番木瓜的抗氧化作用研究

目的探讨番木瓜的抗氧化作用。方法红细胞溶血、肝匀浆MDA生成及羟自由基生成用比色法测定,超氧化物歧化酶活力用羟胺法测定。结果番木瓜提取液体外给药能明显抑制H₂O₂所致红细胞溶血,并抑制小鼠肝匀浆自发性或Fe²⁺-V itC诱发的脂质过氧化反应。对H₂O₂所产生的羟自由基亦有直接的清除作用,并可提高大鼠血浆超氧化物歧化酶活力。结论番木瓜具有抗氧化作用。     

野牡丹提取液的抗氧化活性研究

目的 研究野牡丹提取液的抗氧化活性。方法 采用二苯代苦味肼基自由基（DPPH•）和铁离子还原/抗氧化能力（FRAP）测定法,测定其抗氧化活性,并将其与芦丁和维生素C（Vc）的抗氧化能力进行比较研究。结果 野牡丹提取液具有较强的抗氧化能力,对DPPH自由基有较好的清除率,半数清除浓度（IC₅₀）为23 μg/mL;对Fe³⁺也具有较好的还原能力,0.5 mol/L FeSO₄当量对应野牡丹提取液质量浓度为55 μg/mL。结论 野牡丹的抗氧化能力与芦丁相近,低于Vc。野牡丹的抗氧化活性在一定浓度范围内与黄酮的含量有较好的相关性。     

维吾尔药铁力木不同极性部位体外抗氧化作用的研究

目的 研究维吾尔药铁力木不同极性部位的体外抗氧化活性。方法 以Vc为对照,通过测定铁力木乙醇提取物、水提取物及乙醇提取物石油醚(沸程60~90℃)、乙酸乙酯、正丁醇、水各萃取物对Fe³⁺的还原能力、对DPPH自由基(DPPH·)和超氧自由基(O·-₂)的清除能力,研究铁力木的体外抗氧化活性。结果 铁力木各部位对Fe³⁺均表现出一定的还原能力,对DPPH·及O·-₂均表现出一定的清除作用,但作用均弱于VC。其中水层及正丁醇层对Fe³⁺的还原能力较强,而其石油醚层和乙酸乙酯层还原能力较弱;水层和水提取物对DPPH·具有一定的清除能力;石油醚层及水提取物清除O·-₂的作用较强。结论 铁力木具有较好的抗氧化能力。     

土庄绣线菊茶多酚抗氧化活性作用研究

目的： 以土庄绣线菊为原料提取茶多酚,优化提取条件并研究其抗氧化活性。方法： 比较料液比、浸提时间和浸提溶剂对土庄绣线菊茶多酚提取率的影响,确定提取最佳工艺参数。采用铁氰化钾还原法测定茶多酚的总还原能力,以邻苯三酚自氧化法测定其对超氧阴离子自由基的清除作用、DPPH自由基清除率和对Fe²⁺络合能力来评价其抗氧化能力。结果： 土庄绣线菊料液比1︰20（g/mL）,浸提温度70℃,乙醇体积分数70%,浸提时间20 min时提取的茶多酚含量平均为50.9 mg/g。茶多酚具有显著的还原能力和对Fe²⁺的络合能力;对O^2-·和DPPH自由基清除作用相对较弱,其半数抑制浓度（IC₅₀）分别为0.520 mg/mL和0.376 mg/mL。结论： 土庄绣线菊中茶多酚含量丰富,且抗氧化活性较强,可作为潜在天然抗氧化剂应用于食品和医药工业。     

天门冬多糖的化学结构及体外抗氧化活性

目的　研究天门冬多糖ACP1的化学结构及体外抗氧化活性。方法　用沸水提取天门冬块根粉粗多糖,经DEAE-cellulose及Sephadex G-150柱色谱纯化得纯多糖ACP₁。经酸全水解,PC,GC,IR,高碘酸氧化、Smith降解、CrO3氧化、全甲基化,1H及¹³CNMR等研究化学结构。并利用NADH-PMS-NBT系统产生,Fe2+-Vit C系统产生*OH,H₂O₂诱导红细胞氧化溶血来研究ACP₁清除自由基、抗氧化活性。 结果　ACP₁的分子量为1.04×10⁵, 比旋光度为［α］¹⁵_D=+64°（c 0.64,H₂O）。ACP₁是由Gal及Glc组成,摩尔比为1.00∶0.87。ACP₁是由8个β-（1→4）Gal及6个α-（1→6）Glc连接构成主链,并在其中1个Gal残基的3-O位上接有1个α-Glc残基的支链。ACP₁体外可清除NADH-PMS-NBT系统产生的超氧阴离子自由基,降低Fe²⁺-Vit C引起的小鼠肝微粒体脂质过氧化产物丙二醛的含量,抑制H₂O₂诱导的大鼠红细胞氧化溶血。结论　ACP₁为一半乳萄聚糖,有清除自由基及抗脂质过氧化活性。     

白术挥发油GC-MS指纹图谱与抗氧化活性的谱效关系研究

目的 研究白术挥发油指纹图谱与抗氧化活性的谱效关系,筛选主要抗氧化活性成分。方法 采用GC-MS测定不同产地的15批白术饮片挥发油指纹图谱,通过清除1,1-二苯基-2-苦腈基（DPPH）和Fe³⁺还原/抗氧化能力法测定白术挥发油的抗氧化能力,运用偏最小二乘回归法进行数据分析,研究白术挥发油指纹图谱和抗氧化活性的相关性,并筛选活性色谱峰。结果 28个匹配指纹峰中,对挥发油清除DPPH自由基活性贡献度最大的前5个峰依次为：峰11 > 峰25 > 峰2 > 峰4 > 峰24;对挥发油还原Fe³⁺能力贡献度最大的前5个峰依次为：峰11 > 峰8 > 峰14 > 峰19 > 峰26。其中峰11的峰面积与挥发油清除DPPH自由基能力和还原Fe³⁺能力均呈正相关。通过与对照品比对确定峰11为苍术酮,并具有显著的抗氧化活性。结论 苍术酮不仅是白术挥发油的主要成分,还是主要的抗氧化活性物质。     

银木总黄酮体外抗氧化活性研究

摘 要 目的： 对银木总黄酮的体外抗氧化活性进行研究。方法: 采用铁氰化钾还原法测定其还原能力,并测定其清除DPPH自由基（DPPH·）、羟基自由基（·OH）、超氧阴离子自由基（O₂-·）的能力。结果:银木总黄酮具有良好的还原力,较好地清除DPPH自由基（DPPH·）、羟基自由基（·OH）、超氧阴离子自由基（O₂-·）的能力,且随着浓度逐渐增加抗氧化作用呈递增趋势, 在银木总黄酮浓度为0.15mg·mL^-1时,对DPPH自由基（DPPH·）清除率高达86%、对羟基自由基（·OH）的清除率达到68%、对于超氧阴离子自由基（O₂-·）的清除率可以达到59%。结论: 银木总黄酮有较好的抗氧化活性,是一种天然的抗氧化剂,值得进一步研究开发。     

黄杞苷保护DNA氧化损伤的活性及其可能机制

目的 研究黄杞苷保护DNA氧化损伤的活性与可能机制。方法 采用DNA保护分析法、超氧自由基（·O₂^-）清除法、Ferrozine显色法,探讨其保护DNA氧化损伤的活性与可能机制,并通过紫外可见光谱（UV-vis spectra）考察其与Fe²⁺络合的变化。结果 在DNA保护分析法、·O₂^-自由基清除法、Ferrozine显色法中,黄杞苷在一定浓度范围内,表现出浓度依赖性。其IC₅₀值分别（60.3±9.9）,（44.5±7.6）,（159.7±19.9）μg·mL^-1。UV-vis光谱分析表明,黄杞苷与Fe²⁺混合后,在波长475 nm处出现新的峰,摩尔消光系数为102.5 L·mol^-1·cm^-1。结论 黄杞苷能较好地保护DNA,免受羟基自由基（·OH）诱导的氧化损伤。其保护作用由直接清除ROS和间接清除ROS 2个途径实现。黄杞苷直接清除ROS,可能与氢转移和电子转移有关;间接清除ROS可能通过络合Fe²⁺的方式,阻断·OH自由基生成。不过,受3-位鼠李糖基的空间位阻影响,其Fe²⁺络合能力较弱。     

木贼麻黄多糖的提取及体外抗氧化活性研究

目的 优化木贼麻黄多糖的提取工艺,初步研究木贼麻黄多糖的体外抗氧化活性。方法 采用热水浸提法提取木贼麻黄多糖,利用单因素试验结合响应面法对提取条件进行优化,并研究木贼麻黄多糖的体外抗氧化活性。结果 木贼麻黄多糖的最佳提取条件为：提取时间2.5 h,提取温度73℃,液料比25∶1,在此条件下多糖提取率为（5.57±0.072）%。木贼麻黄多糖对DPPH自由基和羟基自由基具有较强的清除能力,IC₅₀分别为703.9 μg·mL^-1和2 135.1 μg·mL^-1;对超氧阴离子自由基具有一定的清除能力,对Fe³⁺有一定的还原能力。结论 该提取工艺能较好地提取木贼麻黄多糖,所得木贼麻黄多糖具有一定的体外抗氧化能力,但活性低于同浓度的维生素C。     

地榆鞣质提取物对大鼠心、肝、脑及肾组织体外抗脂质过氧化作用的研究

摘 要 目的：研究地榆鞣质提取物对大鼠心、肝、脑、肾组织体外抗脂质过氧化作用。方法: 采用分光光度法测定地榆鞣质提取物对由Fe²+ 半胱氨酸（Fe²+ Cys）体系、Fe²+ 维生素C（Fe²+ VitC）体系、Fe²+ 过氧化氢（Fe²+ H2O2）体系诱导的大鼠心、肝、脑、肾组织体外脂质过氧化的抑制作用。结果: 地榆鞣质对Fe²+ Cys、Fe²+ VitC、Fe²+ H2O2诱导的大鼠脑、心、肝匀浆、肾及线粒体脂质过氧化产生的MDA的抑制作用显著。结论:地榆鞣质对大鼠心、肝、脑及肾组织体外抗脂质过氧化具有较强保护作用,值得进一步研究与开发。     

Lipid peroxidation inhibition and antiradical activities of some leaf fractions of Mangifera indica

This study was undertaken to assess in vitro lipid peroxidation inhibitions and anti-radical activities of methanolic, chloroform, ethyl acetate and water fractions of Mangifera indica leaf. Inhibition of Fe(2+)-induced lipid peroxidation (LPO) in egg, brain, and liver homogenates, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl (OH-) radical scavenging activities were evaluated. Total phenol was assessed in all fractions, and the reducing power of methanolic fraction was compared to gallic acid and ascorbic acid. The results showed that Fe2+ induced significant lipid peroxidation (LPO) in all the homogenates. Ethyl acetate fraction showed the highest percentage inhibition of LPO in both egg yolk (68.3%) and brain (66.3%), while the aqueous fraction exerted the highest inhibition in liver homogenate (89.1%) at a concentration of 10 microg/mL. These observed inhibitions of LPO by these fractions were higher than that of ascorbic acid used as a standard. The DPPH radical scavenging ability exhibited by ethyl acetate fraction was found to be the highest with IC50 value of 1.5 microg/mL. The ethyl acetate and methanolic fractions had the highest OH- radical scavenging ability with the same IC50 value of 5 microg/mL. The total phenol content of ethyl acetate fraction was the highest with 0.127 microg/mg gallic acid equivalent (GAE). The reductive potential of methanolic fraction showed a concentration-dependent increase. This study showed that inhibition of LPO and the DPPH and OH- radicals scavenging abilities of Mangifera indica leaf could be related to the presence of phenolic compounds. Therefore, the ethyl acetate fraction of the leaf may be a good source of natural antioxidative agent.     

Scavenging of reactive oxygen species by Eriobotrya japonica seed extract

We have clarified that Eriobotrya japonica seed extract has strong antioxidative activity, and is effective for the prevention and treatment of various diseases, such as hepatopathy and nephropathy. In this study, to investigate the influences of components of Eriobotrya japonica seed extract on its antioxidative activity, extracts were prepared using various solvents (n-hexane (Hex), ethyl acetate (EtOAc), n-butanol (n-BuOH), methanol (MeOH) and H2O) and the antioxidative activity of the solvent fractions and components was evaluated based on the scavenging of various radicals (DPPH and O2(-)) measured by the ESR method and the inhibition of Fe3+-ADP induced NADPH dependent lipid peroxidation in rat liver microsomes. The radical scavenging activities and inhibitory activities on lipid peroxidation differed among the solvent fractions and components. In the n-BuOH, MeOH and H2O fractions, radical scavenging activity and inhibitory activity on lipid peroxidation were high. In addition, these fractions contained abundant polyphenols, and the radical scavenging activity increased with the polyphenol content. In the low-polar Hex and EtOAc fractions, the radical scavenging activity was low, but the lipid peroxidation inhibition activity was high. These fractions contained beta-sitosterol, and the inhibitory activity on lipid peroxidation was high. Based on these findings, the antioxidative activity of Eriobotrya japonica seed extract may be derived from many components involved in a complex mechanism, resulting in high activity.     

Antioxidant activity of caffeic acid (3,4-dihydroxycinnamic acid)

Caffeic acid (3,4-dihydroxycinnamic acid) is among the major hydroxycinnamic acids present in wine; sinapic acid, which is a potent antioxidant. It has also been identified as one of the active antioxidant. In the present study, the antioxidant properties of the caffeic acid were evaluated by using different in vitro antioxidant assays such as 2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, total antioxidant activity by ferric thiocyanate method, total reductive capability using the potassium ferricyanide reduction method, superoxide anion radical scavenging and metal chelating activities. alpha-Tocopherol, trolox, a water-soluble analogue of tocopherol, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) were used as the reference antioxidant compounds. At the concentrations of 10 and 30 microg/mL, caffeic acid showed 68.2 and 75.8% inhibition on lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, 20 microg/mL of standard antioxidant such as BHA, BHT, alpha-tocopherol and trolox indicated an inhibition of 74.4, 71.2, 54.7 and 20.1% on peroxidation of linoleic acid emulsion, respectively. In addition, caffeic acid is an effective ABTS(+) scavenging, DPPH scavenging, superoxide anion radical scavenging, total reducing power and metal chelating on ferrous ions activities.     

Evaluation of polyphenolic acid esters as potential antioxidants

Six polyphenolic acid esters were synthesized and their antioxidative properties were evaluated in three model systems [2,2'-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH)-induced lipid peroxidation system, and the dye-bleaching assay of peroxynitrite radical]. Among these compounds, we found that compounds 4 [3,4-dihydroxy-benzoic acid-(2-phenoxyethyl ester)], and 5 [3,4-dihydroxy-cinnamic acid-(2-phenoxyethyl ester)] provided comparable activity to caffeic acid phenethyl ester (CAPE) in the DPPH model. Compound 3 [2,5-dihydroxy-benzoic acid-(2-phenoxyethyl ester)], was found to be more active than CAPE in the AAPH system, it also displayed about 2-fold greater activity than CAPE in the peroxynitrite radical model. These results suggest that these phenolic acid ester derivatives, with their potent anti-oxidant activities, may have useful applications as antioxidants.     

Inhibitory activity of epigallocatechin gallate (EGCg) in paraquat-induced microsomal lipid peroxidation--a mechanism of protective effects of EGCg against paraquat toxicity

Recently we have reported that epigallocatechin gallate (EGCg), a major component of Japanese green tea, significantly increased the survival rate of paraquat (Pq) poisoned mice. This paper describes two biochemical activities of EGCg, which relate to its protective effects against Pq toxicity. EGCg inhibited Pq-induced microsomal malondialdehyde (MDA) productions in rat liver microsome system containing 40 microM FeSO(4). Forty micromolar EGCg inhibited MDA production significantly. EGCg may inhibit the Pq-induced MDA production by at least two mechanisms. One may be iron-chelating activity as the inhibition disappeared when excess amounts of FeSO(4) were added to the reaction mixture, which indicated that EGCg reduced iron driven lipid peroxidation by pulling out available irons in the reaction mixture. The other is radical scavenging activity. EGCg scavenged DMPO-OOH spin adducts generated by the microsome-Pq system. The dose response curve of EGCg was similar to that obtained by ascorbic acid which is a typical water-soluble radical scavenger. Although ascorbic acid had a potential activity of scavenging superoxide radicals, it can not be recommended to use for the treatment of Pq poisoning, because ascorbic acid acts as a pro-oxidant in the presence of free transition metal ions by accelerating the Fenton reaction (Fe(2+)+H(2)O(2)-->Fe(3+)+OH(-)+OH*), which is responsible for lipid peroxidation. On the contrary, EGCg inhibited iron-driven lipid peroxidation presumably not only by chelating to Fe ions but also by scavenging superoxide radicals, which are responsible for the reduction of ferric (Fe(3+)) to ferrous (Fe(2+)) that catalyzes the Fenton reaction. Chelating and radical scavenging activity of EGCg can be expected simultaneously in the occurrence of Pq toxicity, which may explain the protective effects of EGCg against Pq toxicity.     

Antioxidant activity of saponins isolated from ivy: alpha-hederin, hederasaponin-C, hederacolchiside-E and hederacolchiside-F

The antioxidant activities of alpha-hederin and hederasaponin-C from Hedera helix, and hederacolchisides-E and -F from Hedera colchica were investigated, in this study. The antioxidant properties of the saponins were evaluated using different antioxidant tests: 1,1-di-phenyl-2-picryl-hydrazyl (DPPH.) free radical scavenging, total antioxidant activity, reducing power, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Alpha-hederin, hederasaponin-C, as well as hederacolchisides-E and -F exhibited a strong total antioxidant activity. At the concentration of 75 pg/mL, these saponins showed 94, 86, 88 and 75% inhibition on lipid peroxidation of linoleic acid emulsion,respectively. These various antioxidant activities were compared with model antioxidants such as a-tocopherol, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).     

Antioxidant and memory enhancing effects of purple sweet potato anthocyanin and cordyceps mushroom extract

The effects of purple sweet potato anthocyanin (SPA) and Cordyceps mushroom extract (CME) on lipid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and cognitive deficits were examined. Both SPA and CME exhibited DPPH radical scavenging activities with similar potency. In contrast, only SPA was shown to effectively inhibit lipid peroxidation initiated by Fe2+ and ascorbic acid in rat brain homogenates. Furthermore, SPA markedly enhanced cognitive performance, assessed by passive avoidance test in ethanol-treated mice. Combined treatments with SPA and CME did not significantly influence the effects of SPA alone. These results demonstrate that anthocyanin prepared from purple sweet potato exhibits memory enhancing effects, which may be associated with its antioxidant properties.     

Evaluation of the antioxidative properties of lipoxygenase inhibitors

BackgroundOxidative stress is a component of many pathological conditions including neurodegenerative diseases and inflammation. An important source of reactive oxygen species (ROS) are lipoxygenases (LOX) – enzymes responsible for the metabolism of arachidonic acid and other polyunsaturated fatty acids. LOX inhibitors have a protective effect in inflammatory diseases and in neurodegenerative disorders because of their anti-inflammatory activity. However, the molecular mechanism of the protective action of LOX inhibitors has not yet been fully elucidated.MethodsThe aim of this study was to compare the antioxidative potential of widely used LOX inhibitors: BWB70C, AA-861, zileuton, baicalein and NDGA. The antioxidative properties were evaluated in cell-free systems. We measured the effect of the tested compounds on iron/ascorbate-induced lipid peroxidation and on carbonyl group formation in the rat brain homogenate. Direct free radical scavenging was analyzed by using DPPH assay.ResultsOur data showed that the inhibitor of all LOXs, i.e., NDGA, 5-LOX inhibitor BWB70C and the inhibitor of 12/15-LOX, baicalein, significantly decreased the level of lipid and protein oxidation. The free radical scavenging activity of these inhibitors was comparable to known ROS scavengers, i.e., resveratrol and trolox. Zileuton (the inhibitor of 5-LOX) slightly prevented lipid and protein oxidation, it also scavenged the DPPH radical. AA-861 (the inhibitor of 5 and 12/15-LOX) slightly protected lipids against Fe/asc-evoked lipid peroxidation at high concentrations, but had no effect on carbonyl group formation and DPPH scavenging.ConclusionsOur results indicate that some LOX inhibitors demonstrate potent anti-oxidative, free radical scavenging properties. AA-861, whose antioxidative potential is very weak, may be a specific tool to be used in experimental and perhaps even clinical applications.     

Chelating and free radical scavenging mechanisms of inhibitory action of rutin and quercetin in lipid peroxidation

Inhibitory effects of flavonoids rutin and quercetin on ferrous ion-dependent lipid peroxidation of lecithin liposomes and NADPH- and CCl4-dependent lipid peroxidation in rat liver microsomes were studied to elucidate the chelating and free radical scavenging activities of these compounds. The interaction of rutin with superoxide ion and ferrous ions and the reaction of quercetin with lipid peroxy radicals were also studied. Both flavonoids were significantly more effective inhibitors of iron ion-dependent lipid peroxidation systems due to chelating iron ions with the formation of inert iron complexes unable to initiate lipid peroxidation. At the same time, iron complexes of flavonoids retained their free radical scavenging activities. The chelating mechanism of inhibition was more important for rutin than for quercetin. The mutual effect of rutin and ascorbic acid on non-enzymatic lipid peroxidation was also studied. It was concluded that rutin and quercetin are able to suppress free radical processes at three stages: the formation of superoxide ion, the generation of hydroxyl (or cryptohydroxyl) radicals in the Fenton reaction and the formation of lipid peroxy radicals.