Copper-pyridineoxazoline (Cu-pyox) complexes are poor homogeneous catalysts for asymmetric cyclopropanation reactions. Pyox ligands have been immobilized by polymerization of monomers possessing a vinyl group directly attached to position 6 with styrene and divinylbenzene. The corresponding heterogeneous catalysts show a significant enhancement in enantioselectivity, up to 7-fold that of the analogous homogeneous Cu-pyox catalysts. This effect is due to a synergic effect between the proximity of the polymeric backbone and the presence of a bulky substituent in the chiral oxazoline ring around copper. The obtained values of enantioselectivity are similar to those found with supported C₂-symmetric bis(oxazolines), but with only half the chiral information given the presence of only one oxazoline ring in pyox. Besides, the co-polymerization in the presence of the right porogen inside a column allows the preparation of monolithic mini-flow reactors. Continuous flow processes contribute to further improve the catalytic efficiency in both classical solvents (dichloromethane) and neoteric greener ones, such as supercritical CO₂. The use of scCO₂ as solvent yields the same selectivities obtained in batch processes in combination with higher productivity avoiding the use of VOC.

Lignocellulosic residues have the potential for obtaining high value-added products that could be better valorized if biorefinery strategies are adopted. The debarking of short-rotation crops yields important amounts of residues that are currently underexploited as low-grade fuel and could be a renewable source of phenolic compounds and other important phytochemicals. The isolation of these compounds can be carried out by different methods, but for attaining an integral valorization of barks, a preliminary extraction step for phytochemicals should be included. Using optimized extraction methods based on Soxhlet extraction can be effective for the isolation of phenolic compounds with antioxidant properties. In this study, poplar bark (Populus Salicaceae) was used to obtain a series of extracts using five different solvents in a sequential extraction of 24 h each in a Soxhlet extractor. Selected solvents were put in contact with the bark sample raffinate following an increasing order of polarity: n-hexane, dichloromethane, ethyl acetate, methanol, and water. The oily residues of the extracts obtained after each extraction were further subjected to flash chromatography, and the fractions obtained were characterized by gas chromatography coupled with mass spectrometry (GC–MS). The total phenolic content (TPC) was determined using the Folin–Ciocalteu method, and the antioxidant activity (AOA) of the samples was evaluated in their reaction with the free radical 2,2-Diphenyl-picrylhydrazyl (DPPH method). Polar solvents allowed for higher individual extraction yields, with overall extraction yields at around 23% (dry, ash-free basis). Different compounds were identified, including hydrolyzable tannins, phenolic monomers such as catechol and vanillin, pentoses and hexoses, and other organic compounds such as long-chain alkanes, alcohols, and carboxylic acids, among others. An excellent correlation was found between TPC and antioxidant activity for the samples analyzed. The fractions obtained using methanol showed the highest phenolic content (608 μg of gallic acid equivalent (GAE)/mg) and the greatest antioxidant activity.

Benzo[b]thiophenesulphonamide 1,1-dioxide (BTS) derivatives are strong cytotoxic agents that induce reactive oxygen species (ROS) overproduction and apoptosis in tumour cells. Although the precise origin of BTS-induced ROS is not known, a clear correlation between their cytotoxic effect and ability to inhibit a tumour-associated NADH oxidase (tNOX) activity of the plasma membrane has been described. To analyse the putative implication of tNOX in BTS-induced ROS generation, in this work we have synthesised and tested a new BTS derivative, the 6-[N-(2-phenylethyl)]benzo[b]thiophenesulphonamide 1,1-dioxide. According to its high lipophilicity, this compound showed a strong cytotoxic activity against a panel of six human tumour cell lines, including two human leukaemia (K-562 and CCRF-CEM) and four human solid tumours (HT-29, HTB54, HeLa and MEL-AC). We also tested the ability of this compound to inhibit the tNOX activity and we found an absolute dependence of this inhibition on the redox state of the tNOX: while under reducing conditions, that is, 100 mM GSH, the drug inhibits strongly the NOX activity with an EC(50) of about 0.1 nM, under oxidising conditions, there is no effect of the drug or just a slight stimulation of activity.