Gustavo S.G. de Carvalho

High selective antileishmanial activity of vanadium complex with stilbene derivative

Leishmaniasis is a group of disease caused by different species of the parasite Leishmania affecting millions of people worldwide. Conventional therapy relies on multiple parenteral injections with pentavalent antimonials which exhibit high toxicity and various side effects have been reported. Hence, the research for an effective and low toxic effect drug is necessary. In the present work, the synthesis, spectroscopic and analytical characterizations of stilbene derivative (H2Salophen) and its vanadium complex (VOSalophen) are reported. Besides the chemical ancillary information, investigation of the leishmanicidal effects of these compounds were provided. The biological assays against promastigote and amastigote forms of L. amazonensis have been shown that VOSalophen exhibited a strong antiparasitic activity (IC50 of 6.65 and 3.51 μM, respectively). Furthermore, the leishmanicidal activity was concentration and time-dependent. Regarding toxicity and selectivity on mammalian cells, VOSalophen have not caused significant damage to human erythrocytes in all concentrations tested and VOSalophen was almost seven times more destructive for the intracellular parasite than for macrophages. Furthermore, the leishmanicidal activity of VOSalophen in promastigote forms of L. amazonensis could be associated to mitochondrial dysfunction and increase of the reactive oxygen species (ROS) production. In L. amazonensis-infected macrophages, VOSalophen induces ROS production and a microbicidal action NO-dependent. Our biological results indicate the effective and selective action of VOSalophen against L. amazonensis and the leishmanicidal effect can be associated to parasite disorders and immumodulatory effects.

Synthesis and antitubercular evaluation of new fluoroquinolone derivatives coupled with carbohydrates

We describe in this work the synthesis of nine new fluoroquinolone derivatives based on modifications at the C-7 position of the known fluoroquinolones cipro-, gati-, and moxifloxacin, as well as their antitubercular evaluation. The synthesis of these new analogues was improved using microwave irradiation, providing several advantages such as better yields and shorter reaction times, in comparison with classical reaction conditions. Derivatives 4, 5, and 7 exhibited promising antitubercular activities.

Synthesis and Anti-Mycobacterium tuberculosis Evaluation of Aza-Stilbene Derivatives

Tuberculosis (TB) is a truly global disease, found in every country on earth. One-third of humanity, over 2 billion people, carry the bacillus that causes TB and 2 million people die of the disease each year. Despite that, no new specific drug against Mycobacterium tuberculosis has been developed since the 1960s. There are several candidates for new anti-TB agents, but none proven clinically effective. Stilbenes are compounds found in numerous medicinal plants and food products with some known biological and even antimycobacterial activity. This paper describes the synthesis and the anti–M. tuberculosis activity of eight stilbene analogues. The synthesis and characterization of these compounds are shown, and the results compared with one “first”-line drug used in current therapy.

Solid-state mechanochemical activation of clay minerals and soluble phosphate mixtures to obtain slow-release fertilizers

Abstract This work describes the development of potential multi-element slow-release fertilizers obtained by mechanochemical activation of mixtures of kaolinite and ammonium or potassium monohydrogen phosphates. Preliminary results of talc amorphization have also been included. The methodology consists of milling the materials in a high-energy ball mill, where the influence of rotation and time of milling were investigated. The samples were characterized by XRD, FTIR, TGA/DTA, SEM and MAS-NMR. The experimental results explain the slow-release behaviour of the amorphous nanostructured materials in aqueous suspensions, especially the MASNMR spectra, which showed the changes in the chemical environment of the elements analysed. The materials displayed slow-release behaviour for phosphates probably because the aluminium ions in the mineral structure interact more thoroughly with phosphate than potassium or ammonium. Nevertheless, in general, all of the nutrients were released slowly.

Three new mononuclear group 12 complexes with benzimidazole

Three iso-structural Zn(II), Cd(II), and Hg(II) complexes with 1-benzyl-2-phenyl-1H-benzimidazole (BPB), ZnBPB, CdBPB, and HgBPB, respectively, were synthesized by reaction of the ligand with the corresponding metal chlorides in methanolic solutions. The complexes [MCl2(BPB)2], where M = Zn(II), Cd(II), or Hg(II), were characterized by elemental analysis, 13C, 1H, and [1H–15N] heteronuclear multiple bond coherence NMR measurements, and Raman spectroscopy. The structures of the cadmium and mercury complexes were solved by single-crystal X-ray diffraction, while the structure of the zinc complex was determined by X-ray powder diffraction. The three compounds crystallize in the triclinic system in P-1 space group with the metal ions lying in a distorted tetrahedral environment. The zinc complex shows high luminescence in the solid state at room temperature. Graphical Abstract

The zwitterionic structure of 2-hydroxy-4-[(2-hydroxybenzylidene)amino]benzoic acid

The title compound, C₁₄H₁₁NO₄, exists in the solid phase in the zwitterionic form, 2-{[(4-carboxy-3-hydroxyphenyl)iminiumyl]methyl}phenolate, with the H atom from the phenol group on the 2-hydroxybenzylidene ring transferred to the imine N atom, resulting in a strong intramolecular N-H∙∙∙O hydrogen bond between the iminium H atom and the phenolate O atom, forming a six-membered hydrogen-bonded ring. In addition, there is an intramolecular O-H∙∙∙O hydrogen bond between the carboxylic acid group and the adjacent hydroxy group of the other ring, and an intermolecular C-H∙∙∙O contact involving the phenol group and the C-H group adjacent to the imine bond, connecting the molecules into a two-dimensional network in the (103) plane. π-π stacking interactions result in a three-dimensional network. This study is important because it provides crystallographic evidence, supported by IR data, for the iminium zwitterionic form of Schiff bases.

Investigation of layered double hydroxides type ZnMgAl-carbonate and derivates.

Layered double hydroxides (LDHs) or hydrotalite-like compounds belong to a class of synthetic two-dimensional inorganic materials with lamellar structures, where the hydroxyl-hydrated compounds are formed by chemical substitution of divalent ion of the brucitelike octahedral layers by trivalent ions [1]. The LDH are represented by the general formula, Figure a , where M2+, M3+ are divalent and trivalent cation and Amis interlayer anion responsible by charge balancing, the range of divalent and trivalent ions (x) varies normally between 0.17 a 0.33. According Montanari and co-works [2] compounds type ZnAl-hydrotalcites (ZnAl-HT) have relevant industrial interest; however the scientific literature concerning this material as catalysts or catalyst precursor is scarce. Based on this fact, in the present communication we will present a studied on how the variation in percentage of Zinc in a ZnMgAl-HT catalyst precursor can influence the formation of mixed oxides after calcination. The ZnMgAl-HTs, Figure b , y=5, 10,15,20,25,50,75 and 100% were prepared by co-precipitation and urea method. Mg-Zn/Al mixed oxides were prepared from calcinations of hydrotalcites precursors at 500°C for 4 hours. The material synthesized were characterized by X-ray powder diffraction, the measurements were carried out in Bruker D8 DaVinci diffractometer, equipped with CuKα radiation , LynxEye linear Position Sensitive Detector, Ni-filter. Data was collect between 8 and 80° in 2θ with step size of 0.02° and the count time of 0.05 per step. Soller slit 2.5° of divergence and 0.2 mm primary slit were used. For the ZnMgAl-HT samples the measurements were performed at different temperatures, range 251200°C, heating rate 5°C/min. It was observed differences among XRD patterns for y greater than 25% of Zn in urea method at 500°C, and for co-precipitation method just for the substitution at 50 and 75% of Zn. These results suggested that the increase in Zn percentage change the structure of calcinated samples.