N,N′-Disubstituted thiourea and urea derivatives: design, synthesis, docking studies and biological evaluation against nitric oxide synthase

The synthesis and biological evaluation of new types of N,N′-disubstituted thiourea and urea derivatives as inhibitors of both neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) are described. These compounds have been designed by reduction of the carbonyl group in the thiourea and urea kynurenamine derivatives 3 previously synthesized by our research group. The synthetic route performed to this new family also allows us to obtain the molecules 3 with less synthetic steps and higher global yield. Regarding the biological results, in general, the new derivatives 4a–q inhibit the neuronal NOS isoform better than the inducible one. Furthermore, thioureas exhibit higher inhibition than ureas for both isoenzymes. Among all the tested compounds, 4g shows significant nNOS (80.6%) and iNOS (76.6%) inhibition values without inhibiting eNOS. This molecule could be an interesting starting point for the design of new inhibitors with application in neurological disorders where both isoenzymes are implicated such as Parkinson's disease.We are very grateful to Dr. Pedro A. Sánchez-Murcia for his help. This work was partially supported by the Instituto de Salud Carlos III through grant FI11/00432 and by Ministerio de Economía y Competitividad, Instituto de Salud Carlos III (RIC RD12/0042/0011)

Experimental Polymer Mechanochemistry and its Interpretational Frameworks

Polymer mechanochemistry is an emerging field at the interface of chemistry, materials science, physics and engineering. It aims at understanding and exploiting unique reactivities of polymer chains confined to highly non-equilibrium stretched geometries by interactions with their surroundings. Macromolecular chains or their segments become stretched in bulk polymers under mechanical loads or when polymer solutions are sonicated or flow rapidly through abrupt contractions. An increasing amount of empirical data suggests that mechanochemical phenomena are widespread wherever polymers are used. In the past decade, empirical mechanochemistry has progressed enormously, from studying fragmentations of commodity polymers by simple backbone homolysis to demonstrations of self-strengthening and stress-reporting materials and mechanochemical cascades using purposefully designed monomers. This progress has not yet been matched by the development of conceptual frameworks within which to rationalize, systematize and generalize empirical mechanochemical observations. As a result, mechanistic and/or quantitative understanding of mechanochemical phenomena remains, with few exceptions, tentative. In this review we aim at systematizing reported macroscopic manifestations of polymer mechanochemistry, and critically assessing the interpretational framework that underlies their molecular rationalizations from a physical chemist's perspective. We propose a hierarchy of mechanochemical phenomena which may guide the development of multiscale models of mechanochemical reactivity to match the breadth and utility of the Eyring equation of chemical kinetics. We discuss the limitations of the approaches to quantifying and validating mechanochemical reactivity, with particular focus on sonicated polymer solutions, in order to identify outstanding questions that need to be solved for polymer mechanochemistry to become a rigorous, quantitative field. We conclude by proposing 7 problems whose solution may have a disproportionate impact on the development of polymer mechanochemistry