Antibacterial activities of polyethylene glycol, tween 80 and sodium dodecyl sulphate coated silver nanoparticles in normal and multi-drug resistant bacteria.

Antibacterial activity of silver nanoparticles coated with different functionalizing agents i.e., polyethylene glycol, tween 80 and sodium dodecyl sulphate were evaluated on both normal and multi-drug resistant strains of bacteria. Under the same reaction conditions, these functionalizing agents were added separately to coat silver nanoparticles. Among these, polyethylene glycol coated nanoparticles were most effective in killing all the bacterial strains which includes Escherichia coli DH5a, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus and multi-drug resistant clinical isolates of Shigella spp. (flexneri, boydii, sohnea) and Vibrio cholerae. The minimum inhibitory concentration of polyethylene glycol coated silver nanoparticles was also less compared to the other two sets of nanoparticles. Consistence with that polyethylene glycol coated nanoparticles produced more intracellular reactive oxygen species in bacteria. Moreover, when human cell lines MCF7 and Chang Liver were incubated in presence of these nanoparticles for 18 h with same concentrations as used for bacteria, no toxicity was observed. But significant increase in cell killing was observed with longer incubation time. Thus our present investigation implicates the potential therapeutic use of silver nanoparticles as antibacterial agent particularly the polyethylene glycol coated one.

Alprazolam induced conformational change in hemoglobin.

Alprazolam (ALP) is a widely prescribed sedative and antidepressant benzodiazepine group of drugs. The wide uses of this drug lead us to investigate its possible interaction with hemoglobin (Hb). Spectrophotometric and spectofluorimetric studies showed strong binding of ALP with Hb. Circular dichroic spectra showed that alpha-helical structure of Hb-subunits has been largely changed. On ALP treatment partial pressure of O(2) is increased in the blood indicating release of O(2) from erythrocytes. Further, the binding of ALP-induced conformational changes in Hb resulting in larger Hb particle size was demonstrated by dynamic light scattering experiment. Thus, the present study unambiguously raises question of danger of random usage of ALP, which binds with and changes the function of Hb.

Differential toxicity of rod and spherical zinc oxide nanoparticles on human peripheral blood mononuclear cells.

The cytotoxic and genotoxic potential of rod and spherical zinc oxide nanoparticles (ZnO NPs) were evaluated on human peripheral blood mononuclear cells (PBMCs). Their sizes and shapes were determined by Transmission electron microscopy (TEM) and physical characterizations were done by X-ray diffraction (XRD) and Dynamic light scattering (DLS). The cytotoxic potential of rod ZnO NPs was greater than spherical ZnO NPs when applied to PBMCs and was limited to the proliferative lymphocytes. Rod ZnO NPs produced more reactive oxygen species (ROS) compared to spherical ones. Additionally rod ZnO NPs induced significant DNA damage to PBMCs as revealed by cytokinesis block micronucleus (CBMN) assay and comet assay. On the other hand UV absorption property was enhanced in case of spherical ZnO NPs compared to rod ZnO NPs. Thus, present study implicates the shape dependent differential application of ZnO NPs in our daily life.

DNA binding ability and hydrogen peroxide induced nuclease activity of a novel Cu(II) complex with malonate as the primary ligand and protonated 2-amino-4-picoline as the counterion.

The DNA binding property of a Cu(II) complex, viz., [Cu(mal)(2)](picH)(2).2H(2)O, (mal)(2) = malonic acid, picH = protonated 2-amino-4-picoline, has been investigated in this study. The binding of this complex with plasmid and chromosomal DNA has been characterized by different biophysical techniques. From the absorption and fluorescence spectroscopic studies, it has been observed that the said copper complex binds strongly with pUC19 plasmid and CT DNA with a binding affinity of 2.368 x 10(3) and 4.0 x 10(3) M(-1), respectively, in 10 mM citrate-phosphate buffer, pH 7.4. Spectrofluorimetric studies reveal that the copper complex exhibits partial DNA intercalation as well as partial DNA minor groove binding properties. Consequently, in agarose gel electrophoresis study, it has been observed that the complex alone induces positive supercoiling in plasmid DNA while in the presence of H(2)O(2) it exhibits nuclease activity. The induction of the breakage in DNA backbone depends upon the relative concentrations of H(2)O(2) and copper complex followed by the time of incubation with DNA. Optical DNA melting study, isothermal titration calorimetry, and absorption spectroscopy have been used to characterize the nuclease activity of this complex in the presence of H(2)O(2). Further, (1)H NMR study indicates that Cu(II) in the complex is converted into the Cu(I) state by the reduction of H(2)O(2). Finally, agarose gel electrophoresis study with different radical scavengers concludes that the production of both hydroxyl radicals and reactive oxygen species is responsible for this nuclease activity.

Alprazolam intercalates into DNA.

In vitro interaction of a benzodiazepine group of drugs Alprazolam (Alp), a hypnotic and tranquilizer, with DNA was studied by various methods. Absorption spectrophotometric study showed that Alp binds strongly with supercoiled pUC 19 DNA and the calculated binding constant is 8.245x10(3) M(-1) in 10 mM Tris-Cl buffer, pH 7.4. Spectrofluorometric study showed that ethidium bromide induced DNA fluorescence intensity was reduced completely after addition of Alp. But Alp did not interfere with the interaction of Hoechst 33258, a DNA minor groove binder, with plasmid DNA. Circular dichroic spectroscopic study showed that with the gradual increase in Alp concentrations, both the positive and the negative peaks of DNA were gradually decreased and at higher concentrations of Alp (60 microM and 80 microM), the negative peaks became positive indicating the intercalation and the conformational change in the DNA. Binding of Alp with DNA increased the thermal stability of DNA by 6 degrees C with respect to the mock treated sample. Gel electrophoresis study of supercoiled pUC 19 DNA showed more compact structure as a result of Alp binding. Transmission electron microscopic observations also confirmed this compactness. Thus, our observations suggest the strong interaction of Alp with DNA, which may raise serious questions about the random uses of Alprazolam.

Caffeine augments Alprazolam induced cytotoxicity in human cell lines.

Combined effects of alprazolam (Alp), a member of benzodiazepine group of drugs and caffeine on human cell lines, HeLa and THP1 were investigated in this study. Alp mediated cytotoxicity was enhanced while caffeine was present. The cell death was confirmed by observing morphological changes, LDH assay and membrane anisotropic study. Also such combined effects induced elevated level of ROS and depletion of GSH. The mechanism of cell death induced by simultaneous treatment of Alp and caffeine was associated with the calcium-mediated activation of mu-calpain, release of lysosomal protease cathepsin B, activation of PARP and cleavage of caspase 3. Our results indicate that, Alp alone induces apoptosis in human cells but in the presence of caffeine it augments necrosis in a well-regulated pathway. Thus our observations strongly suggest that, alprazolam and caffeine together produce severe cytotoxicity in human cell lines.