Cytotoxicities,Telomerase and Topoisomerases I Inhibitory Activities and Interactions of Terpyridine Derivatives with DNAs

A novel compound 4-methyl-7-{[4-(2,2':6',2'-terpyridin-4'-yl)benzyl]amino}-2H-chromen-2-one(1) was synthesized, and its DNA-binding properties, cytotoxicity, and telomerase and Topo I inhibitory activities were evaluated. For comparison, the anti-proliferative and Topo I inhibitory activities of another two analogues 2 and 3 were also investigated. Compound 1 is able to stabilize the structures of human telomere(h-tert) and promoter(c-myc and c-kit2) G-quadruplexes and h-tert i-motif. The association constants(K_b) are about 10⁶ L/mol for h-tert G-quadruplex and i-motif, while the values are about 10⁵ L/mol for both promoter G-qaudruplexes and calf thymus DNA(ct-DNA). The binding of compound 1 induces the change of h-tert G-quadruplex from hybrid to antiparallel structure and exhibits 88.7% inhibition of telomerase activity at 8 mmol/L. Both compounds 1 and 3 inhibit significantly Topo I-mediated relaxation of pBR322 DNA. Compounds 1 and 2 show a high inhibitory efficacy on HepG2 and MCF-7 cancer cell lines with IC₅₀ values of about 10^-6 mol/L. The three compounds also induce a delay of cell cycle progression. The coumarin group is vital for improving the biological activity of terpyridine derivatives.     

Studies on the Interaction of Novel Organogermanium Sesquioxides with DNA

The affinity and mode of interaction of four novel organogermanium sesquioxides with calf thymus DNA(CT-DNA) and two synthetic oligonucleotides, d(AT)₂₂d(AT)₂₂ and d(GC)₂₂d(GC)₂₂, were investigated by a combination of absorption spectroscopy, DNA thermal denaturalization method, viscosity method, fluorometric technique, and competitive binding study with ethidium bromide(EB). The results show that the organogermanium compounds can interact with DNA by intercalation, the binding ability of the compounds to CT-DNA and the synthetic oligonucleotides was found to be modest(in comparison to the proven intercalators), with binding constants on the order of 10³―10⁵ L/mol, respectively. Generally, the binding of the organogermanium sesquioxides with naphthalene moiety to DNA is stronger than that of the compounds with anthraquinone moiety. And the compounds with anthraquinone moiety have preference for binding to AT-rich duplexes, whereas the compounds with naphthalene moiety have a little preference for binding to GC-rich duplexes. DNA may be the primary effect target.     

A study on the binding of two water-soluble tetrapyridinoporphyrazinato copper(II) complexes to DNA

Interaction of N,N′,N″,N-tetramethyltetra-2,3-pyridinoporphyrazinatocopper(II), ([Cu(2,3-tmtppa)]⁴⁺) and N,N′,N″,N-tetramethyltetra-3,4-pyridinoporphyrazinatocopper(II), ([Cu(3,4-tmtppa)]⁴⁺) with calf thymus DNA was studied in 1 mM phosphate buffer and low ionic strength (5 mM NaCl) at various temperatures by UV-visible and circular dichroism (CD) spectroscopies and viscometric method. The binding constants were determined from the changes in the visible part of porphyrazine complexes spectra using SQUAD software. The values of K have been obtained (7.9±0.4)×10⁴ and (2.2±0.1)×10⁵ M⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and [Cu(3,4-tmtppa)]⁴⁺, respectively at 27 °C. The higher affinity of 3,4-isomer of Cu complex towards DNA with respect to the 2,3-isomer was attributed to favorable external positioning of the cationic charges in former, which enables superior interaction with the DNA duplex. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were calculated by van't Hoff equation. The enthalpy and entropy changes were determined, +34.2±3.6 kJ mol⁻¹ and +207.8±12.70 J mol⁻¹ K⁻¹ for [Cu(2,3-tmtppa)]⁴⁺ and +49.7±2.1 kJ mol⁻¹ and +267.8±7.9 J mol⁻¹ K⁻¹ for [Cu(3,4-tmtppa)]⁴⁺. The existence of extensive hypochromicity, large red shift and negative CD in the visible part of [Cu(3,4-tmtppa)]⁴⁺ spectra suggested an intercalation binding mode. Analysis of the moderate hypochromicity, red shift and bisignate CD in the Q-band absorption region of [Cu(2,3-tmtppa)]⁴⁺ spectra possibly led us to the coexistence of intercalation and outside binding modes. The influence of the ionic strength on the binding parameters and binding modes was investigated. The results show that increase in ionic strength causes the decrease in the binding constants. It was also concluded that increase in ionic strength affects the binding characteristics of positively charged complexes with DNA.

The increase in DNA viscosity in the presence of Cu–tmtppa complexes is attributed to the lengthening of DNA helix due to the intercalation. This result is consistent with conclusions obtained from the spectroscopic techniques.     

钯(Ⅱ)三元配合物稳定性及其与DNA作用研究

合成了[Pd(bipy)(DL-gly)]Cl•2H₂₂O(2)两个钯三元配合物. 配合物１和２的稳定常数对数值lgβ分别为13.81和13.71, 表征常数ΔlgK、lgX高于统计值, 表明在配合物分子内存在d-p π电子协同效应. 紫外光谱、荧光光谱结果表明, 配合物１和２与鱼精DNA主要以插入方式键合, 键合常数分别为2.37×10⁶(1)和4.57×10⁶(2). CD光谱图也显示, 配合物与DNA分子之间发生了作用. 质粒pBR322 DNA的凝胶电泳图表明, 配合物浓度在3.0０×10^-3～7.5０×10^-4 mol •L^-1范围内对DNA分子有切割作用, 配合物浓度低于3.75×10^-4 mol •L^-1时则主要以插入方式与DNA键合.     

Interaction of antitumor drug Sn(CH3)2Cl2 with DNA and RNA

Sn(CH₃)₂Cl₂ exerts its antitumor activity in a specific way. Unlike anticancer cis-Pt(NH₃)₂Cl₂ drug which binds strongly to the nitrogen atoms of DNA bases, Sn(CH₃)₂Cl₂ shows no major affinity towards base binding. Thus, the mechanism of action by which tinorganometallic compounds exert antitumor activity would be different from that of the cisplatin drug. The aim of this study was to examine the binding of Sn(CH₃)₂Cl₂ with calf thymus DNA and yeast RNA in aqueous solutions at pH 7.1–6.6 with constant concentrations of DNA and RNA and various molar ratios of Sn(CH₃)₂Cl₂/DNA (phosphate) and Sn(CH₃)₂Cl₂/RNA of 1/40, 1/20, 1/10, 1/5. Fourier transform infrared (FTIR) and UV–visible difference spectroscopic methods were used to determine the Sn(CH₃)₂Cl₂ binding mode, binding constant, sequence selectivity and structural variations of Sn(CH₃)₂Cl₂/DNA and Sn(CH₃)₂Cl₂/RNA complexes in aqueous solution. Sn(CH₃)₂Cl₂ hydrolyzes in water to give Sn(CH₃)₂(OH)₂ and [Sn(CH₃)₂(OH)(H₂O)_n]⁺ species. Spectroscopic evidence showed that interaction occurred mainly through (CH₃)₂Sn(IV) hydroxide and polynucleotide backbone phosphate group with overall binding constant of K(Sn(CH₃)₂Cl₂–DNA)=1.47×10⁵ M⁻¹ and K(Sn(CH₃)₂Cl₂–RNA)=7.33×10⁵ M⁻¹. Sn(CH₃)₂Cl₂ induced no biopolymer conformational changes with DNA remaining in the B-family structure and RNA in A-conformation upon drug complexation.     

DNA Binding Properties and Cytotoxic Activities of Two Trinuclear Ruthenium（Ⅱ） Polypyridyl Complexes

The interactions between two trinuclear Ru（II） complexes and calf thymus DNA（CT DNA） were studied via absorption spectroscopy, reverse salt titrations, binding stoichiometry, DNA melting experiments, as well as viscosity measurement. The results indicate that complexes 1 and 2 bind to DNA via the interaction of the planar π-delocalized system of the complexes with intrinsic binding constants of 4.18 × 10^5 and 3.85 × 10^6 L/tool, respectively, and non-electrostatic binding free energy makes a predominant contribution to the binding free energy. The in vitro cytotoxic activity of complexes 1 and 2 was evaluated by the MTT[3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl- 2H-tetrazolium bromide] method. Complex I shows higher anticancer potency than complex 2 against four tumor cell lines. Further mechanism study indicates that complexes 1 and 2 can cause cell cycle arrest in the G2/M phase.     

邻菲啰啉和氨三乙酸钴配合物与牛血清白蛋白相互作用的荧光分析

利用溶液法合成了邻菲啰啉(phen)和氨三乙酸(H₃nta)钴配合物Co(phen)₂Cl₂(1), Na[Co(nta)]·H₂O(2), [Co(phen)₂(H₂O)₂][Co(nta)(phen)]₂·12H₂O(3), 对配合物3进行了X射线单晶衍射表征, 结果表明: 该配合物属三斜晶系, P1空间群, a=1.2448(2) nm, b=1.5898(3) nm, c=1.7412(3) nm, α=91.746(3)°, β=97.807(3)°, γ=103.745(3)°, V=3.309(1) nm³. 利用荧光光谱法研究了室温下这3种配合物与牛血清白蛋白(BSA)的相互作用, 并测定了不同温度下这3种配合物与BSA相互作用的荧光强度变化, 确定配合物1和3对BSA的荧光猝灭方式均为静态猝灭; 分析了配合物1和3与BSA相互作用时的结合常数、 结合位点数以及热力学函数与温度之间的关系, 进一步讨论了这2种配合物分别与BSA相互作用时的作用位点、 作用力的类型以及两者之间的距离.     

硫黄素T与侧翼连接双链DNA的G-四链体高特异性作用

富G碱基的DNA序列在离子诱导下可形成G-四链体(G4),基于这一构型转化设计了大量的传感检测平台。其中的荧光检测平台是基于G4与荧光小分子的相互作用。但是,G4与荧光小分子的有效结合依赖于G4构型和体系中存在的离子种类和离子浓度,尤其是高Na⁺浓度(140 mmol·L^-1)。那么如何实现G4与荧光小分子普适性地有效结合,并不依赖于体系中的Na⁺和Na⁺浓度,是一个难题。在本研究中,以最简单的富G DNA序列凝血酶适体链TBA (thrombin binding aptamer)为例,在3’端和5’端分别增加10个碱基(TBA-10 bp),K⁺诱导TBA-10 bp形成K⁺稳定TBA (K⁺-TBA,G4)并衔接含有10个互补碱基对的双链DNA (K⁺-TBA-10 bp)。相较于K⁺-TBA,硫磺素T与K⁺-TBA-10 bp结合后的荧光强度增加了100倍,相互作用强度增加了1000倍,而且与体系中的Na⁺ (5-140 mmol·L^-1)无关。结合荧光光谱,紫外吸收光谱和圆二色光谱发现硫磺素T特异性的嵌合于K⁺-TBA和双链DNA衔接处的空腔内。有趣的是,这一结合模式不受G4构型的影响。该研究结果为研究G4与荧光小分子的有效结合提供了新视角,也为拓展G4在生物功能和生化检测领域的应用提供了实验依据。     

邻菲啰啉并1,2,4-三嗪钴(Ⅲ)配合物的合成及其对小牛胸腺DNA的荧光识别

在4个邻菲啰啉并1,2,4-三嗪新型配体分子(ARTP1ARTP4)合成的基础上,通过ARTP1ARTP4与Co³⁺配位,制备了4个钴(Ⅲ)配合物(Co-ARTP1Co-ARTP4)。 通过傅里叶变换红外光谱仪(FT-IR)、核磁共振波谱仪(NMR)和高分辨质谱(HRMS)仪和紫外-可见分光计(UV-Vis)等技术手段表征了ARTP1ARTP4和Co-ARTP1Co-ARTP4的结构和性能。 结果表明,配合物的紫外吸收峰中出现减色效应,最大吸收峰红移。 配合物以插入的方式与小牛胸腺DNA结合,结合常数K_b分别为4.78×10⁵、6.52×10⁵、5.97×10⁵和6.01×10⁵ L/mol,表明配合物可作为潜在的CT-DNA荧光探针,为探索DNA与有机小分子的作用提供了重要的参考。     

Metal-ion sensing and aggregation studies on reactive phthalocyanines bearing soft-metal receptor moieties; synthesis, spectroscopy and electrochemistry

Tetrasubstituted metal-free {2H[Pc(S(CH₂)₆OCOC₄H₃S)₄]} and copperphthalocyanine {Cu[Pc(S(CH₂)₆OCOC₄H₃S)₄]}, bearing thiophene-2-carboxylate-hexylthio moieties, have been prepared as isomeric mixtures via cyclo-tetramerization. Both new compounds have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MS (Maldi-TOF) and UV–Vis spectral data. The cation binding abilities of the functional phthalocyanines with Ag^I, Pd^II, Hg^II, Pb^II and Cd^II are evaluated by a monomer–oligomer formation technique with UV–Vis spectroscopy. Spectroscopic properties of the complexes were affected strongly by the electron-donating sulfanyl units on the periphery. Cyclic voltammetry and differential pulse voltammetry studies show that both compounds give up to three ligand-based reduction processes and one ligand-based oxidation process having diffusion-controlled one-electron transfer properties.     

A highly selective chemosensor for copper ion based on ICT fluorescence

Simple structural compounds 1 to 3 were synthesized.The presence of Cu²⁺ resulted in the fluorescence and absorption spectra change of 1 and 2,which indicated that 1 and 2 showed a highly selective response to Cu²⁺ over other metal ions.However,3 showed no selectivity for metal ions,which means that the compound could bind with several metal ions,such as,Ni²⁺,Zn²⁺,Cd²⁺.Hg²⁺, Pb²⁺,Fe³⁺,Mg²⁺,Ca²⁺,and Co²⁺,except Cu²⁺ and Ag⁺.The different spectral responses were attributed to the difference in binding sites for 1 and 3.     

Density functional theory assessment of the thermal degradation of diclofenac and its calcium and iron complexes

Thermogravimetric analyses of diclofenac sodium, its Ca²⁺ and Fe³⁺ complexes manifested a decreasing trend of the onset decomposition temperatures at which these compounds dissociated. The drop in the temperature was metal ion dependent; the sodium salt showed thermal stability up to 245 °C, whereas the complexes started their degradation processes at temperatures starting from 90 °C. While G* for the cleavage of the acetate moiety in the sodium salt was 63.76 kJmol⁻¹, it was 82.06 and 140.57 kJmol⁻¹ in the cases of Ca²⁺ and Fe³⁺, respectively. However, their complete fusion took place at 187.65, 150.34 and 98.77 °C, respectively, displaying a reversed trend which is probably indicative of some catalytic part on the binding metals.

Using the Gaussian 98 W package of programs, ab initio molecular orbital treatments were applied to diclofenac and its Ca²⁺ and Fe³⁺ metal complexes to study their electronic structure at the atomic level. The thermochemistry of diclofenac sodium was followed through the TG fragmentation peak temperatures using the density functional theory calculations at the 6-31G(d) basis set level. The FT-IR data were in good agreement with the theoretically calculated values.

Single point calculations at the B3LYP/ 6-311G(d) level of theory, were used to compare the geometric features, energies and dipole moments of these compounds to detect the effect of the binding metal ions on the thermal dissociation of their diclofenac complexes.     

基于手机光线传感器为检测器的简易光度计的自组装设计

By using light sensors of the cellphone, we build a simple photometer which can be used in quantitative analysis experiments. We have performed 5 replicate measurements of iron with phenanthroline to verify reproducibility and stability. We find the absorbance of the sample has a good linear relationship with the concentrations of iron with a R² value around 0.999 and the RSD of 2.81%. The result is 4.94 μg·mL^-1 with spectrophotometer and 5.11 μg·mL^-1 with our photometer. The photometer is simple, convenient, accurate and realistic by using a phone as detector, which can replace the traditional spectrophotometer in the laboratory class. The students can enhance their understanding of the structure and principle of spectrophotometer by the DIY photometer experiment.     

Synthesis, structure and nuclease activity of copper complexes of disubstituted 2,2′-bipyridine ligands bearing ammonium groups

A series of Cu(II) complexes of disubstituted 2,2′-bipyridine bearing ammonium groups [Cu(L¹⁻⁴)₂Br]⁵⁺ (1–4, L¹ = [5,5′-(Me₂NHCH₂)₂-bpy]²⁺, L² = [5,5′-(Me₃NCH₂)₂-bpy]²⁺, L³ = [4,4′-(Me₂NHCH₂)₂-bpy]²⁺, L⁴ = [4,4′-(Me₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridyl) were synthesized, of which complexes 1 and 4 were structurally characterized. Both coordination configurations of Cu(II) ions can be described as distorted trigonal bipyramid. The interaction between all complexes and CT-DNA was evaluated by thermal-denaturation experiments and CD spectroscopy. Results show that the complexes interact with CT-DNA via outside electrostatic interactions and their binding ability follows the order: 1 > 2 > 3 > 4. In the absence of any reducing agents, the cleavage of plasmid pBR322 DNA by these complexes was investigated and the hydrolysis kinetics of DNA was studied in Tris buffer (pH 7.5) at 37 °C. Obtained pseudo-Michaelis–Menten kinetic parameters: 15.0, 13.6, 2.01 and 1.69 h⁻¹ for 1, 2, 3 and 4, respectively, indicate that complexes 1 and 2 exhibit very high DNA cleavage activities. According to their crystal data, the high nuclease activity may be attributed to the strong interaction of the metal moiety and two ammonium groups with phosphate groups of DNA.     

Studies on the Interaction of Ru(Ⅱ) Polypyridyl Mixed-ligand Complexes and DNA by Viscosity Measurement

The interaction of transition metal polypyridyl coordination compounds with DNA has been extensively studied in the past few years^[1]. Li the case of double stranded DNA, some coordination compounds may bind in the major groove with one ligand inserting between two base pairs DNA. The viscosity studies provide a strong argument for intercalation^[2].     

AN ULTRASENSITIVE BIOASSAY FOR THE DETECTION OF FUROCOUMARINS AND OTHER PHOTOSENSITIZING MOLECULES

Abstract— A photobiological assay based upon inhibition of growth in the DNA repair-deficient bacterium E. coli B _s-1, is described for the analysis of a number of photosensitizing agents. The lower limits of detection were as follows: psoralen 5 × 10^-11g; 5-methoxypsoralen 1 × 10^-9 g; 8-methoxypsoralen 1 × 10^-9 g; 4,5',8-trimethylpsoralen 1 × 10-¹¹ g; angelicin 5 × 10^-9 g; 5,7-di-methoxycoumarin 1 × 10^-7 g; isoimperatorin 5 × 10^-9 g; dictamnine 1 × 10^-8 g; oxypeucedanin 5 × 10^-7 g; 5-nitroxanthotoxin 5 × 10^-7 g; and α-terthienyl 1 × 10^-6 g. All active compounds with the exception of α-terthienyl were more easily detected by several orders of magnitude by E. coli B _s-1 than with the normal wild type E. coli. 5—Geranoxypsoralen and isopimpinellin were not active. The application of this technique, after TLC, to the analysis of complex mixtures from lemon oil, oil of bergamot, Heracleum lanatum, Angelica dawsonii , and celery and parsnip is illustrated. The bioassay described is more rapid and sensitive than previously published methods, permits replica plates to be made, and allows tentative identification of the photosensitized molecular target.     

Hydrothermal Synthesis,Structure and Property of Transition Metal(Mn,Zn, Cd or Pb) Coordination Frameworks Using Quinoline-8-oxy-acetate Acid and Dicarboxylic Acid as Ligands

Five transition metal coordination compounds, [Mn₂(8-qoac)₂(bdc)(H₂O)₄](1)(8-qoacH=quinoline-8-oxy- acetate acid, H₂bdc=benzene-1,4-dicarboxylic acid), [Zn₄(8-qoac)₄(bdc)₂]_n(2), {[Cd₂(8-qoac)₂(Hip)₂(H₂O)₂]· (H₂O)₄}_n(3)(H₂ip=benzene-1,3-dicarboxylic acid), [Pb₃(8-qoac)₂(bdc)_1.5(H₂O)Cl]_n(4) and [Zn₂(8-qoac)(8-ql)(bdc)]_n (5)(8-Hql=8-hydroxyquinoline), were synthesized by hydrothermal syntheses of metal salts with benzenedicarboxy- lic acid and 8-qoacH. Compound 1 possesses a discrete dimer bridged by bdc^2- ligand. Compound 2 presents a 2D layer network constructed from bdc^2- linkers and 1D infinite ribbons, in which Zn(II) centers are bridged by 8-qoac^- with a tetradentate binding mode. Compound 3 displays a 1D zigzag chain, with adjacent chains further connected via extensive O-H···O hydrogen bonds to generate a 3D supramolecular structure. Compound 4 shows a 3D framework containing trinuclear lead secondary building units and bdc^2- linkers, in which a new coordination mode of 8-qoac^- ligand is observed. In compound 5, Zn(II) ions are simultaneously bridged by 8-qoac^-, 8-ql^- and bdc^2- ligands to form tetranuclear zinc units, which are further interlinked by bdc^2- linkers to yield a 2D wave-like layer. Based on intraligand(IL)(π-π^*) fluorescent emission, compounds 1―5 possess strong purple fluorescent emissions. In addition, the thermal stabilities of compounds 1―5 were studied.     

Determination of stability constants for rare earth elements and fulvic acids extracted from different soils

Fulvic acids (FAs) were extracted by alkali extraction from different soil samples in China, then purified using resins and characterized by Fourier transform infrared spectroscopy. The complexing ability of FAs was investigated by measuring the stability constants of rare earth elements (REEs) (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺, Y³⁺) with FAs by the ion exchange technique. The results indicated that maximum binding ability forY³⁺ (4.414.44) was higher than other REEs (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺) (0.721.03). There were two types of binding sites in the functional groups of fulvic acids. The complexing reaction followed two steps. The stability constants (K₁ and K₂) of REEs with FAs were calculated from experimental data by division of Scatchard plots into two straight-line segments. Y³⁺ (log K₁=5.72±0.05, log K₂=4.83±0.01) also has higher stability constants than the other four REEs (log K₁=4.37±0.16, log K₂=3.62±0.28).     

芳香寡聚磺酸酯桥联大环化合物的合成及其对Sn2+和Bi3+的识别作用

以4,6-二烷氧基-1,3-苯二磺酰氯和芳香二酚为原料,三乙胺作缚酸剂,二氯甲烷作溶剂,采取一步成环法合成了3种磺酸酯桥联大环化合物。合成产物的结构用IR、¹H NMR、¹³C NMR和MALDI-TOF等技术手段进行了确认。利用紫外光谱分析的方法研究了4,6,16,18-四正戊氧基-11,23-二甲基-1,3,13,15-四磺酸酯间苯芳香大环(5)对Ca²⁺、Pb²⁺及部分过渡金属等20种金属离子的识别。结果发现,其对Sn²⁺显示出一定的选择性,由于Sn²⁺和Bi³⁺协同作用的影响,在化合物5-Sn²⁺的体系中加入Bi³⁺,紫外吸收光谱在325 nm左右的吸收增强了许多,这说明化合物5对Bi³⁺显示出优于Sn²⁺的较好选择性。     

水溶性羧酸咔咯铁(Ⅲ)配合物对DNA的氧化断裂作用

合成了5,10,15-三(4-羧基-苯基)咔咯铁配合物(Fe^ⅢTCPC), 采用紫外-可见光谱、 荧光光谱、 圆二色光谱和黏度法研究了Fe^ⅢTCPC与小牛胸腺DNA(ct-DNA)的相互作用, 并用琼脂糖凝胶电泳研究了氧化剂参与下Fe^ⅢTCPC对pBR22 DNA的氧化断裂能力. 结果表明, Fe^ⅢTCPC与DNA的作用方式为外部结合模式, 其结合常数K_b=1.96×10⁵ L/mol. 在过氧化氢(H₂O₂)或叔丁基过氧化氢(TBHP)为氧化剂条件下, Fe^ⅢTCPC展现出良好的DNA氧化断裂能力, 且TBHP的氧化断裂效率比H₂O₂好. 用H₂O₂和TBHP为氧化剂时, Fe^ⅢTCPC可能是通过活性Fe^Ⅴ-oxo机制对DNA氧化断裂.