In vitro study of the interaction of cysteine with a thiazide diuretic (hydrochlorothiazide) at different ph by voltammetric and spectroscopic techniques

The interaction of cysteine (RSH) with a thiazide diuretic, hydrochlorothiazide (HCTZ) was characterized by UV-Vis absorption spectroscopy and square-wave voltammetry in Britton-Robinson (B-R) buffer solution (with pH 5, 7 and 9). On the square-wave voltamogram of cysteine, the reduction peak current of mercurous cysteine thiolate (Hg₂(RS)₂) decreased and its peak potential shifted to more positive values with the addition of HCTZ. This results showed that the RSH interacted with HCTZ. The stoichiometry of HCTZ-RSH molecular complex was determined by voltammetric data with the result of 1: 1. By using linear regression analysis of the voltammetric data at pH 5, 7 and 9, the apparent formation constants of HCTZ-RSH complex were calculated to be 9.54 × 10³, 2.80 × 10⁴ and 2.55 × 10⁴ M^?1, respectively. At the same time, this interaction was also supported by UV-Vis spectroscopic measurements. According to the voltammetric and spectroscopic results, it was suggested that the interaction mode between RSH and HCTZ molecules might be a combination of hydrophobic interactions and hydrogen bonds.     

Analysis of fluorescence quenching of pyronin B and pyronin Y by molecular oxygen in aqueous solution

The fluorescence quenching of pyronin B and pyronin Y molecules by molecular oxygen in aqueous solution was studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques. In order to understand the quenching mechanism, fluorescence decays, absorption and fluorescence spectra of the probes were recorded as a function of the oxygen concentration and temperature. The quenching was found to be appreciable and shows positive deviation in the Stern-Volmer representation obtained from the fluorescence intensity ratio. Fluorescence quenching constants (k_q) were calculated from the τ_o/τ vs. [Q] plots having linear correlation and compared with calculated diffusion-controlled rate constants (k_diff) values. Experimental results were in good agreement with the simultaneous dynamic and static quenching model.     

含黄酮的三价铁配合物合成及其药理性质(英文)

3,3,4,7-四羟基黄酮与1,3-二环己基碳二亚胺在4-二甲胺吡啶存在下反应,得到2,2-双(3,3,4,7-四羟基黄酮)1,3-二环己基碳二亚胺。三价金属离子与上述合成得到的配体螯合,对此四面体结构的双核Fe(Ⅲ)配合物的血液学及病理学数据进行了讨论,同时研究了合成的配体作为螯合剂清除鼠肝胰组织中超载的铁的能力。结果表明作为口服药其作为双齿配体的螯合能力与市售用于治疗地中海贫血的药物"去铁敏"相近。     

Hydrogen‐bond motifs in N‐monosubstituted derivatives of barbituric acid: 5‐allyl‐5‐isopropyl‐1‐methylbarbituric acid (enallylpropymal) and 1,5‐di(but‐2‐enyl)‐5‐ethylbarbituric acid

Both title structures exhibit essentially planar barbiturate rings. The crystal structure of enallylpropymal (5‐allyl‐5‐isopropyl‐1‐methylbarbituric acid), C₁₁H₁₆N₂O₃, is composed of centrosymmetric N—H...O hydrogen‐bonded dimers, while 1,5‐di(but‐2‐enyl)‐5‐ethylbarbituric acid, C₁₄H₂₀N₂O₃, forms N—H...O hydrogen‐bonded helical chains. Each of the ten known crystal structures of closely related N‐monosubstituted derivatives of barbituric acid displays one of the fundamental N—H...O hydrogen‐bonded motifs of the two title structures, i.e. either a dimer or a chain.     

Synthesis,characterization and crystal structures of new Zinc(II) and Nickel(II) complexes containing morpholine moiety and their antibacterial studies

The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX₂ (L = DME, X = Cl or NO₃). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO₃ was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.     

1,3-二吗啉基丙烷与Hg(Ⅱ)和Zn(Ⅱ)的配合物:合成、结构与抗菌研究

以1,3-二吗啉基丙烷(DMP)为配体合成了2个配合物:Hg(DMP)Cl₂(1)和Zn(DMP)Cl₂(2),并对其结构进行了表征。单晶X-射线结构分析表明,2个配合物中的金属离子都与2个N原子和2个Cl原子配位,形成扭曲四面体配位结构。配体和配合物对3种革兰氏阳性菌(S. aureus ATCC25923,E. faecalis ATCC23212和S. epidermidis ATCC34384)和3种革兰氏阴性菌(E. coli ATCC25922,P. aeruginosa ATCC27853和K. pneumonia ATCC70063)都具有抗菌活性,且在一定条件下,Hg(Ⅱ)配合物的抗菌活性超过了作为标准的磺胺异恶唑药物。     

Cytotoxic and apoptotic activities of novel Pd(II) complexes against human leukemia cell lines in vitro

In the investigation for alternative chemotherapeutic strategies against leukemia, Pd(II) complexes were synthesized and investigated for cytotoxic and apoptotic properties on two human leukemia cell lines (HL-60 and K562). Pd(II) complexes (Pd-5a and Pd-6a) with 5a and 6a as ligands were synthesized and characterized by ¹H-NMR and F-TIR. The cytotoxicity of the compounds was quantified using MTT method. Bax, Bcl-2, and caspase 3 gene expression levels were estimated using RT-qPCR. Here we show that Pd(II) complexes have important cytotoxic activity on human leukemia cell lines. RT-qPCR indicated that Bax and caspase 3 gene expression levels were increased after 24 h treatment with Pd-5a and Pd-6a complexes in both HL-60 and K562 cells at some selected dose. Furthermore, Bcl-2 gene expression level decreased after 24 h treatment with Pd-5a and Pd-6a complexes in K562 cells at all selected dose. In HL-60 cells, only one selected Pd-5a dose (25 µM) decreased the gene expression level of Bcl-2. The results obtained in the present investigation indicate that these two newly synthesized Pd(II) complexes have apoptotic effects at appropriate doses through caspase 3 and Bax genes and might represent a novel potentially active agents for the management of human leukemia cell lines.     

Synthesis,p-Nitrophenolate Complexation and Competitive Anion Signaling of Novel Calixpyrrole Dimer

A novel dimeric calixpyrrole has been synthesized. The dimer forms stable complexes with p-nitrophenolate ion with a concomitant reduction in extinction coefficient. The chromogenic anion is displaced by the addition of various anions like fluoride and acetate. Effective optical sensing of these anions is accomplished using the calixpyrrole dimer.     

QCM-DNA biosensor based on plasma modified PT/TiO2 nanocomposites

A quartz crystal microbalance DNA biosensor based on plasma prepared polythiophene /titanium dioxide (PT/TiO₂) nanocomposite was developed for the detection of genetically modified organisms (GMOs). DNA hybridization was studied by quartz crystal microbalance (QCM) and cyclic voltammetry (CV) measurements. Single stranded DNA probes were immobilized on the PT/TiO₂ coated quartz crystal electrode and the hybridization between the immobilized probe and the target complementary sequence in solution was monitored. The developed QCM-DNA biosensor represented promising results for a real-time, label-free, direct detection of DNA samples for the screening of genetically modified organisms.