Selank – Research Compound Profile

Selank – Research Compound Profile

Category: Cognitive / Anxiolytic Research | Molecular Type: Synthetic Heptapeptide (Tuftsin Analog) | Research Status: Approved in Russia as prescription anxiolytic; investigational elsewhere

This page compiles published research data for qualified researchers. Selank is sold exclusively as a research compound and is not approved by the FDA for human use. This page does not constitute medical advice.

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Molecular Overview

Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a synthetic heptapeptide analog of the endogenous immunomodulatory tetrapeptide tuftsin (Thr-Lys-Pro-Arg), which is derived from the Fc region of human immunoglobulin G. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences by appending a C-terminal Pro-Gly-Pro glyproline sequence to the native tuftsin fragment [1][2]. This structural modification was designed to dramatically enhance metabolic stability by conferring resistance to enzymatic degradation, thereby extending the functional half-life of the peptide in biological systems [2][8]. As in Semax, the two proline residues of the PGP unit constrain backbone flexibility at the C-terminus and are believed to sterically limit exopeptidase access, the accepted structural rationale for the enhanced stability of glyproline-extended peptides relative to their native parent fragments.

Originally investigated for its immunomodulatory properties as a tuftsin derivative, Selank was subsequently found to exhibit pronounced anxiolytic-like and nootropic-like activity in preclinical models and in controlled clinical research conducted in Russia [1][3][5]. The compound received regulatory approval in Russia as a prescription anxiolytic formulation. Outside of Russia, Selank remains an investigational research compound with no regulatory approvals for therapeutic use.

Mechanism of Action

Selank’s neurobiological effects have been attributed to a multi-target pharmacological profile encompassing GABAergic, serotonergic, dopaminergic, opioidergic, and neurotrophic pathways.

GABAergic Modulation

The primary anxiolytic-like mechanism proposed for Selank is allosteric modulation of GABA-A receptors. Rather than binding directly to the benzodiazepine binding site as classical anxiolytics do, Selank appears to alter the affinity of GABA for its own receptors, effectively amplifying inhibitory neurotransmission [4][9]. In a gene expression study by Volkova et al. (2016), Selank administration in rats altered the mRNA levels of 45 genes involved in GABAergic neurotransmission in the frontal cortex within 1 hour, with a strong positive correlation to the changes induced by GABA itself [4]. Notably, Selank maintained a broader pattern of gene expression modulation at 3 hours — affecting 17 genes compared to only 9 genes for GABA — suggesting sustained downstream effects beyond simple receptor activation [4].

Monoamine Neurotransmission

Selank modulates serotonin and dopamine pathways. Narkevich et al. (2008) demonstrated in BALB/c mice that Selank administration decreased 5-HT and 5-HIAA levels in the hippocampus, while also upregulating dopamine D1A and D2 receptor gene expression in the frontal cortex [10]. The interplay between serotonergic modulation and dopaminergic upregulation may contribute to the compound’s dual anxiolytic-nootropic pharmacological profile observed in experimental studies [4][10].

Enkephalinase Inhibition

Kost et al. (2001) demonstrated that Selank inhibits enkephalin-degrading enzymes in human serum in vitro, thereby preserving endogenous opioid peptides implicated in mood regulation and stress resilience in the preclinical literature [12]. This opioidergic component provides an additional pathway through which the peptide may influence affective and stress-response circuits.

Neurotrophic Effects

Selank increases brain-derived neurotrophic factor (BDNF) expression in the hippocampus, as documented by Kolomin et al. (2013) in a transcriptomic analysis of rat hippocampal tissue following Selank exposure [13]. BDNF is a critical mediator of neuroplasticity and memory consolidation, and its upregulation is consistent with cognitive effects observed in preclinical behavioral studies [8][13].

Orexin/Hypocretin Upregulation

Volkova et al. (2016) reported that Selank upregulated the expression of the orexin/hypocretin gene by more than 128-fold at 3 hours post-administration in rat frontal cortex [4]. This finding may explain the unique pharmacological profile in which anxiolytic-like effects were observed without accompanying sedation in published studies — the compound appears to simultaneously engage wakefulness-promoting pathways while dampening anxiety-related circuits [1][4].

Published Research Parameters

The following table indexes the study models, durations, and reported observations of selected peer-reviewed publications. Dose and administration-route details are deliberately omitted. This is a bibliographic index only — not a protocol and not a recommendation for any use.

Stability & Storage Characteristics

Published literature and peptide handling guidelines provide the following stability data for Selank and structurally similar glyproline peptides:

• Lyophilized stability: Lyophilized Selank powder is stable for extended periods (12+ months) when stored at −20 °C (−4 °F). Shorter-term storage at 2–8 °C (35.6–46.4 °F) is considered acceptable for periods of several weeks [14].
• Reconstituted solution stability: When reconstituted with bacteriostatic water, peptide solutions in this class are generally stable for approximately 4 weeks at 2–8 °C (35.6–46.4 °F) with minimal potency loss [14].
• Metabolic stability: The C-terminal Pro-Gly-Pro glyproline extension was specifically engineered to confer resistance to enzymatic degradation by serum peptidases, dramatically extending the functional half-life compared to native tuftsin [2][8].
• Bioavailability data: Pharmacokinetic studies using tritium-labeled Selank demonstrated 92.8% absolute bioavailability via the intranasal route in the rat model, indicating minimal degradation during mucosal absorption [7].
• Oxidative and hydrolytic liability: The threonine hydroxyl and the arginine guanidinium group are both potential sites of buffer-pH-dependent side reactions in dilute solution; maintaining a mildly acidic to neutral reconstitution pH is standard practice for glyproline peptides of this type.
• General handling considerations: Peptides in this class are sensitive to repeated freeze-thaw cycles, which may promote aggregation and loss of bioactivity. Light protection during storage is recommended to minimize photodegradation [14].

Analytical Characterization

Research-grade Selank is characterized with an orthogonal analytical panel. Reverse-phase HPLC provides the primary purity measure, with particular attention to resolving deamidation and diketopiperazine-formation products that can arise at Pro-Gly junctions in short prolyl-rich peptides. Electrospray mass spectrometry confirms intact mass and distinguishes the parent peptide from these common degradation products by their characteristic mass shifts. A peptide-content assay separates net peptide mass from residual counter-ion, water, and salt, since gravimetric vial mass alone overstates the peptide actually present. Researchers should retain the quality assurance documentation for each lot.

Key Published Research Findings

Anxiolytic Activity

• Clinical trial findings: In a 2008 controlled clinical study published in Zh. Nevrol. Psikhiatr., Zozulia et al. studied 62 human subjects and observed that a 14-day course of Selank produced a statistically significant anxiolytic effect, together with reported anti-asthenic (energy-restoring) effects, without accompanying sedation, cognitive impairment, or dependence [1].

• Tolerability in a comparative clinical study: In a 2014 study published in Zh. Nevrol. Psikhiatr., Medvedev et al. evaluated Selank’s anxiolytic effect and tolerability in a controlled clinical study and reported a favorable tolerability profile [11].

• Benzodiazepine synergy in chronic stress models: In a 2017 Behavioural Neurology study, Kasian et al. observed in a rat model of unpredictable chronic mild stress that Selank enhanced the anxiolytic-like effect of diazepam, suggesting potential synergistic interactions with GABAergic agents [6].

• Anxiolytic action across genetic phenotypes: Seredenin et al. (1998) demonstrated anxiolytic-like activity of Selank in inbred mouse strains (BALB/c and C57BL/6) exhibiting different phenotypes of the emotional stress reaction, indicating robust effects across varying genetic backgrounds [5].

Neurobehavioral and Cognitive Effects

• Prolonged neurobehavioral stabilization in primates: In a 2008 J. Evol. Biochem. Physiol. study, Sollertinskaya et al. observed that Selank administration in monkeys reduced fear- and anxiety-related behaviors and produced prolonged stabilizing effects on neurobehavior, with compensatory and antiamnestic properties suggesting durable changes in neural circuitry rather than transient effects [8].

• Cognitive effects following catecholamine disruption: Preclinical research has examined whether Selank can offset cognitive deficits induced by damage to the catecholamine system during early development, as documented in primate models [8][12].

• BDNF upregulation and hippocampal transcriptome changes: Kolomin et al. (2013) reported transcriptome alterations in the rat hippocampus under Selank exposure, including increased BDNF expression — a key mediator of neuroplasticity and memory consolidation [13].

• Enkephalinase inhibition: Kost et al. (2001) demonstrated in vitro that both Selank and Semax inhibit enkephalin-degrading enzymes in human serum, suggesting a mechanism for endogenous opioid preservation that may contribute to mood regulation [12].

Immunomodulatory and Antiviral Activity

• Broad immunomodulatory gene expression changes: In a 2011 Mol. Immunol. study, Kolomin et al. documented that Selank modulated the expression of dozens of inflammation-related genes in mouse spleen tissue, including chemokines, cytokines, and their receptors [18].

• Immunomodulatory effects in a clinical population: Uchakina et al. (2008) reported immunomodulatory effects of Selank in a clinical population, providing evidence of immunological changes concurrent with the anxiolytic-like effects reported elsewhere in the literature [3].

• Antiviral activity against influenza A: Ershov et al. (2009) demonstrated antiviral activity of Selank against influenza A virus in an experimental infection model [17].

GABAergic Gene Expression Modulation

• Extensive transcriptomic effects: Volkova et al. (2016) reported that Selank administration altered the expression of 45 genes involved in GABAergic neurotransmission in the rat frontal cortex within 1 hour, with changes strongly correlating to those induced by GABA itself. At 3 hours, Selank maintained broader gene modulation (17 genes) compared to GABA alone (9 genes), and dramatically upregulated orexin/hypocretin gene expression by over 128-fold [4].

Safety Profile in Published Literature

• Clinical study safety data: The principal clinical study by Zozulia et al. (2008) involving 62 human subjects reported a favorable tolerability profile over the 14-day study period, with no serious adverse events documented [1].

• Distinct pharmacological profile relative to benzodiazepines: Across published human and primate studies, Selank did not produce the sedation, amnesia, muscle relaxation, tolerance development, or withdrawal syndrome characteristic of benzodiazepine-class anxiolytics — a mechanistic distinction attributable to its allosteric (rather than direct benzodiazepine-site) mode of action [1][5][8].

• Preserved cognitive performance: Studies in both human subjects and primates reported that cognitive performance was preserved or enhanced during Selank exposure, in contrast to the cognitive impairment commonly associated with benzodiazepine-class pharmacology [1][8].

• Range of exposures explored preclinically: Selank has been tested across a range of exposures in preclinical models — including in alcohol-withdrawal paradigms — without significant toxicity reported, suggesting a favorable preclinical safety margin [5].

• Limited long-term safety data: It should be noted that the longest published controlled human study identified was 14 days in duration [1]. Long-term safety data beyond this timeframe remains limited in the peer-reviewed literature.

Regulatory Status

• Russia: Selank is approved as a prescription anxiolytic pharmaceutical. This regulatory approval is limited to the Russian Federation and does not extend to other jurisdictions [1].
• United States (FDA): Selank has not been approved by the FDA for any therapeutic use. It is not an approved drug, dietary supplement, or food additive in the United States.
• Clinical trial status: As of the available literature, controlled clinical trials have been conducted primarily in Russia. No FDA-registered clinical trials for Selank have been identified on ClinicalTrials.gov.
• Research compound classification: Selank is sold by Iron Peak Peptides exclusively as a research compound for in vitro and preclinical investigation purposes only.

References

1. Zh. Nevrol. Psikhiatr. (2008) — Zozulia AA, Neznamov GG, Siuniakov TS, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic Selank in the therapy of generalized anxiety disorders and neurasthenia. View Source

2. Pathophysiology (2005) — Ashmarin IP, Samonina GE, Lyapina LA, et al. Natural and hybrid (“chimeric”) stable regulatory glyproline peptides. View Source

3. Zh. Nevrol. Psikhiatr. (2008) — Uchakina ON, Uchakin PN, Miasoedov NF, et al. Immunomodulatory effects of Selank in patients with anxiety-asthenic disorders. View Source

4. Frontiers in Pharmacology (2016) — Volkova A, Shadrina M, Kolomin T, et al. Selank administration affects the expression of some genes involved in GABAergic neurotransmission. View Source

5. Zh. Vyssh. Nerv. Deiat. (1998) — Seredenin SB, Kozlovskaia MM, Blednov IuA, et al. The anxiolytic action of an analog of the endogenous peptide tuftsin on inbred mice with different phenotypes of the emotional stress reaction. View Source

6. Behavioural Neurology (2017) — Kasian A, Kolomin T, Andreeva L, et al. Peptide Selank enhances the effect of diazepam in reducing anxiety in unpredictable chronic mild stress conditions in rats. View Source

7. Russ. J. Bioorg. Chem. (2006) — Zolotarev YA, Dadayan AK, Dolotov OV, et al. Evenly tritium labeled peptides in study of peptide in vivo and in vitro biodegradation. View Source

8. J. Evol. Biochem. Physiol. (2008) — Sollertinskaya TN, Shorokhov MV, Kozlovskaya MM, et al. Compensatory and antiamnestic effects of heptapeptide Selank in monkeys. View Source

9. Neurochem. J. (2014) — V’yunova TV, Andreeva LA, Shevchenko KV, et al. Peptide regulation of specific ligand-receptor interactions of GABA with the plasma membranes of nerve cells. View Source

10. Eksp. Klin. Farmakol. (2008) — Narkevich VB, Kudrin VS, Klodt PM, et al. Effects of heptapeptide Selank on the content of monoamines and their metabolites in the brain of BALB/C and C57Bl/6 mice. View Source

11. Zh. Nevrol. Psikhiatr. (2014) — Medvedev VE, Tereshchenko ON, Israelian A, et al. A comparison of the anxiolytic effect and tolerability of Selank and phenazepam in the treatment of anxiety disorders. View Source

12. Bioorg. Khim. (2001) — Kost NV, Sokolov O, Gabaeva MV, et al. Semax and Selank inhibit the enkephalin-degrading enzymes from human serum. View Source

13. Zh. Vyssh. Nerv. Deiat. (2013) — Kolomin TA, Agapova T, Agniullin LaV, et al. Transcriptome alteration in hippocampus under the treatment of tuftsin analog Selank. View Source

14. NIBSC — Peptide storage guidelines: lyophilized and reconstituted stability considerations. View Source

17. Vopr. Virusol. (2009) — Ershov FI, Uchakin PN, Uchakina ON, et al. Antiviral activity of immunomodulator Selank in experimental influenza infection. View Source

18. Mol. Immunol. (2011) — Kolomin TA, Shadrina MI, Andreeva LA, et al. Expression of inflammation-related genes in mouse spleen under tuftsin analog Selank. View Source

⚠️ Disclaimer: This page is provided for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. Selank is sold exclusively as a research compound, has not been approved by the FDA for human consumption, and is not intended for human use or self-administration. It is approved in Russia as a prescription anxiolytic pharmaceutical, but this regulatory status does not extend to other jurisdictions. All information is derived from published peer-reviewed literature. Research must comply with all applicable laws, regulations, and institutional guidelines.

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