Free Radicals as a Double-Edged Sword: The Cancer Preventive and Therapeutic Roles of Curcumin

Free radicals, generally composed of reactive oxygen species (ROS) and reactive nitrogen species (RNS), are generated in the body by various endogenous and exogenous systems. The overproduction of free radicals is known to cause several chronic diseases including cancer. However, increased production of free radicals by chemotherapeutic drugs is also associated with apoptosis in cancer cells, indicating the dual nature of free radicals. Among various natural compounds, curcumin manifests as an antioxidant in normal cells that helps in the prevention of carcinogenesis. It also acts as a prooxidant in cancer cells and is associated with inducing apoptosis. Curcumin quenches free radicals, induces antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), and upregulates antioxidative protein markers–Nrf2 and HO-1 that lead to the suppression of cellular oxidative stress. In cancer cells, curcumin aggressively increases ROS that results in DNA damage and subsequently cancer cell death. It also sensitizes drug-resistant cancer cells and increases the anticancer effects of chemotherapeutic drugs. Thus, curcumin shows beneficial effects in prevention, treatment and chemosensitization of cancer cells. In this review, we will discuss the dual role of free radicals as well as the chemopreventive and chemotherapeutic effects of curcumin and its analogues against cancer.     

Large Femtosecond Two-Photon Absorption Cross-Sections of Fullerosome Vesicle Nanostructures Derived from Highly Photoresponsive Amphiphilic C(60)-Light-Harvesting Fluorene Dyad

We demonstrated ultrafast femtosecond nonlinear optical (NLO) absorption characteristics of bilayered fullerosome vesicle nanostructures derived from molecular self-assembly of amphiphilic oligo(ethylene glycolated) C(60)-(light-harvesting diphenylaminofluorene antenna). Fullerene conjugates were designed to enhance photoresponse in a femtosecond time scale by applying an isomerizable periconjugation linker between the C(60) cage and diphenylaminofluorene antenna subunit in an intramolecular contact distance of only < 3.0 ?. Morphology of C(60)(>DPAF-EG(12)C(1))-based fullerosome nanovesicles in H(2)O was characterized to consist of a bilayered shell with a sphere diameter of 20-70 nm and a chromophore shell-width of 9.0-10 nm, fitting well with a head-to-head packing configuration of the molecular length. At the estimated effective nanovesicle concentration as low as 5.5 × 10(-8) MV (molecular molar concentration of 5.0 × 10(-4) M) in H(2)O, two-photon absorption (2PA) phenomena were found to be the dominating photophysical events showing a large molar concentration-insensitive 2PA cross-section value equivalent to 8500 GM in a form of nanovesicles, on average. The observed NLO characteristics led to a sharp trend of efficient light-transmittance intensity reduction at the input laser intensity above 100 GW/cm(2).     

Reusable Nano-Zirconia-Catalyzed Synthesis of Benzimidazoles and Their Antibacterial and Antifungal Activities

In this article, a zirconia-based nano-catalyst (Nano-ZrO₂), with intermolecular C-N bond formation for the synthesis of various benzimidazole-fused heterocycles in a concise method is reported. The robustness of this reaction is demonstrated by the synthesis of a series of benzimidazole drugs in a one-pot method. All synthesized materials were characterized using ¹HNMR, ¹³CNMR, and LC-MS spectroscopy as well as microanalysis data. Furthermore, the synthesis of nano-ZrO₂ was processed using a standard hydrothermal technique in pure form. The crystal structure of nano-ZrO₂ and phase purity were studied, and the crystallite size was calculated from XRD analysis using the Debye–Scherrer equation. Furthermore, the antimicrobial activity of the synthesized benzimidazole drugs was evaluated in terms of Gram-positive, Gram-negative, and antifungal activity, and the results were satisfactory.     

Micro-Raman investigations of mixed gas hydrates

We report laser Raman spectroscopic measurements on mixed hydrates (clathrates), with guest molecules tetrahydrofuran (THF) and methane (CH₄), at ambient pressure and at temperatures from 175 to 280 K. Gas hydrates were synthesized with different concentrations of THF ranging from 5.88 to 1.46 mol%. In all cases THF molecules occupied the large cages of sII hydrate. The present studies demonstrate formation of sII clathrates with CH₄ molecules occupying unfilled cages for concentrations of THF ranging from 5.88 to 2.95 mol%. The Raman spectral signature of hydrates with 1.46 mol% THF are distinctly different; hydrate growth was non-uniform and structural transformation occurred from sII to sI prior to clathrate melting.     

A facile one step synthesis of 1,6 ‐dihydro‐7H‐pyrazolo[4,3‐d]‐pyrimidin‐7‐ones

A general synthetic approach to pyrazolo[4,3‐d]pyrimidines is reported. Aldehydes, arylideneanilines, carboxylic acids and orthoesters are used as one‐carbon units for bridging the two amino functions of 4‐amino‐1‐alkyl‐3‐propylpyrazole‐5‐carboxamides.     

CFD application for coal/air balancing in power plants

Unbalanced coal/air flow in the pipe systems of coal-fired power plants will lead to non-uniform combustion in the furnace, and hence a overall lower efficiency of the boiler. A common solution to this problem is to put orifices in the pipe systems to balance the flow. It is well known that if the orifices are sized to balance clean air flow to individual burners connected to a pulverizer, the coal/air flow would still be unbalanced and vice versa. However, the current power industry practice throughout the world is to size orifices for balancing the clean air flow and accept the resulting imbalance in coal/air flow. Field tests are mostly conducted to verify a balanced clean air flow.     

Synthesis and antiproliferative activity of new 1,2,3-triazole/flavone hybrid heterocycles against human cancer cell lines

Russian Journal of General Chemistry - A series of new 1,2,3-triazole/flavone hybrid heterocycles were synthesized from 6-amino flavone via key intermediate N-propargyl flavone 6 by adopting the...     

Catalysis of Multi‐walled Carbon Nanotubes Supported PdxCoy Nanoparticles Prepared by a Pyrolysis Method Using Ionic Liquids as the Solvent toward Ethanol Oxidation Reaction

Multi‐walled carbon nanotubes (MWCNTs) decorated with Pd_xCo_y (the nominal atomic ratios of Pd to Co were 3:1, 3:1.5, 3:2, 3:3, respectively) nanoparticles (denoted as Pd_xCo_y/MWCNTs ) were fabricated by a simple pyrolysis process, in which room temperature ionic liquids (RTILs) of butyl‐3‐methylimidazolium hexafluorophosphate (denoted as [BMIM]PF₆) was used as the solvent. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) were all used to characterize the Pd_xCo_y/MWCNTs catalysts, showing that the Pd_xCo_y particles were dispersed on the surface of the MWCNTs with an average particle size of ～25.0 nm. The electro‐catalytic activity of the Pd_xCo_y/MWCNTs catalysts toward ethanol oxidation reaction (EOR) was examined by cyclic voltammetry (CV). It was revealed that the onset potential was ～90 mV lower and the peak current was about four times higher for ethanol oxidation for Pd₃Co_1.5/MWCNTs compared to those of Pd₃Co₁/MWCNTs. The possible catalysis mechanisms of the Pd₃Co_1.5/MWCNTs toward EOR were also discussed.