芦丁等天然产物清除活性氧自由基O_(?)~-和·OH的ESR研究

本文用促癌剂PMA(phorbol myristate acetate)刺激人多形核白细胞(PMN)呼吸暴发产生的活性氧自由基,Fenton反应产生的羟自由基·OH,光照核黄素和黄嘌呤/黄嘌呤氧化酶体系中产生的超氧阴离子自由基O(?)为模型,用自旋捕集方法研究天然产物芦丁,槲皮素,异槲皮苷和汉防已甲素对活性氧自由基(?)和·OH的清除作用.除汉防已甲素外,其它药物都能很明显地清除PMN呼吸暴发过程中产生的活性氧自由基.芦丁和异槲皮苷对(?)的清除率分别高达78.1%和79.9%,远远大于维生素E(12.7%)的作用.除汉防已甲素外,其它三种药物对·OH的清除作用也大于维生素E.四种天然产物对O(?)和·OH的清除作用都小于维生素C.     

用自旋捕集技术研究硒化合物对活性氧自由基的清除作用

亚硒酸钠,硒代甲硫氨酸和硒代硫酸软骨素对黄嘌呤氧化酶体系和人多形核白细胞（ＰＭＮ）呼吸暴发时产生的超氧阴离子（Ｏ）自由基;和Ｆｅｎｔｏｎ反应生成的羟自由基（·ＯＨ）有明显的清除作用,并抑制ＰＭＮ呼吸暴发时对氧的消耗。实验结果说明不同硒化合物不仅能够清除细胞体系产生的活性氧自由基,而且对化学反应生成的活性氧自由基也有清除作用。     

用自旋捕集技术研究硒化合物对活性氧自由基的清除…

亚硒酸钠,硒代甲硫氨酸和硒代硫酸软骨素对黄嘌呤氧化酶体系和人多形核白细胞呼吸暴发时产生的阴离子自由基,和Ｆｅｎｔｏｎ反应生成的羟自由基有明显的清除作用,并抑制ＰＭＮ呼吸暴发时对氧的消耗,实验结果说明不同硒化合物不仅能够清除细胞体系产生的活性氧自由基,而且对化学反应生成的活性氧自由基也有清除作用。     

异槲皮苷对叔丁基过氧化氢诱导的L-02细胞氧化损伤的保护作用

研究异槲皮苷对叔丁基过氧化氢(t-BHP)诱导的L-02细胞氧化损伤的保护作用。体外培养L-02细胞,采用t-BHP(100μmol/L)作用24 h,建立L-02细胞氧化损伤模型,分为正常对照组、模型组(100μmol/L tBHP)、阳性对照(10μmol/L维生素E)组和不同浓度异槲皮苷(1、10、100μmol/L)预处理组。采用MTT法检测细胞活力,通过酶联免疫吸附测定(ELISA)法检测丙二醛(MDA)含量,活性氧(ROS)、乳酸脱氢酶(LDH)、谷胱甘肽过氧化物酶(GSH-Px)和超氧化物岐化酶(SOD)的活性。与模型组比较,异槲皮苷显著提高细胞存活率(P0.05),降低ROS和MDA含量及LDH的外漏(P0.05),明显增加GSH-Px和SOD活性(P0.05)。异槲皮苷能够上调Sirt6表达,降低NF-κBp65含量。异槲皮苷能够保护t-BHP诱导的L-02细胞氧化损伤,其作用可能与提高清除ROS能力,调控Sirt6和NF-κBp65水平相关。     

竹叶花椒黄酮类成分含量及抗氧化活性相关性分析

为比较不同产地竹叶花椒黄酮类成分含量及抗氧化活性差异,探究黄酮成分与抗氧化活性相关性,以21个产地的竹叶花椒为材料,建立HPLC同时测定4种黄酮类成分含量(芦丁、金丝桃苷、异槲皮苷、槲皮苷)的方法,采用分光光度法测定总黄酮组分含量,采用DPPH、ABTS自由基清除试验评价其抗氧化活性,并结合皮尔逊相关分析探究黄酮类成分...     

不同干燥方法对合欢花药材化学成分及其抗氧化活性影响

建立测定合欢花药材中槲皮苷、异槲皮苷和槲皮素3种黄酮类成分含量测定的方法。通过化学成分含量及其抗氧化活性测定,探讨不同干燥方法对不同规格合欢花药材的影响,为合欢花药材的初加工工艺选择提供参考。通过晒干、阴干、蒸汽杀青后烘干、微波杀青后烘干、烘干(30、50、70、90℃)、冷冻干燥的方式对两种规格合欢花药材进行干燥处理,采用紫外分光光度法、高效液相色谱法、比色法和ABTS法、DPPH法等检测样品中总黄酮、异槲皮苷、槲皮苷、槲皮素含量及抗氧化活性。利用主成分分析、聚类分析和相关性分析对干燥后不同规格样品进行综合评价。研究结果表明,不同干燥处理合欢花药材样品化学成分和抗氧化活性结果存在显著差异。相关性分析表明,槲皮苷含量和总黄酮含量呈显著正相关(P<0.05),槲皮苷含量可作为总黄酮含量大小的评价指标,与O^-₂自由基清除能力呈正相关但不显著。槲皮苷含量和总黄酮含量与其他四种抗氧化指标呈显著正相关(P<0.05)或极显著正相关(P<0.01),槲皮素含量与ABTS自由基清除能力呈显著正相关(P<0.05),推测槲皮苷和槲皮素...     

松栎柱锈菌春孢子多糖体外抗氧化活性

为了研究松栎柱锈菌（Cronartium orientale S.Kaneko）春孢子多糖的体外抗氧化活性,制备了该菌破壁春孢子精制多糖,并对所得春孢子多糖进行了总抗氧化能力、总还原力以及清除二苯代苦味酰基（DPPH·）、清除羟基自由基（·OH）、清除超氧阴离子（O₂^·）的活性进行了测定。体外抗氧化活性分析结果表明：松栎柱锈菌春孢子多糖具有较强的总抗氧化能力;虽然该菌多糖不具有清除多数氧自由基母体（O₂^·）的作用,也不具有清除人工合成自由基DPPH·的作用,但是其能够有效清除对机体破坏力最强的自由基·OH。这表明本文获得的松栎柱锈菌春孢子多糖具有对自由基选择性清除的能力,对其他自由基研究者具有参考价值,可为该菌的开发利用提供参考,也能够为森林有害生物开发利用提供理论依据。     

多形核白细胞(PMN)引起鼠缺血心脏产生活性氧自由基的研究

本文用电子(?)磁共振(ESR)在低温条件下直接研究了由维生素D_3(V_(D3))过量所致大白鼠心肌缺血损伤时血液中多形核白细胞(PMN)产生的活性氧自由基.实验结果发现,过量VD_3造成缺血损伤心肌中氧自由基含量比正常心肌增加了43%,比用10ml生理盐水冲洗的正常心肌增加了73%,比用过量V_(D3)造成心肌缺血损伤再用10ml生理盐水和冲洗的心肌增加了65%.这就说明,PMN在心肌缺血过程中对产生活性氧自由基起着主要作用.     

3′－大豆苷元磺酸钠的体外抗氧化研究

为研究3′-大豆苷元磺酸钠（DSS）的体外抗氧化活性,测定了DSS对超氧自由基（02&#183;）、羟基自由基（&#183;OH）和1,1-二苯基-2-苦苯肼自由基（DPPH&#183;）的清除能力,及其对Fe^2＋诱导的脂质过氧化反应和β-胡萝卜素／亚油酸自氧化体系的抑制作用。结果表明,DSS对DPPH&#183;有一定的清除能力,对超氧自由基的清除能力较强,能很好地清除&#183;OH自由基,对脂质过氧化有一定的抑制作用,对β-胡萝卜素／亚油酸自氧化体系有明显的抑制作用。说明DSS的药理作用可能与其较强的抗氧化能力有关。     

鸢尾苷抗氧化活性的研究北大核心CSCD

在成功从中草药射干中提取纯化得到鸢尾苷的基础上,应用灵敏、简单易行有效的方法考察鸢尾苷的抗氧化能力。选择氧自由基清除、羟基自由基清除、二苯代苦味肼基自由基清除、烷基自由基清除和抗油脂氧化作用等实验体系进行抗氧化活性的试验。结果显示纯化得到的鸢尾苷的抗氧化作用比维生素C稍强,但比2,6-二叔丁基对甲酚稍弱,表明其具有较显著的抗氧化作用。     

Scavenging effects on active oxygen radicals by schizandrins with different structures and configurations

We have studied the scavenging effects of different structures and configurations of schizandrins isolated from Fructus Schizandrae, a traditional Chinese herb, on active oxygen radicals with the method of spin-trapping technique. The active oxygen radicals were produced from human polymorphonuclear leukocytes (PMN) stimulated with phorbol myristate acetate (PMA). In addition, the scavenging effects of schizandrins on hydroxyl radicals (.OH) in Fenton's reaction and the scavenging effects on superoxide anions (O2-.) in both riboflavin/EDTA and xanthine/xanthine oxidase systems have also been studied. They are compared with the scavenging effects of both Vitamin C (Vc) and Vitamin E (VE). The experimental results have shown that the scavenging effect of schizandrin B (Sin B) on the active oxygen radicals is stronger than that of S(-) Sin B and R(+) Sin B. For schizandrins of the same molecular structures with different stereoconfigurations the scavenging effects of S type of the benzene ring on active oxygen radicals are stronger than those of R type and for schizandrins of the same stereoconfigurations with different structures the scavenging effects of schizandrin C (Sin C) on the active oxygen radicals are stronger than those of Sin B.     

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and vitamin E (VE). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger than VE. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger than VE (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems. The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.     

Scavenging effect of schizandrins on active oxygen radicals

The reactive oxygen radicals produced from human polymorphonuclear leukocytes (PMN) stimulated with PMA (phorbol myristate acetate), hydroxyl radicals generated by a Fenton reaction, and superoxide anion radicals produced by irradiating solutions of riboflavin in the presence of EDTA have been taken as the models for production of oxygen radicals. With the use of the electron spin resonance spin trapping method, the scavenging effects of schizandrol A (solA) (5 x 10(-4) M) and schizandrin B (sinB) (5 x 10(-4) M) have been studied and compared with the effects of vitamin E (5 x 10(-4) M) and vitamin C (5 x 10(-4) M). It has been found that in cell system the scavenging effects of sinB and solA, as judged by ESR spin trappings, on hydrpxyl radicals (.OH) are greater than vitamin E and vitamin C and the scavenging effects on superoxide anion (O2) are greater than vitamin E but lower than vitamin C. With respect to the Fenton reaction, sinB has the strogest scavenging effect on .OH (77%) and solA has strong scavenging effect on .OH (63%), both of them larger than that of vitamin E (35%) and vitamin C (56%). In the riboflavin/EDTA system, the scavenging effect of sinB (46%) is smaller than that of vitamin C (96%) but larger than that of vitamin E (23%); the scavenging effect of solA is not obvious (14%). With the use of spin probe oximetry, the oxygen consumption during the respiratory burst of stimulated PMN has been measured when exposed to schizandrins. The experiment results demonstrated that they do not affect the activity of production of active oxygen radicals in the respiratory burst of PMN stimulated with PMA.     

Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals

With the use of the spin trapping methods, the scavenging effects of the extracts of green tea and other natural foods are studied. In stimulated polymorphonuclear leukocytes (PMN) system, water extract fraction 6 (F6) from green tea and green tea polyphenols (GTP) have the strongest scavenging effect on the active oxygen radicals, much stronger than vitamin C (Vc) and, vitamin E (Ve). Rosemary antioxidants (RA) and Curcumin (Cur) have weaker scavenging effects than Vc, but stronger thanVe. In Fenton Reaction, Cur has the strongest scavenging effect (69%) on hydroxyl radicals. In irradiation, riboflavin system F6(74%) and GTP(72%) have very strong scavenging effects that are weaker than Vc, but much stronger thanVe (23%). With the use of spin probe oxymetry, the oxygen consumption in respiratory burst of stimulated PMN were measured when the antioxidants existed in these systems The results demonstrated that these antioxidants did not affect the respiratory burst of human polymorphonuclear leukocytes stimulated with PMA.     

Direct scavenging of free radicals by captopril, an angiotensin converting enzyme inhibitor

Captopril, an angiotensin converting enzyme (ACE) inhibitor, was hypothesized to be a potential scavenger of free radicals because of the presence of a thiol group. The scavenging action of captopril was examined against superoxide anion (O2-), hydroxyl radical (OH.), hypohalite radical (HOCL) either generated biochemically, or derived from activated polymorphonuclear leukocytes (PMN). Our results indicate that captopril is an extremely potent free radical scavenger, scavenging power being as effective as superoxide dismutase (SOD) against O2-, or dimethylthiourea against OH., but better than allopurinol against OCL. plus HOCL. Free radical scavenging action of captopril against PMN-derived free radical is equivalent to the combined effects of SOD, catalase and allopurinol.     

藜叶中黄酮类化合物体外抗氧化活性研究

为了探讨藜叶中黄酮类化合物的体外抗氧化活性,采用有机溶剂提取法和色谱柱法对藜叶中化学成分进行提取与分离;以Vc作对照,对分离纯化的芦丁、乙酸乙酯浸膏和正丁醇浸膏进行DPPH&#183;、O2^-&#183;和&#183;OH的清除效果试验。结果表明：三者对DPPH&#183;、O2^-&#183;、&#183;OH均具有清除作用,且与浓度呈量效关系,芦丁对&#183;OH清除效果优于Vc,芦丁具有较强的清除DPPH&#183;能力,其IC50为0．05μg／mL。     

Free radical scavenging efficiency of Nano-Se in vitro

In this study, we showed that smaller size particles of Nano-Se have better scavenging effects on the following free radicals: carbon-centered free radicals (R*) generated from 2,2'-azo-bis-(2-amidinopropane) hydrochloride (AAPH), the relatively stable free radical 1,1-diphenyl-2-picryhydrazyl (DPPH), the superoxide anion (O2*-) generated from the xanthine/xanthine oxidase (X/XO) system, singlet oxygen (1O2) generated by irradiated hemoporphyrin. Furthermore, the three sizes of Nano-Se studied also show protective effects against the oxidation of DNA. The three samples all have potential size-dependent characteristics on scavenging the free radicals. Although in this study we regarded Nano-Se as a whole without considering interactions between BSA and the red selenium nano-particles, there is the possibility that the apparent free radical scavenging effects may be partially contributed by such interactions.     

Free radical scavenging actions of hippocampal metallothionein isoforms and of antimetallothioneins: an electron spin resonance spectroscopic study.

The high concentration of zinc in the hippocampal mossy fiber axon boutons is localized in the vesicles and is mobilized by exocytosis of the zinc-laden vesicles. Furthermore, the mammalian hippocampi contain metallothionein (MT) isoforms which regulate the steady state concentration of zinc, an important antioxidant. Indeed, zinc deprivation leads to an increased lipid peroxidation, reduces the activity of Cu++-Zn++ superoxide dismutase, and protect against oxidative stress such as exposure to ultraviolet A irradiation. By employing electron spin resonance (ESR) spectroscopy, we have demonstrated that rat hippocampal MT isoforms 1 and 2 were able to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), hydroxyl radicals (*OH) generated in a Fenton reaction, and superoxide anions (O2*-) generated by the hypoxanthine and xanthine oxidase system. In addition, MT-1 isoform protected the isolated hepatocytes from lipid peroxidation as determined by thiobarbituric acid bound malondialdehyde. MT antibodies scavenged DPPH radicals, hydroxyl radicals and reactive oxygen species but not superoxide anions. The results of these studies suggest that although both isoforms of MT are able to scavenge free radicals, the MT-1 appears to be a superior scavenger of superoxide anions and 1,1-diphenyl-2-picrylhydrazyl radicals. Moreover, antibodies formed against MT isoform retain some, but not all, free radical scavenging actions exhibited by MT-1 and MT-2.     

On the nature of biochemically generated hydroxyl radicals. Studies using the bleaching of p-nitrosodimethylaniline as a direct assay method.

An efficient scavenger for radiolytically generated hydroxyl (OH) radicals, p-nitrosodimethylaniline, was used to try to substantiate the presence of this oxygen radical species in several biochemical systems. Most of these systems which were investigated had previously been assumed to generate OH radicals, e.g. the autoxidation of 6-hydroxydopamine, the hydroxylating system NADH/phenazine methosulfate, and the oxidation of xanthine or acetaldehyde by xanthine oxidase. We did not observe inhibition of the bleaching of p-nitrosodimethylaniline in oxygenated solutions by other scavengers of OH radicals nor, in the case of xanthine/xanthine oxidase, by catalase and superoxide dismutase. We therefore conclude that, under biochemical conditions as opposed to radiolysis or photolysis, no freely diffusable OH radicals are formed. Rather, a strongly oxidizing OH-analogous complex is considered to represent the p-nitrosodimethylaniline-detectable species formed under these conditions.