Antioxidant Activity of Caffeine: A Focus on Human Red Blood Cells and Correlations with Several Neurodegenerative Disorders

Abstract Caffeine, as many molecules of the vegetable world, acting on a wide range of molecular targets, is able to exert its beneficial effects on the metabolic function in the human body. Several caffeine effects derive from its action as an antagonist of adenosine receptors, many others from its antioxidant properties. Particularly, in the erythrocytes the xanthine, despite the destabilization of hemoglobin, guarantees the stability of phosphorylation–dephosphorylation balance, the “caspase silence,” and the integrity of cytoplasmic domain of band 3 protein promoting several positive metabolic conditions, resulting in an increase of the cellular reducing power. All these findings associated with the strong scavenger activity of caffeine toward hydroxyl radical already evident at low doses of the alkaloid could be connected with the positive effects of xanthine with respect to the risk of neurodegenerative diseases, conditions now mostly associated with oxidative stress.