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 IC
50 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 IC
50 values were 60.0
μM and 9.7
μM when the reaction was done in methanol and buffered methanol, respectively.
Pomegranate fruit is to rich in phenolic compounds and antioxidant properties and can show difference in the composition according to cultivars, part of fruit, environmental conditions and analysis ...method. Therefore, the aim of the present study was to analyse and to compare the chemical composition and antioxidant properties from the different parts of fruit Valenciana and Wonderful pomegranate cultivars. The pomegranate fruits were separated into aril, peel, membrane and seeds manually and analysed by phenolic compounds, flavonoids, antioxidant activity (DPPH method), soluble solids, titratable acidity, pH and vitamin C content. The phenolic content and flavonoids were significantly affected by pomegranate cultivars and part of fruit. In the part of fruit showed differences by the DPPH, however the pomegranate cultivars not showed. Significant differences were revealed between the pomegranate cultivars and part of fruit for total soluble solids, titratable acidity and pH. The differents part of pomegranate fruit (aryl, membrane peeling and seed) has influences on the phenolic content, flavonoids, antioxidants, total soluble solids, pH and acidity. The cultivar does not show diffences on the antioxidants by DPPH method, pH and vitamin C.This study suggests the importance of the selection the different parts of fruit and cultivar that will be used as raw material in the preparation of pomegranate products with higher antioxidant activities.
► Simple TLC-DPPH method was standardized. ► Influence of adsorbent type, time and solvent of derivatizing agent solution was examined. ► Antioxidant activity of selected natural polyphenolics was ...investigated.
TLC-DPPH test belongs to a group of frequently performed assays aimed at detection of compounds with desired activity (effect directed analysis). Despite its popularity a standard procedure has not been elaborated so far causing difficulties in comparing results obtained in different laboratories. Thus the aim of the presented research was an approach to develop a standardized procedure for assessing free radical scavenging properties of plant polyphenols. It was observed that specifically positive adsorbent (silica gel) strengthened the observed result of radical-antioxidant reaction, while polar bonded stationary phase CN-silica weakened it. Based on the observed results it was concluded that the TLC-DPPH assay should be preferably performed on the surface of non-specific adsorbents (e.g.: RP-18) with the use of n-hexane for DPPH dissolution. It is also proposed to document the results every 5min after staining, as they change in time.
Use and Abuse of the DPPH(•) Radical Foti, Mario C
Journal of agricultural and food chemistry,
2015-Oct-14, Letnik:
63, Številka:
40
Journal Article
Recenzirano
The 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) radical is approaching 100 years from its discovery in 1922 by Goldschmidt and Renn. This radical is colored and remarkably stable, two properties that ...have made it one of the most popular radicals in a wide range of studies. First, there is the evaluation of the antioxidant abilities of phenols and other natural compounds (A-H) through a "test" that-at a closer look-is utterly inappropriate. In fact, the test-derived EC50, that is, the concentration of A-H able to scavenge 50% of the initial DPPH(•), is not a kinetic parameter and hence its purported correlation with the antioxidant properties of chemicals is not justified. Kinetic measurements, such as the second-order rate constants for H-atom abstraction from A-H by DPPH(•), in apolar media, are the only useful parameters to predict the antioxidant ability of A-H. Other applications of DPPH(•) include kinetic and mechanistic studies, kinetic solvent effects, EPR spectroscopy, polymer chemistry, and many more. In this review these applications are evaluated in detail by showing the usefulness of some and the uselessness of others. The chemistry of DPPH(•) is also briefly reviewed.
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. EC
50 (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 EC
50 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.
The antiradical capacity (radical-scavenging capacity, RSC) of seven tropical fruit from the Brazilian north-east (açaí, acerola, cashew apple, mangaba, murici, umbu and uvaia) were studied using the ...2,2-diphenyl-1-picrylhydrazyl radical (DPPH
) assay. To determine their RSC, the second-order rate constants (
k
2) for the oxidation of these extracts by DPPH
were calculated. The values of
k
2 were compared to natural and synthetic antioxidants. The
k
2 values (l/mol
g
s), in methanol at 25
°C, were 38.0, 29.7, 21.3, 20.1, 10.1, 9.54 and 5.47 for acerola, cashew apple, mangaba, umbu, açaí, uvaia and murici, respectively.
•C60 Fullerene adduct with glycine (C60-Gly) was synthesised.•C60-Gly physicochemical characteristics were investigated.•C60-Gly binds to human serum albumin and can be applied as a drug ...carrier.•C60-Gly possesses pronounced antioxidant properties in the reaction with DPPH radical.
The article presents a comprehensive physicochemical and biological study of water-soluble fullerene adduct with glycine. The investigation included density, speed of sound, and viscosity temperature and concentration data with subsequent calculation of thermodynamic characteristics; correlation of the obtained results using fourth-order polynomial; determination of associate sizes; measurements of isobaric heat capacity; binding to human serum albumin; antiradical activity in the reaction with 2,2-diphenyl-1-picrylhydrazyl radical.
A novel Streptomyces, strain MUSC 149(T) was isolated from mangrove soil. A polyphasic approach was used to study the taxonomy of MUSC 149(T), which shows a range of phylogenetic and chemotaxonomic ...properties consistent with those of the members of the genus Streptomyces. The diamino acid of the cell wall peptidoglycan was LL-diaminopimelic acid. The predominant menaquinones were identified as MK9(H8) and MK9(H6). Phylogenetic analysis indicated that closely related strains include Streptomyces rhizophilus NBRC 108885(T) (99.2% sequence similarity), S. gramineus NBRC 107863(T) (98.7%) and S. graminisoli NBRC 108883(T) (98.5%). The DNA-DNA relatedness values between MUSC 149(T) and closely related type strains ranged from 12.4 ± 3.3% to 27.3 ± 1.9%. The DNA G + C content was determined to be 72.7 mol%. The extract of MUSC 149(T) exhibited strong antioxidant activity and chemical analysis reported identification of an antioxidant agent, Pyrrolo1,2-apyrazine-1,4-dione, hexahydro-. These data showed that metabolites of MUSC 149(T) shall be useful as preventive agent against free-radical associated diseases. Based on the polyphasic study of MUSC 149(T), the strain merits assignment to a novel species, for which the name S. mangrovisoli sp. nov. is proposed. The type strain is MUSC 149(T) (=MCCC 1K00699(T)=DSM 100438(T)).
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