Photocytotoxic and anaerobic DNA cleavage activity of binuclear 3,3′-dithiodipropionic acid cobalt(II) complexes having phenanthroline bases

Dicobalt(II) complexes [{(B)Co^II}₂(μ-dtdp)₂] (1–3) of 3,3′-dithiodipropionic acid (dtdp) and phenanthroline bases (B), viz. 1,10-phenanthroline (phen in 1), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq in 2) and dipyrido[3,2-a:2′,3′-c]phenazine (dppz in 3), have been prepared, characterized and their photo-induced anaerobic DNA cleavage activity studied. The elemental analysis and mass spectral data suggest binuclear formulation of the complexes. The redox inactive complexes have magnetically non-interacting dicobalt(II) core showing magnetic moment of ∼3.9 μ_B per cobalt(II) center. The complexes show good binding propensity to calf thymus DNA giving K_b values within 4.3 × 10⁵–4.0 × 10⁶ M⁻¹. Thermal melting and viscosity data predict DNA groove binding and/or partial intercalative nature of the complexes. The complexes show significant anaerobic DNA cleavage activity in green light under argon atmosphere possibly involving radical species generated from the disulfide moiety in a type-I pathway. The DNA cleavage reaction under aerobic medium in green light is found to involve hydroxyl radical species. The dppz complex 3 exhibits significant photocytotoxicity in HeLa cervical cancer cells with an IC₅₀ value of 2.3 μM in UV-A light of 365 nm, while it is essentially non-toxic in dark giving an IC₅₀ value of >200 μM. A significant reduction of the dark toxicity of the organic dppz base (IC₅₀ = 8.3 μM in dark) is observed on binding to the cobalt(II) center while essentially retaining its photocytotoxicity in UV-A light (IC₅₀ = 0.4 μM).     

蛹虫草超氧化物歧化酶理化性质的研究

超氧化物歧化酶[Superoxide d ismutase,SOD,(EC.1.15.1.1)]是广泛存在于生物体内的超氧阴离子自由基(·O2-)的天然清除剂,在机体保护方面起重要作用。在对SOD进行的一系列研究中,发现SOD的存在与生物体抗衰老、抗肿瘤、营养状况、免疫性疾病、炎症及辐射防护[1]有关。许多动植     

冷应激对铜预投大鼠血清铜锌代谢、SOD活性及GSH含量的影响

为揭示应激对体内微量元素代谢的影响和机制，预先给予大鼠不同水平的铜3周后，采用冷束缚法使大鼠产生应激，测定了血清铜、锌水平及超氧化物歧化酶(SOD)活性、还原型谷胱甘肽(GSH)和丙二醛(MDA)含量。结果表明，高铜给予没有对清洁级大鼠生长产生明显的影响．血清铜、锌及铜锌比值变化不明显，但适量的铜给予能显著提高血清中SOD活性和GSH含量；冷应激处理后大鼠血清中Cu水平下降，Zn水平升高，同时SOD消耗降低，而GSH含量显著升高。表明冷应激可使大鼠体内铜锌代谢及SOD活性和GSH含量发生变化，适量的铜给予在应激状况下才发挥出积极的生理作用。     

无穷维动力系统

本文简要介绍了无穷维动力系统研究中的一些重要问题。     

Chlorophyll a π-Cation Radical as Redox Mediator in Superoxide Dismutase (SOD) Mimetics

The extensive speciation of copper(II) chloride in organic solvents varies with concentration, temperature, pressure and oxygen content, providing the ability to switch between different chlorophyll transmetalation pathways. We found that one of them is exceptionally suitable for the formation and stabilisation of the chlorophyll π-cation radical. This is due to unique redox cycling, which is coupled to the generation and transformation of various reactive oxygen species. In the presence of a proton donor, our system shows behavior which resembles that of superoxide dismutase (SOD). Regardless of light, chlorophyll acts as an electron transfer mediator.     

PREPARATION AND X-RAY CRYSTAL STRUCTURES OF TWO ALIPHATIC SELENENYL BROMIDES STABILIZED BY N─SE COORDINATION

(1R)-2-endo-(Dimethylamino)methyl-2-exo-methoxy-3-endo-camphor- ylselenenyl bromide and its 2-endo-(pyrrolidenyl)methyl analogue were prepared from (1R)-2-endo-acetamidomethyl-2-exo-hydroxy-3-endo-camphoryl diselenide. Both compounds showed an unusual lack of reactivity in electrophilic oxyselenenylation and cyclization reactions that are typical of other selenenyl bromides. X-ray crystallography indicated that both compounds have strong N─Se interactions, with N─Se interatomic distances of ca. 2.1 Å, which diminish the electrophilic character of the selenium atom.     

Antioxidant Properties of Garcinia Mangostana L (Mangosteen) Rind

Many diseases correlate with antioxidant deficiencies. Garcinia mangostana L rind (GMR) belong to waste product, contains xanthones which are antioxidant compounds. The aim of this study was to determine antioxidant properties of its ethanolic extract, hexane, ethylacetate, butanol, and water fractions in DPPH scavengingactivity, level of SOD and total antioxidant (TAS) compared against α-mangostin. Extract and all of these fractions had high DPPH trapping activity while α-mangostin had low activity. Level of SOD was highest in GMR water fraction while TAS level was highest in GMR ethylacetate fraction. It was concluded that GMR products had potential antioxidant properties     

一种制作多色彩全息图的新方法

本文首先提出了一种制作二维透射物彩虹全息图的新方法，即利用一专门设计的全息光学元件──色编码板，采用单光束制作所需物体的彩虹全息图；在此基础上，通过对色编码板的进一步理论设计，制作了一组对应不同主波长的色编码板，实现了记录物体的多色彩虹再现全息图。实验结果表明，此方案简便易行，光路布置灵活性高，且能有效地消除纵向色差的影响，特别适合于模压全息图制造中母全息图的拍摄，并降低了对环境稳定性的要求。     

金电极上自组装L-cy/SOD膜修饰电极的电化学行为

采用自组装方法制备了N-乙酰-L-半胱氨酸SAM-SOD修饰电极,运用循环伏安法研究了电极的电化学行为,该电极上的反应是一个受吸附控制的准可逆过程,并发现该修饰电极能够催化H<,2>O<,2>的电还原,还原峰电流随H<,2>O<,2>浓度的增大而减小,并且在2.4×10<'-6>～2.0×10<'-4>moL/L范围内...