New seleno-glycoconjugates inspired by D-mannose

Every day, the cells of our organism are subject to the phenomenon of oxidative stress (OS). OS occurs from the imbalance between production of oxidizing and antioxidant defenses. The oxidizing agents are free radicals, unstable and reactive molecules with unpaired electron in their outer orbital. The most common cellular free radicals are reactive oxygen (ROS) and nitrogen species (RNS). They are produced by several endogenous and exogenous process, and their negative effects are neutralized by antioxidant defenses.1 Antioxidants are molecules that would react with and annihilate active reactive species before they could inflict oxidative damage to vital components, such as DNA or cell membranes.2 The role of polyphenols and selenium in the prevention of OS is well known in literature. Polyphenols are molecules with antioxidant capacity due to their structure: they have a broad conjugate system and hydroxyl function capable of deactivating or inhibiting radical precursors or free radicals. Polyphenols are present in foods of vegetable origin, such as fruit, oil, wine, tea, chocolate, and other cocoa-based products.3 Selenium, instead, is a non-metal element that can be assumed by diet. In nature, it can be found in plants, including cereals, broccoli, mushrooms, and brazil nuts but also in fish, eggs, and meat.4 Moreover, it is well known that selenoproteins are involved into antioxidant process and have essential biological functions. This work is part of a project aimed to the preparation of new glycoderivates with antioxidant functions to produce a new class of supplements for the prevention of OS: namely, selenoglycoconjugates linking the antioxidant function of selenium and the antioxidant and chelating properties of polyphenols. Based on remarkable results5 obtained with previous generation of compounds, using D-ribose, in this work we started from the commercially available D-mannose, which was then used as donor for the preparation of glycoconjugates using different