Free‐radical scavenging activity of wormwood (Artemisia absinthium L) extracts

In an effort to discover new antioxidant natural compounds, wormwood (Artemisia absinthium L) an aromatic‐bitter herb, was screened. The sequential extraction was realized with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, n‐butanol). The antioxidative activity was tested by measuring their ability to scavenge stable 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical during the Fenton reaction trapped by 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO), using electron spin resonance (ESR) spectroscopy. Results demonstrated that the antiradical and antioxidative activity depend on the type and concentration of applied extracts and increased in the order ethyl acetate > methanol > n‐butanol > chloroform > petroleum ether > remaining water extracts. The investigation showed that the antiradical activity increased with increasing concentration of all extracts. The high contents of total phenolic compounds (25.6 mg g^?1) and total flavonoids (13.06 mg g^?1) indicated that these compounds contribute to the antiradical and antioxidative activity. In a model system, the formation of o‐semiquinone radicals from quercetin and chlorogenic acid was obtained to prove the mechanism (hydrogen donating and/or one‐electron reduction) of free‐radical scavenging activity. Copyright © 2004 Society of Chemical Industry     

Antioxidant activities of different Teucrium montanum L. Extracts

The sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g^?1. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g^?1) had the best antioxidant activity (100% at 0.16 mg mL^?1 in Fenton reaction system; 90.57% at 5 mg mL^?1 in system I; 100% at 5 mg mL^?1 in system II).     

Antioxidant and antiproliferative activities of mango (Mangifera indica L.) flesh and peel

The antioxidant and antiproliferative properties of flesh and peel of mango (Mangifera indica L.) were investigated. The cytoprotective effect of mango flesh and peel extracts on oxidative damage induced by H₂O₂ in a human hepatoma cell line, HepG2, were determined, and the underlying mechanism was examined by a single-cell electrophoresis assay (comet assay). Treatment of HepG2 cell with mango peel extract prior to oxidative stress was found to inhibit DNA damage. The free radical scavenging activities of mango flesh and peel extracts were evaluated by electron spin resonance (ESR). The mango peel extract exhibited stronger free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals than mango flesh extract, regardless of ripeness. Similarly, peel extract exhibited significant antiproliferative effect against all tested cancer cell lines, compared to that of flesh extract, in a dose-dependent manner. The result also showed that the antiproliferative activity of mango flesh and peel extracts correlated with their phenolic and flavonoid contents. Thus, mango peel, a major by-product obtained during the processing of mango product, exhibited good antioxidant activity and may serve as a potential source of phenolics with anticancer activity.     

Antioxidant activity of natural vitamin E extracted from soybean sludge as assessed by chemiluminescence

The antioxidant activity of natural vitamin E (VE) towards superoxide anion, hydroxyl radical and lipid free radicals was investigated using a chemiluminescence technique. VE was extracted from soybean sludge, where it was present at a concentration of 600 g kg^?1 as determined by HPLC. Superoxide anions, hydroxyl radicals and lipid free radicals were generated by the pyrogallol autoxidation system, the Fenton reaction system and the AAPH‐induced γ‐linolenic acid peroxidation system respectively. VE rapidly scavenged hydroxyl radicals and lipid free radicals. The efficient concentration (EC₅₀) of VE against both was 0.1 mg ml^?1. A reaction time of 6 s was adequate to scavenge hydroxyl radicals and a reaction time of 24 s was enough to scavenge lipid free radicals. However, VE scavenged superoxide anions at a relatively low rate, and the extent of scavenging was less than 20% even after 3 min at a VE concentration of 4.3 mg ml^?1. © 2001 Society of Chemical Industry     

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

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

Electron spin resonance spectroscopy studies on the free radical scavenging activity of wine anthocyanins and pyranoanthocyanins

Anthocyanins are a group of natural occurring pigments responsible for the red-blue color of grapes and many fruits and vegetables. Anthocyanins and derived pigments are of double interest, one technological, as they can be used as natural colorants, and another one due to their implication on human health through their antioxidant activity. Although there are numerous studies regarding the antioxidant activity of grape extracts as well as red wine, the free radical scavenging activity of purified anthocyanins and pyranoanthocyanins is largely unknown. In the present study, the hydroxyl and superoxide anion scavenging activities of anthocyanins and their pyruvic acid adducts were systematically investigated by electron spin resonance spectroscopy and spin trapping. The 3-glucosides of delphinidin, cyanidin, petunidin, pelargonidin and malvidin, and the pyruvic adduct of the 3-glucoside of delphinidin exhibited a potent superoxide anion radical scavenging and, to a lesser extent hydroxyl anion radical scavenging activity. The pyranoanthocyanins of cyanidin, petunidin, malvidin and pelargonidin showed a high capacity to scavenge superoxide anion radicals but did not scavenge hydroxyl radicals. Current data indicate that formation of anthocyanin adducts with pyruvic acid, which may occur during wine ageing or fruit juice processing, decreases the hydroxyl and superoxide anion scavenging and thus could decrease the antioxidant potential of these compounds.     

Evaluation of Irradiation and Heat Treatment on Antioxidant Properties of Fruit Peel Extracts and Its Potential Application During Preservation of Goat Fish <Emphasis Type="Italic">Parupenaeus indicus</Emphasis>

The quenching capacities of Vitus vinifera seed extract, Citrus limon peel extract, Punica granatum peel extract, and Citrus sinensis peel extract were studied together with their antioxidant activity in goat fish (Parupenaeus indicus). The functionality of the extracts was evaluated using β-carotene-linoleic acid model system, reducing power assay, DPPH, hydroxyl, and nitrite radical scavenging assay. V. vinifera and P. granatum extract demonstrated best radical scavenging potential in all multifunctional antioxidant assays. Radical scavenging activity measured by electron paramagnetic resonance against a stable radical 1,1,-diphenyl-2-picrylhydrazil revealed radical peaks of lower intensity in antioxidant-infused samples. Compounds possessing antioxidant properties were identified from purified fruit extracts by GC–MS analysis. Treatments with these extracts increased the stability of irradiated goat fish against lipid oxidation. TBARS values for irradiated control was 4.26 ± 0.10, whereas it was 2.44 ± 0.14, 2.97 ± 0.01, 2.93 ± 0.03, 3.89 ± 0.05, and 4 ± 0.01 mg of MDS per kilogram fish for BHA, P. granatum peel, V. vinifera seed, C. sinensis peel, and C. limon peel extract-treated samples, respectively. This study also elucidated the relationship between heating temperature and irradiation dose on the antioxidant activity of extracts. Maximum antioxidant activity was observed at 150 °C heated and 10-kGy irradiated extracts. These results suggest that fruit peels will be a potential material for extracting antioxidants.     

Antioxidant activity of 1,3-dicaffeoylquinic acid isolated from Inula viscosa

Inula viscosa is a perennial herbaceous plant used topically in folk medicine as an anti-scabies, anti-inflammatory, and wound-healing agent. We examined the antioxidant activity of the methanolic extract of I. viscosa. We isolated and identified several polyphenolic antioxidants from I. viscosa leaves and focused on 1,3-dicaffeoylquinic acid (1,3-diCQA). Antioxidant activity was measured using ABTS and DPPH assays, which measure antioxidant activity. The concentrations of 1,3-diCQA required for the inhibition of oxidation were lower than those required by other known antioxidants. 1,3-diCQA inhibited oxidative damage caused by various factors, including FeSO₄ and AAPH (2,2′-azobis(2-amidinopropane) dehydrochloride). Antioxidant activity can also be detected by the ability of a compound to scavenge reactive oxygen species (ROS). 1,3-diCQA was found to scavenge hydroxyl radical and superoxide radicals, as measured by electron spin resonance (ESR). These data demonstrate that 1,3-diCQA exhibits antioxidant properties, probably through the involvement of a direct scavenging effect on several free radicals.     

Dittany (Origanum dictamnus) as a source of water-extractable antioxidants

Extracts of dittany (Origanum dictamnus L.) made with solvents of varying polarity were evaluated (i) by electron spin resonance (ESR) spectrometry using the spin trapping technique for their efficiencies as scavengers of free radicals, and (ii) by measurement of oxygen depletion in a methyl linoleate emulsion for their efficiencies as chain-breaking antioxidants. Aqueous extracts of dittany most efficiently scavenged hydroxyl radicals as generated by the Fenton reaction and this extract also most efficiently reduced oxygen consumption when initiated by metmyoglobin. Ethanol and acetone extracts of dittany showed less activity in both assays with methanol extract being intermediate. The high efficiencies found in the aqueous (and methanol) extracts of dittany were closely related to a high content of phenolic compounds in these extracts, while the amounts of phenolics in the ethanol and acetone extract were lower. In aqueous extracts, the antioxidative activity was confirmed in a turkey thigh meat homogenate, where development of thiobarbituric reactive substances was increasingly inhibited by increasing additions from 0.0018 mg dittany/g meat to efficient inhibition for 0.011 mg dittany/g meat and higher additions. Dittany should be further explored as a source of water-extractable antioxidants.     

Scavenging effect of tea catechins and their epimers on superoxide anion radicals generated by a hypoxanthine and xanthine oxidase system

Catechins are a major group of polyphenolic compounds contained in abundance in green tea. Using electron spin resonance spectroscopy along with a spin‐trapping agent, the scavenging effect of tea catechins and their corresponding epimers against superoxide anion radicals generated by a hypoxanthine and xanthine oxidase reaction system was evaluated. The presence of 3′,4′,5′‐trihydroxyl groups attached to the B‐ring of the flavan skeleton of tea catechins elevated their radical‐scavenging efficiency in comparison to those with 3′,4′‐dihydroxyl groups. There were no significant differences between the four dominant tea catechins and their corresponding epimers with regard to radical‐scavenging ability. Under the different spin‐trapping agent concentrations, the sigmoid curves of reducing spin‐trapping adducts produced by tea catechins were shifted leftward, suggesting that a likely possible action of tea catechins is to scavenge superoxide anion radicals directly, not to inhibit the function of xanthine oxidase. Although caffeine is also known as a major ingredient of tea, its superoxide anion radical‐scavenging effect was much weaker than that of the catechin family. It is concluded that tea catechins and their epimers serve as powerful antioxidants for directly eliminating superoxide anion radicals, and may be useful in the prevention of diseases relating to in vivo oxidative stress. © 2000 Society of Chemical Industry     

Importance of Deoxyribose Degradation Assay for Evaluating Hydroxyl Radical Scavenging Activity of Punica Extract

Punica granatum L. (Family: Punicaceae), commonly known as pomegranate (Anar) has been used traditionally as medicine to treat a number of diseases and disorders. Various parts of the plant and their active constituents are known to possess diverse biological activity. However, little is known about the antioxidant potential of pomegranate fruit peel, which is otherwise considered as waste. Therefore, the concentration-dependent hydroxyl radical scavenging ability of Punica granatum seed and peel extracts (alcoholic and aqueous) using deoxyribose degradation assay were analyzed and compared. The hydroxyl radical scavenging activity at different concentrations of extract (10 to 250 μg/mL) both in presence and/or absence of ascorbic acid and ethylenediamine tetra acetic acid was determined. It was observed that a higher concentration of extract suppresses scavenging activity and lower promotes antioxidant property. Based on the observations, it may be inferred that pomegranate extract, especially from the spent/waste prt, has a strong antioxidant property as assessed by its property of scavenging hydroxyl radical formation.     

Detection of Free Radicals in Beer Oxidation

Short-lived radicals produced during the incubation of beer at 60°C were detected by electron spin resonance (ESR) spectroscopic analysis using N-tert-butyl-α-phenylnitrone (PBN) as a spin trapping reagent. The hyperfine splitting (hfs) constants were 15.7 ± 0.2 G and 3.2 ± 0.2 G for α_N and a^β_H, respectively. The hfs constants of PBN adducts produced by Co⁶⁰γ irradiation were 15.6 ± 0.3 G and 3.1 ± 0.2 G for α_N and α^β_H in beer and 15.7 ± 0.3 G and 3.3 ± 0.3 G for α_N and α^β_H in double distilled water. It is proposed, therefore, that short-lived radicals produced during the incubation of beer at 60°C may be hydroxyl radicals.     

ANTIOXIDANT ACTIVITIES OF ENZYMATIC EXTRACTS FROM AN EDIBLE SEAWEED SARGASSUM HORNERI USING ESR SPECTROMETRY

The antioxidant activity of water-soluble natural extracts from an edible seaweed , Sargassum horneri, was evaluated by examining the radical scavenging activities of the extracts of hydrolyzates from S. horneri on 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and alkyl radicals. A spin-trapping electron spin resonance (ESR) spectrophotometer was employed and the results were compared for their ESR signal intensity. The brown seaweed S. horneri was enzymatically hydrolyzed to prepare water-soluble extracts by five carbohydrases (AMG, Celluclast, Termamyl, Ultraflo and Viscozyme) and five proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase, Protamex). The extracts so prepared exhibited strong scavenging activity on DPPH, hydroxyl and alkyl radicals. The scavenging activity of the radicals increased with increased concentration of the extracts. The scavenging results were higher or similar for hydroxyl and alkyl radicals, and lower for DPPH radical compared with vitamin C as a reference. Viscozyme and Alcalase extracts were superior and scavenged radicals examined better than the extracts prepared by other carbohydrases and proteases.     

Antioxidant activity of enzymatic extracts from a brown seaweed Ecklonia cava by electron spin resonance spectrometry and comet assay

The potential antioxidant activity of enzymatic extracts from Ecklonia cava was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and alkyl radical scavenging using a electron spin resonance (ESR) spectrophotometer compared with ESR signal intensity and inhibitory effect of DNA damage on comet assay. E. cava was enzymatically hydrolyzed with five food industrial carbohydrases (AMG, Celluclast, Termamyl, Ultraflo and Viscozyme) from Novozyme Nordisk. All the tested extracts exhibited strong radical scavenging activities and the values were dose-dependent. The DPPH and hydroxyl radical scavenging activities of the enzymatic extracts were compatible with the vitamin C, which the alkyl radical scavenging activity was even higher than that of vitamin C. Also in the present study, the enzymatic extracts showed strong inhibitory effect against DNA damage in a dose dependent manner. These results indicated that the E. cava might be valuable natural antioxidative source.     

荷叶功能成分的提取及其对自由基清除作用的研究

研究了荷叶中的功能成分黄酮类化合物和生物碱的水提取工艺条件。结果表明 :以水为溶剂来提取荷叶中的黄酮类化合物及生物碱时 ,较佳的工艺条件为 ,m (水 )∶m(荷叶 ) =30∶1,于 80～ 90℃提取 1.5h ,提取液呈酸性。同时采用电子自旋共振捕集技术 (ESR) ,研究了以荷叶在水溶剂中的提取物 (LLE)对羟基自由基 (·OH)和超氧阴离子自由基 (O-2 ·)的清除效果。结果表明 :LLE对·OH和O- 2 ·有很强的清除能力 ,2 6.94 μg/mL的LLE对次黄嘌呤 黄嘌呤氧化酶体系产生O-2 ·的清除率达 65 .60 % ,LLE浓度大于 8.98mg/mL时 ,可以全部清除由Fenton反应体系产生的·OH。     

Antioxidative and prooxidative effects of extracts made from cherry liqueur pomace

The effect of phenolics extracted from cherry liqueur pomace on the Fenton reaction was tested in a model system, where hydroxyl radicals from iron (II) reduction of H₂O₂ reacted with ethanol, forming 1-hydroxyl radicals. The extent of the radical formation was monitored by electron spin resonance (ESR) detection of spin adducts formed from 1-hydroxyethyl radicals and 4-pyridyl-1-oxide-N-tert-butylnitrone (POBN). Small phenol–iron ratios gave low amounts of detected radicals, indicating an antioxidative effect of the extracts, whereas high phenol–iron ratios gave high levels of radicals, indicating decreasing antioxidant or dominating prooxidant effects. Extracts made with pure solvents (water, methanol, ethanol, acetone or 2-propanol) gave higher antioxidant effects than extracts made with 70% aqueous solvent mixtures. The prooxidant effect of the extracts increased with the polarity of the extraction solvent. Gallic acid gave a prooxidative effect, p-coumaric acid only an antioxidative effect, while epicatechin gave an antioxidative effect at low concentrations and a prooxidative effect at high concentrations.     

Resistance of Lactobacillus casei KCTC 3260 to Reactive Oxygen Species (ROS): Role for a Metal Ion Chelating Effect

The antioxidative capacity of 4 Lactobacillus strains, isolated from a milk product, was evaluated by measuring total antioxidative ability (TAA) and resistance to reactive oxygen species (ROS). Both intact cells and intracellular cell‐free extracts of Lactobacillus casei KCTC 3260 demonstrated the highest antioxidative activity and inhibited lipid peroxidation by 46.2% and 72.9%, respectively. To evaluate the resistance of 4 Lactobacillus strains to ROS, we tested the survival under conditions of 1 mM hydrogen peroxide, 0.4 mM hydroxyl radicals, and 10 mM paraquat‐induced superoxide anions. L. casei KCTC 3260 was viable even after 8 h in the presence of 1 mM hydrogen peroxide and after 7 h in 0.4 mM hydroxyl radicals. Moreover, this strain was not influenced by superoxide anions, indicating that it has resistance to superoxide anions. To define the antioxidative mechanism, superoxide dismutase (SOD) and metal ion chelating activity were determined. All tested strains did not possess detectable SOD activity except Lactobacillus rhamnosus GG, but L. casei KCTC 3260 had the higher level of chelating activity for both Fe²⁺ and Cu²⁺ ions at 10.6 ppm and 21.8 ppm, respectively. These results suggested that the antioxidative capacity of L. casei KCTC 3260 may be caused by chelating metal ions instead of SOD activation.     

利用植物提取物降低卷烟主流烟气中的自由基

本文采用自旋捕集技术和电子自旋共振波谱法(ESR)捕集并检测卷烟主流烟气中的气相自由基和粒相自由基,研究了不同植物提取物降低卷烟主流烟气中自由基的效果,结果表明葡萄籽提取物、碧罗芷、松树皮提取物和复合植物提取物清除自由基效果较好。本文讨论了复合植物提取物添加到烟丝中的添加量对粒相自由基清除效果的影响。将筛选的复合植物提取物负载在介孔固体上制成介孔复合体二元复合滤嘴,同时把复合植物提取物喷加到烟丝中并卷制成卷烟,检测结果表明烟气中气相自由基和粒相自由基分别降低了36.2%和29.1%。本文还讨论了降低自由基的可能机理。      

Antioxidant activity of enzymatic extracts from the brown seaweed Undaria pinnatifida by electron spin resonance spectroscopy

Enzyme assisted extraction of Undaria pinnatifida was performed using five proteases (Alcalase, Flavourzyme, Neutrase, Trypsin and Protamex) and six carbohydrases (AMG, Dextrozyme, Maltogenase, Promozyme, Viscozyme and Celluclast) in order to acquire extracts rich in antioxidants. Antioxidant activity of the extracts was investigated using electron spin resonance (ESR) spectroscopy on 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide radicals. Extracts exhibited strong radical scavenging activity on DPPH and hydroxyl radical, and activity increased with increasing extract concentration. In contrast to DPPH and hydroxyl radical scavenging activity, extracts showed weak scavenging activity on superoxide radical. Extracts exhibited weak radical scavenging activity compared to vitamin C as a reference compound. However, they are still a good source of antioxidant materials that are safe for consumption and show water-soluble properties.     

Comparison of antioxidant activities of juice, peel, and seed of pomegranate (Punica granatum L.) and inter-relationships with total phenolic, Tannin, anthocyanin, and flavonoid contents

In this study, the antioxidant activities of juice, peel, and seed parts of pomegranate were investigated by using DPPH scavenging activity, β-carotene bleaching method, reducing power, and metal chelating activity. Sample of pomegranates which are named Punica granatum L. cv. Hicaznar, genotype 19–121, genotype 17–67, and genotype 19–66 obtained from BATEM (West Mediterranean Agricultural Research Institute) in Anlalya. The EC₅₀ values of DPPH scavenging activities in peel extracts (PE) had 23.4-fold higher than the juice extracts (JE), and the seed extracts (SE) had 2.3-fold higher than JE. The reducing power in peel extracts was found to be 4.7-fold higher than SE and 10.5-fold higher than the JE. The highest metal chelating capacity (37.22%) was determined in peel, while the lowest (7.151%) in seed. Generally, in peel, the total polyphenol, flavonoid, tannin contents, and in juice, the total polyphenol, anthocyanin, tannin contents, and acidity significantly affected to antioxidant activities.