Antiradical Efficiency Values Research Articles

THE ACTIVITY OF RADICAL SCAVENGING OF 2,2-DIPHENYL-1-PYCRILHYDRAZIL (DPPH) BY ETHANOLIC EXTRACTS OF MENGKUDU LEAVES (Morinda citrifolia L.), BROTOWALI STEM ( Tinospora crispa L.), ITS WATER FRACTION AND ITS HYDROLIZED FRACTION

We have investigated the antiradical activity of ethanolic extract of mengkudu leaves ( Morinda citrifolia L. ) and brotowali stem ( Tinospora crispa L. ) using radical scavenging assay or DPPH radical. Thin layer chromatograms were also studied to estimate the group of compounds that have antiradical activity. The objective of this research was to compare the DPPH antiradical efficiency values of water fraction and acid hydrolyzed water fraction in both extracts. The radical scavenging IC 50 value of ethanolic extract, water fraction, and hydrolised water fraction (one and thee hours) of mengkudu leaves were 75,65 µg/mL ; 98,68 µg/mL ; 36,27 µg/mL and 33,36 µg/mL respectively. The IC 50 value for brotowali stem were 33.75 µg/mL, 52.29 μg/mL, 31.12 μg/mL and 18.26 μg/mL. The highest antiradical activity was the hydrolyzed water fraction three hour namely 200 µg/mL of this fraction was able to inhibit 33.12% and 18.26 μg/mL DPPH radicals.

Antiradical properties of essential oils and extracts from clove bud and pimento

The antiradical properties of essential oils and extracts from the clove bud (Eugenia caryophyllata Thumb.) and berries of tree (Pimenta dioica (L.) Meriff) were studied and compared with the properties of synthetic antioxidant ionol (2,6-ditret-butyl-4-hydroxytoluene, BHT) in model reactions with the stable free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The essential oils of clove bud and pimento had qualitatively close composition of the main components but differed by their quantitative content. In the studied samples, eugenol was the main compound with high antiradical activity. The reaction rates of essential oils and extracts with the DPPH radical were practically the same for essential oils and twice the reaction rate of BHT. The values of antiradical efficiency (AE) were also close for essential oils and were twice that for extracts and ionol. A synergetic action of components in the essential oil and extract of pimento on antiradical efficiency values was found.

Антирадикальные свойства эфирных масел орегано, тимьяна и чабера

In model reactions with the stable free 2,2-diphenyl-1-picrylhydrazyl radical, the antiradical properties of essential oils of thyme (Thymus vulgare), oregano (Origanum vulgare), and savory (Satureja hortensis) that are similar in the qualitative composition, but differ in the quantitative content of the main components, were studied and compared with the properties of synthetic antioxidant ionol. The reaction rates of components of essential oils with the radical were almost identical for all essential oils and were twice the reaction rate of ionol. The antiradical efficiency values were close to each other for all essential oils and by an order of magnitude smaller than for ionol.

Comparison of the antiradical activity of ionol, components of fresh ginger, and its extracts

The antiradical properties of three samples of ginger (Zingiber officinale R.)-juice from fresh rhizome, essential oil, and extracts (oleoresin)-were studied and compared with the properties of synthetic antioxidant ionol (butylatedhydroxy-toluene, BHT). Reaction antioxidants with stable free 2,2-diphenyl-1-picrylhydrozyl radicals were used as model systems. DPPH equivalents per gram of ginger sample, EC50, and antiradical efficiency (AE) were determined. The EC50 and AE values for ginger oleoresin and BHT were similar. They were the same as those of highly active natural antioxidants, and the values for essential oil and ginger juice were lower by two orders of magnitude. On the base of kinetic parameters, the ginger samples may belong to antiradical compounds with prolonged action.

Scavenging activity of C4‐hydroxyphenyl‐ and polyhydroxyphenyl‐1,4‐dihydropyridines toward free radicals

AbstractThe radical‐scavenging ability of synthesized C4‐phenolic‐substituted 1,4‐dihydropyridines (1,4‐DHPs) toward 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•) and alkyl/alkylperoxyl ABAP‐derived radicals at pH 7.4 was assessed by UV–visible spectroscopy. Reactivity of 1,4‐DHPs toward DPPH• was measured by following the decay of the absorption corresponding to the radical λmax at 525 nm, permitting the calculation of EC50, tEC50, and antiradical efficiency values. Pseudo–first‐order kinetic rate constants for the reactivity between the C4‐phenolic‐substituted 1,4‐DHP compounds and alkyl/alkylperoxyl ABAP‐derived radicals were followed by the decrease in λmax at 356 nm corresponding to 1,4‐DHP moiety. C4‐phenolic‐substituted 1,4‐DHPs were more reactive toward alkyl free radicals than the other tested radicals. The 3,4,5‐trihydroxyphenyl‐1,4‐DHP was the most reactive derivative toward this radical with a kinetic rate constant value of 513.2 s−1. Also, this derivative was the most effective toward the DPPH• radical with the lowest EC50 value (5.08 µM). Comparative studies revealed that synthesized 1,4‐DHPs were more reactive than commercial 1,4‐DHPs. The scavenging mechanism involves the contribution of both pharmacophores, that is, hydroxyphenyl and 1,4‐DHP rings, which was supported by the identification of the reaction products. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 810–820, 2012

Relation of total antiradical activity and total polyphenol content of sweet cherries (Prunus avium L.) and tart cherries (Prunus cerasus L.)

In present study the quantification of total phenolics content (TPC), total antioxidant activity (TAA) and their relation in sweet and tart cherries were studied. Aqueous and pure polar solvents were used to compare the yield of present phenolic compounds in prepared extracts. The solubility of phenolics was the most effective in sweet cherry extracts with using of 50 % methanol and in tart cherry extracts with using of 50 % acetone. The yield of TPC of both tested cherry fruit extracts was higher with pure methanol in comparison to pure acetone. Substantial TPC assessed with Folin-Ciocealteu assay in tart cherry extracts were in range from 70.6?8.46 mg to 241.4?7.26 mg GAE/100 g FW. Extracts from lyophilised tart cherries (methanolic and water-acetone mixtures) contain in average 2-times higher amount of polyphenols than ethanol extracts. The DPPH antiradical efficiency values of the both tested fruit extracts were higher in extracts of tart cherries (from 5.4 to 9.9 % of inhibition of DPPH radical) when compared to those of sweet cherries (from 2.4 to 3.5 % of inhibition of DPPH radical). Total antioxidant activity (TAA) of sweet cherry extracts (using 70 % ethanol and with 70 % methanol) and of tart cherry extracts (with 50 % methanol) depended on phenolics content.

Relation of total antiradical activity and total polyphenol content of sweet cherries (Prunus avium L.) and tart cherries (Prunus cerasus L.)

In present study the quantification of total phenolics content (TPC), total antioxidant activity (TAA) and their relation in sweet and tart cherries were studied. Aqueous and pure polar solvents were used to compare the yield of present phenolic compounds in prepared extracts. The solubility of phenolics was the most effective in sweet cherry extracts with using of 50 % methanol and in tart cherry extracts with using of 50 % acetone. The yield of TPC of both tested cherry fruit extracts was higher with pure methanol in comparison to pure acetone. Substantial TPC assessed with Folin-Ciocealteu assay in tart cherry extracts were in range from 70.6±8.46 mg to 241.4±7.26 mg GAE/100 g FW. Extracts from lyophilised tart cherries (methanolic and water-acetone mixtures) contain in average 2-times higher amount of polyphenols than ethanol extracts. The DPPH antiradical efficiency values of the both tested fruit extracts were higher in extracts of tart cherries (from 5.4 to 9.9 % of inhibition of DPPH radical) when compared to those of sweet cherries (from 2.4 to 3.5 % of inhibition of DPPH radical). Total antioxidant activity (TAA) of sweet cherry extracts (using 70 % ethanol and with 70 % methanol) and of tart cherry extracts (with 50 % methanol) depended on phenolics content. IZVLECEK

Fatty Acids, Sterols, and Antioxidant Activity in Minimally Processed Avocados during Refrigerated Storage

Avocado ( Persea americana Mill.) is a good source of bioactive compounds such as monounsaturated fatty acids and sterols. The impact of minimal processing on its health-promoting attributes was investigated. Avocados cut into slices or halves were packaged in plastic bags under nitrogen, air, or vacuum and stored at 8 degrees C for 13 days. The stabilities of fatty acids and sterols as well as the effect on antioxidant activity were evaluated. The main fatty acid identified and quantified in avocado was oleic acid (about 57% of total content), whereas beta-sitosterol was found to be the major sterol (about 89% of total content). In general, after refrigerated storage, a significant decrease in fatty acid content was observed. Vacuum/halves and air/slices were the samples that maintained better this content. With regard to phytosterols, there were no significant changes during storage. Antioxidant activity showed a slight positive correlation against stearic acid content. At the end of refrigerated storage, a significant increase in antiradical efficiency (AE) was found for vacuum samples. AE values were quite similar among treatments. Hence, minimal processing can be a useful tool to preserve health-related properties of avocado fruit.

Oxidation of 8-hydroxyquinoline catalyzed by laccase from Trametes pubescens yields an antioxidant aromatic polymer

We report for the first time the enzyme-catalyzed production of poly (8-hydroxyquinoline) using laccase from the white rot fungus Trametes pubescens (CBS 696.94). The oxidative polymerisation of 8-hydroxyquinoline was catalyzed by laccase in a reaction medium containing 8% acetone, 0.01–0.05 mg/ml 8-hydroxyquinoline and sodium acetate buffer (0.1 M, pH 5.0) at 30 °C. The average molecular weight of the polymeric product, as determined by matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI-TOF) analysis, was 789 m/ z. Further structural characterisation of the product was achieved using Fourier transform infrared (FT-IR) spectroscopy. The potential for application of poly (8-hydroxyquinoline) as an antioxidant was investigated by evaluating its ability to quench the stable free radical 2,2′-diphenyl-1-picrylhydrazyl (DPPH). The antiradical efficiency (AE) was calculated to be 2 × 10 −3, a value which is comparable to the AE values for gallic acid (2.6 × 10 −3) and ascorbic acid (11.4 × 10 −3), and greater than that of polymeric lignin fractions of similar molecular weight (5 × 10 −4).

Hydrophilic and Lipophilic Antioxidant Capacities of Commercial Mediterranean Vegetable Soups (Gazpachos)

ABSTRACT: Gazpacho is a traditional cold Mediterranean soup consisting of 5 vegetables (tomato, cucumber, green pepper, onion, and garlic) and olive oil. Antioxidant activities of commercial gazpachos, processed by different technologies (traditional pasteurized [TP], slight pasteurized [SP], and frozen [F]), were assessed. Both lipophilic and hydrophilic DPPH* radical scavenging capacities (L-RSC and H-RSC, respectively) were determined in terms of EC50 and antiradical efficiency (AE). AE parameter takes into account not only antioxidant concentration but also antioxidant kinetic. L-RSC values were approximately 3-fold lower than the H-RSC values in all the gazpacho soups. Lycopene and total carotenoid concentration showed statistically significant correlation against L-RSC as follows: for lycopene, EC50 (r2= 0.4549, P = 0.0001) and AE (r2= 0.5982, P < 0.0001); for total carotenoid, EC50 (r2= 0.4381, P = 0.0002) and AE (r2= 0.5881, P< 0.0001). In the case of H-RSC, a correlation was found between EC50 values and total phenol content (r2= 0.1570, P = 0.0452) and vitamin C (r2= 0.1751, P = 0.0299). Also, a correlation was found between vitamin C and AE values (r2= 0.3485, P = 0.0012), suggesting a predominant role of vitamin C among others constituents in the kinetic of H-RSC. One serving (200 mL) of TP, SP, or F gazpacho soup corresponds to an intake of 16.4 ± 2.6 mg, 16.3 ± 2.1 mg, or 10.6 0.8 mg of vitamin C equivalents of H-RSC, respectively; and to an intake of 7.0 ± 1.0 mg, 6.9 ± 1.0 mg, or 5.3 ± 0.1 mg of lycopene equivalents of L-RSC, respectively.

Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit.

The ellagic acid, total phenolic, and vitamin C contents in four raspberry cultivars (Heritage, Autumn Bliss, Rubi, and Zeva) grown in Spain were detected and quantified by HPLC in fresh, just frozen, and stored fruits at -20 degrees C for a one year period. Ellagic acid [207-244 mg kg(-)(1) of fresh weight (fw)], total phenolic (137-1776 mg kg(-)(1) of fw), and vitamin C (221-312 mg kg(-)(1) of fw) contents in raw material were higher in the late cultivars Zeva and Rubi than in the early cultivars Autumn Bliss and Heritage. The freezing process slightly affected the values of extracted ellagic acid, total phenolic, and vitamin C content. At the end of long-term frozen storage (12 months), no significant change of total phenolic content extracted was observed, but significant decreases of 14-21% in ellagic acid and of 33-55% in vitamin C were quantified. Free radical scavenging capacity measured as antiradical efficiency (AE) depends on the seasonal period of harvest. Late cultivars, Rubi (6.1 x 10(-)(4)) and Zeva (10.17 x 10(-)(4)), showed higher AE than early cultivars, Heritage (4.02 x 10(-)(4)) and Autumn Bliss (4.36 x 10(-)(4)). The freezing process produced a decrease of AE values in the four cultivars ranging between 4 and 26%. During the frozen storage, the AE values reached after the freezing process remained unchanged.

A procedure to measure the antiradical efficiency of polyphenols

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/EC50 TEC50. 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.