Caterina Tidei

Selenium Containing Compounds from Poison to Drug Candidates: A Review on the GPx-like Activity

Abstract : Oxidative stress results from the formation of reactive oxygen species (ROS) such as peroxides that cause dam-age to cell membranes and react with various biomolecules in mammalian cells. The selenoenzyme glutathione peroxidase (GPx) destroys peroxides by catalyzing their reduction to alcohols or water with the stoichiometric reductant glutathione. The effects of oxidative stress have been implicated in a variety of degenerative processes and disease states and for these reasons, there is considerable interest in the discovery of small molecule compounds that could reproduce a GPx-like ac-tivity. A review on the most recent acquisition in this area is here reported. Keywords: Selenium, selenoprots, glutathione, ROS, ebselen. INTRODUCTION For a long time selenium has been considered a poison. The first observation about the toxicity of this element dates back to 1285 when Marco Polo lost his horses crossing the Shanxi Province of Western China; this event was explained only after the discovery of selenium in 1817 by the Swedish chemist Jons Jacob Berzelius and it was ascribed to the high concentration of this element in forages growing in the re-gion that caused selenosis in livestock. Later, several studies confirmed the occurring of important disorders in animals [1, 2] and humans [3] due to selenium bioaccumulation and thereby a role in the genesis of cancer was postulated [4]. In the second half of the 20

Selenium Catalyzed Oxidation of Aldehydes: Green Synthesis of Carboxylic Acids and Esters

The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is here reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters. The method affords the desired products in good to excellent yields under very mild conditions starting directly from commercially available aldehydes. Using benzaldehyde as a prototype the gram scale synthesis of benzoic acid is described, in which the aqueous medium and the catalyst could be recycled at last five times while achieving an 87% overall yield.

“On-water” thiolysis of epoxides promoted by PhSZnBr

The synthesis of a new bench-stable and odorless zinc thiolate is here reported. The thiolysis of epoxides effected using this reagent showed a considerable rate acceleration of the reaction when effected in “on-water” conditions. In addition, the reactions evidenced a good regioselectivity combining the advantage of the procedures effected in organic solvent with those effected using Lewis acid catalysis. GRAPHICAL ABSTRACT

Thiols Oxidation for the Evaluation of Gpx-Like Activity

GRAPHICAL ABSTRACT

Non Conventional Zinc Mediated Synthesis of Chalcogenoesters

Chalcogenoesters are important intermediates in several organic transformations, they were used as precursors of acyl radicals and anions and have attracted attention for the synthesis of new molecular materials, especially superconducting materials and liquid crystals. Applications of selenoesters have been expanded to the synthesis of proteins by chemical ligation, to the synthesis of substrates which undergo facile and efficient radical decarboxylation, as well as to the synthesis of the natural alkaloyd (+)- geissoschizine, ciguatoxins, and (-)- pseudolaric Acid B.We report here new zinc mediated and non-conventional protocols for their eco-friendly preparation.