Selenium is an essential trace element. In Nature, its main biological function is associated with the incorporation in the form of selenocysteine into certain proteins having redox motifs, such as Glutathione Peroxidase (GPx), among others. Different selenium containing compounds resulted to be bio-inspired catalysts, good antioxidant agents and good GPx-mimics. On the other hand, chitosan the chiral polysaccharide obtained by alkaline deacetylation of chitin has been applied in many fields, due to its biocompatible and biodegradable properties as well as its relative ease to manage compared to its chemical N-acetylated precursor. The control of their chemical and physical properties allows chitosan derivatives to be used for different biomedical and industrial applications. Degree of deacetylation (DD) and polymer chain length (molecular weight, Mw) can be considered the most important features to determine the physico-chemical properties of these systems and consequently decisive factors to give desired results in formulations and applications.

We report here, the synthesis of new selenoureidyl chitosan derivatives with tunable physicochemical properties by reaction of the biopolymer with a series of diversely substituted aryl isoselenocyanates. All new compounds have been characterized by NMR techniques both in solution and in solid state. Finally, in order to study the applicability of the new chitosan-derived selenoureas, antioxidant capacity and GPx-mimics ability have been investigated.

The authors thank the Junta de Andalucía (2011/FQM-142, and Project P09-AGR-4597); Spanish Ministerio de Economía, Industria y Competitividad (MINECO), Spain (CTQ2016-78703-P); A. J. Galera-Carrillo also thanks Universidad de Sevilla (PEJUS-2, 2017-2-EJ-070) for funding support. The authors also thank the CITIUS, Universidad de Sevilla, for the facilities.