Selank

What Selank is

Selank, also designated TP-7, is a synthetic seven-amino-acid peptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro and the molecular formula C₃₃H₅₇N₁₁O₉ (MW 751.87 Da, CAS 129954-34-3) ^[1]. It was created by researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences in collaboration with the V.V. Zakusov Institute of Pharmacology as a chemically modified, enzymatically resistant analog of tuftsin, a naturally occurring tetrapeptide (Thr-Lys-Pro-Arg) cleaved from the Fc fragment of immunoglobulin G ^[2]. Tuftsin itself is rapidly degraded in vivo, which limits its pharmacological utility; the appended Pro-Gly-Pro C-terminal extension in Selank substantially prolongs its plasma stability while retaining and expanding the parent peptide's biological profile ^[3].

The design objective was to produce a compound combining anxiolytic and nootropic activity with a broad spectrum and minimal side-effect burden—specifically one that lacked the sedation, tolerance, and withdrawal potential linked to classical benzodiazepine anxiolytics ^[2]. Large-scale pharmacological screening at the Research Institute of Pharmacology of the Russian Academy of Medical Sciences identified a distinctive psychotropic profile that includes anxiolytic, antidepressant-like, antiamnestic, and immunomodulatory components ^[4]. Selank was registered in Russia in 2009 for the treatment of generalized anxiety disorder and neurasthenia, though it remains investigational and without regulatory approval in the United States, Canada, and most other Western jurisdictions ^[5].

What it is being researched for

1. Anxiety reduction and generalized anxiety disorder

The most extensively studied application of Selank is the reduction of pathological anxiety. A 2008 randomized controlled trial compared Selank with the benzodiazepine medazepam in 62 patients diagnosed with generalized anxiety disorder (GAD) or neurasthenia, assessing outcomes with the Hamilton, Zung, and Clinical Global Impression scales ^[6]. Investigators reported comparable anxiolytic effects for both compounds, while Selank additionally demonstrated antiasthenic and mild psychostimulant properties not seen with medazepam ^[6]. A separate 2015 randomized trial enrolled 70 patients with anxiety-phobic, hypochondriac, and somatoform disorders (ICD-10 F40–F45 range) and found that combining Selank with phenazepam reduced the side-effect burden associated with phenazepam alone ^[7]. Importantly, all published human trials were conducted in Russia, used active benzodiazepine comparators rather than placebo controls, and were published primarily in one Russian psychiatric journal, limiting independent replication and generalizability ^[5].

2. Cognitive enhancement and memory

Preclinical studies have consistently attributed nootropic properties to Selank, with animal models demonstrating improvements in learning consolidation, working memory, and performance on avoidance tasks, particularly under conditions of stress-induced cognitive impairment ^[4]. Hippocampal gene-expression profiling revealed that Selank influenced the expression of 36 genes associated with neuronal plasticity, signal transduction, and neurotransmitter regulation ^[8]. One Springer-published rodent study found that Selank protected against ethanol-induced memory and attention disturbances in a long-term alcohol-exposure model, an effect investigators linked mechanistically to its regulation of BDNF levels in the hippocampus and prefrontal cortex ^[8]. In clinical studies, mild nootropic effects complementing its anxiolytic action were also reported, though no large-scale human cognitive-enhancement trial has been completed ^[6].

3. BDNF expression and neuroprotection

Brain-derived neurotrophic factor (BDNF) is a key regulator of synaptic plasticity, hippocampal neurogenesis, and neuronal survival. Research in rats demonstrated that intranasal administration of Selank produced a statistically significant approximately 30% increase in hippocampal BDNF protein levels measured 24 hours after treatment, and also elevated BDNF mRNA, indicating the peptide stimulated local gene expression rather than merely redistributing BDNF via axonal transport from remote brain areas ^[4]. A related study confirmed that Selank prevented ethanol-induced dysregulation of BDNF content in the hippocampus and frontal cortex, pointing toward a neuroprotective potential in contexts of chronic metabolic stress ^[8]. Because BDNF is widely implicated in resilience to depression, anxiety, and age-related cognitive decline, its upregulation by Selank is considered one of the core putative nootropic mechanisms, though translational evidence in humans remains limited ^[3].

4. Enkephalin metabolism and endogenous opioid signalling

An early mechanistic study published in the Bulletin of Experimental Biology and Medicine showed that Selank dose-dependently inhibited enkephalin-degrading enzymes (enkephalinases) in human plasma, with a measured inhibitory potency (IC₅₀ approximately 15 µM) exceeding that of reference peptidase inhibitors such as bacitracin and puromycin ^[9]. The same research group observed that patients with generalized anxiety disorder had markedly shortened enkephalin half-lives compared to healthy controls, and that treatment with Selank was associated with normalization of this parameter, a finding that correlated with reductions in anxiety symptom severity ^[6]. By slowing the enzymatic breakdown of leucine- and methionine-enkephalin, Selank may prolong the activity of these endogenous calming peptides at their delta and mu opioid receptors, providing an anxiolytic effect through a pathway entirely distinct from GABAergic or serotonergic mechanisms ^[9]. This enkephalin-stabilization hypothesis is supported by animal data but has not been definitively confirmed by receptor-binding studies demonstrating direct opioid receptor engagement ^[10].

5. Immunomodulation and cytokine regulation

Reflecting its structural origin from tuftsin—a naturally occurring immunoregulatory tetrapeptide—Selank retains significant immunological activity. In vitro experiments demonstrated that Selank at nanomolar to micromolar concentrations modulated the expression of Interleukin-6 (IL-6) and affected the balance of T-helper cell cytokines ^[3]. A rodent social-stress study found that Selank reduced concentrations of the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α while restoring IL-4 toward control values, suggesting a net anti-inflammatory, stress-protective immunological action ^[10]. Importantly, these immunomodulatory effects appear to operate through mechanisms that are at least partially independent of the central anxiolytic pathway, leading researchers to characterize Selank as a neuroimmunoregulatory peptide ^[5].

6. Antiviral research

A 2009 study published in Voprosy Virusologii evaluated Selank against the influenza A/Aichi 2/68 (H3N2) strain in both cell-culture and live-animal models ^[7]. The peptide exhibited pronounced antiviral activity in both systems, with the highest efficiency observed in a preventive-use scheme administered before viral inoculation, in which viral reproduction was fully suppressed in cell culture ^[7]. In vivo, Selank administration induced expression of interferon-alpha (IFN-α) gene without significantly altering the expression of IL-4, IL-10, or TNF-α, leading investigators to propose that its antiviral mechanism involves modulation of the Th1/Th2/Treg cytokine equilibrium, both directly and indirectly via the central nervous system ^[7]. Subsequent structural-fragment studies identified Gly-Pro and Arg-Pro-Gly-Pro as the sub-sequences carrying the most pronounced antiviral pharmacophore activity ^[5]. All published antiviral data are preclinical; no human antiviral trials of Selank have been published.

7. Stress-protective and adaptogenic research

Several Russian preclinical studies have examined Selank's capacity to preserve normal physiological and behavioural function under acute or chronic stress conditions. A PMC-indexed study using the unpredictable chronic mild stress (UCMS) model in rats found that Selank enhanced the anxiolytic effect of diazepam in stress conditions while producing its own significant anti-anxiety action, assessed in the elevated plus-maze test ^[1]. Hepatocyte functional-state studies under restraint-stress conditions have also appeared in the Bulletin of Experimental Biology and Medicine, extending the stress-protective research beyond the central nervous system ^[5]. Human data supporting an adaptogenic claim in healthy individuals is extremely limited; most claims in this area rest on animal data or small, uncontrolled clinical observations.

How it is thought to work

Selank's anxiolytic and cognitive effects are understood to arise from a network of overlapping, complementary mechanisms rather than a single dominant pathway. Unlike classical benzodiazepines, Selank does not act as a direct agonist at the GABA-A receptor benzodiazepine-binding site; instead, radioligand studies identified it as a subtype-selective positive allosteric modulator of GABA-A receptors, capable of enhancing GABA binding and—at higher concentrations—of partially competing with diazepam for its binding site on rat brain membrane preparations ^[1]. This indirect GABAergic modulation is considered one molecular basis for the anxiolytic effect. Simultaneously, Selank modulates serotonin metabolism in brainstem and limbic regions associated with affect and stress response, and has been shown to influence dopaminergic neurotransmitter tone through effects on apomorphine-sensitive dopamine pathways via its action on the endogenous opioid system ^[10].

A second major mechanism involves the stabilization of enkephalins—the brain's endogenous opioid signalling peptides. Selank dose-dependently inhibits the enzymes (enkephalinases) responsible for breaking down leu-enkephalin and met-enkephalin in human plasma and brain tissue, thereby prolonging these peptides' availability and activity ^[9]. Clinically, patients with GAD were found to have shortened enkephalin half-lives; Selank treatment normalized this parameter in parallel with anxiety symptom reduction ^[6]. Third, preclinical evidence demonstrates that Selank upregulates the expression of BDNF in hippocampal cells at both the mRNA and protein levels, supporting synaptic plasticity and potentially contributing to both the nootropic and the antidepressant-like effects observed in animal models ^[4]. Finally, consistent with its tuftsin heritage, Selank modulates cytokine balance—reducing pro-inflammatory markers such as IL-1β, IL-6, and TNF-α under stress conditions—and induces interferon-alpha expression, linking its central nervous system actions to peripheral immune regulation ^[7].

Where the evidence stands

The bulk of mechanistic evidence for Selank derives from well-controlled in vitro and rodent studies conducted primarily in Russian academic institutions over the period 2001–2021. These experiments established plausible biochemical rationales for the anxiolytic (GABAergic allosteric modulation, enkephalinase inhibition), nootropic (BDNF upregulation, gene-expression changes in hippocampus), and immunomodulatory (cytokine normalisation, IFN-α induction) activities described in the literature ^{[1][4][9][10]}. Animal behavioural studies using the elevated plus-maze, open-field, and unpredictable chronic mild stress paradigms consistently support an anxiolytic profile in rodents ^[1][6].

Human trial data are more limited in scope and methodological robustness than the preclinical body of work. Across four published Russian clinical trials enrolling a combined total of several hundred patients with GAD, neurasthenia, and anxiety-spectrum disorders, Selank was compared with benzodiazepine-class drugs (medazepam or phenazepam) rather than placebo; no trial was conducted outside Russia, the author lists overlap across studies, and all primary publications appeared in a single Russian psychiatric journal ^[5][6]. Findings from these trials are broadly consistent—Selank produced anxiolytic effects comparable to benzodiazepines without their sedative or dependence-related side effects—but the absence of placebo controls and independent international replication represents a significant evidentiary gap ^[5]. No large multi-centre randomised placebo-controlled trials, no systematic review, and no published meta-analysis of Selank's human clinical data have appeared in the indexed literature as of 2026. Regulatory agencies outside Russia (including the FDA and Health Canada) have not reviewed or approved Selank for any indication, and long-term human safety data remain sparse ^[5].

Frequently asked questions

What is Selank and where does it come from?

Selank is a synthetic seven-amino-acid (heptapeptide) molecule created by Russian scientists as an enhanced, enzymatically stable version of tuftsin, a naturally occurring immune-regulating peptide found in the human body. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and has been approved in Russia for anxiety-related conditions since 2009. In most Western countries, including Canada and the United States, it remains a research compound without regulatory approval.

How is Selank different from benzodiazepines like diazepam?

Both Selank and benzodiazepines are studied for their ability to reduce anxiety through the GABAergic system, but they act differently. Benzodiazepines directly bind the GABA-A receptor, producing strong sedation and carrying risks of tolerance and physical dependence. Selank appears to act as an indirect allosteric modulator of the GABA-A receptor and additionally works through enkephalin stabilization and BDNF upregulation—pathways that may account for its reported lack of sedation, tolerance, or withdrawal in the clinical trials published to date.

What does the human clinical evidence actually show for Selank?

Four Russian clinical trials have been published, collectively enrolling several hundred patients with generalized anxiety disorder, neurasthenia, and related disorders. Investigators found anxiolytic effects broadly comparable to benzodiazepine comparator drugs, plus additional antiasthenic and mild cognitive-stimulant properties. However, none of these trials used a placebo control, none were conducted outside Russia, and the findings have not been independently replicated, so the evidence base has significant methodological limitations.

What is the BDNF connection to Selank research?

Brain-derived neurotrophic factor (BDNF) is a protein essential for the growth, maintenance, and plasticity of neurons, especially in the hippocampus. Rodent studies showed that Selank administration produced a roughly 30% increase in hippocampal BDNF protein levels at 24 hours, stimulating its expression locally in hippocampal cells. Researchers propose that this BDNF upregulation may underlie both the nootropic (memory-supporting) and the antidepressant-like effects observed in animal models, though direct human BDNF data for Selank are not yet available.

Is Selank legal and approved in Canada?

Selank is not approved by Health Canada for any therapeutic indication and does not hold a Drug Identification Number (DIN) in Canada. It is classified as a research compound. Researchers should consult applicable Canadian federal and provincial regulations before handling any research peptide.

Does Selank have immune system effects?

Yes. Because Selank is derived from tuftsin—an endogenous immunomodulatory peptide—it retains immunological activity. Preclinical studies show that Selank modulates cytokine balance (reducing IL-1β, IL-6, and TNF-α under stress conditions), induces interferon-alpha gene expression, and demonstrated antiviral activity against influenza A and several other viruses in cell-culture and animal models. These immune effects appear to operate partly independently from its central anxiolytic mechanism.

How does Selank relate to enkephalins?

Enkephalins are naturally occurring opioid signalling peptides that help regulate anxiety and mood. Research demonstrated that Selank inhibits the enzymes (enkephalinases) responsible for breaking down enkephalins in human plasma, effectively prolonging their activity. Studies found that patients with generalized anxiety disorder had unusually short enkephalin half-lives, and Selank treatment was associated with normalization of this parameter alongside reductions in anxiety symptoms. This enkephalin-stabilizing action is considered one of Selank's distinct mechanisms compared to conventional anxiolytics.

What are the known limitations of Selank research?

The key limitations are: (1) all human clinical trials were conducted in Russia with overlapping authorship, published primarily in one journal, and used active comparators rather than placebo; (2) no large multi-centre, placebo-controlled, internationally replicated randomised controlled trial has been published; (3) long-term human safety data are sparse; (4) there is no published systematic review or meta-analysis; and (5) the regulatory agencies of the US, Canada, and EU have not reviewed the compound for any indication.

Is Selank the same as Semax?

No. Selank and Semax are two distinct synthetic heptapeptides both developed at the same Russian institute. Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is derived from a fragment of adrenocorticotropic hormone (ACTH 4–10) and is primarily researched as a nootropic and neuroprotective agent. Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is derived from tuftsin and is primarily studied for anxiolytic and immunomodulatory properties. Both share a Pro-Gly-Pro C-terminal extension designed to improve enzymatic stability, but their sequences, origins, and primary research areas differ substantially.

What animal models have been used to study Selank?

Researchers have employed a variety of rodent behavioural paradigms to study Selank, including the elevated plus-maze (anxiety quantification), the open-field test, the unpredictable chronic mild stress (UCMS) model, object recognition tasks (memory), and the conditioned active avoidance reflex paradigm. Immunological studies used mouse spleen gene-expression profiling after single administration. Antiviral experiments used cell cultures challenged with influenza A, herpes simplex, and other viruses, as well as live-animal infection models. These preclinical systems provide mechanistic insight but do not directly predict effects in humans.

Glossary

Heptapeptide

A peptide chain composed of exactly seven amino acid residues linked by peptide bonds; Selank's full sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro.

Tuftsin

A naturally occurring tetrapeptide (Thr-Lys-Pro-Arg) cleaved from the Fc region of immunoglobulin G that stimulates macrophage and neutrophil activity, and from which Selank was structurally derived.

Positive allosteric modulator (PAM)

A molecule that binds to a site on a receptor other than the primary active site and enhances the receptor's response to its natural ligand without directly activating the receptor itself.

Enkephalin

A class of endogenous opioid pentapeptides (leu-enkephalin and met-enkephalin) produced by the brain and adrenal gland that modulate pain, stress, and mood by acting at delta and mu opioid receptors.

Enkephalinase

Any of several peptidase enzymes—including neprilysin and aminopeptidase N—responsible for the rapid enzymatic degradation of enkephalins in plasma and brain tissue.

BDNF (Brain-Derived Neurotrophic Factor)

A neurotrophin protein that promotes the survival, growth, and differentiation of neurons, and plays a central role in hippocampal synaptic plasticity, learning, and memory consolidation.

GABAergic system

The network of neurons, receptors (primarily GABA-A and GABA-B), and transporters that use gamma-aminobutyric acid (GABA) as the primary inhibitory neurotransmitter in the central nervous system.

Neurasthenia

A clinical diagnostic category (ICD-10 F48.0) characterized by persistent mental and physical fatigue, difficulty concentrating, irritability, and somatic complaints; one of the indications studied in Selank clinical trials.

References

1. Peptide Selank Enhances the Effect of Diazepam in Reducing Anxiety in Unpredictable Chronic Mild Stress Conditions in Rats — Behavioural Neurology (PMC5322660)
2. Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity — PubMed / Frontiers in Neuroscience (PMID 30255741)
3. Selank — Wikipedia synthesis of primary literature (tuftsin, IL-6 modulation, T-helper cytokines) — Wikipedia (citing peer-reviewed primary sources)
4. Intranasal administration of the peptide Selank regulates BDNF expression in the rat hippocampus in vivo — Doklady Biological Sciences (Springer)
5. Selank human trials: what exists, and what every one of them compared against — Artemis Peptides evidence review (citing PMID 18454096, 25176261, 26356395)
6. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia — Zh Nevrol Psikhiatr Im S S Korsakova (PubMed PMID 18454096)
7. Antiviral activity of immunomodulator Selank in experimental influenza infection — Voprosy Virusologii (PubMed PMID 19882898)
8. Selank, Peptide Analogue of Tuftsin, Protects Against Ethanol-Induced Memory Impairment by Regulating of BDNF Content in the Hippocampus and Prefrontal Cortex in Rats — Bulletin of Experimental Biology and Medicine (Springer, DOI 10.1007/s10517-019-04588-9)
9. The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity — Bulletin of Experimental Biology and Medicine (PubMed PMID 11550013)
10. The Influence of Selank on the Level of Cytokines Under the Conditions of "Social" Stress — Current Reviews in Clinical and Experimental Pharmacology (PubMed PMID 32621722, DOI 10.2174/1574884715666200704152810)