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Chalcones are polyphenols that belong to the flavonoids family, known for their broad pharmacological properties. They have thus attracted the attention of chemists for their obtention and potential activities. In our study, a library of compounds from 2′-hydroxychalcone's family was first synthesized. A one-step mechanochemical synthesis via Claisen–Schmidt condensation reaction under ball mill conditions was studied, first in a model reaction between a 5′-fluoro-2′-hydroxyacetophenone and 3,4-dimethoxybenzaldehyde. The reaction was optimized in terms of catalysts, ratio of reagents, reaction time, and influence of additives. Among all assays, we retained the best one, which gave the highest yield of 96% when operating in the presence of 1 + 1 eq. of substituted benzaldehyde and 2 eq. of KOH under two grinding cycles of 30 min. Thus, this protocol was adopted for the synthesis of the selected library of 2′-hydroxychalcones derivatives. The biological activities of 17 compounds were then assessed against Plasmodium falciparum, Leishmania donovani parasite development, as well as IGR-39 melanoma cell lines by inhibiting their viability and proliferation. Compounds 6 and 11 are the most potent against L. donovani, exhibiting IC50 values of 2.33 µM and 2.82 µM, respectively, better than the reference drug Miltefosine (3.66 µM). Compound 15 presented the most interesting antimalarial activity against the 3D7 strain, with IC50 = 3.21 µM. Finally, chalcone 12 gave the best result against IGR-39 melanoma cell lines, with an IC50 value of 12 µM better than the reference drug Dacarbazine (IC50 = 25 µM). [ABSTRACT FROM AUTHOR]

A series of isoniazid derivatives bearing a phenolic or heteroaromatic coupled frame were obtained by mechanochemical means. Their pH stability and their structural (conformer/isomer) analysis were checked. The activity of prepared derivatives against Mycobacterium tuberculosis cell growth was evaluated. Some compounds such as phenolic hydrazine 1a and almost all heteroaromatic ones, especially 2, 5 and 7, are more active than isoniazid, and their activity against some M. tuberculosis MDR clinical isolates was determined. Compounds 1a and 7 present a selectivity index >1400 evaluated on MRC5 human fibroblast cells. The mechanism of action of selected hydrazones was demonstrated to block mycolic acid synthesis due to InhA inhibition inside the mycobacterial cell. [ABSTRACT FROM AUTHOR]

The article presents information on a study which examined the surface properties of talc particles modified by dry coating with hydrophobic silica properties. Variables studied included the concentration of silica properties and the dry coating processing time. It describes the talc powders and their characterization. The quantification of dispersion kinetics is detailed. A discussion on the findings of the study including surface morphology and wettability measurements is detailed.

Natural diatomite from Sig/Algeria was treated with 0.5, 1.0, 3.0 and 5.0 M nitric acid solutions for 2 h under reflux at 333 K in order to improve its performance as support of catalyst. The purified silica powders obtained from frustules can also be used to reinforce composites. The solids obtained were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, thermal analyses, and nitrogen adsorption–desorption at 77 K. Treatment of diatomite earth with nitric acid reduced mineral impurities, such as Fe 2 O 3 and alkali metal oxides (CaO, MgO), eliminated carbonates and increased SiO 2 ratio from 88% to 98%. The SEM micrographs showed the original geometry of the pores to be preserved. The surface properties were also evaluated using inverse gas chromatography at infinite dilution (IGC-ID) and finite concentration (IGC-FC). The interest here was to establish whether the technique is sufficiently sensitive to detect variations in the surface properties of the diatomite due to this chemical treatment. The IGC analysis permitted to reach several surface energy components with organic probes. Between them, the distribution function of the adsorption energy sites obtained with the isopropanol probe revealed a silica structure after the 5 M nitric acid treatment. [ABSTRACT FROM AUTHOR]

Abstract: The mechanism of the solvent-free solid-state dibenzophenazine synthesis by dry co-grinding in a vibratory ball-mill has been investigated. The kinetics of the transformation was followed by HPLC and granulometry evolutions were quantified after co-grinding. The mechanism assumed involves a quinone imine intermediate formed during the first step of the reaction (addition of an amino group to a carbonyle) which is favored by the orbital overlaps between reagents. A water molecule formation occurs during the following step and hydrogen bonds are formed: the water molecule forms a bridge between the reactive centers of the quinone imine, and acts as a catalyst for the completion of the reaction. A push–pull mechanism involving the water bridge is proposed: the energy barrier is reduced by this way. Finally, two thermodynamic drivers favor the dibenzophenazine formation: the increased aromacity number in the product and the stabilization, thanks to water molecules. [Copyright &y& Elsevier]

Abstract: An investigation into the effects of the operating conditions on a dry particle coating process has been performed with mixtures of sugar grains (Suglet®) and magnesium stearate (MgSt) as the host and invited particles, respectively. Dry coating has been carried out in a high shear mixer (Cyclomix®) at different processing times t, rotational speeds ω, and filling ratios J, of the mixer. In order to determine the effect of the operating conditions on the properties of the products, the changes in flowability and wettability of the mixtures as a function of ω, J and the operating time t have been analyzed. The flowability is found to be improved by longer processing times. Higher speeds of rotations can improve the flowability more rapidly. However, the flowability does not seem to be sensitive to the filling ratio and it may be concluded that operating with higher filling ratios gives higher production. A method is proposed to measure the mass fraction of invited particles on the surfaces of the host particles. This fraction is linked to the product properties as the flowability and wettability. This result can be predicted by a model using a coating rate constant kc which can be used to optimize dry coating processes to give desired properties of coated particles. This coating rate constant can define and represent the efficiency of the dry coating. [Copyright &y& Elsevier]