Structure-activity relationship of pyrazolo pyrimidine derivatives as inhibitors of mitotic kinesin Eg5 and anticancer agents.

Human kinesin Eg5 is a potential inhibiting site for cancer chemotherapy. Blocking metaphase by binding foreign inhibitors with Eg5 eventually leads to apoptotic cell death. Here, we report the pyrazolopyrimidine derivates as potent inhibitors of Eg5 that prevents mitotic kinesin progression. IC50 values were evaluated against the motor domain of Eg5 using steady-state ATPase assay. To better understanding, we have performed molecular docking simulation. It reveals that the interactions of the proposed inhibitors with both the allosteric sites (helices α2, α3 and loopL5, and helices α4 & α6). Out of fifteen pyrazolopyrimidine derivates, three compounds (12, 25, and 27) have shown significant inhibition of Eg5. The synthesized compounds (12, 25, and 27) were tested for their in-vitro anticancer activity against cervical cancer cell line (HeLa).

Synthesis of N-(1-(6-acetamido-5-phenylpyrimidin-4-yl) piperidin-3-yl) amide derivatives as potential inhibitors for mitotic kinesin spindle protein.

Kinesin Spindle Protein (KSP) or Eg5 is an essential kinesin that is involved in spindle separation process during mitosis and also unregulated in certain cancer cells. Inhibitors of this enzyme have proved to be effective to block spindle separation followed by mitotic arrest and apoptosis of the cancer cells. Since this enzyme has two allosteric inhibitor binding sites, it's an excellent target for developing drugs for cancer chemotherapy. Many pyrimidine derivatives have been proved to be active against cancer and other enzymes. In this report, we have synthesized a set ten novel N-(1-(6-acetamido-5-phenylpyrimidin-4-yl)piperidin-3-yl)amide derivatives and have evaluated their activity against the KSP. The SAR of these active compounds was further analyzed using in silico molecular docking studies using GOLD and AutoDock softwares. All these compounds form hydrophobic interaction, aromatic π-π stacking and hydrogen bond efficiently with the Eg5.

Improved conductivity and antibacterial activity of poly(2-aminothiophenol)-silver nanocomposite against human pathogens.

A rapid and simple chemical synthesis of poly(2-aminothiophenol)­silver (P2ATP-Ag) nanocomposite using conductive and electroactive silver nanoparticles (AgNPs) is reported. The AgNPs was synthesized by chemical reduction method using tri­sodium citrate as reducing agent and poly(N-vinyl-2-pyrrolidone) (PVP) as stabilizing agent. P2ATP-Ag nanocomposite was synthesized by using potassium peroxodisulphate as oxidant and the samples were characterized. The presence of AgNPs in the composite was confirmed from UV-Vis, FTIR and X-ray diffraction studies. Morphology of the P2ATP and its composite were investigated by SEM. HR-TEM images show spherical, trigonal and rod like morphologies with sizes of Ag nanoparticles and its composite. Thermal analysis revealed that the thermal stability of the P2ATP-Ag nanocomposite is improved when compared with pure P2ATP. The synthesized AgNPs, pure P2ATP and P2ATP-Ag nanocomposite were screened for antibacterial activity test against human pathogen such as Gram positive (Bacillus subtilis, ATCC-6051) and Gram negative (Vibrio cholerae, ATCC-14035), carried out by agar-well diffusion method at micro molar concentration. The result shows that P2ATP-Ag nanocomposite has excellent antibacterial activity due to the presence of Ag nanoparticles. The electrical conductivity of the P2ATP-Ag nanocomposite is better than that of pure P2ATP. The reported nanocomposite will be a potential material for electrocatalysis, sensors and biomedical applications.

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C.

Nanomaterials for Electrochemical Sensing and Decontamination of Pesticides.

We are all aware of growing environmental concerns, and the need to provide new and improved means for maintaining a healthy environment. Pesticides are the only toxic chemicals released intentionally into the environment to kill living organisms. Pesticide detection and destruction has become a very important and inevitable area of research because of the rapid expansion of agriculture and stringent environmental protection acts. Electrochemistry offers promising approaches for the determination and destruction of pollutants. The interaction of nanotechnology opens the possibility for a wide variety of chemical and biological research topics and day-to-day applications at the molecular and cellular level. Nanotechnology has allowed introducing novel strategies in sensors and biosensor research. Recently researchers have become increasingly interested in nanomaterial assisted electrochemical techniques. This review emphasizes the recent developments of electrochemical methods combined with nanotechnology for sensing and decontamination of pesticides.

Ethyl 3-(4-chloro-phen-yl)-2-phenyl-3-(4-phenyl-1,2,3-selena-diazol-5-yl)propano-ate.

In the title compound, C25H21ClN2O2Se, the selena-diazole ring is almost planar [maximum deviation = 0.004 (2) Å], and the adjacent benzene ring is twisted by 50.6 (1)° with respect to this ring.

A kinetic study on the formation of poly(4 aminodiphenylamine)/copper nanocomposite using UV-visible spectroscopy.

The course of the reaction between copper sulfate (CuSO4) and 4-aminodiphenylamine (4ADPA) was monitored by UV-visible spectroscopy in p-toluene sulfonic acid (p-TSA). Formation of poly(4-aminodiphenylamine)/copper nanoparticle composite (P4ADPA/CuNC) was witnessed through the steady increase in absorbance at 410, 580 and >700 nm. The absorbance at 410 nm as well as >700 nm are correlated to the amount of P4ADPA/CuNC formation and was subsequently used to determine the rate of formation of P4ADPA/CuNC (RP4ADPA/CuNC) at any time during the course of the reaction. RP4ADPA/CuNC shows a first-order dependence on [4ADPA] and a half-order dependence on [CuSO4]. A kinetic rate expression was established between RP4ADPA/CuNC and experimental parameters such as [4ADPA] and [CuSO4]. The rate constant for the formation of P4ADPA/CuNC was 8.98 × 10(-3) mol(-0.5) l(0.5) s(-1). Field emission scanning electron and transmission electron micrographs revealed that the morphology of the P4ADPA/CuNC was influenced by the reaction conditions.

5-[1-(4-Methyl-phen-yl)-2-nitro-but-yl]-4-phenyl-1,2,3-selenadiazole.

In the title compound, C19H19N3O2Se, the selenadiazole ring is roughly planar [maximum deviation 0.033 (6) Å]. The attached phenyl ring is twisted away at an angle of 47.5 (1)°. The butyl group is in an extended conformation [C-C-C-C torsion angle = 174.7 (2)°]. In the crystal, C-H⋯O inter-actions form C(10) chains running aling the c-axis direction.

Ethyl 3-(4-meth-oxy-phen-yl)-2-phenyl-3-(4-phenyl-1,2,3-selenadiazol-5-yl)propano-ate.

In the title compound, C(26)H(24)N(2)O(3)Se, the selenadiazole ring is planar [maximum deviation = 0.002 (2) Å]. The dihedral angle between the selenadiazole ring and the attached phenyl ring is 49.00 (13)°. The crystal structure is stabilized by inter-molecular C-H⋯N and C-H⋯π inter-actions.

5-[1-(4-Meth-oxy-phen-yl)-2-nitro-but-yl]-4-phenyl-1,2,3-selenadiazole.

In the title compound, C(19)H(19)N(3)O(3)Se, the selenadiazole ring is essentially planar (r.m.s. deviation = 0.001 Å). The heterocyclic ring makes dihedral angles of 50.2 (2) and 76.3 (9)°, respectively, with the meth-oxy-phenyl and phenyl rings.

5-(2-Nitro-1-phenyl-but-yl)-4-phenyl-1,2,3-selenadiazole.

In the title compound, C(18)H(17)N(3)O(2)Se, the selenadiazole ring is planar [maximum deviation = 0.012 (2) Šfor the ring C atom bearing the phenyl substituent]. The dihedral angle between the selenadiazole ring and the attached benzene ring is 46.5 (1)°. There is one short intra-molecular C-H⋯Se contact.

1-(2-Naphth-yl)-3-phenyl-3-(4,5,6,7-tetra-hydro-1,2,3-benzoselenadiazol-4-yl)propan-1-one.

In the title compound, C(25)H(22)N(2)OSe, the fused six-membered cyclo-hexene ring of the 4,5,6,7-tetra-hydro-1,2,3-benzoselenadiazole group adopts a near half-chair conformation and the five-membered 1,2,3-selenadiazole ring is essentially planar (r.m.s. deviation = 0.004 Å). There are weak inter-molecular C-H⋯O and C-H⋯π inter-actions in the crystal structure. Inter-molecular π-π stacking is also observed between the naphthyl units, with a centroid-centroid distance of 3.529 (15) Å.

3-(4-Methyl-phen-yl)-1-phenyl-3-(4,5,6,7-tetra-hydro-1,2,3-benzoselenadiazol-4-yl)propan-1-one.

In the title compound, C(22)H(22)N(2)OSe, the fused six-membered ring of the 4,5,6,7-tetra-hydro-benzo[d][1,2,3] selenadiazole group adopts a near to envelope (E form) conformation and the five-membered 1,2,3-selenadiazole ring is essentially planar (r.m.s. deviation = 0.0059 Å). In the crystal, adjacent mol-ecules are inter-linked through weak inter-molecular C-H⋯π inter-actions.

4-{(4-Chloro-phen-yl)[4-(4-methyl-phen-yl)-1,2,3-selenadiazol-5-yl]meth-yl}-4,5,6,7-tetra-hydro-1,2,3-benzoselenadiazole.

In the title compound, C(22)H(19)ClN(4)Se(2), the mean plane of the non-fused selenadiazole ring forms dihedral angles of 54.20 (16)° and 70.48 (11)°, respectively, with the essentially planar [maximum deviations of 0.025 (5) and 0.009 (2) Å, respectively] methyl-phenyl and chloro-phenyl substituents. The tetra-hydro-1,2,3-benzoselenadiazole group is disordered over two sets of sites with a refined occupancy ratio of 0.802 (5):0.198 (5). In the crystal, weak inter-molecular C-H⋯N inter-actions are observed.

Course of poly(4-aminodiphenylamine)/Ag nanocomposite formation through UV-vis spectroscopy.

Kinetics of chemical oxidative polymerization of 4-aminodiphenylamine (4ADPA) was followed in aqueous 1 M p-toluene sulfonic acid (p-TSA) using silver nitrate (AgNO3) as an oxidant by UV-vis spectroscopy. The medium was found to be clear and homogeneous during the course of polymerization. The absorbances corresponding to the intermediate and the polymer were followed for different concentrations of 4ADPA and AgNO3 and at different reaction time. The appearance of a band around 450 nm during the initial stages of polymerization corresponds to the plasmon resonance formed by the reduction of Ag+ ions. Rate of poly(4-aminodiphenylamine)/Ag nanocomposite (RP4ADPA/AgNC) was determined for various reaction conditions. R(P4ADP/AgNC) showed second order power dependence on 4ADPA and first order dependence on AgNO3. The observed order dependences of 4ADPA and AgNO3 on the formation of P4ADPA/AgNC were used to deduce a rate equation for the reaction. Rate constant for the reaction was determined through different approaches. The good agreement between the rate constants obtained through different approaches justifies the selection of rate equation.

Spectral Analysis and Crystal Structures of 4-(4-Methylphenyl)-6-Phenyl-2,3,3a, 4-Tetrahydro-1H-Pyrido[3,2,1-jk]Carbazole and 4-(4-Methoxyphenyl)-6-Phenyl-2,3,3a, 4-Tetrahydro-1H-Pyrido[3,2,1-jk]Carbazole.

The crystal structures of 4-(4-methylphenyl)-6-phenyl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazole (IIa) and 4-(4-methoxyphenyl)-6-phenyl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazole (IIb) were elucidated by single crystal X-ray diffraction. Compound (IIa), C28H25N, crystallizes in the triclinic system, space group P-1, with a = 8.936(2) Å, b = 10.490(1) Å, c = 11.801(1) Å, α = 102.69(5) (°) ,  ß = 103.27(3) (°) , γ = 93.80(1) (°) , and Z = 2. The compound (IIb), C28H25NO, crystallizes in the monoclinic system, space group P21/a, with a = 11.376(5) Å, b = 14.139(3) Å, c = 13.237(4) Å, ß = 97.41(3) (°) , and Z = 4. In both the structures, the pyrido ring adopts a twist boat conformation and the carbazole molecule has the twisted envelope structure with C3 and C13 at the flap. No classical hydrogen bonds are observed in the crystal structures. Details of the preparation, structures, and spectroscopic properties of the new compounds are discussed.

Spectral, magnetic, biocidal screening, DNA binding and photocleavage studies of mononuclear Cu(II) and Zn(II) metal complexes of tricoordinate heterocyclic Schiff base ligands of pyrazolone and semicarbazide/thiosemicarbazide based derivatives.

We depict the synthesis and characterization of copper(II) and zinc(II) coordination compounds of 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-semicarbazone (1a), 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1b), 4-(3'-hydroxy-4'-nitrobenzaldehydene)2-3-dimeth yl-1-phenyl-3-pyrazolin-5-semicarbazone (1c) and 4-(3'-hydroxy-4'-nitrobenzal dehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1d). All the remote compounds have the general composition [ML(2)] (M=Cu(II) and Zn(II)); L=Schiff base (1a-1d). All the complexes were characterized by elemental analysis, molar conductivity, IR, (1)H NMR, UV-vis, ESI-Mass, magnetic susceptibility measurements, cyclic voltammetric measurements, and EPR spectral studies. It has been originated that the Schiff bases with Cu(II) and Zn(II) ions form mononuclear complexes on 1:2 (metal:ligand) stoichiometry. Distorted octahedral environment is suggested for the metal complexes. The conductivity data confirm the non-electrolytic nature of the complexes. The interaction of CuL(2)(1a-1d) complexes with CT DNA was investigated by spectroscopic, electrochemical and viscosity measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode. Moreover, the complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The Schiff bases and their metal complexes were screened for their antifungal and antibacterial activities against different species of pathogenic fungi and bacteria and their biopotency has been discussed.

Electroanalysis of some common pesticides using conducting polymer/multiwalled carbon nanotubes modified glassy carbon electrode.

The cyclic voltammetric behaviour of three common pesticides such as isoproturon (ISO), voltage (VOL) and dicofol (DCF) was investigated at glassy carbon electrode (GCE), multiwalled carbon nanotubes modified GCE (MWCNTs/GCE), polyaniline (PANI) and polypyrrole (PPY) deposited MWCNT/GCE. The modified electrode film was characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The electroactive behaviour of the pesticides was realized from the cyclic voltammetric studies. The differential pulse voltammetric principle was used to analyze the above-mentioned pesticides using MWCNT/GCE, PANI/MWCNT/GCE and PPY/MWCNT/GCE. Effects of accumulation potential, accumulation time, Initial scan potential, amplitude and pulse width were examined for the optimization of stripping conditions. The PANI/MWCNT/GCE performed well among the three electrode systems and the determination range obtained was 0.01-100 mgL(-1) for ISO, VOL and DCF respectively. The limit of detection (LOD) was 0.1 microgL(-1) for ISO, 0.01 microgL(-1) for VOL and 0.05 microgL(-1) for DCF on PANI/MWCNT/GCE modified system. It is significant to note that the PANI/MWCNT/GCE modified system results in the lowest LOD in comparison with the earlier reports. Suitability of this method for the trace determination of pesticide in spiked samples was also realized.

Determination of pesticides using heteropolyacid montmorillonite clay-modified electrode with surfactant.

Redox behavior of three pesticides, namely isoproturon, carbendazim and methyl parathion was investigated electrochemically using heteropolyacid montmorillonite clay-modified glassy carbon electrode in the presence and absence of a surfactant, cetyl trimethyl ammonium bromide. A solution of 0.1M H(2)SO(4) in 50% aqueous alcohol (pH 1.0) was found to be suitable medium for electroanalysis. Isoproturon exhibited one well-defined oxidation peak around 1.2 V along with one more oxidation and reduction peaks. Carbendazim showed only one well-defined anodic peak around 1.4 V. Methyl parathion exhibited one well-defined reduction peak around -0.26 V and the oxidation peak appeared around 0.510 V. In the second cycle, a new cathodic peak was found around 0.420 V. The presence of surfactant enhanced the peak current and hence stripping voltammetric determination procedures for all the three pesticides were developed. Square wave stripping mode was employed and the maximum current experimental conditions were arrived at. Calibration plot was made for all the three pesticides. The determination limit and standard deviations were arrived at. The applicability of the method was also verified in a soil sample and water analyte.

Effect of halides in the electrochemical treatment of distillery effluent.

Electrochemical treatment can solve the problems arising due to effluents and offer an effective alternative to the existing methods. An undivided static electrolyser was charged with distillery effluent and the organics were oxidized electrochemically. Anodized graphite plate anodes and graphite cathodes were used for the treatment of distillery effluent. The effect of pH and current density on the treatment was studied. Sodium fluoride, sodium chloride and sodium bromide were chosen as electrolyte and their influence was found out. Complete decolorization has been observed in all cases. A maximum of 93.5% of biological oxygen demand reduction, 85.2% of chemical oxygen demand reduction and 98.0% absorbance reduction were obtained in the presence of sodium chloride as supporting electrolyte. Probable mechanism was also proposed for the oxidation of organics present in the effluent.