Developing pyrrole-derived antimycobacterial agents: a rational lead optimization approach

Tuberculosis (TB) represents a never-ending challenge toward which research efforts are needed. Drug resistance is the key problem that scientists in the field need to fight. The development of new drugs endowed with novel modes of action against different biological targets is of extreme importance; these new agents should also exhibit lower toxicity compared with the anti-TB drugs currently available. Furthermore, new drugs should be inexpensive since most of the TB-infected population lives in developing nations. In the last few years, numerous researchers have focused their attention on TB, leading to the discovery of some interesting compounds. Among these, the pyrrole-derived compounds we developed can be considered very promising antimycobacterial agents. Aided by molecular modeling studies, we synthesized numerous compounds characterized by the same 1,5-diarylpyrrole scaffold and elucidated very interesting antitubercular/antimycobacterial properties. Some compounds identified are extremely promising and represent a step towards the design of novel lead structures in the fight against TB. Our efforts to this end are reviewed here.     

Corrosion behavior of Eurofer 97 and ODS-Eurofer alloys compared to traditional stainless steels

In the present work, the corrosion resistance of ferritic-martensitic EUROFER 97 and ODS-EUROFER steels was tested in solutions containing NaCl or H₂SO₄ and KSCN, both at 25 °C. The results were compared to those of AISI 430 ferritic and AISI 410 martensitic conventional stainless steels. The as-received samples were tested by electrochemical techniques, specifically, electrochemical impedance spectroscopy, potentiodynamic polarization curves, and double-loop electrochemical potentiokinetic reactivation tests. The surfaces were observed by scanning electron microscopy after exposure to corrosive media. The results showed that EUROFER 97 and ODS-EUROFER alloys present similar corrosion resistance but lower than ferritic AISI 430 and martensitic 410 stainless steels.     

A Highly Active and Selective Manganese Oxide Promoted Cobalt-on-Silica Fischer�CTropsch Catalyst

A highly active and selective manganese oxide-promoted silica-supported cobalt catalyst for the Fischer?CTropsch reaction is reported. Co/MnO/SiO₂ catalysts were prepared via impregnation of a cobalt nitrate and manganese nitrate precursor, followed by drying and calcination in an NO/He flow. The catalysts were studied with STEM?CEELS, infrared spectroscopy measurements of adsorbed CO and Steady-State Isotopic Transient Kinetic Analysis experiments. Based on those experiments, a relation between C₅₊-selectivity and surface-coverages of CH _x -intermediates on cobalt was found.     

Dechlorination of fuels in pyrolysis of PVC containing plastic wastes

The objective of this work is the study of several dechlorination methods devoted to reduce the chlorine content of the liquids obtained in pyrolysis of PVC containing plastic wastes. A mixture of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) has been pyrolysed in a 3.5 dm³ semi-batch reactor at 500 °C for 30 min. Stepwise pyrolysis carried out at several temperature and time conditions, the addition of CaCO₃ for chlorine capture and a combination of both methods have been studied. Additionally, some thermogravimetric analyses have been carried out in order to establish the best conditions for PVC dehydrochlorination in the presence of other plastics. It has been proved that the application of dehydrochlorination methods plays a significant role in the characteristics of pyrolysis liquids. Stepwise pyrolysis is an effective method for reduction of the chlorine content of pyrolysis liquids; additionally, heavier hydrocarbons and lower quantity of aromatics in the liquids than in conventional pyrolysis are obtained. The addition of CaCO₃ leads to the retention of a significant amount of chlorine in the solid, but more chlorine than in a conventional run is found in the liquids, which contains a higher amount of aromatics.     

Continuous production of soybean biodiesel with compressed ethanol in a microtube reactor using carbon dioxide as co-solvent

This work investigates the production of fatty acid ethyl esters (FAEE) from the transesterification of soybean oil in supercritical ethanol in a continuous catalyst-free process using carbon dioxide as co-solvent. The experiments were performed in a microtube reactor in the temperature range of 523 K to 598 K, from 10 MPa to 20 MPa, oil to ethanol molar ratio from 1:20 to 1:40, and co-solvent to substrates mass ratio from 0.05:1 to 0.2:1. Results showed that ethyl esters yield obtained increased with increasing addition of carbon dioxide to the system. Considerable reaction yields were achieved at 598 K, 20 MPa, oil to ethanol molar ratio of 1:20 and using a CO₂ to substrate mass ratio of 0.2:1.     

Effect of modifiers in n-pentane on the supercritical extraction of Athabasca bitumen

Experiments involving the supercritical extraction of bitumen using various solvent mixtures were carried out in a 2-l batch autoclave to determine the effect of modifier type and concentration on deasphalted oil (DAO) yield and quality. Athabasca bitumen was used as the feedstock and n-pentane was used as the primary solvent for extraction. Acetone, toluene, methanol and ethyl acetate were each added to n-pentane as modifiers in different concentrations to form the solvent mixtures. Extraction temperatures and pressures were maintained at around 200 °C and 1100 psi to achieve supercritical conditions for solvents, and the solvent-to-feed volume ratio was kept around 6.5. Higher DAO yields were obtained with increasing modifier concentrations in n-pentane. DAO yields ranged from 79 to 92 wt.% of the bitumen, with n-pentane/toluene mixtures providing the highest yields and n-pentane/methanol mixtures producing the lowest. Increases in DAO yield were accompanied by higher nickel, vanadium, nitrogen, sulfur and microcarbon residue content in DAO. Moreover, it was found that n-pentane/methanol and n-pentane/acetone solvent mixtures had lower selectivities for metals impurities than the other modifiers, while n-pentane/toluene had the highest selectivities.     

Compositional studies: antioxidant and antidiabetic activities of Capparis decidua (Forsk.) Edgew

Capparis decidua is one of the traditional remedies used for various medicinal treatments in Pakistan. This study presents the determination of proximate composition, amino acids, fatty acids, tocopherols, sterols, glucosinolate and phenolic content in extracts obtained from different aerial parts of C. decidua, as well as their antidiabetic and antioxidant activity. All examined extracts were prominently rich in phenolics and glucosinates, and they showed potent antidiabetic and antihemolytic activity. The present study could be helpful in developing medicinal preparations for the treatment of diabetes and related symptoms.     

Organic-based molecular switches for molecular electronics

In a general sense, molecular electronics (ME) is the branch of nanotechnology which studies the application of molecular building blocks for the fabrication of electronic components. Among the different types of molecules, organic compounds have been revealed as promising candidates for ME, due to the easy access, great structural diversity and suitable electronic and mechanical properties. Thanks to these useful capabilities, organic molecules have been used to emulate electronic devices at the nanoscopic scale. In this feature article, we present the diverse strategies used to develop organic switches towards ME with special attention to non-volatile systems.     

Processing cherries (Prunus avium) using supercritical fluid technology. Part 2. Evaluation of SCF extracts as promising natural chemotherapeutical agents

In the last years, there has been a growing interest in the recovery of bioactive compounds from natural sources for the development of novel functional foods.In this study, natural extracts, previously obtained by fractioned high pressure extraction from “Saco” cherry culls, were characterized in terms of anticancer activity. The product derived from CO₂:EtOH (90:10, v/v) extraction after a pre-treatment of raw material with supercritical CO₂ during 1 h, exhibited the highest antiproliferative activity in human HT29 colon cancer cells. In addition, when compared with doxorubicin, cherry extracts induced cell cycle arrest in a different cell cycle checkpoint.In order to obtain extracts with enhanced antiproliferative activity, the extraction process was further explored. Using highly pure CO₂ and EtOH 96% the inhibition of cancer cell growth was significantly enhanced by 16-fold. In addition, the incorporation of a conventional extraction step with MetOH or EtOH:H₂O (50:50, v/v) prior to fractioned process allowed to obtain cherry extracts more concentrated in antiproliferative compounds. Perillyl alcohol present in cherry extracts was pointed to be one of the major responsible for anticancer properties of cherry extracts.