一品红花色素抗氧化性能的研究

从一品红红色苞片中提取花色素,并用自由基测定试剂盒测试了一品红花色素的体外抗氧化性能,并用碘量法测定了其抑制猪油氧化的效果,用TBARS法测定其对血浆脂蛋白氧化的抑制能力。结果表明:一品红花色素具有较强的清除超氧阴离子(O2.-)和羟自由基(.OH)的能力,清除效果优于同浓度的VC;其对猪油氧化的抑制效果和同浓度的VC相近,而对人血浆脂质过氧化的抑制效果显著高于VC。     

疏毛罗勒提取物抗氧化活性分析

本文研究了疏毛罗勒抗氧化活性。实验中用7种不同溶剂提取疏毛罗勒活性成份,以维生素C(Vc)为对照,通过FRAP法对比不同提取液总抗氧化能力、采用改良的邻苯三酚自氧化法检测了水提物对超氧阴离子的清除作用。结果表明,7种不同溶剂提取的疏毛罗勒活性成分中,以水提物的总抗氧化效果最好,但随着提取浓度的增加总抗氧化能力反而减弱,疏毛罗勒水提物对超氧阴离子的清除率接近Vc的作用。     

谷胱甘肽的抗线粒体脂质过氧化作用

谷胱甘肽是细胞内重要的抗氧化损伤物质之一．以NADH诱导的牛心肌线粒体脂质过氧化体系为模型,研究了谷胱甘肽的抗氧化作用．结果表明,一定浓度的谷胱甘肽能够部分抑制该体系中线粒体的脂质过氧化．保护组的丙二醛含量为损伤组72．5％;线粒体的膨胀度较损伤组降低;细胞色素C氧化酶及ATP酶活力分别较损伤组提高了1．5及2．2倍．     

嗜麦芽假单胞菌黑色素的抗氧化作用研究

采用ＮＢＴ光化学反应法测定嗜麦芽假单胞菌黑色素对超氧阴离子自由基的清除作用,结果表明黑色素能明显地清除超氧阴离子自由基。４μｇ的黑色素对超氧阴离子自由基的清除率为８３．６％。黑色素有明显的抗脂质过氧化作用,能抑制鼠肝匀浆在３７℃温育下生成丙二醛,７２μｇ抑制率为９２．５％。黑色素能够降低由Ｈ２Ｏ２所致的红细胞溶血作用,经Ｈ２Ｏ２作用后,溶血率为６５．３％,经黑色素抗氧化作用后溶血率为５２．５％。     

红托竹荪多糖抗氧化活性的研究

本文采用DPPH自由基、羟自由基及超氧阴离子自由基体系对红托竹荪多糖的抗氧化活性进行了研究,并同Vc和BHT进行了比较.结果表明,在0.2～1.2 mg/mL质量浓度范围内,红托竹荪多糖对DPPH自由基、羟自由基、超氧阴离子自由基的半数清除率(EC50)值分别为1.468、2.580和2.330,抗氧化活性稍强于BHT,但弱于VC.     

谷胱甘肽的抗线粒体脂质过氧化作用

谷胱革肽是细胞内重要的抗氧化损伤物质之一,以ＮＡＤＨ诱导的牛心肌线粒体脂质过氧化体系为模型,研究了谷胱甘肽的抗氧化作用。结果表明,一定浓度的谷胱甘肽能够部分抑制该体系中线粒体的脂质过氧化,保护组的丙二醛含量为损伤组７２．５％;线粒体的膨胀度较损伤组降低;细胞色素ｃ氧化酶及ＡＴＰ酶活力分别较损伤组提高了１．５及２．２倍。     

Rhizobium sp. N613胞外多糖的抗氧化活性

以铁氰化钾和铁离子为检测系统测定了Rhizobium sp.N613胞外多糖(REPS)对氧化物的还原力;H2O2和Fe2+为羟自由基生成系统检测了REPS对羟自由基的清除作用;邻苯三酚自氧化法检测了REPS对超氧阴离子的清除作用;并体外检测了REPS对H2O2引起的氧化溶血现象的抑制作用及对小鼠肝组织脂质过氧化损伤的保护作用。结果显示,REPS对氧化物具有明显的还原力,其对羟自由基的清除作用达到35.46%(多糖浓度为2mg/mL),对超氧阴离子的清除作用达到36.84%(多糖浓度为0.78mg/mL),对H2O2引起的氧化溶血现象的抑制作用达到43.84%(多糖浓度为1.14mg/mL),对小鼠肝组织脂质过氧化的保护作用达到34.46%(多糖浓度为1.14mg/mL),表明REPS具有良好的抗氧化作用,有着重要的应用价值。     

菟丝子黄酮体外清除自由基活性的研究

采用DPPH体系、羟基自由基体系、烷基自由基引发的亚油酸氧化体系、超氧阴离子自由基体系对菟丝子黄酮的抗氧化活性进行研究,并同Vc、BHT进行了比较。结果表明:在试验质量浓度范围内(0.008 mg/mL~1 mg/mL),菟丝子黄酮对DPPH.、.OH自由基、O2-.自由基的清除率可达91.56%、89.39%和87.65%;其对烷基自由基的抑制率为84.22%,且其抗氧化活性强于Vc和BHT,表明菟丝子黄酮是一种天然有效的自由基清除剂。     

家蝇幼虫提取物清除氧自由基的作用

探讨了家蝇Musca domesticaL.幼虫提取物对氧自由基的清除作用。采用脱氧核糖-铁体系和邻苯三酚自氧化体系分别测定了不同浓度的提取物对羟自由基和超氧阴离子自由基的清除率,同时采用H2O2氧化体系测定了提取物的抗氧化值。结果显示家蝇幼虫提取物对羟自由基和超氧阴离子自由基的IC50分别为1.93 mg/mL和3.26 mg/mL;浓度为0.5%的提取物的抗氧化值为9.01 mg/g,为同浓度维生素C抗氧化值的1.29倍。     

酶解骨胶原多肽的抗氧化特性研究

本文主要研究了酶解法制备的骨胶原多肽的总抗氧化能力、羟自由基清除作用和抑制超氧阴离子自由基的能力.通过与谷胱甘肽(GSH)的比较发现,溶液浓度在1130～150 mg/mL时,该骨胶原多肽的总抗氧化能力为GSH的71.92%.溶液浓度在2.5～20 mg/mL时,该多肽羟自由基清除作用为谷胱甘肽的1.36倍.溶液浓度为10～150 mg/mL时,多肽抑制超氧阴离子自由基的能力低于谷胱甘肽.     

Antioxidant activity of extract from Polygonum cuspidatum

Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oí Polygonum cuspidatum extract is 110 microg/ml in free radical scavenging assays, 3.2 microg/ml in superoxide radical scavenging assays, and 8 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 +/- 42.6 mg/g and 62.3 +/- 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects.     

Structure and protective effect of exopolysaccharide from P. Agglomerans strain KFS-9 against UV radiation

The water-soluble exopolysaccharide (WSEPS) from Pantoea agglomerans strain KFS-9 isolated from mangrove forest was prepared by removing bacterial cell from the fermentation liquid following by concentration and cold ethanol precipitation of the supernatant. The polysaccharide material was purified by gel permeation chromatography on a Sephacryl S-300HR column and characterized using chemical and spectral methods. The results show that WSEPS is protein-bound polysaccharide, and it is composed of arabinose, glucose galactose and gulcuronic acid in the molar ratio of 1.0:2.2:2.8:0.9. Their antioxidant activities in vitro were studied by various antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging and antilipid peroxidation. The results show that the WSEPS extracted had a high antioxidant activity in a concentration-dependent manner (except the activity of antilipid peroxidation). WSEPS quenched hydroxyl radicals, superoxide radicals at low amounts, the IC(50) of which were 0.07 and 0.15 mg/ml, respectively. These results indicate that the protective effect of WSEPS against UV radiation is most likely to be due to the free radicals-scavenging ability.     

Antioxidant activity of extract from Polygonum aviculare L

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation, and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum aviculare L. (Polygonaceae) has antioxidant activity is unknown. In this study, dried Polygonum aviculare L. was extracted by ethanol, and the extract was lyophilized. The antioxidant activities of extract powder were examined by free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays. The results show that the IC50 value of Polygonum aviculare L. extract is 50 microg/ml in free radical scavenging assays, 0.8 microg/ml in superoxide radical scavenging assays, and 15 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum aviculare L. extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 677.4 +/- 62.7 microg/g and 112.7 +/- 13 microg/g. The results indicate that Polygonum aviculare L. extract clearly has antioxidant effects.     

Antioxidant activity of differently regioselective chitosan sulfates in vitro

Differently regioselective chitosan sulfates were prepared according to Hanno Baumann's methods. Their antioxidant potencies were investigated employing various established in vitro systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH)/superoxide/hydroxyl radicals scavenging, reducing power, iron ion chelating and total antioxidant activity. All kinds of sulfated chitosans (HCTS, TSCTS, SCTS, TCTS) showed strong inhibitory activity toward superoxide radical by the PMS-NADH system compared to Vc. According to the above-mentioned order their IC50 were 0.012, 0.040, 0.015, 0.022 mg/mL, respectively, however, scavenging activity of Vc on superoxide radical was 68.19% at 2.0 mg/mL. Scavenging activity of superoxide radical was found to be in the order of HCTS>SCTS>TCTS>TSCTS>Vc. Furthermore, all kinds of sulfated chitosans exhibited strong concentration-dependent inhibition of deoxyribose oxidation. Except for HCTS, others had stronger scavenging activity on hydroxyl radical than Vc. Scavenging effect of TSCTS on 1,1-diphenyl-2-picrylhydrazyl radical was little lower than that of BHA, but better than that of others. All kinds of sulfated chitosans were efficient in the reducing power, especially TSCTS. TSCTS and TCTS showed considerable ferrous ion chelating potency. The data obtained in vitro models clearly establish the antioxidant potency of all kinds of sulfated chitosans. These in vitro results suggested the possibility that sulfated chitosans could be effectively employed as ingredient in health or functional food, to alleviate oxidative stress. However, comprehensive studies need to be conducted to ascertain the in vivo safety of sulfated chitosans in experimental animal models.     

Effect of molecular weight on the antioxidant property of low molecular weight alginate from Laminaria japonica

In this study, three alginate fractions with different molecular weights and ratios of mannuronic acid (M) to guluronic acid (G) were prepared by enzymatic hydrolysis and ultrafiltration to assess the antioxidant property of alginates from Laminaria japonica with molecular weight below 10 kDa. The antioxidant properties of different molecular weight alginates were evaluated by determining the scavenging abilities on superoxide, hydroxyl, and hypochlorous acid and inhibitory effect on Fe²⁺-induced lipid peroxidation in yolk homogenate. The results showed that low molecular weight alginates exhibited high scavenging capacities on superoxide, hydroxyl, and hypochlorous acid radicals and good inhibition of Fe²⁺-induced lipid peroxidation in yolk. By comparison, alginate A1 with molecular weight below 1 kDa and M/G of 1.84 had better scavenging activity on superoxide, hydroxyl, and hypochlorous acid radicals in vitro than A2 (1–6 kDa), A3 (6–10 kDa), ascorbic acid, and carnosine. With similar M/G ratio, A2 exhibited better antioxidant activity on superoxide and hypochlorous acid radicals than A3. However, fraction A3 with molecular weight of 6–10 kDa exhibited higher inhibitory ability on lipid peroxidation in yolk in vitro than A1 and A2. The results indicated that molecular weight played a more important role than M/G ratio on alginate to determine the antioxidant ability. By comparison, low molecular weight alginates composed of guluronic acid and mannuronic acid exhibited better antioxidant ability on oxygen free radicals than sulfated polysaccharides from L. japonica in our previous study and represent a good source of marine polysaccharide with potential application as natural antioxidant.     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO*), superoxide anion (O2*-), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC50 = 2.3 +/- 0.2 and 1.9 +/- 0.1 microg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 +/- 0.2 and 0.2 +/- 0.1 microg/ml, respectively), and also showed a considerable antioxidant activity against O2*- (87.3 +/- 0.1 and 73.1 +/- 0.4 microg/ml, respectively) and DPPH radicals (55.4 +/- 0.3 and 38.3 +/- 0.4 microg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl4 significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl4 in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

In vitro antioxidant activity of Diospyros malabarica Kostel bark

Antioxidant activity of defatted methanol extract of D. malabarica bark was studied for its free radical scavenging property on different in vitro models e.g. 1,1-diphenyl-2-picryl hydrazyl (DPPH), nitric oxide, superoxide, hydroxyl radical and lipid peroxide radical model. The extract showed good dose-dependent free radical scavenging property in all the models except in hydroxyl radical inhibition assay. IC50 values were found to be 9.16, 13.21, 25.27 and 17.33 microg/ml respectively in DPPH, nitric oxide, superoxide and lipid peroxidation inhibition assays. In hydroxyl radical inhibition assay 1000 microg/ml extract showed only 10% inhibition with respect to the control. Measurement of total phenolic compounds by Folin-Ciocalteu's phenol reagent indicated that 1 mg of the extract contained 120.7 microg equivalent of pyrocatechol. The results indicate that the antioxidant property of the extract may be due to the high content of phenolic compounds. However, the underlying mechanism may not involve hydroxyl radical scavenging property.     

Antioxidant properties of EPC-K1: a study on mechanisms.

Scavenging effects of L-ascorbic acid 2-[3,4-dihydro-2,5,7,8- tetramethyl-2-(4,8,12-trimethytridecyl)-2H-1-benzopyran- 6-yl-hydrogen phosphate] potassium salt (EPC-K1) on hydroxyl radicals, alkyl radicals and lipid radicals were studied with ESR spin trapping techniques. The inhibition effects of EPC-K1 on lipid peroxidation were assessed by TBA assay. The kinetics of EPC-K1 reacting with hydroxyl radicals and linoleic acid radicals were studied by pulse radiolysis. The active site of EPC-K1 and the structure-antioxidative activity relationships were discussed. The superoxide radicals scavenging capacity of the brain homogenate of EPC-K1-treated rats was measured. The results revealed that in comparison with Trolox and vitamin C, EPC-K1 showed better overall antioxidative capacity in vitro and in vivo. EPC-K1 was a moderate scavenger on hydroxyl radicals and alkyl radicals, a potent scavenger on lipid radicals, and an effective inhibitor on lipid peroxidation. EPC-K1 could react with hydroxyl radicals with a rate constant of 7.1 x 10(8) dm3 mol-1 s-1 and react with linoleic acid radicals with a rate constant of 2.8 x 10(6) dm3 mol-1 s-1. The active site of EPC-K1 was the enolic hydroxyl group. After administration of EPC-K1, the ability of rat brain to scavenge superoxide radicals was significantly increased. The potent scavenging effects of EPC-K1 on both hydrophilic and hydrophobic radicals were relevant with its molecular structure, which consisted of both hydrophilic and hydrophobic groups.     

Tyrosinase Inhibitory Effects and Antioxidative Activities of Saponins from Xanthoceras Sorbifolia Nutshell

Certain saponins are bioactive compounds with anticancer, antivirus and antioxidant activities. This paper discussed inhibitory effects of saponins from Xanthoceras Sorbifolia on tyrosinase, through the research of the rate of tyrosinase catalyzed L-DOPA oxidation. The inhibition rate of tyrosinase activity presented non-linear changes with the saponins concentration. The rate reached 52.0% when the saponins concentration was 0.96 mg/ml. Antioxidant activities of saponins from Xanthoceras Sorbifolia were evaluated by using hydroxyl and superoxide radical scavenging assays. The hydroxyl radical scavenging effects of the saponins were 15.5–68.7%, respectively at the concentration of 0.18–2.52 mg/ml. The superoxide radical scavenging activity reduced from 96.6% to 7.05% with the time increasing at the concentration of 1.44 mg/ml. All the above antioxidant evaluation indicated that saponins from Xanthoceras Sorbifolia exhibited good antioxidant activity in a concentration- dependent manner.     

Antioxidant and antitumor activities of the polysaccharide from seed cake of Camellia oleifera Abel

To explore biomedical potential of the polysaccharide from seed cake of Camellia oleifera Abel, we investigated antioxidant and antitumor capacities of the polymer. The results showed that the polysaccharide is capable of scavenging both superoxide anion and hydroxyl radicals in vitro. The highest scavenging rate of superoxide anion and hydroxyl radicals is 85% and 76%, respectively. Using the model animal, Caenorhabditis elegans, we further show that the polysaccharide can increase antioxidant enzyme activity, decrease lipid peroxidation level, and reduce paraquat-induced oxidative damage at a polysaccharide concentration more than 50mg/l. We also revealed that the polysaccharide has some ferric chelating ability and strong in vivo antitumor activity. The antitumor rate against Sarcoma180 solid tumor grown in BALB/C mice reached 85.6% at the highest dose of 40×20mg/kgdays.