腐植酸钠清除自由基作用的研究

利用DPPH自由基清除法、羟自由基清除法、超氧阴离子自由基清除法、总还原力的测定4种方法对腐植酸钠的抗氧化活性进行了检测和评价。研究结果表明,腐植酸钠具有较强的自由基清除能力和一定的抗氧化能力,且随着腐植酸钠浓度的增加,其抗氧化能力逐渐增强。     

PM6 and DFT study of free radical scavenging activity of morin

Flavonoids have long been recognised for their general health-promoting properties, of which their antioxidant activity may play an important role. In this work, we have studied the properties of flavonoid morin using semiempirical and density functional theory (DFT) methods in order to validate the application of the recently developed parametric method 6 (PM6). Reaction enthalpies related to mechanisms of free radical scavenging by flavonoid morin were calculated by DFT and PM6 methods in gas-phase, water, DMSO and benzene. It has been shown that fast semiempirical PM6 method can mimic results obtained by means of more accurate time consuming DFT calculations. Thermodynamically favoured mechanism depends on reaction medium: SPLET (sequential proton loss electron transfer) is preferred in water and DMSO, and HAT (hydrogen atom transfer) is predominant in gas-phase. In benzene these two mechanisms are competitive.     

紫苏提取物体外清除自由基能力的研究

以紫苏茎、叶为研究对象,采用不同溶剂获取各种提取物,用茶多酚、维生素E、TBHQ作为对照,采用DPPH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、羟基自由基体系,研究各种提取物对不同自由基的清除作用。结果表明,提取物对四种自由基均有清除作用,其清除效果依次为羟基自由基>DPPH自由基>烷基自由基>超氧阴离子自由基。紫苏茎、叶的95％乙醇(v/v)与碱水混合物提取物(8:2v/v)的总黄酮得率最高,紫苏叶提取物的抗氧化性强于紫苏茎提取物。      

Comparison of antioxidant activities of onion and garlic extracts by inhibition of lipid peroxidation and radical scavenging activity

The antioxidant activities of the methanol extracts of selected varieties and parts of garlic and onion were determined by two methods: inhibition of lipid peroxidation induced by tert-butyl hydroperoxide in isolated rat hepatocytes and scavenging activity against diphenylpicrylhydrazyl radical. The total phenolics and the main flavonoids of the hydrolysed onion and garlic samples were also analysed. The antioxidant activities obtained by the two methods were compared. Both methods gave similar antioxidant activities for pure compounds and Allium extracts. However, the radical scavenging method had many benefits compared to the lipid peroxidation method, being easier, cheaper, more specific and reproducible. The radical scavenging activities also correlated positively with the total phenolics of the extracts. Onions had clearly higher radical scavenging activities than garlic, red onion being more active than yellow onion. The skin extracts of onion possessed the highest activities.     

不同产地板蓝根多糖体外清除自由基活性的比较

采用邻二氮菲-Fe~(2+)氧化法测定板蓝根多糖对羟基自由基(·OH)的清除作用;采用邻苯三酚自氧化法检测超氧阴离子自由基(·O_2~-)的清除作用;采用DPPH孤电子配对法测定DPPH自由基的清除作用。结果表明,在羟基自由基体系中,菘蓝根多糖显示较强的清除作用,清除率为52.60%;草大青根和马蓝根多糖最高分别可达到41.29%,39.35%;在超氧阴离子自由基体系中,菘蓝根多糖、草大青根和马蓝根多糖的清除率最高分别可达到50.00%、39.75%、39.15%;在DPPH自由基体系中,3种多糖最高清除率为42.75%。     

毛豆腐提取物的自由基清除活性研究

利用20%、40%、60%乙醇溶液（v/v）、pH4.5水、pH6.5水作为提取溶剂,对发酵时间为3、5、7、9d的毛豆腐分别进行提取,测定提取物中蛋白质的提取率、水解度,以及采用DPPH、ABTS法评价提取物的体外自由基清除活性。研究结果表明,随着毛豆腐发酵时间的延长,提取物中蛋白质的提取率、水解度均逐渐增加,并且提取物的自由基清除活性也明显地提高;通过比较还发现,毛豆腐乙醇提取物的自由基清除活性高于水提取物,且随着乙醇浓度的提高,提取物的自由基清除活性提高。排阻色谱分析结果证明,发酵9d后毛豆腐中蛋白质充分水解,5种提取物的主要成分为肽与氨基酸。     

茶绿色素的提取及体外清除自由基活性研究

目的研究几种不同提取方法提取的茶绿色素的得率、化学组成、色相及体外清除自由基活性。方法分别用95%乙醇经常温浸泡、热水提取、超声波提取及微波提取茶绿色素,采用常规方法分析该色素化学组成及色相,试剂盒检查其清除自由基活性。结果与其他几种提取方法相比,微波提取茶绿色素的得率、色素中叶绿素含量均最高,分别为37.02%、8.92%;该色素所含茶多酚、总黄酮、氨基酸含量也相对较高;微波提取色素的绿度最高,为-27.63,亮度(40.21)仅略低于常温提取色素的亮度(40.29);该色素清除羟自由基(·OH)、超氧阴离子自由基(O_2~-·)的活性也较高,分别仅略低于热水提取色素的清除活性,但没有显著性差异。结论微波提取茶绿色素不仅得率高、色相好,且该色素清除自由基活性高,是茶绿色素提取的最佳方法。     

低聚原花色素的提取及清除自由基活性研究

采用磷酸溶液与乙酸乙酯混合试剂冷浸法,从葡萄籽中提取低聚原花色素,用CO2超临界纯化初级产品.结果表明:在提取24 h,料液比为1∶ 5,磷酸浓度为2%,混合试剂中磷酸与乙酸乙酯体积比为1∶ 10的条件下,原花色素收率较高,达到0.5%;提取液减压浓缩后,通过CO2超临界去除脂溶性杂质和色素后得到的产品,经1,1-二苯基-2-苦肼基法清除自由基活性测定,其抗氧化活性是80%乙醇浸提所得产品的2.4倍,是天津尖峰产品的1.3倍.     

五谷酸奶的研制及其清除自由基的能力

根据动植物蛋白营养平衡互补的原理,以黑芝麻、黑豆、玉米为主要原料,研制新型五谷酸奶。通过单因素和正交试验确定五谷酸奶的最佳制作工艺为黑芝麻汁添加量10mL/100mL、黑豆汁添加量13.3 mL/100 mL、玉米汁添加量13.3mL/100mL、奶粉添加量7.9g/100mL、白砂糖添加量5g/100mL、接种量3mL/100mL、发酵时间7h、发酵温度42℃。该条件下制得的五谷酸奶酸甜可口,质地细腻。通过研究五谷酸奶、五谷汁原液和市售某品牌酸奶的DPPH自由基和羟基自由基清除能力,结果表明:五谷酸奶对DPPH自由基、羟自由基的清除率均随其浓度的增加而增强。当其浓度为50mg/mL时,五谷酸奶对DPPH自由基清除率为(84.9±0.10)%,羟基自由基的清除率为(55.6±0.12)%,且在相同浓度时,五谷酸奶的自由基清除率高于市售某品牌酸奶。     

蛋清酶解多肽的制备及其清除自由基活性

为探索蛋清酶解多肽体外清除自由基活性,开发功能性蛋制品,本文采用碱性蛋白酶、胰蛋白酶、中性蛋白酶,通过对比实验、单因素实验和正交实验确定了蛋清酶解多肽的制备方法,采用体外清除自由基对比实验研究了蛋清酶解多肽的体外清除自由基活性。结果表明:蛋清蛋白浓度调整至4 g/100 mL(m/V),用18000 U/g蛋白的碱性蛋白酶在pH9.0于60 ℃水解7 h,制备的蛋清多肽清除DPPH自由基能力最强;用碱性蛋白酶制备的蛋清多肽在体外对超氧阴离子、羟自由基、DPPH自由基清除能力和Fe³⁺还原能力均明显优于蛋清,但远不及V_C。证明蛋清经碱性蛋白酶控制水解能明显增强其清除自由基能力,提高其保健性能。     

襄麦冬总甾体皂苷提取工艺优化及体外清除自由基活性评价

以山麦冬皂苷B含量为考察指标,通过响应面法对襄麦冬总甾体皂苷的提取工艺进行优化,并评价甾体皂苷的体外抗氧化能力。结果表明,当采用超声时间0.5h、超声液料比19.51.0(mL/g)、超声温度39.7℃、索氏提取时间3h处理襄麦冬块根粉碎物时,提取物中甾体皂苷的含量最高,山麦冬皂苷B可达到0.073 8 mg/mL。襄麦冬总甾体皂苷对OH自由基、O-2自由基、DPPH自由基以及ABTS自由基均具有一定的体外清除能力,且清除活性与甾体皂苷的浓度呈线性关系;对OH自由基和O-2自由基,在设定的最高浓度(1.28 mg/mL)时,清除率均超过50%,分别达到59.66%和52.3%。     

In vitro antioxidant/free radical scavenging and antibacterial properties of endemic oregano and thyme extracts from Greece

The present investigation was to evaluate the antioxidant and antibacterial activities of hexane and methanol extracts from Origanum vulgare ssp. hirtum and Thymus vulgaris (Komotini, Greece). The methanol extracts of oregano and thyme against DPPH radical were more active than the hexane extracts (mean values 0.94 and 0.47, respectively) and oregano exhibited stronger activity than thyme (mean values 0.82 and 0.55, respectively). The results from the β-carotene/linoleic acid assay showed that all plant extracts inhibited linoleic acid oxidation up to 70.78±1.17%. The oregano extracts exhibited the strongest inhibition against Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus using the disc diffusion assay. The chemical composition of the hexane and methanol extracts, by using GC-MS, showed that carvacrol, thymol, and p-cymene were the most prominent compounds. The methanol extract of oregano was found the most potent antioxidant with the highest content of total phenolics (138.92 mg GA/g extract) and carvacrol (76.7%).     

量子化学计算在天然抗氧化物研究中的应用

量子化学(quantum chemistry)是应用量子力学的基本原理和方法来研究原子、分子体系中的各种物化现象及其内在规律的一门学科,因其涉及到原子、分子层面,可以揭示化学反应本质,因此非常适合于物质间相互作用机制和原理的研究,而量子化学计算是实现该研究的具体途径和方法。本文介绍了自由基和天然抗氧化物的种类,总结了抗氧化物清除自由基的机制;并介绍了量子化学计算的原理及相应计算方法,归纳了与清除自由基活性相关的量子化学参数及其表征意义,展望了今后量子化学计算在抗氧化剂构效关系研究中的发展趋势及前景。     

Antibacterial and free radical scavenging activity of a medicinal plant Solanum xanthocarpum

The present study describes the phytochemical profiles, antibacterial, and antioxidant properties of different solvent extracts of Solanum xanthocarpum leaves. Phytochemical analysis results revealed the presence of terpenoids, tannins, steroids, and phenols. Methanolic extract of plant had a maximum quantity of phenol (28.3 ± 2.0 mg) and flavonoids (25.2 ± 1.2 mg) than others. Similarly, the methanolic extract showed excellent antibacterial activity and exhibited the highest inhibitory effect against Pseudomonas aeruginosa (12 ± 0.5 mm), Salmonella typhi (10 ± 0.6 mm), Staphylococcus aureus (9 ± 1.0 mm), and Escherichia coli (7 ± 1.3 mm). The average minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were reported in the range of 3.2 to 6.9 µg/ml (for MIC) and 6.0 to 14.5 µg/ml (for MBC), respectively. The remarkable antioxidant activity was observed in chloroform and methanol extract on the DPPH radical scavenging activity with the lowest IC₅₀ value of 197.245 μg/ml (chloroform) and 201.04 μg/ml (methanol) and compared with control (ascorbic acid 239.36 μg/ml). GC-MS analysis revealed the presence of six major bioactive compounds as follows; 2,Octylcyclopropene-1-Heptanol (42.81%), Hexadecanoic acid (26.63%), 1-methylene-2b Hydroxymethyl-3,3-Dimethyl-4b-(3Methylbut-2enyl)-C (9.3%), Phytol (7.5%), (1,3,3-Trimethyl-2-Hydroxymethyl-3,3-Dimethyl-4–3-Methylbut-2-Enyl)-C (7.2%). 3,7,11,15-Tetramethyl-2-Hexadecen-1-Ol (6.3%). The FT-IR spectrum reflected the presence of the twelve peaks at the range of 3746.38 cm-1 (O-H stretch alcohols), 3424.18 cm-1 (O-H stretch phenols), 2926.01 cm-1 (C-H stretch alkanes), 2857.55 cm-1 (C-H stretch alkanes), 2084.04 cm-1 (-C = C stretch alkynes), 1595.76 cm-1 (N-H bend primary amines), 1402.49 cm-1 (C-C stretch in ring aromatics) and others. This study suggests S. xanthocarpum as a potential candidature for having better antibacterial and antioxidant property and identified several bioactive compounds by GC-MS analysis.     

向日葵黄色素抗氧化活性及清除自由基活性能力的初探

本文从向日葵花中提取黄色素,研究其抗氧化活性。结果表明,向日葵黄色素对DPPH、超氧阴离子自由基（O2-·）、羟自由基（·OH）、过氧化氢（H2O2）都具有较强清除作用,并且随加入量的增加而增大。说明向日葵花黄色素是一种很有开发前景的抗氧化剂,具有很高的利用价值。      

Iron complexes of dietary flavonoids: Combined spectroscopic and mechanistic study of their free radical scavenging activity

Combined spectroscopic (UV/visible, Raman, MS) and theoretical approaches were used to assess interaction of iron(III) with quercetin and baicalein in aqueous buffered solutions. Obtained results implicated formation of two iron quercetin complexes, with pH-dependent stoichiometries of 1:2 and 1:1, and one iron baicalein complex with stoichiometry of 1:1. Results of vibrational analysis and theoretical calculations implicated 3-hydroxy-4-carbonyl and the 3′-hydroxy-4′-hydroxy group of catechol as chelating sites for quercetin. For baicalein 5-hydroxy-6-hydroxy group is energetically the most favourable, although 5-hydroxy-4-carbonyl and 6-hydroxy-7-hydroxy chelating sites are energetically similar. Antiradical activity, reaction stoichiometry and number of inactivated DPPH molecules per mole of antioxidant indicated quercetin as a better antioxidant than its iron complex, baicalein and iron baicalein complex. The same structural features appeared to be important both in complexation and antioxidant activity. The equilibrium geometries, optimised using the B3LYP/6-31G (d, p) level of theory, predicted structural modifications between the ligand molecules in free state and in the complex structures. Correlation between experimental and theoretical results was very good.     

凌枣黄酮提取及自由基清除能力研究

对凌枣黄酮回流提取工艺和凌枣黄酮提取液的自由基清除能力进行了研究,凌枣黄酮回流提取的最佳工艺条件为:液固比30∶1（mL/g）、提取时间2h、提取温度75℃、乙醇浓度75%。在最佳提取条件下,凌枣黄酮的得率为5.01mg/g;三种体外抗氧化体系（还原力、羟自由基清除力及DPPH自由基清除力）结果表明,凌枣不同部位黄酮均具有抗氧化作用,作用大小呈浓度-剂量效应,在不同浓度范围内,不同部位凌枣黄酮的自由基清除能力顺序均为:枣肉黄酮>全枣黄酮>枣核黄酮>枣皮黄酮,结果表明凌枣果肉中含有较高活性或浓度的黄酮类组分,但凌枣各部位黄酮的自由基清除能力均低于同浓度的维生素C。      

接骨木花青素的纯化工艺及清除DPPH自由基活性的研究

通过乙醇浸提法从接骨木鲜果和干果中提取花青素,通过膜分离技术、正己烷萃取、大孔吸附树脂纯化,从接骨木鲜果和干果中提取得到的花青素冻干粉得率分别为0.43%和1.52%,花青素含量可以达到29.32%。接骨木花青素在质量浓度为200 μg/mL时,DPPH自由基的清除率最高为89.40%,相当于维生素C的96.28%。结果表明,接骨木花青素有一定的抗氧化能力。     

Detection and activity evaluation of radical scavenging compounds by using DPPH free radical and on-line HPLC-DPPH methods

The antiradical activity of crude extracts (80% methanol, 20% water) of S. officinalis, S. glutinosa, S. sclarea and S. aethiopis was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging method. For validation of this method several well known antioxidants (ascorbic acid-6-palmitate, gallic, chlorogenic, ferulic, caffeic, uric, gentisic and vanillic acids, catechin, quercetin, epicatechin, phloridzin, rutin and naringin) were investigated additionally. In these experiments ascorbic acid-6-palmitate had highest antiradical activity. Within the group of phenolic acids gentisic acid had the highest antiradical activity comparing with the other tested phenolic acids. Uric acid, vanillic acid, phloridzin and naringin have a much lower antiradical activity. Different reaction kinetics behaviour was observed. The validated DPPH radical scavenging method was applied to the evaluation of the antiradical activity of plant extracts. The Salvia extracts showed very high antiradical activity towards the DPPH·. An on-line HPLC-DPPH method was developed using a methanolic solution of DPPH· for a rapid detection of radical scavenging components after HPLC separation. The HPLC-DPPH on-line method was also applied to a screening of several radical scavenging components in plant extracts as well as for quantitative analysis. The HPLC analysis revealed the presence of several radical scavenging components in the all Salvia extracts. This HPLC-DPPH on-line method can also be used for quantitative determination of radical scavenging compounds.     

酵母源金属硫蛋白体外清除自由基及抑菌活性的研究

目的:比较两种异构体形式酵母源金属硫蛋白与动物源金属硫蛋白体外清除自由基及抑菌活性。方法:以VC为对照,分光光度法测定金属硫蛋白对自由基清除率,以金黄色葡萄球菌、大肠杆菌和李斯特氏菌为指示菌,研究金属硫蛋白对致病菌的抑制作用。结果:金属硫蛋白对羟基自由基及DPPH自由基清除能力明显强于VC,但对超氧阴离子自由基的清除效果却低于VC,金属硫蛋白对金黄色葡萄球菌、李斯特氏菌具有一定的抑制作用。金属硫蛋白清除自由基关系为Zn-MT>MT-Ⅰ>MT-Ⅱ。结论:金属硫蛋白具有较强的清除自由基能力,对部分致病菌具有一定的抑制作用,作用效果因金属硫蛋白来源、纯度及构型而不同。