三聚氰胺对DNA潜在损伤作用的研究

在生理酸度条件下(pH 7.4),采用溴化乙锭(EB)为荧光探针的荧光光谱法、I-离子荧光猝灭效应、DNA熔点和粘度效应等手段,研究了三聚氰胺与DNA的相互作用。随着DNA的加入,三聚氰胺的荧光强度明显减小而且三聚氰胺能够猝灭DNA-EB复合物的荧光,说明三聚氰胺能够竞争置换EB而与DNA作用;三聚氰胺的加入使得DNA的粘度增大,DNA-EB的熔点降低;DNA的加入减小了I-对三聚氰胺荧光的猝灭程度。三聚氰胺以嵌插方式作用于DNA的亲核位点,意味着三聚氰胺进入生物体后有可能通过形成DNA加合物的形式造成DNA损伤,从而最终导致基因突变。     

光谱法和电化学法研究甲硫氨酸二肽与DNA的相互作用

利用紫外-可见光谱、荧光探针、循环伏安等方法研究了甲硫氨酸二肽(Met-Met)与DNA的相互作用.结果发现:加入甲硫氨酸二肽后,DNA-Met-Met体系的紫外光谱呈减色效应,同时甲硫氨酸二肽的加入使得EB-DNA荧光强度减弱;循环伏安法表明,DNA的加入使得甲硫氨酸二肽的峰电流减小,峰位负移;Stern-Volmer方程说明二肽对DNA-EB的作用属于静态猝灭.这几种方法的实验结果都表明两者的作用模式为静电结合,多种计算方法得到两者作用的结合常数达到103 L/mol.     

红茶、绿茶和乌龙茶多糖及多酚对DNA的保护作用研究

用溴化乙锭(EB)作为荧光探针研究了各种茶叶多糖、多酚类化合物对DNA的保护作用.测定了龙井、普耳茶、乌龙茶等8种茶叶中多糖和多酚类提取物存在下DNA与EB混合液的荧光积分强度,并把不同茶叶与DNA相互作用的常数定义为结合常数D,根据D的大小讨论了多糖及多酚类化合物的存在DNA保护作用的影响.结果表明,8种茶叶与DNA...     

二氢杨梅素-锌配合物的合成及其与DNA相互作用研究

合成了二氢杨梅素-锌配合物(DMY-Zn),采用紫外可见光谱、红外光谱、元素分析及热重分析(TG-DTA)法对其结构进行了表征,结果表明二氢杨梅素与Zn2+离子形成了配合物,其组成为[C15H10O8Zn].2H2O。采用EB为荧光探针利用荧光滴定法和粘度法进一步研究了二氢杨梅素-锌配合物与DNA的相互作用,发现二氢杨梅素-锌配合物与DNA有较强的相互作用,能和EB竞争与DNA结合,插入到ctDNA相邻的碱基对中,其作用方式为插入作用,Stern-Volmer线性猝灭常数Ksq为1.01。     

光谱法研究对氨基苯乙酮缩对二甲氨基苯甲酰腙与DNA的相互作用

合成了对氨基苯乙酮缩对二甲氨基苯甲酰腙(AAPABH),采用荧光光谱法和UV-Vis吸收光谱法研究了AAPABH与DNA的相互作用。在pH 7.4Tris-HCl缓冲溶液中,以345 nm激发该化合物发射弱荧光,加入DNA后出现明显的荧光增强现象,表明探针分子与DNA结合形成了稳定配合物,其结合常数为5.48×107L/mol。研究了离子强度对体系荧光强度的影响,结果显示NaCl的加入未引起AAPABH-DNA体系荧光强度明显变化,表明AAPABH和DNA间不存在静电作用;同时DNA对AAPABH吸收光谱的影响表现为减色效应、探针分子与热变性后的DNA作用力明显小于与未变性DNA间的作用力、探针分子与溴化乙锭(EB)竞争结合DNA使得EB-DNA体系荧光猝灭,上述实验结果均表明探针分子主要以嵌插作用方式与DNA作用。     

表柔比星-镁体系与DNA相互作用初步研究

表柔比星是临床上用于治疗快速增殖肿瘤的药物。本文应用紫外、荧光、圆二色、黏度、凝胶电泳等方法研究了表柔比星-Mg2+体系与DNA的作用。结果发现:在pH=7.4时,表柔比星可与Mg2+形成稳定体系。加入DNA后表柔比星-Mg2+体系的紫外吸收明显降低;Scatchard图表明表柔比星-Mg2+体系对溴化乙锭(EB)与DNA的结合为竞争性抑制;同时此体系可使DNA-EB体系荧光偏振度增大;使DNA的热变性温度(Tm)上升;黏度增大;凝胶电泳表明表柔比星-Mg2+体系对pBR322DNA有非常好的切割活性;圆二色谱法表明随着表柔比星-Mg2+体系的加入,DNA碱基间作用能迅速减弱,二级结构发生了显著的变化。综上所述:表柔比星-Mg2+体系与DNA之间为嵌插作用;且表柔比星-Mg2+体系具有更好的切割活性。这些结果,可为合理改善药效和设计新药提供依据。     

乙酰阿魏酰酪氨酰酪氨酸的合成及其与DNA相互作用初探

用固相法合成了乙酰阿魏酰酪氨酰酪氨酸(F-Tyr-Tyr),并用ESI-MS、IR、NMR对其结构进行表征。应用紫外光谱法、荧光光谱法研究了F-Tyr-Tyr与小牛胸腺DNA(ctDNA)的相互作用。结果表明,F-Tyr-Tyr与ctDNA相互作用后体系的紫外吸收呈减色效应,且F-Tyr-Tyr加入后,DNA-EB体系的荧光强度减弱。根据Stern-Volmer方程求出F-Tyr-Tyr-DNA-EB体系的猝灭常数为K SV=6.28×103L·mol-1,猝灭方式为静态猝灭,推测F-Tyr-Tyr与ctDNA的相互作用模式主要是静电结合。     

染料木素及其镧配合物与DNA相互作用的研究

本文利用荧光光谱法、紫外吸收光谱法和粘度法研究了染料木素及其镧(Ⅲ)配合物与DNA的作用,结果发现:该配合物的荧光强度在加入DNA后增大,而染料木素则降低;配合物使DNA-EB体系的荧光强度降低要明显强于染料木素;配合物相较于配体与DNA相互作用之后,其紫外光谱的减色效应以及红移现象均强于配体;配合物使DNA粘度的增加的程度也大于配体。结果显示,染料木素及其镧(Ⅲ)配合物都能与DNA发生插入结合作用,但配合物与DNA结合得更加紧密。抗肿瘤活性体外测试的结果表明,无论染料木素还是配合物对于筛选的瘤株均具有一定的抑制作用,但是配合物对瘤株的抑制强于配体。     

抗肿瘤前药物β-二酮Ti(Ⅳ)与DNA相互作用研究

在生理酸度(pH 7.4)下,采用荧光光谱、紫外光谱法并结合溴化乙锭(EB)荧光探针、I-效应、离子强度及DNA热变性效应等实验手段研究了自制的β-二酮Ti(Ⅳ)新型抗肿瘤前药与DNA之间的相互作用。前药能极大地猝灭溴化乙锭(EB)-DNA体系的荧光,其电子吸收光谱在280 nm处的最大吸收峰在加入DNA后产生明显红移和减色效应。实验还发现KI对前药-DNA体系的荧光猝灭效率明显小于自由形式存在的前药的荧光猝灭效率;这些实验结果说明前药以嵌插方式作用于DNA的亲核位点。     

葛根素与DNA相互作用的光谱法研究

以中性红为光谱探针,采用荧光光谱和紫外-可见光谱法研究了葛根素与DNA的相互作用,考察了离子强度和I-离子浓度对葛根素与DNA作用的影响。结果表明,在生理条件下(pH 7.4),葛根素通过沟槽结合方式与DNA发生作用,DNA对葛根素荧光猝灭属于静态猝灭,测得其结合常数为4.81×104L/mol。     

Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method

Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.     

N,N-二(8-黄酮甲基)香叶胺类化合物的合成及生理活性

设计合成了4个N,N-二（8-黄酮甲基）香叶胺类化合物,所有目标化合物的结构均经1H NMR、MS和元素分析测试技术确证。采用MTT法考察了目标化合物对K562（白血病细胞）和SMMC7721（肝癌细胞）2种肿瘤细胞的体外抑制活性,结果表明,所测化合物对2种肿瘤细胞都有体外抑制活性,其中N,N-二(3′,4′-二甲氧基-8-黄酮甲基）香叶胺(1c)的活性最好,IC50值分别为5.78和3.85 μmol/L,N,N-二（4′-氟-8-黄酮甲基）香叶胺(1a)和化合物1c对K562（白血病细胞）的体外抑制活性明显优于商品药物美法仑(Melphalan)。以溴化乙锭(EB)为荧光探针测定了化合物1c与鲱魚精DNA有较强的相互作用。     

Morphological consequences of metal ion-peptide vesicle interaction

The triskelion peptide conjugate 1, having a Trp-Trp dipeptide unit on the three arms, was synthesized and studied for the interaction of peptide-based soft structures with metal ions, by fluorescence and microscopic analyses. We observed that fluorescence was significantly quenched upon addition of Cu(II) metal ions, whereas the addition of other metal ions also caused moderate to insignificant changes in the fluorescence emission, suggesting specificity of this triskelion peptide 1 for Cu(II) ions. The addition of Cu(II) and other metal ions also altered the morphology of preformed vesicles obtained from triskelion peptide 1 in a concentration-dependent fashion, as observed from microscopic analysis. Such metal-responsive soft structures may find potential use as novel materials for delivery and sensing applications.     

Study of interactions of anthraquinones with DNA using ethidium bromide as a fluorescence probe

The interactions of fish sperm deoxyribonucleic acid (DNA) with anthraquinones, such as chrysophanol, physcion and 1,8-dihydroxy anthraquinone, were investigated by using ethidium bromide (EB) as fluorescence probe. The binding constants of anthraquinones and DNA were obtained by the fluorescence quenching technique. Further, the binding mechanisms on the reaction of the three anthraquinones with DNA and effect of ionic strength on the fluorescence property of the system have also been investigated. The results of the assay indicate that the binding modes of chrysophanol, physcion and 1,8-dihydroxy anthraquinone with DNA were evaluated to be groove binding. And the binding constants of chrysophanol, physcion and 1,8-dihydroxy anthraquinone with DNA-EB complex were 1.64x10(4), 3.04x10(4) and 2.88x10(5) l mol(-1), respectively.     

IR-LD spectroscopic characterization of L-Tryptophan containing dipeptides

IR-spectroscopic and stereo-structural analysis of aromatic l-Tryptophan containing dipeptides l-Tryptophan-l-Tryptophan (Trp-Trp), l-Tyrosine-l-Tryptophan (Tyr-Trp) and cyclo(Trp-Trp) have been carried out by means of solid-state linear-dichroic infrared (IR-LD) spectroscopy of oriented as suspension in nematic liquid crystal solids. The experimental data have been compared with analogous ones of the simple amino acids l-Tyrosnine (l-Tyr) and l-Tryptophan (l-Trp). In cyclo(Trp-Trp), the IR-spectral changes towards the IR-ones of acyclic Trp-Trp have been determined. A theoretical analysis of Tyr-Trp at Hartree-Fock level of theory and 6-31G** basis set is also applied.     

Study on the fluorescence spectra and electrochemical behavior of ZnL2 and Morin with DNA

The interactions of Morin (2', 3, 4', 5, 7-pentahydroxyflavone) and its Zn-complex, ZnL2.3H2O [L = Morin (2'-OH group deprotonated)], with calf thymus DNA have been studied using fluorimetric and electrochemical methods. ZnL2.3H2O has different spectral characteristics and electrochemical behavior from that of Morin in the presence of DNA. Increasing fluorescence is seen for ZnL2.3H2O with DNA addition whereas decreased fluorescence is observed for Morin. An isosbestic point appears at 560 nm for the DNA-ZnL2.3H2O system with ethidium bromide (EB) addition while no isosbestic point is detectable for Morin. Quenching fluorescence is observed for DNA-EB system when ZnL2.3H2O is added whereas no quenched fluorescence is seen for DNA-EB system with Morin addition. The above results suggest that Morin and ZnL2.3H2O can both bind to DNA, but the binding mode is different. The complex binds to DNA mainly by intercalation, while Morin binds in a non-intercalating mode. The binding constant and binding site sizes are derived from electrochemical methods. For ZnL2.3H2O, the binding constant is 5.0 x 10(4) l mol(-1) at 20 degrees C, and the binding site size n(s) is 5.     

表柔比星-铜体系与DNA作用的光谱和电化学法研究

表柔比星是临床上广泛用于治疗增殖很快的肿瘤. 应用紫外、荧光、黏度、循环伏安等方法研究了表柔比星及表柔比星-Cu^2＋体系与DNA的作用. 结果发现: 在pH＝7.4时, 表柔比星可与Cu^2＋形成稳定体系. 加入DNA后表柔比星-Cu^2＋体系的紫外吸收明显降低; Scatchard图表明表柔比星-Cu^2＋体系对溴化乙锭(EB)与DNA的结合为竞争性抑制; 同时此体系可使DNA-EB体系荧光偏振度增大; 使DNA的热变性温度(t_m)上升; 黏度增大; 循环伏安法表明DNA的加入使得表柔比星及表柔比星-Cu^2＋体系的式量电位正移; 凝胶电泳表明表柔比星-Cu^2＋体系对pBR322 DNA有非常好的水解切割活性. 综合以上结果得出: 表柔比星及表柔比星-Cu^2＋体系与DNA之间均为嵌插作用; 表柔比星-Cu^2＋体系具有更好的水解切割活性. 这些结果可为合理改善药效、降低抗癌药物毒性和设计新药提供依据.     

Synthesis, antimicrobial and antiproliferative activity of novel silver(I) tris(pyrazolyl)methanesulfonate and 1,3,5-triaza-7-phosphadamantane complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh(3))] (2), [Ag(Tpms)(PCy(3))] (3), [Ag(PTA)][BF(4)] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh(3) = triphenylphosphane, PCy(3) = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N(3)-facially coordinating mode, while in 2 and 5 a N(2)O-coordination is found, with the SO(3) group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA159), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of Ag complexes shows that the fluorescence quenching of DNA-EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO(3), which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO(3)? 4.     

Radiation induced DNA strand breaks measured by a modified method of gel scanning

Gel electrophoresis is an effective method for assaying plasmid DNA fractions, and UV lights with long wavelengths such as 315 nm is used to image the gel. In the present work, the sensitivities of detecting the fluorescence emitted from ethidium bromide (EB) stained DNA bands in the gel illuminated with UV lights of various wavelengths were compared. It was found that, in the range 245 to 320 nm, shorter excitation wavelength had higher detection sensitivity, thus 260 nm was selected for further studies. With this excitation light, as little as 0.7 ng DNA was detected. The fluorescence of DNA-EB bands had a good linear response to DNA quantity in a wide range. In addition, measured via this modified method, the yield of DNA strand breaks and the second-order rate coefficient of the reaction between DNA and √OH radical were consistent with many previous studies.