic antioxidant, slowly reacts with DPPH.reaching a steady state within 5 h. This 2.8-stoichiometric complete reaction follows a 1.5-order with respect to DPPH.and 0.5 to BHT. The kinetic rate constant, k, is estimated to be 5.0 L/(mol·s) at 20 °C and the energy of activation,Ea, is equal to 35 kJ/mol in methanol. Eugenol reacts with DPPH.reaching a steady state within 2 h. This 1.9-stoichiometric reaction follows a 2-order with respect to both DPPH.and eugenol, k andEaare estimated to be 5.4 × 1010L3/(mol3·s) at 20 °C and 30 kJ/mol, respectively. The eugenol mechanism may involve a dimerization between two phenoxyl radicals. The reaction with isoeugenol is rapid and reversible, with a stoichiometry of 1.1. It is first order with respect to isoeugenol with k (direct reaction) equal to 8.9 × 10−2s−1at 10 °C. This reaction is consistent with a pseudo-monomolecular mechanism.
Article
Scavenging of DPPH free radical is the basis of a common antioxidant assay. A number of protocols have been followed for this assay resulting in variation in the results of different laboratories. We present a perspective of the protocols followed by different workers with incongruity in their results and recommend a standard procedure within the sensitivity range of spectrophotometry. Three common standard antioxidants viz. ascorbic acid, BHT and propyl gallate have been used in this study. The IC50 values for ascorbic acid and propyl gallate were 11.8 μM and 4.4 μM in methanol and 11.5 μM and 4.7 μM in buffered methanol as reaction medium, respectively. The free radical scavenging by BHT was markedly influenced by the reaction medium. The IC50 values were 60.0 μM and 9.7 μM when the reaction was done in methanol and buffered methanol, respectively.
Article
The phenolic compounds content and antioxidant activity of pomace from the vinification of grape varieties widely produced in Brazil (Cabernet Sauvignon, Merlot, Bordeaux and Isabel) were investigated with a view to their exploitation as a potential source of natural antioxidants. Cabernet Sauvignon grape pomace was found to have the highest content of total phenolic compounds (74.75 mg gallic acid equivalent (GAE)/g), the highest antioxidant activity (determined using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging methods; 485.42 and 505.52 μMol Trolox equivalent antioxidant capacity (TEAC)/g, respectively), and the highest reducing power (determined using the FRAP method; 249.46 μMol TEAC/g). The Bordeaux variety showed the highest oxidation inhibition power (41.13%), determined using the β-carotene/linoleic acid method and the highest content of total anthocyanins (HPLC; 29.17 mg/g). Catechin was the most abundant non-anthocyanic compound identified in the grape pomace (150.16 mg/100 g) for all varieties. In this study, pomaces of the red wine vinification of Cabernet Sauvignon and Bordeaux varieties showed the highest potential as a source of antioxidant compounds and natural colourants, respectively.
Article
Phenolic complexes are a major group of polyphenols in aged red wine. The objective of this work was to evaluate the in vitro antioxidant activity of the phenolic complexes. Thus, red wine polyphenols were fractionated into various fractions including monomers, oligomers, polymers, anthocyanins, and complexes. The in vitro antioxidant activities of these fractions and other phenolic standards (catechin, epicatechin, quercetin, and malvidin 3-glucoside) as well as ascorbic acid were verified by DPPH* test. On the other hand, the variation of antioxidant activities during the reaction between epicatechin and malvidin 3-glucoside mediated by acetaldehyde in a model wine solution was also monitored. The results showed that both the phenolic complex fraction and newly formed condensation products between epicatechin and malvidin 3-glucoside maintain antioxidant activities as strong as those of their compositional phenolics. This work provides, for the first time, direct evidence about the in vitro antioxidant activities of red wine phenolic complexes.
Article
An ethanol extract of the stem of Opuntia ficus-indica var. saboten (OFS) was assessed to determine the mechanism(s) of its antioxidant activity. The ethanol extract exhibited a concentration-dependent inhibition of linoleic acid oxidation in a thiocyanate assay system. In addition, the OFS extract showed dose-dependent free-radical scavenging activity, including DPPH radicals, superoxide anions (O(2)(*-)), and hydroxyl radicals (*OH), using different assay systems. The OFS ethanol extract was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in a Fenton's reaction mixture. Furthermore, the extract showed significant (p < 0.01) dose-dependent protection of mouse splenocytes against glucose oxidase-mediated cytotoxicity. Finally, the OFS extract was characterized as containing a high amount of phenolics (180.3 mg/g), which might be the active compounds responsible for the antioxidant properties of the OFS extract.
Article
Many byproducts and wastes generated by agroindustries contain polyphenols with potential application as food antioxidants and preventive agents against skin cancer and other diseases. The performance of polyphenolic fractions from Parellada grape (Vitis vinifera) pomace as antioxidants in different physicochemical environments was tested. Fractions containing oligomers with mean degree of polymerization between 3 and 4 and percentage galloylation ca. 30% were the most potent free radical scavengers and efficient antioxidants in an oil-in-water emulsion. A fraction including glycosylated flavonols was also efficient in the emulsion. All the fractions showed low aquatic toxicity and weak influence on proliferation of human melanoma cells.