两种芳香植物非挥发性组分抗氧化和对DNA损伤的保护作用

采用6种化学发光体系和两种比色体系研究了芳香植物罗勒和香柠檬的非挥发性组分(简称罗勒、香柠檬)直接清除活性氧、活性氮和对^.OH引起的DNA损伤的保护作用。结果表明,罗勒和香柠檬不仅能直接清除O2,而且可抑制黄嘌呤氧化酶的活性从而减少O2的产生。罗勒和香柠檬也能有效清除^.OH、H2O2、ONOO^.和DPPH^.,两者相比,香柠檬除对^.OH的清除作用弱于罗勒外,清除以上各种自由基的能力均强于罗勒。结果还显示,罗勒和香柠檬都能抑制脂质过氧化,明显地抑制和延缓DNA损伤,起到预防型抗氧化剂和断链型抗氧化剂的双重作用。这些结果表明,罗勒和香柠檬的非挥发性组分是有效的、多功能的天然抗氧化剂和自由基清除剂。     

一种新颖的测定和分析羟自由基氧化损伤RNA及其分子机理的化学发光体系

近年来，羟自由基（^.OH)对DNA氧化损伤已受到广泛关注，但是很少研究^.OH对RNA的氧化损伤。其实，RNA与DNA一样，也是核酸的两大组分之一，也有许多重要功能。所以^.OH攻击RNA也会引起重后果，会造成细胞功能衰退甚至细胞死亡等。为此，我们建立了Vit.C-CuSO4-Phen-H2O2-PNA这一产生和测定^.OH氧化损伤RNA的化学发光体系，以便加强^.OH氧化损伤RNA的研究。通过对本体系测定条件的研究，得出了本体系最佳组方是：Vit.C,CuSO4,Phen,H2O2和RNA，浓度分别为350μmol/L,55μmol/L,350μmol/L,0.2mol/L和20μg/mL,体系pH为5．5，体系终体积为1mL。随后，利用本体系检测了槲皮素，咖啡酸，黄芩甙和芦丁抗^.OH氧化损伤RNA的作用，发现这四种抗氧化剂均能有效抑制^.OH氧化损伤RNA的分子机理，结果发现，^.OH清除剂硫脲几乎抑制全部发光，推测是因硫脲清除了引发剂^.OH所致；O^-.2清除剂SOD只能抑制小部分发光；^1O2清除剂叠氮化钠和苯甲酸都能抑制绝大部分发光。这些事实提示，^.OH是RNA氧化损伤的引发剂；O^-.2只是导致RNA氧化损伤的次要因素，^1O2才是导致RNA氧化损伤的最主要因素。     

香叶天竺葵叶非精油组分清除自由基、抗氧化作用

活性氧与许多疾病的发生和发展密切相关,与食品的氧化也息息相关。所以筛选天然抗氧化剂显得非常重要。因此,分别采用水、乙醇和乙酸乙酯提取法从提取精油后的残渣中提取香叶天竺葵叶非精油有效组分,并分别采用超氧阴离子自由基(O2-·),羟自由基(·OH),过氧亚硝基(ONOO-)和.OH氧化损伤DNA的四种化学发光体系和二苯代苦味肼基自由基(DPPH·)和脂质过氧化两种比色体系检测香叶天竺葵叶非精油组分清除多种自由基、活性氧的能力以及对DNA的保护作用。结果表明,香叶天竺葵叶非精油组分的3种不同提取物均能有效地清除O2-·、·OH、DPPH·和ONOO-,减轻或消除·OH对DNA的氧化损伤,抑制脂质过氧化,是一种有效的、多功能的天然抗氧化剂和自由基清除剂。由于非精油组分是从制取精油组分后的残渣中提取的,提取装置和工艺也非常简单,故本研究不仅为香叶天竺葵种植效益的提高和综合利用提供了可能,也为天然香料加工后废弃物的开发研究提供了资料,对经济环境保护和资源的再利用也有借鉴意义。目前国内外对芳香植物的研究与开发主要聚焦于精油组分,而研究表明,更多的抗氧化物质是存在于非精油组分中,由于非精油组分是从制取精油组分后的残渣中提取的,并且提取装置和工艺简单,是值得进一步开发利用的天然产物。     

白桦液及白桦液复方清除自由基防止沙土鼠脑缺血再灌注氧化损伤的研究

本文用化学发光体系检测白桦液及其复方的清除活性氧自由基的功能。用羟胺法测实验动物化及脑组织的SOD活性,硫代巴比妥酸法测定MDA含量,细胞化学发光法测PMN细胞的免疫功能,化学发光法测脑组织的自发发光,直接法检测GSH-PX活性,氰高铁Hb法测Hb浓度,放免法测血浆TXB2的含量。结果表明,白桦液及其复方在离体体系中有清除O2-、OH-、H2O2的作用,在沙土鼠胞缺点再灌注模型中,可提高血和脑组织的SOD、GSH-PX活性,增强PMN细胞的免疫功能,降低血浆和脑组织LPO,TXB2及Hb浓度。本研究首次发现白桦液及其复方有抗氧化功能。     

流动注射化学发光法及光度法用于巴戟天提取液抗氧化活性的研究

将中药巴戟天提取液加入鲁米诺-H2O2-CuSO4化学发光体系,测量其发光强度,根据系统化学发光被抑制的程度可以评价巴戟天的抗氧化活性,并将巴戟天与抗坏血酸的抗自由基活性进行了对比实验,实验证明巴戟天提取液具有明显的抗自由基活性;采用分光光度法测定体系吸光度的变化来研究巴戟天对OH·及O2-·自由基的清除作用,以抗坏血酸作阳性对照,结果发现:巴戟天对OH·及O2-·自由基均有良好的清除作用,结果较为满意.提示中药巴戟天可作为潜在的具有抗氧化活性的天然药物.     

褪黑素清除活性氧作用的研究

采用多种分析体系检测了褪黑素清除活性氧的作用，结果表明，褪黑素能有效地清除包括２、Ｏ２、Ｈ２Ｏ２在内的多种活性氧，能显著地抑制ＯＨ对ＤＮＡ的损伤，是一种有效的抗氧化剂。     

海红果渣总黄酮的体外抗氧化活性

研究了海红果渣总黄酮(TFMM)的体外抗氧化作用,测定了TFMM对油脂过氧化、脱氧核糖氧化损伤的抑制作用以及对超氧阴离子(O2-)的清除作用,并与BHT比较.结果显示,TFMM对脂质过氧化以及脱氧核糖氧化损伤有明显的抑制作用,对超氧阴离子(O2-)有较强的清除作用,效果明显优于同浓度的BHT.且随着海红果总黄酮添加量的增加,对脂质过氧化、脱氧核糖氧化损伤的抑制作用以及超氧阴离子(O2-)的清除抑制作用也随之增强.     

香蕉皮中总黄酮的体外抗氧化性

以芦丁为对照品,测定了香蕉皮中总黄酮的含量.并采用Fenton反应体系产生羟自由基和邻苯三酚自氧化产生超氧阴离子自由基,研究了香蕉皮总黄酮对两者的清除作用.结果表明,香蕉皮中总黄酮含量为0.946％.香蕉皮黄酮对O2-·和·OH均有较强的清除作用,在一定范围内随着黄酮浓度增大其抗氧化能力也随之增强.     

掌裂草葡萄提取物的抗氧化性

通过测定掌裂草葡萄提取物对羟自由基(.OH)的清除率、对超氧阴离子(O2-.)的抑制率,研究其抗氧化活性。结果显示:提取物对羟自由基(·OH)、超氧阴离子(O2-·)有较强的清除抑制作用,并随着提取物添加量的增加,抗氧化作用以及对羟自由基及超氧阴离子的清除抑制作用也随之增强。     

新型羟基和醌碳自由基产生的分子机理

羟基自由基（·OH）被公认是生物系统中最具活性的活性氧物种,能导致生物体内DNA等生物大分子氧化损伤. 目前,最被广泛接受的·OH的产生机理是过渡金属离子催化的Fenton反应. 五氯酚(PCP)是一种重要的生物杀灭剂,主要用作木材保护. 采用电子自旋共振二级自旋捕获等分析手段,发现H₂O₂和五氯酚的代谢产物之一四氯苯醌（TCBQ）能通过不依赖于金属离子的途径产生·OH;进一步的研究发现是TCBQ,而非其相应的半醌自由基对·OH的产生极其重要. 基于这些数据和分析,提出以下新型·OH产生分子机理：H₂O₂对TCBQ进行亲核攻击形成不稳定的三氯氢过氧基苯醌中间产物,其可均裂产生·OH. 综合采用电子自旋共振自旋捕获和其他分析方法,第1次检测到一种新型的以碳为中心的醌自由基.     

Volatile–char interactions: Roles of in situ volatiles with distinctly-different chemistry in determining char structure and reactivity

This study reports the roles of volatiles with distinctly-different chemistry in determining char reactivity and char structure during in situ volatile–char interactions under non-catalytic conditions. Volatiles were generated in situ from polyethylene (PE), double-acid washed biosolid (DAWB), polyethylene glycol (PEG) or cellulose and interacted with char prepared from DAWB that is free of catalytically-active inorganic species in a two-stage reactor at 1000 °C. The experimental results show that both H- and O-containing reactive species play different roles during in situ volatile–char interactions. It has been found that char reactivity decreases substantially after in situ volatile–char interactions. Results from Raman analysis of the char after in situ interactions with the PE volatiles show H-containing reactive species substantially enhance the condensation of the aromatic ring systems within the char, thus slightly decreasing the H content in char and also making char carbon structure considerably less reactive. It has also been found that the reactivity of char after in situ volatile–char interactions increases with increasing O/H molar ratio of volatiles. The results indicate that O-containing reactive species in volatiles can react with char to form CO complex oxides that mitigate the carbon structure from condensing into large aromatic ring systems, thus increasing O and H contents in char and enhancing char reactivity.     

X射线致HeLa细胞损伤过程中NADPH氧化酶的作用

以HeLa细胞为实验材料， 探讨了NADPH氧化酶在X射线诱导细胞损伤过程中的作用。 结果显示， 12 Gy X射线辐照后细胞内活性氧(ROS)明显增加， 在用NADPH氧化酶抑制剂处理后再辐照， 则细胞内ROS降低到未辐照水平； 同时辐照后NADPH 氧化酶细胞质亚基p47phox 在细胞质积聚并和细胞膜亚基 gp91phox 结合； Western blotting检测结果显示， NADPH 氧化酶的关键亚基 gp91phox 的表达量明显增加。 以上结果说明， NADPH氧化酶可以被X射线激活， 由其介导产生的ROS在X射线诱导HeLa细胞损伤过程中扮演重要角色。 To investigate the role of NADPH oxidase in HeLa cell lesion induced by X ray irradiation, the change of cell survival was detected with MTT assay， reactive oxygen species (ROS) was measured by fluorospectrophotometer. Immunostaining and confocal laser scanning microscopy was employed to detect the co localization of two subunit of NADPH oxidase, p47phox and gp91phox in the cell. Western blotting was used to detect the expression of gp91phox before and after X ray irradiation. After X ray irradiation， intra cellular level of ROS increased obviously. But the increase could be blocked by diphenyleneiodonium (DPI)， an inhibitor of NADPH oxidase. Meanwhile， cytosolic subunit p47phox moved to membrane and co localizated with gp91phox after irradiation. Moreover, the results also show that gp91phox increased sharply after 12 Gy X ray irradiation. Therefore， NADPH oxidase mediated production of ROS plays an important role in HeLa cell lesion induced by X ray.     

Quantitative Detection of Superoxide Ions in Whole Blood of the American Alligator (Alligator mississippiensis)

WST-1 and nitroblue tetrazolium (NBT) were used to quantify production of superoxide ions by leukocytes of the American alligator in whole blood. Because of the difficulty of isolating healthy leukocytes in alligators, these compounds were employed in whole blood instead of leukocyte preparations commonly used in other studies. The detection of superoxide was concentration- and time-dependent and linear with serial dilutions of whole blood. WST-1 reduction was inhibited by superoxide dismutase, indicating that the reduction was due to the presence of superoxide. Light microscopy revealed that superoxide production occurred in leukocytes, with no detectable contributions from other blood components.     

Increasing the ·OH radical concentration synergistically with plasma electrolysis and ultrasound in aqueous DMSO solution

In recent years, significant increases in waste processing and material engineering have been seen by using advanced oxidation processes. The treatment results and energy yields of these processes are largely determined by the generation and retention of reactive oxygen species (ROS). However, increasing the amount of ROS remains a key challenge because of the unavailability of performance- and energy-efficient techniques. In this study, plasma electrolysis, ultrasound, and plasma electrolysis combined with ultrasound were used to treat dimethyl sulfoxide (DMSO) solutions, and the results showed that the two methods can synergistically convert filament discharge into spark discharge, and the conversion of the discharge mode can significantly increase the concentration of OH radicals and effectively improve the efficiency of DMSO degradation. We verified the rationality of the results by analyzing the mass transfer path of ROS based on the reaction coefficients and found that the ·OH radicals in aqueous solution were mainly derived from the decomposition of hydrogen peroxide. These findings indicated that the synergistic action of plasma electrolysis and ultrasound can enhance the production of chemically reactive species, and provide new insights and guiding principles for the future translation of this combined strategy into real-life applications. Our results demonstrated that the synergistic strategy of ultrasound and plasma electrolysis is feasible in the switching mode and increasing the ROS, and may open new routes for materials engineering and pollutant degradation.     

Degradable Nanomotors Using Platinum Deposited Complex of Calcium Carbonate and Hyaluronate Nanogels for Targeted Drug Delivery

Recently, micro/nanomotor systems have been widely investigated for biomedical applications especially for the active transport and delivery of specific drugs. However, there are few stimuli-responsive micro/nanomotor systems to enhance the drug delivery efficiency and reduce side effects by the spatiotemporal controllability. Here, a degradable nanomotor is first fabricated for targeted drug delivery using a platinum (Pt)-deposited complex of calcium carbonate and cuccurbit[6]uril-conjugated hyaluronate (Pt/CaCO₃@HA-CB[6]). The nanomotors could efficiently deliver model drugs to the cells in reactive oxygen species (ROS) abundant environments such as the tumor site. After reaching the tumor site around pH 6.5, Pt/CaCO₃@HA-CB[6] nanomotors (≈1 µm) are pH-responsively disintegrated by the dissociation of CaCO₃ and the encapsulated HA-CB[6] (≈300 nm) are released for cancer cell uptake. The released HA conjugate are finally uptaken into cancer cells via HA receptor-mediated endocytosis. Moreover, model drugs are modularly loaded into the nanomotors via the host–guest chemistry of CB[6] for stable delivery to cancer cells. Taken together, Pt/CaCO₃@HA-CB[6] nanomotors systems could be successfully harnessed for active drug delivery to cancer cells.     

Size and Shape Effects of Near-Infrared Light-Activatable Cu2(OH)PO4 Nanostructures on Phototherapeutic Destruction of Drug-Resistant Hypoxia Tumors

Development of simple, robust, and noninvasive therapeutic approaches to treat cancers and improve survival rates is a grand challenge in clinical biomedicine. In particular, the sizes and shape of the nanomaterials play a vital role in dictating their biodistribution and clearance pathways. It remains elusive how the size and shape of a nanomaterial affect its therapeutic efficacy in cancer diagnosis and treatments. To tackle the above problem, the effects of size and shape of Cu₂(OH)PO₄ nanostructures (nanosheets and quantum dots) on the photodynamic therapy (PDT) in destroying malignant drug-resistant lung tumors and on combating the tumor hypoxia problem are investigated and compared. The photocatalytic mechanism of Cu₂(OH)PO₄ nanostructures mainly involves the generation of reactive oxygen species (ROS), such as hydroxyl radical (^·OH) and singlet oxygen (¹O₂). Under an oxygen deprivation condition, Cu₂(OH)PO₄ nanosheets still can generate OH radicals to kill cancer cells upon near-infrared (NIR) light irradiation. Overall, in vitro and in vivo experiments show that Cu₂(OH)PO₄ nanosheets can overcome tumor hypoxia problems and effectively mediate dual modal PDT and photothermal therapeutic (PTT) effects on destruction of NCI-H23 lung tumors in mice using ultralow doses (350 mW cm⁻²) of NIR (915 nm) light.     

电离辐射诱导的旁观者效应研究

列举了一些具有代表性的研究结果， 概括介绍了一些产生旁观者效应的可能机制以及辐照引起的活性氧基团或分子、 细胞通讯和细胞因子在旁观者效应中的重要作用. 此外， 还讨论了旁观者效应的表达程度与辐照剂量和射线品质的关系. 旁观者效应的研究结果表明: 辐射产生的潜在危害可能要比以前估计的大， 这给如何评估辐射对人类造成的危害带来了新的冲击. Recent studies have indicated that biological effects, such as chromosomal aberration, gene mutation and cell death and so on, can be induced in cells that are not traversed by radiation directly. This phenomenon has been termed as bystander effects. In this paper, a few representative studies were reported and the possible mechanisms underlying the bystander effects were summarized. The reactive oxygen species (ROS) induced by ionizing radiation, cellular communication and some factors play important roles. Besides, the expression extent of bystander effects depended on radiation dose and quality were discussed. Bystander effects suggest that potential health risks associated with radiation exposure may be greater than those of original thought and this makes ultimate impact on human radiation risk assessment.     

Doxorubicin‐Anchored Curcumin Nanoparticles for Multimode Cancer Treatment against Human Liver Carcinoma Cells

Curcumin (Curcuma longa L), a yellow‐colored Indian spice, receives immense attention for the prevention and treatment of various cancers. Despite the superlative therapeutic efficacy, its poor solubility and instability in the aqueous medium hinder the effectiveness of cancer treatment. The novel preparation of curcumin nanoparticles by mechanical grinding of curcumin crystals without any toxic organic solvents is described here for the first time. The surface of curcumin nanoparticles is modified with the negatively charged polyelectrolyte poly(sodium 4‐strynesulfonate) through hydrogen bonding, which is the key to increasing the solubility and stability in the aqueous medium. The negative surface charge is exploited to conjugate doxorubicin drug molecule on the surface of curcumin nanoparticles as evidenced by fluorescence quenching experiments. Doxorubicin‐conjugated curcumin nanoparticles have a higher solubility with an enhanced cytotoxic effect toward the human hepatocellular carcinoma cell line by a reactive‐oxygen‐species‐mediated p53‐dependent apoptotic pathway. The combination of chemotherapy and photodynamic therapy significantly enhances antitumor activity of doxorubicin‐conjugated curcumin nanoparticles, and is expected to be a promising anticancer agent with special reference to human liver carcinoma cells.     

Reciprocal Response of Human Oral Epithelial Cells to Internalized Silica Nanoparticles

Silica nanoparticles (SiO₂ NPs) are one of the most widely used engineered nanoparticles and can been found in a wide range of consumer products. Despite their massive global production scale, little is known about their potential effects in the context of unintended exposure or ingestion. Using TR146 cells as an in vitro model of the human oral buccal mucosa, the uptake, spatial intracellular distribution, reactive oxygen species (ROS) production, inflammatory response, and cytotoxic effects of commercial SiO₂ NPs are examined. SiO₂ NPs are shown to dock and cross the cellular membrane barrier in a dose–time‐dependent manner. Confocal sectioning reveals translocation of SiO₂ NPs into the cell nucleus after 12 h of exposure. A concentration threshold of more than 500 × 10^?6 m is observed, above which SiO₂ NPs are shown to exert significant oxidative stress with concomitant upregulation of inflammatory genes IL6 and TNFA. Further analysis of the p53 pathway and a series of apoptotic and cell cycle biomarkers reveals intracellular accumulation of SiO₂ NPs exert marginal nanotoxicity. Collectively, this study provides important information regarding the uptake, intracellular distribution, and potential adverse cellular effects of SiO₂ NPs commonly found in consumer products in the human oral epithelium.     

Renal Clearable Luminescent WSe2 for Radioprotection of Nontargeted Tissues during Radiotherapy

High‐energy ionizing radiation is widely used in medical diagnosis and cancer radiation therapy. However, high‐energy radiation can also impose significant damages in healthy tissues during medical treatments via direct DNA damages and indirect damages from production of reactive oxygen species (ROS). Therefore, it is urgent to develop highly effective radioprotectants with low toxicities that can meet the increasing needs for alleviating the adverse effects from cancer radiation therapy and nuclear emergency. In this work, strongly catalytic ultrasmall (sub‐5 nm) cysteine‐protected WSe₂ dots are employed to protect healthy tissues against radiation via diminishing radiation‐induced free radicals. The WSe₂ dots with high surface activities can recover radiation‐induced DNA damages and eliminate the excessive ROS generated from radiation. In vivo experiments confirm that the survival rate of mice treated with WSe₂ dots is significantly elevated with radiation damages postponed under exposure to high‐dose ionizing radiation. Furthermore, the free radicals in major organs and hematological system can be appreciably omitted, suggesting their unique role as free radical scavengers. These WSe₂ dots in ultrasmall size show rapid renal clearance of ≈74% injection dose via urine excretion in 24 h and do not cause any apparent toxicity in vivo for up to 30 d.