Synthesis,and biological screening of chloropyrazine conjugated benzothiazepine derivatives as potential antimicrobial,antitubercular and cytotoxic agents

A series of twenty new chloropyrazine conjugated benzothiazepines (22–41) have been synthesized with 58%–95% yields. The compounds were characterized by using different spectroscopic techniques including FT-IR, ¹H NMR, ¹³C NMR spectroscopy and mass spectrometry. The synthesized compounds (22–41) and their precursor chalcones (2–21) were evaluated for antitubercular and cytotoxic activities. Additionally, compounds 22–41 were also tested for antimicrobial activity. Among the chalcone series (2–21), compounds 7 and 14 showed significant antitubercular activities (MICs 25.51 and 23.89 µM, respectively), whereas among benzothiazepines (22–41), compounds 27 and 34 displayed significant antimicrobial (MICs 38.02 µM, 19.01 µM) and antitubercular (MIC 18.10 µM) activities. Compounds 7 and 41 displayed cytotoxic activities with IC₅₀ of 46.03 ± 1 and 35.10 ± 2 µM respectively. All the compounds were evaluated for cytotoxic activity on normal human liver cell lines (L02) and found to be relatively less selective towards this cell line. The most active compounds identified through this study could be considered as potential leads for the development of drugs with possible antimicrobial, antitubercular, and cytotoxic activities.     

Label‐Free and Ultra‐Low Level Detection of Salmonella enterica Serovar Typhimurium Using Electrochemical Impedance Spectroscopy

An immunosensor for rapid and low level detection of the bacterial pathogen Salmonella enterica Serovar Typhimurium was designed and developed based upon label‐free electrochemical impedance spectroscopy and correlated to viable cell counts. The immunosensor was fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode by immobilizing monoclonal antibody (MAb) specific against Salmonella typhimurium cell surface lipopolysaccharide (LPS) onto the surface of the electrode. Use of mass‐fabricated and electroplated PCB electrodes allowed for disposable, highly sensitive, and rapid detection of Salmonella in an aqueous environment. Results demonstrate that in purified solution, Salmonella can be detected as low as 10 CFU in a 100 μL volume and label‐free and rapid manner in fewer than 90 s. The cost effective approach described here can be used for detection of pathogens with relevance for healthcare, food, and environmental applications.     

2-(Alkylamino)-3-aryl-6,7-dihydrobenzofuran-4(5H)-ones: Improved Synthesis and their Photophysical Properties

Furans are an important class of compounds and exhibit a diverse range of activities and properties. As such, improved synthetic access to furans is an important research goal. In the present report, a solvent- and catalyst-free reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone), an aryl aldehyde and an isocyanide under microwave irradiation is presented. This method is significantly improved from previously described protocols in terms of applicability of wide ranging aryl aldehydes, better yields, shorter reaction times, facile work up and essentially no need of column chromatography. The photophysical properties of this series of compounds were studied for their possible applicability in the field of metal ion sensors. In solution, two compounds, 2-(cyclohexylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 i) and 2-(tert-butylamino)-3-(1H-indol-3-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-4(5H)-one (1 j), underwent an observable color change from yellow to colorless in the presence of aluminum(III) ions. Further studies to investigate the UV absorption and luminescence behavior of these compounds revealed their utility as “naked-eye sensors” for aluminum detection.     

The Microwave-assisted syntheses and a conductivity study of a platinum phthalocyanine and its derivatives

The parent platinum phthalocyanine (PtPc) and its derivatives with tetranitro (PtTNPc) and tetramine (PtTAPc) on the peripheral benzene were synthesized in the pure state for the first time by microwave irradiation. These complexes were characterized using physico-chemical methods like elemental, electronic absorption, IR spectral, magnetic susceptibility, thermogravimetry and X-ray powder diffraction studies. Kinetic and thermodynamic parameters associated with the thermal decomposition were calculated using the thermogravimetric analytical data. Electrical conductivity studies were carried out using the two-probe technique in the temperature range 298–473 K for each complex to study the effect of the donor and acceptor substituents on the platinum phthalocyanine macrocycle. The electrical conductivities observed at room temperature are in the order PtTAPc > PtTNPc > PtPc. The improvement in the intrinsic electrical conductivity of PtTAPc is due to the electron donating amine substituents which are expected to facilitate greater intermolecular contact and increase interactions, providing a greater pathway for charge carriers.     

Self assembled films of porphyrins with amine groups at different positions: influence of their orientation on the corrosion inhibition and the electrocatalytic activity

Self-assembled molecular films of two cobalt porphyrins with amine groups at different positions-(5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II), [Co(II) (T(o-NH(2))PP)] and (5,10,15,20-tetrakis-(4-aminophenyl) porphyrin-cobalt(II), [Co(II)(T(p-NH(2))PP)]-were formed on a gold substrate. The functionalized surfaces were characterized using Raman spectroscopy, atomic force microscopy and electrochemical methods. Both modified gold surfaces completely mask the charge transfer of a [Fe(CN)(6)](3-/4-) redox couple in solution, indicating the layer is highly resistive in behavior. Electrochemical impedance spectroscopy analyses revealed that the porphyrin film with amine groups at ortho positions shows a higher charge-transfer resistance with a better protective behavior compared to the para position modified surface. Raman, AFM and EIS data suggests that an ortho amine positioned molecule forms a more compact layer compared to the para-positioned molecule. This can be explained in terms of their orientation on the gold surface. [Co(II)(T(o-NH(2))PP)] adopted a saddle shape orientation whereas [Co(II)(T(p-NH(2))PP)] adopted a flat orientation on the gold surface. The porphyrin modified gold electrode catalyzes the oxygen reduction at lower potentials compared to the bare gold electrode. The shift in the overvoltage was higher in case of molecules with flat orientation compared to the saddle shaped oriented porphyrin molecules on the surface.     

Spectral,physicochemical and biological characterization of 2,5,11,14,19,20-hexaaza-3,12-dimethyl-4,13-dipropyl-tricyclo [13.3.1.1(6-10)]cosane-1(19),2,4,6(20),7,9,11,13,15,17-decaene and its transition metal complexes

The synthesis of a tetradentate nitrogen donor macrocyclic ligand i.e. 2,5,11,14,19,20-hexaaza-3,12-dimethyl-4,13-dipropyl-tricyclo[13.3.1.1(6-10)]cosane-1(19),2,4,6(20),7,9,11,13,15,17-decaene and its complexes with manganese(II), cobalt(II), nickel(II) and copper(II) have been reported. The complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, ¹H-n.m.r. (Ligand), i.r., electronic, and e.p.r. spectral studies. On the basis of molar conductance the complexes may be formulated as [M(L)X₂] [where M = Mn(II), Co(II), Ni(II) and Cu(II), and X = Cl⁻ & NO ₃⁻ ] due to their nonelectrolytic nature in dimethylformamide (DMF). All the complexes are of the high spin type and are six coordinated. On the basis of i.r., electronic and e.p.r. spectral studies an octahedral geometry has been deduced for Mn(II), Co(II) and Ni(II) complexes, and tetragonal geometry for Cu(II) complexes. The antimicrobial activities of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against several species of bacteria and plant pathogenic fungi.     

Sensitive and rapid electrochemical bioassay of glycosidase activity

Here we present a highly sensitive, rapid and simple electrochemical assay for glycosidases based on treatment of the glycosidase with the appropriate p-nitrophenyl glycoside and anodic detection of released p-nitrophenol. The attractive characteristics of the new bioassay should facilitate advanced glycomic research and routine clinical diagnostics since glycosidases are associated with various diseases.     

Electronic, EPR, magnetic and mass spectral studies of mono and homo-binuclear Co(II) and Cu(II) complexes with a novel macrocyclic ligand

A series of 20-memebered macro-cyclic metal(II) complexes have been synthesized by a macro-cyclic ligand, i.e. 1,5,11,15-tetraaza-6,10,16,20-tetraoxo-8,18-dithia-cyclocosane, it was prepared by the condensation reaction of 1,3-diaminopropane with thiodiglycolic acid. The bonding and stereochemistry of the complexes have been characterized by elemental analysis, magnetic moment, molar conductance, mass, 1H NMR, IR, electronic and EPR spectral studies. The mononuclear complexes of the type [ML]X2 have been found to have distorted octahedral geometry and the binuclear complexes [M2LX2]X2 were found to possess square planar configuration around the central metal ion.