Aim. Medicines based on nucleic acid derivatives, primarily nucleotides (N), are effective, non-toxic and widely used in medical practice. However, the currently known drugs based on N are used only in indeprotonated (D) forms. We studied the mechanism of action, antiviral, antitumor and cardioprotective properties of protonated (P)N, which still remain outside the attention of researchers. Conclusions. The ability of protonated forms of nucleotides to bind to proteins has been established, changing their conformation in the direction of reducing their rigidity, which ultimately provide the antiviral, antitumor, and cardioprotective effects.