Effect of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside

This work aims at studying the influence of sugar acylation on the antioxidant properties of Vitis vinifera red grape malvidin‐3‐glucoside. The antioxidant properties of malvidin‐3‐glucoside, malvidin‐3‐acetylglucoside, malvidin‐3‐coumaroylglucoside and malvidin‐3‐caffeoylglucoside were measured using different techniques. Their antiradical and reducing properties were determined using the DPPH and FRAP method, respectively. Malvidin‐3‐caffeoylglucoside displayed a DPPH value (20.2 μm Trolox eq.) much higher than malvidin‐3‐glucoside (13.6 μm Trolox eq.), but no significant differences were observed from the FRAP assay. Furthermore, the ability of these compounds to inhibit lipid peroxidation in a liposome membrane system was examined by monitoring oxygen consumption and the formation of conjugated dienes. Both assays allowed concluding that malvidin‐3‐caffeoylglucoside and malvidin‐3‐coumaroylglucoside inhibit lipid peroxidation significantly more than malvidin‐3‐glucoside. Altogether, the results reported herein indicate that acylation of malvidin‐3‐glucoside with phenolic acids like caffeic or coumaric acids, but not acetic acid, increases their overall antioxidant properties.     

Antioxidant Properties of Flavone C-Glycosides from Atractylodes japonica Leaves in Human Low-density Lipoprotein Oxidation

ABSTRACT: Three antioxidant flavone C -glucosides, isoorientin, vitexin, and isovitexin, were identified for the 1st time from Atractylodes japonica leaves by an activity-guided fractionation with various analytical techniques including column chromatography, high-performance liquid chromatography (HPLC), fast atom bombardment mass spectrometry (FAB-MS), and nuclear magnetic resonance (NMR). Hydroxyl and superoxide anion radicals scavenging activities of these compounds were examined using electron spin resonance (ESR). Inhibitory activities of these compounds on human low-density lipoprotein (LDL) oxidation were evaluated by malondialdehyde (MDA) and thiobarbituric acid-reactive substances (TBARS), both representing intermediates of lipid peroxidation. These flavone C -glucosides displayed about 50% of scavenging activity against hydroxyl radicals at the concentrations below 10 μ M . The superoxide dismutase (SOD)-equivalent activities of isoorientin, vitexin, and isovitexin at 1 m M were 31.37, 2.71, and 2.63 unit/mL, respectively. Isoorientin at 1 μ M exhibited over 60% inhibition of MDA formed during copper-mediated human LDL oxidation. Amounts of free MDA in LDL treated with isoorientin, vitexin, isovitexin, and control were 20.06, 40.73, 34.08, and 48.03 n M /mg protein, respectively. These compounds also prolonged the lag phase time of the conjugated diene formation. There was a positive correlation between the free radical scavenging activities and the inhibitory effects on the LDL oxidation of these compounds. These results suggest that the flavone C -glucosides isolated from the leaves of A japonica possess beneficial antioxidant properties against free radicals as well as LDL oxidation.     

Free radical scavenging and antioxidant activity of 5,7,3′,4′-hydroxy-substituted flavonoids

The antioxidant efficiencies of 5,7,3′,4′-hydroxy-substituted flavonoids were examined. The tested compounds (quercetin, luteolin, taxifolin, (+)-catechin and eriodictyol) were selected with a view to their C-ring differentiated pattern. Each one was added in cottonseed oil at equimolar amounts and the retardation of lipid peroxidation was estimated by means of peroxide value. Furthermore, their ability to scavenge DPPH radical was studied in two solvents (methanol and ethyl acetate) and the DPPH method proved a satisfactory prediction test for the antioxidant action of flavonoids in oils when methanol was used as the reaction media. Furthermore, the comparison of the C-ring structural element contribution to the antioxidant action revealed the full substitution to be the most important followed by the 3-OH and 2,3-double bond in the presence of the 4-carbonyl. Concerning the monosubstituted flavonoids, the 4-carbonyl group induced minor activity, whereas the 3-OH increased significantly the antiradical and antioxidant action.     

蓝莓花青素的酰化及其抗氧化性评价

以三乙酰没食子酰氯作为酰基化剂,对蓝莓花青素提取物进行酰基化反应,制得酰基化蓝莓花青素产物没食子酸酰化花青素(GAA)。薄层色谱追踪反应进程、毛细管法测定熔点保证酰化剂合成纯度。对原花青素提取物、酰化中间产物和酰化花青素进行了红外光谱扫描,对比三者谱图,证实了酰基化实验的成功,并利用HPLC测定了酰化度。分别通过DPPH法、邻苯三酚自氧化法、卵磷脂脂质体法测定了酰化花色苷对于清除自由基、清除超氧阴离子和抑制脂质体过氧化的能力,酰化花色苷对于以上3实验的IC50分别为26.8、17.5、171.7μg/mL;相比较,原蓝莓花青素为39.8、27.0、219.7μg/mL;抗坏血酸为45.1、51.2、1084.8μg/mL。实验表明没食子酸酰化花青素方法切实可行,产物没食子酸酰化花青素的抗氧化性得到提升。      

沙棘籽原花色素对卵磷脂脂质体氧化的抑制和促进作用

分别采用2,2’-盐酸脒基丙烷（AAPH）和Cu^2＋引发的卵磷脂脂质体氧化模型体系,以共轭二烯氢过氧化物为指标,通过监测氧化的动力学过程,研究了沙棘籽原花色素对氧化的抑制和促进作用。结果表明：沙棘籽原花色素显著抑制AAPH诱导的卵磷脂脂质体氧化,抑制效果强于葡萄籽原花青素,抑制作用与清除水溶性过氧自由基和脂过氧化物自由基有关;低浓度沙棘籽原花色素促进Cu^2＋催化的卵磷脂脂质体氧化,高浓度则抑制Cu^2＋催化的卵磷脂脂质体氧化。     

10株乳酸杆菌吸附铅离子及抗氧化能力的比较

为了筛选出高吸附铅离子且具高抗氧化能力的菌株,本文对10株乳杆菌进行了铅离子吸附研究,以DPPH·清除力、还原能力、羟自由基清除及抗脂质过氧化能力为指标进行了体外抗氧化能力的评定。结果表明:不同乳杆菌之间的清除铅离子能力不同,抗氧化能力也不相同,其中德式乳杆菌保加利亚亚种KLDS1.0207具有高吸附铅离子和高抗氧化能力,该菌株铅离子去除率达79.18%,还原能力达99.00μmol/L的半胱氨酸当量,DPPH·清除率为50.40%,羟自由基清除率26.88%,抗脂质过氧化能力达15.62%。此菌株可用于体内缓解铅中毒造成的氧化损伤的研究。      

Stability and Color of Unreported Wine Anthocyanin-derived Pigments

Grape anthocyanin-3-glucosides and unreported natural pigments characterized as vinylphenol anthocyanin-3-glucoside adducts were studied. Our investigations were undertaken to compare color and stabilities when processed and stored under identical conditions. Studies of molecular concentration, color density and Hunter color values were done at pH levels. Grape anthocyanin-3-glucosides were less stable than their 4-vinylphenol derivatives and the color stability of the unreported pigments was higher than that of anthocyanin-3-glucosides. Moreover, the compounds were resistant to SO₂ discoloration whereas anthocyanins were completely bleached.     

生何首乌体外抗氧化活性及抗菌活性的研究

研究生何首乌不同提取物的体外抗氧化活性及抗菌活性。在体外化学模拟的条件下,采用比色法,测定了何首乌水提物和醇提物对DPPH自由基的还原能力及抗脂质过氧化能力,羟基自由基的清除能力以及总体抗氧化能力。同时测定了何首乌水提物和醇提物的总酚酸和总黄酮的含量。利用滤纸片扩散法测定了何首乌水提物和醇提物对6种微生物的抗菌活性。何首乌醇提物的体外抗氧化活性强于水提物,具有显著的DPPH自由基和羟基自由基清除能力和较强的抗脂质过氧化能力,具有一定的还原能力,其总体抗氧化能力也比较强。何首乌水提取物和醇提取物的总酚酸和总黄酮含量分别126.52、77.25μg/mg和153.04、126.11μg/mg。另外何首乌的醇提物对金黄色葡萄球菌、四联球菌和大肠杆菌显示出较强的抑制活性,水提物对金黄色葡萄球菌和荧光假单胞菌显示出一定的抑菌活性。何首乌具有强的抗氧化活性与一定的抗菌活性。     

The effect of simulated digestion in vitro on bioactivity of wheat bread with Tartary buckwheat flavones addition

The antioxidant activity of bread enriched in an extract from the green parts of buckwheat plant (TBF - Tartary buckwheat flavones) was determined. The bread's quality was slightly decreased when 2.5% TBF was added; however, with an addition of 5% TBF caused a high decrease in the bread's quality. Despite the digestion stage, the content of total phenolic compounds were the lowest in the case of the samples from the control bread (without buckwheat addition). Despite the kinds of bread, the lowest content of total phenolics and flavonoids and the highest phenolic acids content were detected in the fluids after simulated saliva digestion. Despite the digestion stage, the highest antiradical activity, reducing power and ability to inhibition of lipid peroxidation was observed in the samples with a 5% TBF addition. The free radical scavenging activity grew along with the increase of buckwheat preparate addition and in the progress of the in vitro digestion. The maximum of reducing and chelating power in the control sample were observed after simulated saliva digestion, whereas in the case of bread with the TBF addition the highest reducing power was observed after simulated gastric digestion, and maximum of chelating power - after simulated intestinal digestion.     

Antioxidant activity and total phenolic content of Agaricus brasiliensis (Agaricus blazei Murril) in two stages of maturity

The antioxidant capability and total phenolic contents of methanolic extracts of Agaricusbrasiliensis in two stages of maturity, young (YB) and mature (MB), were evaluated in this work. Four complementary assays, reducing power, radical scavenging capacity, inhibition of lipid peroxidation and chelating ability for ferrous ions were used to screen the antioxidant properties of extracts. Minor differences in the composition of phenolic compounds were detected, but the extracts showed similar antioxidant activities, except for the chelating ability for ferrous ions, higher in MB than in YB. Our results support the use of both young and mature fruiting bodies of Agaricus blazei as sources of antioxidant compounds.     

Effects of Ultrasound,High Pressure,and Manosonication Processes on Phenolic Profile and Antioxidant Properties of a Sulfur Dioxide-Free Mulberry (<Emphasis Type="Italic">Morus nigra</Emphasis>) Wine

The present investigation aimed to evaluate the effects of ultrasound, high pressure, and manosonication on phenolic profile in correlation to antioxidant properties of aged mulberry wines (AMWs). The results indicated a positive effect of non-thermal processes on total phenol content of the AMW conversely to total anthocyanin content, which was negatively affected by pressurization and manosonication. With regard to total flavonoid content, sonication was found to exert a positive effect. A similar trend was also observed for each of the 18 phenolic compounds quantified. The outcome suggests that these phenolic compounds have potent antioxidant properties. From correlation analysis, phenolic acids were noted to be responsible for 1,1-diphenyl-2-picrylhydrazyl, N,N-dimethyl-p-phenylenediamine, and hydrogen peroxide capacities, while total antioxidant, ferric reducing antioxidant power, reducing power, cupric ion, metal chelating, lipid peroxidation, superoxide anion, 2,2′-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid), nitric oxide, and hydroxyl radical capacities were attributed to flavonols and anthocyanins.     

Bioactivity of propolis from Santiago del Estero, Argentina, related to their chemical composition

Propolis, an extremely complex resinous material gathered by honeybees from various plant sources, exhibits valuable pharmacological and biological properties attributed to the presence of polyphenols. This study examined the antibacterial, antiradical and antioxidant activities of propolis from different provenances and correlated the values with total levels of polyphenolic compounds and flavonoids. Besides, individual contents of those polyphenols with antioxidant ability were determined and related with their bioactivity. Analyzed samples presented a noticeable variability in their antioxidant and antiradical activities, although, linear relationships were found between them and also between polyphenol and flavonoid total levels. Propolis antiradical and protective abilities against lipid oxidation are related to its high levels of polyphenols, but their correlations with individual active-compound contents were not simple. Antibacterial activity against Staphylococcus aureus of the samples presented low variability. This bioactivity is assigned to pinocembrin, present in high concentrations in all the samples studied. Good correlation was found between such activity and pinocembrin content. Linear relationships between antibacterial activity and polyphenol and flavonoid total levels were also found.     

Studies on the antioxidative activity of Graptopetalum paraguayense E. Walther

This study was aimed to evaluate the antioxidative activities of water (GWE), 50% ethanolic (GE50), and 95% ethanolic (GE95) extracts of Graptopetalum paraguayense. The antioxidant activities, including the radical-scavenging effect, reducing power, and antioxidative effect on Fe/ascorbate-induced lipid peroxidation in a liposome model system, were studied in vitro. The results showed that GWE, GE50 and GE95 possessed antioxidant characteristics including radical scavenging, reducing power, and lipid peroxidation inhibition. It was found that the antioxidative activities of all the extracts increased with increasing concentrations, and the activities correlated with both the total phenol and anthocyanin contents. A comparison of the 50% inhibition concentration (IC₅₀) values of different antioxidative reactions revealed that GE50 was more effective in scavenging α,α-diphenyl-β-picrylhydrazyl (DPPH) radical and showed a higher reducing power than GWE and GE95. However, there were no significant differences (P > 0.05) in the lipid peroxidation-prevention effects among the extracts.     

Catalytic mechanisms of metmyoglobin on the oxidation of lipids in phospholipid liposome model system

The catalytic mechanism of metmyoglobin (metMb) on the development of lipid oxidation in a phospholipid liposome model system was studied. Liposome model system was prepared with metMb solutions (2.0, 1.0, 0.5, and 0.25 mg metMb/mL) containing none, diethylenetriamine pentaacetic acid (DTPA), desferrioxamine (DFO), or ferric chloride and lipid oxidation was determined at 0, 15, 30, 60, and 90 min of incubation at 37 °C. Metmyoglobin catalysed lipid oxidation in the liposome system, but the rate of lipid oxidation decreased as the concentration of metMb increased. The amount of free ionic iron in the liposome solution increased as the concentration of metMb increased, but the rate of metMb degradation was increased as the concentration of metMb decreased. The released free ionic iron was not involved in the lipid oxidation of model system because ferric iron has no catalytic effect without reducing agents. Both DFO and DTPA showed antioxidant effects, but DFO was more efficient than DTPA because of its multifunctional antioxidant ability as an iron and haematin chelator and an electron donor. The antioxidant activity of DTPA in liposome solution containing 0.25 mg metMb/mL was two times greater than that with 2 mg metMb/mL due to the increased prooxidant activity of DTPA-chelatable compounds. It was concluded that ferrylmyoglobin and DTPA-chelatable haematin generated from the interaction of metMb and LOOH, rather than free ionic iron, were the major catalysts in metMb-induced lipid oxidation in phospholipid liposome model system.     

葡萄酒中酚类物质抗氧化活性及构效关系

<正>酚类物质是芳香环上连有一个或多个羟基的低分子量有机化合物,其不但决定了葡萄酒的口感、色泽、贮藏寿命及稳定性,而且具有很强的抗氧化活性。葡萄酒中酚类物质对机体的防御作用归功于它特有的化学结构——酚羟基结构,它们具有供电子作用,通过提供活泼的氢捕捉机体内活性氧等自由基,阳断了自由基对机体的损伤。另外,葡萄酒中酚类物质也具有络合过渡金属离子能力、激活抗氧化酶的活性、减少α-生育酚自由基及降低氧化酶活性的能力。然而,尽管现在不同实验模式已证实了酚类化合物的这种多功效作用,但对于它们的构效关系的描述还不尽一致,因此,本文总结了酚类化合物(以类黄酮酚为例,见图1)在自由基清除作用和金属离子络合作用中关键的化学结构特征及影响,以旨为葡萄酒中酚类物质构效关系研究提供理论参考。     

不同处理条件对花生抗氧化肽抗氧化活性的影响

以花生蛋白粉为原料,采用Viscozyme L预水解,Alcalase水解法制备花生抗氧化肽。通过7种不同的处理条件(加热、食品添加剂、防腐剂、金属离子、杀菌、调pH值、低温)对花生抗氧化肽的4种体外抗氧化指标(清除DPPH自由基、还原力、铁离子螯合力、抗脂质体过氧化能力)进行研究。结果显示：加热处理和添加食品防腐剂有利于提高抗氧化肽的抗氧化活性;添加酒石酸、柠檬酸对抗氧化活性有较大影响,而添加氯化钠和蔗糖后对抗氧化活性影响小;添加铜离子对抗氧化活性影响较大;各种杀菌工艺有利于清除DPPH自由基、还原力、铁离子螯合力,但却降低脂质过氧化抑制率;碱性pH值条件有利于提高抗氧化肽的还原力、铁离子螯合力和脂质过氧化抑制力,酸性pH值条件不利于铁离子螯合力和脂质过氧化抑制力;低温处理降低抗氧化肽抗氧化活性。     

Antioxidant Activity of Ripe and Unripe Pepino Fruit (Solanum muricatum Aiton)

Abstract: Ripe and unripe exotic pepino fruit were evaluated for antioxidant activity, total phenols, and flavonoid content. The antioxidant potency was investigated by employing various established in vitro systems, such as 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), 2–2′‐azinobis(3‐ethylbenthiazoline‐6‐sulphonic acid (ABTS), hydroxyl radical scavenging, reducing power, ferrous ion chelation, ferric reducing antioxidant power (FRAP), and lipid peroxidation. The EC₅₀ values of ripe ethanolic extract on DPPH radical, reducing power, ferrous ion chelation, ABTS radical, FRAP, hydroxyl radical, lipid peroxidation (brain), and lipid peroxidation (liver) were obtained to be 2.20, 2.81, <5.00, 34.06, 8.53, 1.30, 1.75, and 0.51 mg/mL, respectively. However, the EC₅₀ values for unripe fruit extract were noted to be 3.75, 3.40, 11.25, 40.12, 9.75, 0.80, 1.91, and 0.63 mg/mL, respectively. Ripe fruit exhibited the highest values of antioxidant activity in all the scavenging assays except for hydroxyl radical scavenging assay. Ripe pepino had higher total phenol and flavonoid content than unripe fruit. This study suggests that possible mechanism of the biological activities may be due to free radical scavenging and antioxidant characteristics, which may be due to the presence of polyphenols in the fruit extracts. Practical Application: The ripe and unripe pepino fruit have excellent antioxidant properties, so the results obtained in this study clearly indicate that pepino fruit has a significant potential to use as a natural antioxidant agent and possibly as a food supplement.     

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.     

莲房多酚提取工艺优化及其抗氧化活性研究

在单因素实验的基础上,通过正交实验优化了热回流提取莲房多酚的工艺,并通过测定其清除ABTS+自由基、DPPH自由基、OH自由基的能力,还原力,亚铁离子螯合活性及对大鼠脑匀浆脂质过氧化的影响,对莲房多酚的抗氧化活性进行综合研究。结果表明,热回流提取莲房多酚的最佳工艺参数为:乙醇浓度50%,料液比1∶25,提取温度80℃,提取时间为2h,最优条件下的得率是5.23%。莲房多酚的体外抗氧化实验表明莲房多酚对DPPH自由基、ABTS+自由基、OH自由基有很强的清除能力,对亚铁离子的螯合活性和还原力均较强,并能显著抑制大鼠脑匀浆脂质过氧化。本研究表明在该优化工艺下提取的莲房多酚具有较强的抗氧化活性。      

St. John’s Wort (Hypericum perforatum) extracts and isolated phenolic compounds are effective antioxidants in several in vitro models of oxidative stress

The antioxidant potential of a total ethanolic extract of Hypericum perforatum (TE) was assessed, and correlated with the phenolic composition. TE was fully characterized by HPLC-DAD and HPLC-MSn, and phenolic compounds were isolated by semi-preparative HPLC. The free radical-scavenging properties of the TE were studied using DPPH (EC₅₀ = 49 μg dwb/ml), AAPH (EC₅₀ = 50 μg dwb/ml) and the antioxidant potential was evaluated using lipid peroxidation induced by ascorbate/iron (EC₅₀ = 28 μg dwb/ml). Moreover, the TE was able to scavenge NO (by using sodium nitroprusside) and HOCl (by evaluating TNB reduction). Furthermore, the antioxidant potentials of the isolated compounds were evaluated and several compounds, namely flavonoids, were significantly less effective at DPPH- and AAPH-scavenging, compared to their ability to prevent iron-mediated lipid peroxidation. Therefore, TE was able to scavenge several free radicals, indicating beneficial cellular protection against oxidative stress.