艾叶多糖的提取、含量测定及对羟自由基清除作用的研究

目的:探讨艾叶多糖的提取、含量测定及其对羟自由基(·OH)的清除作用.方法:采用热水浸提法提取艾叶多糖并进行初步纯化;苯酚-硫酸法测定其含量;·OH清除实验观察艾叶多糖对·OH的作用.结果:样品中多糖含量为2.56%,回收率为98.45%,RSD = 0.391%(n = 5),其纯度和产率均较高;艾叶多糖溶液对由Fenton体系产生的·OH有一定的清除作用,随着艾叶多糖浓度的增加,对·OH自由基的清除能力也增强.结论:艾叶中含有一定量的多糖;艾叶多糖对·OH具有较好的清除作用,在一定范围内呈现良好的量效关系.     

石榴皮鞣质对羟自由基和超氧阴离子自由基的清除作用

目的：研究石榴皮鞣质清除自由基的作用。方法：通过罗丹明B—Cu^2＋-H2O2体系产生·OH，邻苯三酚自氧化体系产生O2^-。同时比较石榴皮鞣质提取物，鞣花酸一没食子酸混合溶液，以及维生素C的作用效果，根据作用常数的大小讨论3种溶液及其各自的浓度对自由基的清除作用，并初步推断作用机制。结果：石榴皮鞣质对羟自由基和超氧阴离子自由基均具有较好的清除作用，较低浓度时即可发挥清除作用。结论：石榴皮鞣质对自由基侵害有保护作用。     

响应曲面优化提取半枝莲中总黄酮及清除DPPH自由基作用的研究

目的:研究半枝莲中总黄酮的提取方案,并初步检测其抗氧化能力.方法:在单因素试验的基础上,使用Box-Behnken响应曲面设计法优化提取半枝莲中总黄酮的工艺条件,并研究其对DPPH自由基的清除作用.结果:以10 g半枝莲粉末为原料,在乙醇浓度为59％、提取时间为2 h、液料比为1:15的提取条件下,半枝莲黄酮化合物得率...     

超声波提取少花龙葵总黄酮及鉴别方法

目的为充分利用少花龙葵植物资源,探讨少花龙葵总黄酮的提取及鉴别方法、方法采用超声波乙醇浸提法从少花龙葵中提取黄酮类物质,对所提取的黄酮类物质进行验证,并用分光光度法测定其含量,结果测得样品中总黄酮的含量C=0．720（1mg／mL,回收率为103．1％,其纯度和产率均较高。结论该方法采用全物理过程,无任何污染,是提取少花龙葵黄酮类物质的有效途径。     

川芎嗪及其衍生物对羟自由基的清除作用

目的:探讨川芎嗪及其衍生物对羟自由基的清除作用。方法:应用Fenton反应检测并计算50％羟自由基被清除时的药物浓度(EC_(50))。结果:结果显示对羟自由基均有明显清除作用,且呈剂量依赖关系。川芎嗪及其衍生物与苯甲酸和甘露醇的清除作用差异有极显著性(P<0.01),而相互间作用无明显差异(P>0.05)。结论:川芎嗪及其衍生物对羟自由基有明显的清除作用。     

阿糖胞苷对羟自由基的清除作用

近年来,有关自由基与癌的研究已被广泛重视.羟自由基(·OH)是最强的氧化剂之一,甚至能引起连KMnO_4都不能引起的反应。·OH具有细胞毒素,因此·OH自由基抑制剂的研究,将会对癌的预防和治疗有一定作用。实验证明阿糖胞苷对羟自由基有一定的清除作用,其清除率随药物浓度的增加而加大,同时证明它对羟自由基的生成速率也有一定抑制作用。     

阿糖胞苷对羟自由基的清除作用

The cell damages caused by superoxide free radical (O₂^-) include a series of biochemical processes, including lipid peroxidation, DNA and chromosomal damage as well as deactivation of enzyme. It has been suggested that the intrinsic attacking agent is hydroxyl free radical (.OH), which is generated through Fenton reaction. Thus, any .OH scavenging agent may inhibit the relevant cell damage. Cytosine arabinoside was found to be able to scavenge .OH generated by Co~(60) radiolysis and Fe(11)-EDTA with H₂O₂ in aqueous solutions. Determination of the fluorescence of hydroxylated derivatives from benzoate was used to estimate the level of .OH. The scavenging percentage and inhibition ratio of .OH by cytosine arabinoside were measured.     

定心藤中总黄酮的超声波提取工艺研究

目的 探讨定心藤总黄酮的提取及鉴别方法 ,为定心藤进一步研究和资源开发利用提供一定的科学依据.方法 采用超声波乙醇浸提法从定心藤中提取黄酮类物质,对所提取的黄酮类物质进行验证,并用分光光度法测定含量.结果 测得样品中总黄酮的含量C=0.5667mg·mL-1,回收率为99.8%,其纯度和产率均较高.结论 该方法 采用全物理过程,无任何污染,是提取定心藤黄酮类物质的有效途径.     

橡皮树叶总黄酮提取工艺及清除·OH自由基能力的研究

目的 优化橡皮树叶中总黄酮的最佳提取工艺.方法 在进行单因素试验的基础上,以乙醇浓度、料液比、提取温度、提取时间作为因素,进行L<,9>(3<'4>)正交试验.结果 各因素对提取橡皮树叶总黄嗣的影响为:料液比>提取潼度>提取时间>乙醇浓度;提取总黄酮的最佳工艺为1:6的50%乙醇70℃提取120min.在该工艺条件下,...     

仙茅苷对自由基的清除作用

目的研究仙茅(Curculigo orchioides Gaertn.)主要成分仙茅苷(curcu ligoside)对羟自由基和超氧阴离子自由基的清除作用。方法分别采用比色法及电子顺磁共振技术(ESR)测定仙茅苷对羟自由基和超氧阴离子自由基的清除效果。结果仙茅苷对羟自由基和超氧阴离子自由基均有良好的清除作用,其清除率略低于茶多酚。结论仙茅苷对自由基具有明显的清除作用,是一种有效的天然抗氧化剂。     

Quantification of total oxidant scavenging capacity of antioxidants for peroxynitrite, peroxyl radicals, and hydroxyl radicals

We have extended the application of our previously reported total oxidant scavenging capacity (TOSC) assay (Winston et al., Free Radical Biol. Med. 24, 480-493, 1998) to permit facile quantification of the absorbance capacity of antioxidants toward three potent oxidants, i.e., hydroxyl radicals, peroxyl radicals, and peroxynitrite. Respectively, these oxidants were generated by the iron plus ascorbate-driven Fenton reaction, thermal homolysis of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (ABAP), and 3-morpholinosydnonimine N-ethylcarbamide (SIN-1). Each of these oxidants reacts with alpha-keto-gamma-methiolbutyric acid (KMBA), which is oxidized and yields ethylene. The antioxidant capacity of the compounds tested is quantified from their ability to inhibit ethylene formation relative to a control reaction. Assay conditions were established in which control reactions give comparable yields of ethylene with each of the oxidants studied. Thus, the relative efficiency of various antioxidants could be compared under conditions of quantitatively similar KMBA oxidizing capability by the three oxidants. Reduced glutathione was an efficient scavenger of peroxyl radicals, but scavenged peroxynitrite and hydroxyl radicals relatively poorly. Uric acid, Trolox, and ascorbic acid were comparable scavengers of peroxynitrite and peroxyl radicals. Uric acid and Trolox were approximately an order of magnitude less efficient as scavengers of hydroxyl radicals. The classical hydroxyl radical scavenging agents mannitol, dimethyl sulfoxide, and benzoic acid had much higher TOSC values with hydroxyl than with peroxyl radicals or peroxynitrite. The very different chemical reactivity toward KMBA by the SIN-1- and iron-ascorbate-generated oxidants indicates that hydroxyl radical is not a major oxidant produced by the SIN-1 system. The data show that the TOSC assay is useful and robust in distinguishing the reactivity of various oxidants and the relative capacities of antioxidants to scavenge these oxidants.     

Antioxidant behaviour of caffeine: efficient scavenging of hydroxyl radicals.

Considerable controversy exists in the literature regarding the toxicity of coffee, including its possible carcinogenic and anticarcinogenic properties. This study reports on the reaction of 1,3,7-trimethylxanthine (caffeine) with the hydroxyl radical (.OH), as investigated by electron spin resonance (ESR) spin trapping. The .OH was generated by the Fenton reaction (Fe2+ + H2O2) as well as by the reaction of chromium(V) with H2O2. The results show that caffeine effectively scavenges .OH with a reaction rate constant of approximately 5.9 x 10(9) M-1 sec-1 that is comparable with those of other efficient .OH radical scavengers. ESR measurements provide evidence that a caffeine-derived oxygen-centred radical is formed in the reaction of caffeine with .OH and suggest a biochemical basis for the understanding of the reported anticarcinogenic properties of caffeine and related methylxanthine compounds.     

不同产地薄荷饮片中挥发性成分的比较分析

目的：通过分析比较安徽、湖南、广东、广西及江苏等五个产地薄荷饮片挥发油含量和化学成分,为薄荷饮片的质量控制及临床应用提供参考。方法：采用水蒸气蒸馏法对不同产地薄荷饮片挥发油进行提取,利用气相色谱-质谱联用技术（GC-MS）对其中的挥发性成分进行分离鉴定,并采用面积归一化法计算各成分的相对含量。结果：五个产地薄荷饮片中挥发油提取量存在明显差异,安徽产挥发油含量最高,广西产挥发油含量最低。五个产地挥发油中共计检出49种化学成分,其中16种为共有成分,11种为产地特有成分。在16种共有成分中,薄荷醇、薄荷酮、胡薄荷酮及乙酸薄荷酯是四种主要成分,其相对含量之和介于51.51~81.73%之间,存在一定的地域差异。结论：不同产地薄荷饮片挥发油主要成分含量存在的地域性差异,在一定程度上折射出目前中药市场薄荷饮片质量良莠不齐的现状,需引起足够重视。     

Investigations concerning the correlation of COX-1 inhibitory and hydroxyl radical scavenging activity

The aim was to study the COX-1 inhibiting efficacy in context with hydroxyl radical scavenging properties of compounds bearing a carboxylic acid and ester function, respectively. In general, the acids are more potent radical scavengers than the corresponding esters but there is no clear correlation with their COX-1 inhibiting potencies. A feasible scavenging mechanism of carboxylic acids is discussed.     

薄荷的化学成分和临床药理作用

本文主要针对薄荷的化学成分及其临床药理作用的研究进展进行综述,为进一步开发和应用薄荷在临床应用上提供更新的科学依据。     

三种藻类硫酸多糖的提取及其清除自由基活性研究

目的通过对紫莱、海带、羊栖莱3种藻类硫酸多糖进行提取和体外活性检测,以期筛选出具有一定开发潜力的抗氧化剂。方法以稳定自由基(DPPH)等抗氧化检测方法对提取物进行抗氧化活性的测定。结果3种硫酸多糖均有不同程度的抗氧化活性。但它们之间的抗氧化活性大小差异较大,并且用不同溶剂提取的硫酸多糖抗氧化活性也有差异。结论水提的羊栖菜硫酸多糖(SPS)具有较强抗氧化活性。     

超声波提取芒果叶总黄酮

目的为充分利用芒果叶植物资源,避免资源的浪费,探讨芒果叶总黄酮的提取方法。方法采用超声波乙醇浸提法从芒果叶中提取黄酮类物质,对所提取的黄酮类物质进行验证,并用紫外分光光度法测定含量。结果测得样品中总黄酮的含量C=2.900mg/mL,回收率为100.2%,其纯度和产率均较高。结论该方法采用全物理过程,无任何污染,是提取芒果叶黄酮类物质的有效途径。     

阿魏酸及其类似物的合成及其清除自由基活性研究

目的:合成阿魏酸及其类似物并研究其清除1,1-二苯基苦基苯肼自由基(DPPH·)的能力。方法:不同对羟基苯甲醛衍生物和丙二酸进行Knoevenagel缩合反应,得到阿魏酸及其类似物;用体外清除DPPH·测定法检测其清除自由基的能力。结果:合成了9个化合物,其中7个为新报道化合物;在体外清除DPPH·测定中,这些化合物对DPPH·的清除率有较大差异。结论:阿魏酸及其类似物苯环上3,5位取代基可以明显地影响此类化合物清除DPPH·的能力。甲氧基和乙氧基可明显提高活性,溴次之,硝基则降低活性。     

Antioxidant activity of Hypericum androsaemum infusion: scavenging activity against superoxide radical,hydroxyl radical and hypochlorous acid

Hypericum androsaemum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic acids. Since polyphenolic compounds have high antioxidant potential, the ability of H. androsaemum infusion to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. Superoxide radical was generated by the xanthine/xanthine oxidase and phenazine methosulphate/NADH systems. The infusion-mediated prevention of nitroblue tetrazolium reduction by the superoxide radical was used as the measured endpoint. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and assayed by evaluating deoxyribose degradation using the thiobarbituric acid method. Hypochlorous acid scavenging activity was tested by measuring the inhibition of hypochlorous acid-induced 5-thio-2-nitrobenzoic acid oxidation to 5,5'-dithiobis(2-nitrobenzoic acid). The tested infusion mainly exhibited a potent scavenging effect on superoxide radicals (although a noncompetitive inhibitory effect on xanthine oxidase was also observed). The infusion also acted as a moderate scavenger of hydroxyl radicals and hypochlorous acid. A phytochemical study of the infusion was also undertaken, and nine phenolic compounds were identified.     

薄荷脱病毒苗的农艺性状和有关生理指标的测定

对薄荷进行了组织培养条件下的脱病毒研究，并进行了农艺性状和有关生理指标的测定。结果显示：脱病毒薄荷的田间农艺性状和和挥发油含量、品质均明显优于未脱毒薄荷。同时脱病毒薄荷的过氧化物酶同工酶活性和可溶性蛋白含量均高于未脱毒薄荷。薄荷的脱病毒可望显著提高薄荷田间生长量，从而提高薄荷油的产量，同时脱毒薄荷油的质量也有所提高，因此脱毒薄荷有望较大程度提高薄荷的经济效益。