硒多糖的抗氧化活性及与过氧化氢酶协同作用的研究

对自行培养的富硒蛹虫草中提取的有机硒多糖进行抗氧化活性研究.采用循环伏安法(CV),在铂电极表面构筑支撑磷脂双层膜 (Supported bilayer lipid membrane, s-BLM),以0.1 mol/L KCl-1.0 mmol/L K3Fe(CN)6-1.0 mmol/L K4Fe(CN)6为探针溶液,利用Fenton体系中Fe2+和H2O2反应产生的羟自由基对模拟生物膜的损伤程度考察有机硒多糖的生物活性.结果表明:羟自由基使s-BLM的通透性增强,造成膜体损伤;而在硒多糖存在下,可使羟自由基对膜的这种损伤受到抑制,硒多糖能够清除自由基保护生物膜;采用紫外-可见(UV-Vis)吸收光谱法比较研究不同浓度的过氧化氢酶与硒多糖对羟自由基的清除率.结果表明:硒多糖对羟自由基的清除效果好于过氧化氢酶,且当体系中硒多糖和过氧化氢酶共存时,二者对羟自由基的清除效果具有协同作用.进一步讨论了硒多糖抗氧化活性的可能机理,为有机硒多糖在保护生物膜、抗氧化活性方面的开发与利用提供科学的理论依据.     

新型壳聚糖双季铵盐的制备及其抗氧化活性

将2,3-环氧丙基三甲基氯化铵(CTA)与壳聚糖反应,制备了水溶性壳聚糖季铵盐(HTCC),然后,以HTCC与氯乙酰氯反应得到氯乙酰壳聚糖季铵盐(CAHTCC),最后,以吡啶取代CAHTCC中的活泼氯,得到水溶性壳聚糖双季铵盐(PAHTCC)。 通过红外光谱和¹³C核磁共振光谱等技术手段对产物结构进行了表征,同时测试了原料壳聚糖及其衍生物清除羟自由基、超氧阴离子以及DPPH的活性。 结果表明,PAHTCC的活性较原料壳聚糖及壳聚糖单季铵盐HTCC均有明显提高,在实验浓度1.6 g/L时,其对羟自由基、超氧阴离子及DPPH的清除率分别达到68.5%、74.3%和80.8%。 聚阳离子性大幅增强,进而抗氧化活性提高。     

硫酸酯化川芎粗多糖的半合成及其抗氧化活性

以水提醇沉法制备川芎粗多糖(1)。首次报道了1与氯磺酸-吡啶经亲核取代反应半合成硫酸酯化川芎粗多糖(2)的方法,其结构经UV和IR表征。用氯化钡-明胶比浊法测定2的取代度。考察了1和2对邻苯三酚自氧化反应产生的超氧阴离子(O2-·)和1,1-二苯基-2-苦基肼(DPPH)体外清除自由基能力。结果表明:在测定浓度范围内,1和2对O2-·清除能力极弱,但对DPPH自由基有一定的清除作用。     

植物多糖清除羟自由基作用的研究

研究当归、黄芪、鬼臼和猫人参的多糖对羟自由基的清除作用.采用分光光度法测定羟自由基清除率,并计算出半数清除率(IC50).当归多糖、黄芪多糖、鬼臼多糖对羟自由基的IC50分别为1.38 mg/mL、0.485 mg/mL、0.1 mg/mL,猫人参的最大清除率仅为36.84%.其清除能力鬼臼多糖＞黄芪多糖＞当归多糖＞猫人参多糖.鬼臼多糖、黄芪多糖均具有较强的清除自由基作用,且清除能力与浓度呈明显的正相关.     

富硒蛹虫草的抗氧化活性研究

采用现代分离技术从富硒蛹虫草中提取硒多糖,然后以苯酚-硫酸法、电感耦合等离子体质谱（ICP—MS）法对硒多糖中多糖含量和硒含量进行测定;在Fenton体系的最佳实验条件下,研究了硒多糖对羟自由基的清除作用及硒多糖对支撑磷脂双层膜（Supported Bilayer Lipid Membranes,s—BLM）的保护作用。结果表明：硒多糖清除羟自由基的效果比与之相同浓度的无机硒、多糖都要明显。其中硒多糖对羟自由基的最高清除率可达38．02％,硒多糖具有很强的抗脂质过氧化、保护支撑磷脂双层膜的作用。     

水解珍珠体外抗氧化活性的研究

本文以L-抗坏血酸(VC)为对照组,测定水解珍珠对DPPH自由基、羟基自由基、超氧阴离子自由基和ABTS自由基的清除能力,研究水解珍珠的体外抗氧化活性。结果表明:水解珍珠对DPPH和ABTS自由基具有较强的清除能力,IC_(50)分别为0.07%和0.14%;而对羟基自由基和超氧阴离子自由基的清除能力相对较弱,IC_(50)分别为12.60%和7.65%;其IC_(50)均低于VC,差异具有统计学意义(p0.05)。另外,水解珍珠对DPPH自由基、羟基自由基、超氧阴离子自由基和ABTS自由基的清除率都随着体积分数的增大而显著增加(p0.05)。水解珍珠具备较高的抗氧化能力,可为珍珠资源的开发利用提供理论依据。     

纳米化对维生素E抗氧化作用的影响

为探讨纳米化对vitamin E抗氧化作用的影响,检测了纳米化vitamin E对抑制超氧阴离子自由基产生的能力、总抗氧化能力以及对4℃贮存红细胞SOD活性的影响。结果表明,与乳化vitamin E相比,纳米化vitamin E能显著提高vitamin E总抗氧化能力和保护4℃贮存红细胞SOD活性的能力(P<0.001);在抑制超氧阴离子自由基的产生方面,乳化vitamin E在低质量浓度(<640μg/L)时,能抑制超氧阴离子自由基的产生,而在高质量浓度(>1 280μg/L)时,则助超氧阴离子自由基的产生;而纳米vitamin E表现为其抗超氧阴离子自由基的能力随其剂量的增加而增强,提示纳米vitamin E在生物学效应方面已发生了某种变化,对纳米化vitamin E的生物学效应还需进一步研究。     

不同工艺的荔枝核提取物抗氧化活性的比较

分别采用回流提取、热浸提取、微波辅助提取法分离荔枝核活性成分,测定了不同工艺制备的荔枝核提取物抑制油脂氧化以及清除羟基自由基和超氧阴离子自由基的抗氧化活性.结果表明,荔枝核提取物具有较强的抗氧化活性,能够有效地抑制油脂氧化;不同工艺的提取物对油脂抗氧化作用的排序为微波提取物热浸提取物回流提取物.与此同时,荔枝核提取物能够有效地清除羟基自由基,其中微波提取物的半清除率质量浓度(EC50)约为0.76 g/L,热浸提取物的EC50约为0.94 g/L,回流提取物的EC50约为2.0 g/L.此外,荔枝核提取物对超氧阴离子自由基也有一定的清除效果.     

漏芦花中生物碱类化合物含量测定及抗氧化性研究

采用分光光度法测定了漏芦花中生物碱类化合物的含量,并测定漏芦花中生物碱类化合物提取液对超氧阴离子自由基的清除能力.结果表明,漏芦花中生物碱类化合物含量为3.493mg/g,样品回收率为92.4%~98.8%.漏芦花中生物碱类化合物对超氧阴离子自由基有很好的清除作用,其清除作用随生物碱类化合物含量的增加而增加.     

芜菁籽不同溶剂提取物体外抗氧化活性研究

通过体外试验初步研究芜菁籽提取物的抗氧化活性。用95%乙醇为溶剂提取芜菁籽,采用有机溶剂萃取法将提取物分为石油醚相,乙酸乙酯相,正丁醇相和水相等4个不同极性部位、同时测定了各相提取物对羟自由基,超氧阴离子自由基,DPPH自由基的清除能力,并与合成抗氧化剂BHT进行对照。结果表明,芜菁籽提取物的不同极性部位均有抗氧化活性,其抗氧化效果随着浓度的增加而增强,乙酸乙酯相和正丁醇相的还原能力及清除O-2.,DPPH和.OH的能力均强于水相和石油醚相,乙酸乙酯相和正丁醇相的抗氧化作用强,是天然抗氧化剂的良好来源,应对其进一步分离纯化。     

一种脂溶性异黄酮化合物的晶体结构及抗氧化活性研究

本文合成了5-甲基-7-羟基-4-甲氧基异黄酮,采用IR,UV,1H NMR,和元素分析对其结构进行了表征,并利用X射线单晶衍射仪测定了该化合物的晶体结构。用紫外光谱法研究了它们对超氧阴离子自由基和1,1-二苯基-2-苦肼基自由基(1,1-diphenyl-2-picrylhydrazyl free radical简称DPPH.)的清除活性.实验结果表明5-甲基-7-羟基-4′-甲氧基异黄酮化合物(C17H14O4)属于三斜晶系,空间群为P1。a=0.82255(2)nm,b=0.93123(2)nm,c=1.04547(2)nm,α=89.0432(2)°,β=69.1950(10)°,γ=66.9790(10)°,Z=2,V=0.681 99(3)nm3,Dc=1.375 g.cm-3,F(000)=296,R1=0.044 4,wR2=0.115 6,而且该化合物具有较好的清除羟基自由基和超氧自由基的作用。     

A Study on the In Vitro Antioxidant Activity of Juniper (Juniperus communis L.) Fruit Extracts

Abstract

This study aimed at evaluating the in vitro antioxidant activity of water and ethanol extracts of juniper (Juniperus communis L., Family Cupressaceae) fruit. The antioxidant properties of both Juniper extracts were studied using different antioxidant assays, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Both the water and the ethanol extracts exhibited strong total antioxidant activity. The concentrations of 20, 40, and 60 µg/mL of water and ethanol extracts of juniper fruit showed 75%, 88%, 93%, 73%, 84%, and 92% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 60 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α‐tocopherol exhibited 96, 96, and 61 inhibitions on peroxidation of linoleic acid emulsion, respectively. However, both extracts of juniper had effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities at these same concentrations (20, 40, and 60 µg/mL). Those various antioxidant activities were compared to BHA, BHT, and α‐tocopherol as standard antioxidants. In addition, total phenolic compounds in both aqueous and ethanolic juniper extracts were determined as gallic acid equivalents. Accordingly, these results indicate that juniper has in vitro antioxidant properties and these may be major reasons for the inhibition of lipid peroxidation properties.     

两种新型水溶性异黄酮衍生物的合成与抗氧化活性

合成了未见文献报道的水溶性的3'-磺酸钠-4',7-二羧甲氧基异黄酮(L1)和3'-磺酸钠-4'-羟基-7-羧甲氧基异黄酮(L2), 采用IR, UV, ¹H NMR和元素分析对其结构进行了表征, 利用荧光光谱法研究了它们和母体大豆甙元(D)对羟基自由基的清除活性, 用紫外光谱法研究了其对超氧阴离子自由基和1,1-二苯基-2-苦肼基自由基(1,1-diphenyl-2-picrylhydrazyl free radical, 简称DPPH)的清除活性; 并采用量子化学AM1方法在全几何构型优化的基础上进行了电荷布居分析, 计算了它们抽氢反应的生成热(∆H_f), 从而从理论上探讨了目标化合物清除羟基自由基的活性. 实验结果表明本文合成的两种水溶性化合物清除超氧阴离子自由基和DPPH自由基的活性要优于母体大豆甙元, 对于目标化合物清除羟基自由基的活性, 实验和理论结果都显示其清除活性要优于大豆甙元．     

Radical scavenging activity and antioxidant capacity of bay leaf extracts

Bay leaves (BL) (Laurus nobilis L., Family: Lauraceae) are traditionally used orally to treat the symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructation, and flatulence. In this study, lyophilized extracts (both water and ethanol) of BL were studied for their antioxidant properties. The antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities were evaluated to determine the total antioxidant capacity of both BL extracts. Both extracts exhibited strong total antioxidant activity in linoleic acid emulsion. Concentrations of 20, 40, and 60 μg ml^?1 showed 84.9, 95.7, 96.8, and 94.2, 97.7, and 98.6% inhibition of lipid peroxidation of linoleic acid emulsion, for water and ethanol extracts, respectively. On the other hand, 60 μg ml^?1 of the standard antioxidants butylated hydroxyianisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol exhibited 96.6, 99.1, and 76.9% inhibition of lipid peroxidation in linoleic acid emulsion, respectively. In addition, the both BL extracts had effective reducing power, DPPH? free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities at 20, 40, and 60 μg ml^?1. The total amount of phenolic compounds in each BL extract was determined as gallic acid equivalents.     

Radical scavenging and antioxidant activity of tannic acid

Tannic acid, a naturally occurring plant polyphenol, is composed of a central glucose molecule derivatized at its hydroxyl groups with one or more galloyl residues. In the present paper, we examines the in vitro radical scavenging and antioxidant capacity of tannic acid by using different in vitro analytical methodologies such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination using by Fe³⁺–Fe²⁺ transformation method, superoxide anion radical scavenging by riboflavin–methionine-illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe²⁺) chelating activities. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant radical scavenger compounds.Tannic acid inhibited 97.7% lipid peroxidation of linoleic acid emulsion at 15 μg/mL concentration. On the other hand, the above mentioned standard antioxidants indicated an inhibition of 92.2%, 99.6%, 84.6% and 95.6% on peroxidation of linoleic acid emulsion at 45 μg/mL concentration, respectively. In addition, tannic acid had an effective DPPH scavenging, ABTS⁺ radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, Fe³⁺ reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and trolox as references antioxidant compounds. The present study shows that tannic acid is the effective natural antioxidant component that can be used as food preservative agents or nutraceuticals.     

Antioxidative and DNA Protective Effects of Bacillomycin D-Like Lipopeptides Produced by B38 Strain

In the present study, we evaluated the antioxidant and the scavenging ability of C14, C15 and C16 bacillomycin D-like lipopeptides produced by B38 strain. They all displayed strong reducing power activity, hydroxyl and superoxide anion radicals scavenging activities and inhibition of lipid peroxidation. In addition, they were found to protect plasmid DNA damage from hydroxyl radical oxidation. Data suggested that their antioxidant potency can be attributed to the hydrophobic and aromatic side-chain groups of their amino acids as well as to the aliphatic chain of their beta amino fatty acids. Note that the hydrocarbon chain length did not interfere with the antioxidant power. Overall, such bacillomycin D lipopeptides which exhibit antioxidant and radical scavenging activities may be useful for cosmetic, therapeutic or pharmaceutical purposes in order to delay or prevent oxidative deterioration of manufactured products.     

C70-β-丙氨酸衍生物抗氧化性的研究

在非均相碱性体系中,合成了C70-β-丙氨酸衍生物.采用FT-IR和1H NMR手段对其结构进行了表征,并考察了它对超氧阴离子清除能力、羟基自由基清除能力、还原能力及金属螯合能力.结果表明:C70-β-丙氨酸衍生物具有良好的抗氧化活性,并且β-丙氨酸在四个体系中并未表现出抗氧化活性,说明C70-β-丙氨酸衍生物的抗氧化能力可能主要来自于C70上的双键.     

Methodological aspects about in vitro evaluation of antioxidant properties

Several of the most commonly used methods for in vitro determination of antioxidant capacity are reviewed in the present paper. The chemical principles of methods based either on biological oxidants (peroxyl radical, superoxide radical anion, hydrogen peroxide, hydroxyl radical, hypochlorous acid, singlet oxygen, nitric oxide radical, and peroxynitrite) or on non-biological assays (scavenging of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical cation (TEAC assay), scavenging of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH assay), ferric reducing antioxidant power (FRAP assay), Folin-Ciocalteu reducing capacity (FC assay), electrochemical total reducing capacity) are outlined and critically discussed. The scope of application, the advantages and shortcomings of each method are also highlighted.     

Determination of in vitro antioxidant and radical scavenging activities of propofol

Propofol (2,6-diisopropylphenol) is a hypnotic intravenous agent with in vivo antioxidant properties. This study was undertaken to examine the in vitro antioxidant activity of propofol using different antioxidant tests including by 1,1-diphenyl-2-picryl-hydrazil (DPPH.) radical scavenging, metal chelating, hydrogen peroxide scavenging, superoxide anion radical scavenging, reducing power and total antioxidant activities. At the concentrations of 25, 50, and 75 microg/ml, propofol exhibited 97.7, 98.6 and 100% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, at the 75 microg/ml concentration of standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and alpha-tocopherol exhibited 88.7, 94.5, and 70.4% inhibition on peroxidation of linoleic acid emulsion, respectively. In addition, at same concentrations, propofol was shown that it had effective reducing power, DPPH. free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. These various antioxidant activities were compared to standard antioxidants such as BHA, BHT and alpha-tocopherol. These results indicate that propofol prevents lipid peroxidation and radicalic chain reactions. At the same time, propofol revealed more effective antioxidant capacity than BHA, BHT and alpha-tocopherol.     

分光光度法测定二氢黄酮化合物对超氧阴离子自由基的清除作用

采用分光光度法测定了来源于几种药用植物的天然二氢黄酮类化合物清除超氧阴离子自由基(O-2·)的能力,探讨了二氢黄酮类化合物清除O-2·的活性与结构之间的关系,以期为开发利用天然抗氧化剂提供科学依据.