NA-Selank

NA-Selank (N-acetyl-Thr-Lys-Pro-Arg-Pro-Gly-Pro) and NA-Selank Amidate (the same N-acetylated heptapeptide with C-terminal amidation, Pro-NH2) are N-terminal-modified derivatives of Selank, the seven-residue peptide anxiolytic developed at the Russian Academy of Sciences as an analog of the endogenous tetrapeptide tuftsin (Thr-Lys-Pro-Arg). The parent Selank is registered as a medicine in the Russian Federation as an intranasal anxiolytic at 0.15 percent solution; the principal pharmacological signature is anxiolysis without sedation, modest pro-cognitive activity, and immunomodulation through tuftsin-receptor binding on monocytes and natural killer cells. Selank itself has a short plasma half-life of minutes and is administered intranasally to leverage direct olfactory and trigeminal transport to the central nervous system; the N-acetyl modification at the threonine N-terminus blocks the principal aminopeptidase cleavage site and extends plasma half-life by approximately 5-fold, while the C-terminal amidation in the Amidate variant similarly blocks carboxypeptidase cleavage at the proline C-terminus. The combined modifications produce a heptapeptide with substantially extended exposure suitable for parenteral administration with central nervous system effect. Mechanism includes BDNF transcriptional upregulation, GABAergic and serotonergic modulation, and tuftsin-receptor immunomodulation. Both NA-Selank and NA-Selank Amidate are research-grade peptides without regulatory approval; published characterization is principally in Russian-language journals and is dominated by the originating Institute of Molecular Genetics RAS research group. Investigators should treat the extended-PK variants as research tools for studying parenteral Selank pharmacology and should consider that the immune-modulatory profile may be more pronounced with extended exposure than with the brief intranasal pulse achieved by the parent.