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Abstract: A simple and rapid colorimetric chemosensor for the detection of several nitro-explosives is presented. The method is based on the oxidation of colorless ABTS to its intense blue–green colored radical cation ABTS+ by nitrogen dioxide, which can be generated from nitro-explosives by one of the following two methods: (i) digestion of very small amounts of explosives with alkali hydroxide, yielding nitrite anions, which in acidic medium generate nitrogen dioxide, or (ii) by thermal decomposition of nitro-explosives, which generates directly nitrogen dioxide. In these processes nitrogen dioxide acts as a catalytic intermediate, thus enhancing the detection. [Copyright &y& Elsevier]

The paper describes a rapid and simple method for preparing silver nanoparticles coated with tunable silica shell thickness and their further functionalization with vitamins. Monodispersed silver nanoparticles (Ag NPs) with a mean particle size of 10 nm were prepared by chemical reduction. Silica coating was carried out using the Stober method, by mixing the as prepared silver nanoparticles with tetramethoxysilane and 3-aminopropyltrimethoxysilane. These core–shell nanoparticles were further functionalized with B vitamins in order to facilitate their rapid functionalization to a wide range of end applications. Characterization of the newly synthesized materials was made by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS) and thermal analysis (TG). Their antibacterial activity against Gram-positive and Gram-negative bacterial strains was investigated and the results of our study showed that the linked vitamins on silver nanoparticles coated with silica lead to an increased antimicrobial activity at lower concentrations against planktonic bacterial cells and microbial biofilms. The present study can be useful for future development of different types of biological active materials. [ABSTRACT FROM AUTHOR]

4-Amino-TEMPO, a stable nitroxide free radical, was covalently grafted onto graphene oxides through an amide bond and the new composite solid materials thus obtained were characterized using scanning electron microscopy, thermal and elemental analysis, infrared, Raman and electron spin resonance spectroscopy. It was found that these materials can be successfully used as easily recoverable solid catalysts for selective oxidation of alcohols, using NO x as co-catalyst and oxygen as final oxidant, under very mild conditions. [ABSTRACT FROM AUTHOR]

Various primary and secondary alcohols were selectively oxidized to the corresponding aldehydes and ketones using silica supported TEMPO as a heterogeneous catalyst and nitrosonium tetrafluoroborate as a cocatalyst. No over-oxidation of aldehydes to acids, nitration processes or oxidation of double bonds was observed. The reported procedure is very convenient, and uses mild experimental conditions (room temperature and dioxygen as the terminal oxidant). Furthermore, the reactions proceeded cleanly and the isolation of the desired compounds required minimal work-up. A mechanistic pathway has been proposed, in which nitrogen oxides and oxoammonium ions act as an electron transfer double bridge. [ABSTRACT FROM AUTHOR]

We describe herein the synthesis of 2-alkynylbenzoxazole and 2-alkynylbenzothiazole derivatives through the Sonogashira cross-coupling reaction of the corresponding thioethers and terminal alkynes under aerobic conditions, using CuI and Pd(dppf)Cl 2 as catalysts. The synthetic methodology allows the convenient cross-coupling of heteroaromatic substrates with a wide variety of aromatic and aliphatic alkynes, in moderate to good yields. The behavior of mercapto benzoxazoles and benzothiazoles were also investigated in the desulfitative Sonogashira cross-coupling reaction. It is noteworthy that the reaction occurred better under aerobic conditions rather than an inert atmosphere, although with increased amounts of the diyne side-product. [ABSTRACT FROM AUTHOR]

A series of several new isoniazid derivatives, isonicotinic acid 2-(2-hydroxy-8-substituted-tricyclo[7.3.1.0 2.7 ]tridec-13-ylidene)-hydrazides, were synthesized and fully characterized. These new isoniazid derivatives were studied regarding their antibacterial activity and cytotoxicity, as well as their influences on some metabolizing enzymes. The best anti-mycobacterial activity was observed in the case of compounds containing alkyl side chains in the 8 position of tricyclo[7.3.1.0 2.7 ]tridec-13-ylidene group. On contrary, the antimicrobial activity of these new compounds against various non-tuberculosis strains showed the best activity to be with the phenyl side chain of compound 6 . It proved also to be the most toxic, inducing apoptosis and blocking the cell cycle in G0/G1 phase. The cell cycle was blocked in G0/G1 phase also by compound 3 , but this compound did not show any toxicity. All compounds induced the expression of NAT1 and NAT2 genes in HT-29 cell line, and the expression of CYP1A1 in HT-29 and HCT-8 cell lines. The expression level of CYP3A4 was increased by compounds 1 , 6 and 7 in HCT-8 cells. These results indicated that the activation of other metabolizing pathways, apart from those of isoniazid, take place. It might also point out the possibility of an increased isoniazid acetylation ratio by co-administration with new compounds in slow acetylators. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the study was to synthesize some new compounds with potential anti-tuberculosis activity, containing isoniazid and α,β-unsaturated thiocinnamamide-like thioamides as precursors. The obtained derivatives were evaluated regarding their biological activity (antioxidant and antibacterial), as well as their influence on the eukaryotic cell cycle. The results suggested that the newly obtained derivatives of isoniazid exhibited different biological activities, depending on their structure; thus, the most active compound in terms of anti-oxidant and anti-Mycobacterium tuberculosis effects proved to be the isonicotinic acid N′-(1-amino-1-mercapto-3-phenyl-propen-1-yl)-hydrazide. This compound also increased the expression of NAT1 and NAT2 genes, which are implicated in the metabolism of the isoniazid, demonstrating that it could be rapidly metabolized, and thus well tolerated. The largest spectrum of antibacterial activity (excluding M. tuberculosis) was noticed for the isonicotinic acid N′-[1-amino-1-mercapto-3-(p-chloro-phenyl)-propen-1-yl]-hydrazide, which was also the most cytotoxic, especially at high concentrations, although not significantly affecting the cellular cycle phases. The obtained results showed that the new derivatives could represent potential candidates for the treatment of M. tuberculosis infections, but further research is needed in order to improve their pharmacological properties, by increasing their antimicrobial activity and reducing the risk of side-effects. [Copyright &y& Elsevier]