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Background: Ixora coccinea Linn (Rubiaceae) is an evergreen shrub with bright scarlet colored flowers found in several tropical and subtropical countries. It is used as an ornamental and medicinal plant. Phytochemical studies revealed that its major special metabolites are triterpene acids, such as ursolic and oleanolic acid. Objective: To evaluate the isolation of ursolic acid (UA) (1) from methanol extracts of I. coccinea flowers through two methodologies, to prepare four derivatives, and to evaluate the cytotoxic effect against six cancer cell lines. Materials and Methods: The UA was isolated from vegetal material by percolation at room temperature and by ultrasound-assisted extraction. The preparation of derivatives was performed according to literature methods, and the cytotoxic effects were evaluated using the MTT (3,4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide) assay. Results: The most efficient extraction was achieved through ultrasound irradiation with a yield of 35% after KOH-impregnated silica in chromatography column. Furthermore, four derivatives (3, 5, 6, 7) of UA were prepared and evaluated, including 1, against two lung cancer (A549 and H460) and four leukemia (K562, Lucena, HL60, and Jurkat) cell lines. Generally, results showed that 1 and 7 were the most active compounds against the assayed cell lines. Also, the cytotoxic effects observed on terpenes 1 and 7 were higher when compared with cisplatin, used as positive control, with the exception of Jurkat cell line. Conclusion: The efficiency of such an alternative extraction method led to the principal and abundant active component, 1, of I. coccinea, thus representing a considerable contribution for promising triterpenoid in cancer chemotherapy. [ABSTRACT FROM AUTHOR]

Vanadium-containing polyoxometalates (POM) were synthesized by two distinct procedures (hydrothermal and under acidic conditions) and were thoroughly characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer−Emmett−Teller (BET) method, UV−vis, 31P and 51V magic angle spinning NMR, scanning electron microscopy, and extended X-ray absorption fine structure spectroscopy-X-ray absorption near-edge spectroscopy (EXAFS-XANES). POM crystals were successfully grown under acidic atmosphere, thus forming a self-assembled structure constituted by cubic crystals that are between 20 and 80 μm in size. EXAFS-XANES experiments and molecular orbital calculations upon the Keggin unit cell allowed the determination of both the nature of the interactions and the assembly of the polyanions. A growth model was therefore developed based on the aggregation of Keggin units, ranging from one heteropolyanion unit to a crystal. Herein, we report a bottom-up approach which can serve as a powerful tool to assemble complex nanostructures via self-assembly, as well as to identify the building blocks present in solution during the assembly process. Finally, these auto-organized cubic vanadomolybdate crystals exhibit the highest catalytic activity and selectivity in the liquid phase partial oxidation of 2-methylnaphtalene into K3vitamin. [ABSTRACT FROM AUTHOR]

Abstract: Different methods were used to introduce cerium in a HUSY zeolite. The samples obtained from ion-exchange, precipitation and wetness impregnation procedures were characterized both before and after hydrothermal deactivation in order to determine and compare the nature of the cerium species and their location in the catalyst. A variety of techniques were used: XRD, HRTEM, XPS, infrared and Raman spectroscopy and catalytic test of dehydration of 2-propanol. The presence of amorphous phases of extra framework aluminium species (EFAL) depends on the preparation method as was evidenced by TEM. The presence of CeO2 and exchanged cerium was determined in catalysts prepared by precipitation and impregnation methods. The quantification of both types of cerium species was accomplished by Rietveld refinement. For the catalyst prepared by impregnation, it is suggested that cerium species interact with EFAL species. This interaction determines the cerium dispersion. [Copyright &y& Elsevier]

Context: Croton cajucara Benth has been widely used in folk medicine, especially in the Amazonian region of Brazil, to treat several illnesses. Objectives: The objective of the study is to evaluate the stem bark hydroalcoholic extract (CC-EHA) of C. cajucara and their clerodane-type diterpene fractions (F1-7, F25-27, and F28) on promastigotes and axenic amastigotes of Leishmania amazonensis and trypomastigotes and epimastigotes of Trypanosoma cruzi. Materials and Methods: The extract was obtained in ethanol: water and the fractions with solvents of increasing polarity. The antiparasitic activities were assessed by 3,4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide method against promastigotes and axenic amastigotes from L. amazonensis in 24-h cultures and trypomastigotes and epimastigotes of T. cruzi in 72-h cultures. The experiments in triplicate were made in quadruplicate way in each time. The statistical tests used were t-Students and ANOVA. Results: Among those evaluated samples, the CC-EHA extract showed the higher antileishmanial activity of promastigote cultures (IC50 = 18.00 ± 0.01 μg/mL at 24 h). However, against axenic amastigotes, the polar fraction (F28), rich in diterpene transdehydrocrotonin (t-DCTN), showed the highest effect with an IC50 = 6.18 ± 0.02 μg/mL in culture of 24 h. In the T. cruzi assays, F28 also showed the greatest effect against trypomastigotes and epimastigotes, IC50 = 0.43 ± 0.02 μg/mL and 0.27 ± 0.02 μg/mL, respectively, at 72 h of culture. The results showed that the diterpene t-DCTN is the most important antiparasitic component in the hydroalcoholic extract obtained from C. cajucara, specifically against L. amazonensis and T. cruzi. Conclusion: Our results contribute to knowledge of these folk medicinal species as a promising antiparasitic phytotherapeutic alternative. [ABSTRACT FROM AUTHOR]

In this work, an epidemiological model is constructed based on a target problem that consists of a chemical reaction on a lattice. We choose the generalized scale-free network to be the underlying lattice. Susceptible individuals become the targets of random walkers (infectious individuals) that are moving over the network. The time behavior of the susceptible individuals' survival is analyzed using parameters like the connectivity γ of the network and the minimum (K min ) and maximum (K max ) allowed degrees, which control the influence of social distancing and isolation or spatial restrictions. In all cases, we found power-law behaviors, whose exponents are strongly influenced by the parameter γ and to a lesser extent by K max and K min , in this order. The number of infected individuals diminished more efficiently by changing the parameter γ , which controls the topology of the scale-free networks. A similar efficiency is also reached by varying K max to extremely low values, i.e., the number of contacts of each individual is drastically diminished. [ABSTRACT FROM AUTHOR]

Zeolite/glass composite materials with hierarchical trimodal pore size distributions have been successfully prepared and subsequently characterized. Starting from glass monoliths having meso- and macropores, additional microporosity was introduced while allowing the growth of zeolite crystals via partial recrystallization of the glass support into ZSM-5 zeolite phase. Structured zeolitic catalytic materials were produced using a combination of supramolecular templating methods to produce the glass support, followed by conventional self-assembly of template cations and silica species. Zeolite crystals are therefore in intimate contact with the glass support, featuring micropores in addition to the mesopores. Hence, these zeolite/glass composites exhibit enhanced diffusional properties in comparison with purely microporous zeolite materials. These enhanced mass transport properties allowed improvement of the selectivity toward light olefins in the important n-hexane cracking reaction. [ABSTRACT FROM AUTHOR]

Abstract: Zeolite crystals coated on mesoporous glass materials with hierarchical tri-modal pore size distributions have been successfully prepared and characterized. Starting glass monoliths, having regular meso- and macro-pores, were partly re-constructed into zeolite material, thus introducing additional microporosity via the growth of these zeolite crystals. Hierarchical 3D porous glass scaffolds were prepared by a combination of sol–gel, double polymer templating, and rapid prototyping (RP) techniques. Structured zeolitic catalytic materials were produced by conventional self-assembly of template cations and silica species on the glass surface. Zeolite crystals are therefore in an intimate contact with the glass support, featuring micropores in addition to the mesopores. A higher catalytic performance and selectivity toward low alkenes were achieved in n-hexane cracking reaction over these zeolite/glass composites in comparison with purely microporous zeolite materials. [Copyright &y& Elsevier]