Soo Han Kwon

Antibacterial Activity of Novel Naphthoquiones Derivatives

Abstractl,4-naphthoquinone moiety is Known to confer numerous molecules with distinct-hiological activities including anti -mycobacterial, anticancer and anti-inflammatory activities. Vitamin K2, doxorubicin and mitomycin are among the few examples of this class of chemicals used in the treatment of bleeding, lymphoma and carcinoma respectively. Although the exact action mechanism of these molecules is still under investigation, proposed mechanisms include their interact ion with DNA inhibition of topoisomerase II, and production of ROS, contributing individually or in combination with DNA damage and cell death . In the present study, 6 naphthoquinones were synthesized and assayed for their antimicrobial activity againstStaphylococcus aureus by disc diffusion assay and spectrophotometric analys is. DNA topoisomerase II activity was also measured to investigate the degreee of conformation change of a test plasmid DNA affected by the naphthoquinone deriva tives.

Sorption of aqueous uranium(VI) ion onto a cation-exchangeable K-birnessite colloid

This paper describes the sorption behaviors of aqueous uranium ions on the K-birnessite. K-birnessite was synthesized by adding a concentrated HCl to an aqueous solution of . Physicochemical characteristics of the K-birnessite, such as structure, specific surface area and surface charge, were investigated. K-birnessite is a layered material and the ions exist in the interlayer of layered K-birnessite. BET specific surface area of the K-birnessite was 38.30 m2/g. The surface charge of K-birnessite was at pH 5.00 and ionic strength of 0.010 M , at which the sorption experiments of uranium ions were carried out. Uranium ions were incorporated into the interlayer of the K-birnessite by cation-exchange reaction with ions, and the distribution coefficient is quite similar to those of common ion-exchange materials. The results might be applicable in the retardation of migration of radioactive materials from the underground disposal site of high-level radioactive waste.

Apoptotic effect of Naphthoquinone derivatives on HCT116 colon cancer cells

Naphthoquinone is found in the core structure of many natural compounds, most notably the K vitamins. Numerous molecules with the 1,4-naphthoquinone moiety are known to display distinct biological activities including anti-cancer, anti-inflammatory and anti-bacterial activities. Vitamin K2 and doxorubicin, which are used to treat bleeding and lymphoma respectively, belong to this class of chemicals. Although the exact mechanism of action of these molecules is still under investigation, it may include interactions with DNA, inhibition of topoisomerase II, and production of ROS, all of which contribute individually or in combination to DNA damage and cell death. Based on our previous study, 3 novel naphthoquinone derivatives were synthesized and their anti-proliferative activity against HCT116 colon cancer cells was assessed using FACS and Caspase assays. Using this analysis, we found that the production of ROS by naphthoquinones played a critical role in the induction of apoptosis, since pre-treatment of the cells with antioxidant NAC decreased the cytotoxicity level of these compounds.

Electrochemical Characteristics of Platinum Nanocluster Catalysts Using Oxyfluorinated Carbon Nanotubes Supports

Multi-walled carbon nanotubes (MWNTs) were oxyfluorinated at several different temperatures. The results indicated that graphitic carbon was the major carbon functional component on the MWNT surfaces and other functional groups, such as C–O, C=O, HO–C=O, C–Fx, were also present after oxyfluorination. The changes of surface properties of oxyfluorinated MWNTs were investigated using FT-IR, EDS and XRD. From the surface analysis, it was found that surface fluorine and oxygen contents increased with increasing oxyfluorination temperature and showed a maximum value at 100 °C. Consequently, it was found that optimal treatment temperature was 100 °C for the best electro activity of Pt/MWNT-100 catalyst and the oxyfluorinated Pt/MWNTs possessed the better electrochemical properties than the pristine Pt/MWNTs.

Influence of Atmospheric-Pressure Plasma Treatment on Surface of Polyimide Film

In this work, the effects of atmospheric-pressure plasma treatment of polyimide films on surface and dielectric characteristics were studied by using X-ray photoelectron spectroscopy (XPS), surface free energies, and dielectric spectrometer. The total surface free energies and dielectric constants of plasma treated polyimide film were deareased with increasing the treatment time, which was mainly due to a lower London-dispersive component, while the specific component was increased. This could be attributed to an increase of the polar fluorine groups of polyimide per unit surface area. And the fluorine content of the polyimide film was increased with increasing the amount of the treatment time, resulting in decreasing dielectric constant of the film. It was found that the replacement of fluorine led to the decrease of the local electronic polarizability of polyimide, or to the increase of the free volume, which could be attributed to the relatively large volume of fluorine.