Antiprotozoal and Antibacterial Activity of Ravenelin,a Xanthone Isolated from the Endophytic Fungus Exserohilum rostratum

The natural compound ravenelin was isolated from the biomass extracts of Exserohilum rostratum fungus, and its antimicrobial, antiplasmodial, and trypanocidal activities were evaluated. Ravenelin was isolated by column chromatography and HPLC and identified by NMR and MS. The susceptibility of Gram-positive and Gram-negative bacteria strains to ravenelin was determined by microbroth dilution assay. Cytotoxicity was evaluated in hepatocarcinoma cells (HepG2) and BALB/c peritoneal macrophages by using MTT. SYBR Green I-based assay was used in the asexual stages of Plasmodium falciparum. Trypanocidal activity was tested against the epimastigote and intracellular amastigote forms of Trypanosoma cruzi. Ravenelin was active against Gram-positive bacteria strains, with emphasis on Bacillus subtilis (MIC value of 7.5 µM). Ravenelin’s antiparasitic activities were assessed against both the epimastigote (IC₅₀ value of 5 ± 1 µM) and the intracellular amastigote forms of T. cruzi (IC₅₀ value of 9 ± 2 µM), as well as against P. falciparum (IC₅₀ value of 3.4 ± 0.4 µM). Ravenelin showed low cytotoxic effects on both HepG2 (CC₅₀ > 50 µM) and peritoneal macrophage (CC₅₀ = 185 ± 1 µM) cells with attractive selectivity for the parasites (SI values > 15). These findings indicate that ravenelin is a natural compound with both antibacterial and antiparasitic activities, and considerable selectivity indexes. Therefore, ravenelin is an attractive candidate for hit-to-lead development.     

Residual stress analysis near a cold expanded hole in a textured alclad sheet using X-ray diffraction

In this paper we present the methods of determination and the stress obtained at the periphery of a cold expanded hole in a 2024-T3 Alclad aluminum alloy sheet. The measurements in the aluminum clad were performed by the sin²Ψ method, taking experimental precautions to deal with the texture effects. In the core aluminum a special method had to be implemented to determine the stress values in a direction not accessible to the X-ray diffraction. The strains were measured in sample orientations selected according to the texture characteristics and stress factorsF _ij were used to calculate the stress tensor. TheF _ij values were determined assuming a quasi-isotropic material behavior, after concluding that the stress results were not significantly affected by factors calculated for textured material. The residual stress profile, both in the clad and in the sheet, shows a nearly axisymmetric stress state. Compressive stresses were observed near the periphery of the hole, with values that are higher on the exit than on the entrance face. Residual stresses were also higher in the hoop direction than in the radial direction. They decreased with the radial distance to the hole and affected the previous stress state over a distance of 6 mm. The plastic deformation induced by the cold expansion is well evidenced by the FWHM values, which in the affected zone decrease with increasing distance from the hole edge.     

Effect of microcrystalline and microfibrillated cellulose on the evolution of hydration of cement pastes by thermogravimetry

Journal of Thermal Analysis and Calorimetry - The interest in the use of cellulose fibers of increasingly smaller sizes in cementitious materials has increased in recent years. This paper brings...     

Alcoholic monoterpenes found in essential oil of aromatic spices reduce allergic inflammation by the modulation of inflammatory cytokines

Allergic inflammation is a response of the body against pathogens by cytokine release and leucocyte recruitment. Recently, there was an increase in morbimortality associated with allergic inflammation, especially asthma. The treatment has many adverse effects, requiring the search for new therapies. Monoterpenes are natural products with anti-inflammatory activity demonstrated in several studies and can be an option to inflammation management. Thus, we investigated the effects of citronellol, α-terpineol and carvacrol on allergic inflammation. The model of asthma was established by OVA induction in male Swiss mice. The monoterpenes were administered (25, 50 or 100 mg/kg, i.p.) 1 h before induction. After 24hs, the animals were sacrificed to leucocytes and TNF-α quantification. Monoterpenes significantly decrease leucocyte migration and TNF-α levels, possibly by modulation of COX, PGE₂ and H1 receptor, as demonstrated by molecular docking. These findings indicate that alcoholic monoterpenes can be an alternative for treatment of allergic inflammation and asthma.     

Synthesis and properties of azomethines based on 1-nitrophenyl-2-formylpyrroles

Schiff bases were obtained by the reaction of 1-nitrophenyl-2-formylpyrroles with aromatic amines, and their spectral characteristics were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 53–56, January, 1989.     

Industrial Applications of Gold Catalysis

Gold catalysis has recently found its first large‐scale applications in the chemical industry. This Minireview provides a critical analysis of the success factors and of the main obstacles that had to be overcome on the long way from the discovery to the commercialization of gold catalysts. The insights should be useful to researchers in both academia and industry working on the development of tomorrow's gold catalysts to tackle significant environmental and economic issues.