Anxiolytic; nootropic; neuropsychiatric; antidepressant; anti-stress
Selank does not have a single defined target but rather modulates multiple neurochemical systems including GABAergic neurotransmission. It affects the expression of genes involved in GABAergic neurotransmission, which underlies its anxiolytic effects. The peptide also influences serotonin and dopamine systems. It has immunomodulatory properties as a derivative of tuftsin.

Selank is a member of the synthetic regulatory peptide family. It was designed and produced at the Institute of Molecular Genetics, Russian Academy of Sciences, in cooperation with the V.V. Zakusov Research Institute of Pharmacology, Russian Academy of Medical Sciences. This peptide is a synthetic analog of the tuftsin molecule (the short Thr-Lys-Pro-Arg fragment of the human immunoglobulin G heavy chain), which was elongated at the C terminus via the addition of three natural L-amino acids (Pro-Gly-Pro) to improve its metabolic stability and yield a relatively longer duration. Recent studies have shown that Selank has pronounced anxiolytic and nootropic activities, as well as a marked antiviral activity against the influenza A virus (H3N2), the herpes simplex virus (HSV-1 and HSV-2), the cytomegalovirus (CMV), and other viruses (Andreeva et al., 2010a, Ershov et al., 2009, Uchakina et al., 2008). Moreover, the individual fragments of regulatory peptides have their own specific physiological effect (Ashmarin et al., 2005), and Selank is no exception. Some Selank fragments have their own biological activity, which may differ significantly from the action of the original peptide (Andreeva et al., 2010b). However, the mechanisms that underlie the wide range of Selank biological effects remain unknown. [1]

---

In vitro, Selank diacetate has been shown to affect the expression of genes involved in GABAergic neurotransmission in neuronal cell cultures. As a synthetic peptide derived from tuftsin, it also exhibits immunomodulatory activity by activating phagocytosis and modulating cytokine production. The acetate salt form enhances peptide stability and solubility for cell-based assays.

Researchers have studied, using an animal model, the temporal dynamics of the expression of the C3, Casp1, Il2rg, and Xcr1 genes under the action of Selank and its Gly-Pro fragment. The results are shown in 1A–B and 2A–B. Fig. 1A shows a significant 3-fold decrease in the C3 mRNA level just 30 min after Selank injection. A similar alteration of the C3 mRNA level was observed after Gly-Pro administration: 5.8- and 3.7-fold decreases in the expression of this gene were observed 30 min and 90 min after the injection of the dipeptide, respectively. Unlike Selank, Gly-Pro evoked a significant 2-fold increase in the C3 mRNA level 3 h after its injection.
A wave-like alteration in the Casp1 mRNA level was observed after Selank injection (Fig. 1B): a significant increase in the expression of the gene (2.4-fold) was noted 90 min and 6 h after the injection of the peptide. The administration of Gly-Pro led to a decrease in the level of the Casp1 mRNA 30 min (5-fold) and 6 h (2.6-fold) after injection.
A statistically significant alteration in the mRNA level of the Il2rg gene was observed at early time points after Selank and Gly-Pro administration (Fig. 2A). For instance, as early as 30 min after the injection of the two peptides, the expression of the Il2rg gene decreased 5.9- and 14.3-fold, respectively; 90 min after their injection, the expression of this gene decreased 2.4- and 2.6-fold, respectively. Three hours after the administration of the peptides, a multidirectional alteration in the level of the Il2rg mRNA was observed: a 3.8-fold decrease after Selank injection and 3.5-fold increase of after Gly-Pro injection.
Fig. 2B shows that an almost equal reduction in the Xcr1 mRNA level was observed 90 min after the administration of Selank and its fragment. Moreover, the mRNA level of this gene increased 1.8-fold 3 h after Selank administration. The administration of Gly-Pro resulted in an increase in the Xcr1 mRNA level (2.1-fold) 6 h after its injection. [1]

---

In vivo, Selank diacetate has demonstrated anxiolytic activity in various animal models of anxiety (e.g., elevated plus maze, open field test). It also shows nootropic (cognitive-enhancing) and anti-stress properties. The peptide is water-soluble (250 mg/mL) and can be administered via intraperitoneal injection or intranasal routes for central nervous system effects.

Non-cell-based target binding assay: For Selank, specific receptor binding studies are limited. The peptide can be radiolabeled with 125I or tritium for binding studies using brain membrane preparations. Membranes (200 ug protein) are incubated with labeled Selank (0.1-10 nM) and increasing concentrations of unlabeled Selank (0-1000 nM) in binding buffer (50 mM Tris-HCl pH 7.4, 5 mM MgCl2, 0.1% BSA) for 60 min at 25degC. Bound radioactivity is separated by filtration. Saturation and competition binding curves are analyzed by non-linear regression.

Cell viability and neuroprotection assay: Primary neuronal cells (e.g., rat hippocampal neurons) or neuronal cell lines are seeded in 96-well plates (10,000 cells/well). Selank diacetate is added at concentrations of 0.01-100 uM for 24-72 hours. Cell viability is assessed using MTT or CellTiter-Glo assay. For neuroprotection studies, cells are exposed to stress (e.g., glutamate 10 mM) with or without Selank pre-treatment. LDH release and caspase-3 activity are measured.

Animal models: The male white mongrel mice (n = 75; average weight, 20 g) used in our experiment were kept under a 12 h light/dark cycle with free access to water and food. The animals were divided into 15 groups: five “control” groups (n = 25), five groups with Selank injection (n = 25) and five groups with Gly-Pro injection (n = 25). Each experimental group was divided into five subgroups (n = 5 per subgroup), according to the time points (30 min, 90 min, 3 h, 6 h, and 24 h). All groups were handled twice a day every day for 10 days. All animals were treated at the middle of the light phase of the diurnal cycle and had free access to water and food. After this period of preparation, all “control” groups were treated with saline solution (single intraperitoneal injections), and the experimental groups were treated with Selank or Gly-Pro solution (100 μg/kg; single intraperitoneal injections). Animals were decapitated at 30 min, 90 min, 3 h, 6 h, and 24 h after the treatment (all mice of one “control” and one “experimental” group per time point). [1]

---

Behavioral pharmacology protocol (anxiety model): Male BALB/c or C57BL/6 mice (6-8 weeks old) are treated with Selank diacetate via intraperitoneal injection at 0.1-5 mg/kg, 30-60 min before behavioral testing. Elevated plus maze: mice are placed in the center of a plus-shaped maze with two open arms and two enclosed arms. Time spent in open arms and number of open arm entries are recorded for 5 min. Open field test: locomotor activity and time spent in center zone are measured. Anxiety-like behavior is quantified. For anti-stress studies, chronic unpredictable mild stress protocols are used.

Pharmacokinetic data for Selank diacetate are limited. As a peptide (MW 872.42 base, acetate salt), it is water-soluble (250 mg/mL in water). The compound has limited oral bioavailability due to proteolytic degradation in the GI tract. Intranasal administration is used for CNS delivery, bypassing the blood-brain barrier. Intraperitoneal administration results in rapid absorption, with peak brain concentrations achieved within 30-60 minutes. Short plasma half-life (minutes to hours).

Toxicity data for Selank diacetate are limited. The peptide is generally well-tolerated in animal studies at anxiolytic doses (0.1-5 mg/kg). No significant acute toxicity has been reported. In Russia, Selank has been approved as a prescription medication for the treatment of generalized anxiety disorder and has a favorable safety profile in clinical use. For research purposes, the compound is intended for non-human use only.

[1]. The temporary dynamics of inflammation-related genes expression under tuftsin analog Selank action. Mol Immunol. 2014 Mar;58(1):50-5.

Previous studies have shown that the synthetic tuftsin analog Selank and its fragments can induce alterations in the expression of certain inflammation-related genes in the mouse spleen. This study used real-time quantitative PCR to investigate the transient dynamic changes in the expression of C3, Casp1, Il2rg, and Xcr1 genes in the mouse spleen after a single intraperitoneal injection (100 μg/kg) of Selank and its short fragment Gly-Pro. The results showed that C3 mRNA levels decreased significantly by 3-fold within 30 minutes after Selank injection; a similar change was observed after Gly-Pro administration. Casp1 mRNA levels showed fluctuating changes after Selank injection. Il2rg mRNA levels changed significantly in the early stages after Selank and Gly-Pro administration; Xcr1 mRNA levels showed almost the same decrease 90 minutes after Selank and its fragment administration. Our results indicate that Selank and its short fragment Gly-Pro can influence the expression of genes mediating different types of immune responses, thereby maintaining the balance of the immune system. It is noteworthy that, in most cases, the expression profiles of the studied genes were consistent after administration of Selank and Gly-Pro. This may indicate that the dipeptide contributes positively to the final effect of Selank. [1]

---

Our previous in vitro and in vivo experiments have confirmed that Selank has immunomodulatory effects. For example, Selank has antiviral activity against human influenza A/Aichi 2/68 virus (H3N2), human influenza B/Ohio 01/05 virus, avian influenza virus (H5N1), herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2), cytomegalovirus (CMV), and mouse encephalomyocarditis virus (EMCV). In vivo introduction of Selank can induce the expression of the INFα gene without affecting the expression of IL4, IL10 and TNFα genes (Andreeva et al., 2010a; Andreeva et al., 2010b; Ershov et al., 2009). The peptide-based drug "Selank" is used to treat patients with anxiety-asthenia and completely inhibits the expression of the IL-6 gene (while IL-6 mRNA levels are elevated in patients with neurological disorders). Furthermore, "Selank" has no significant effect on the expression of this gene in healthy individuals (Uchakina et al., 2008). Andreeva et al. (2010a) conducted in vitro and in vivo studies on the antiviral activity of Selank structural fragments, showing that two Selank fragments, namely peptides Gly-Pro and Arg-Pro-Gly-Pro, exhibited the most significant antiviral activity, comparable to the reference formulation. In our previous experiments, we investigated the effects of Selank and its three fragments (tuftsin, Arg-Pro-Gly-Pro, and Gly-Pro) on the expression of inflammation-related genes. The results showed that in mouse spleens, 6 and 24 hours after a single intraperitoneal injection of these peptides, the expression of 35 genes encoding chemokines, cytokines, their receptors, and other genes involved in the formation of immune responses was altered. Among them, the dipeptide Gly-Pro showed the most significant changes in gene expression 6 hours after injection. After the introduction of each peptide, the mRNA levels of Bcl6, C3, Casp1, Il2rg and Xcr1 genes changed most significantly. The expression profiles of Bcl6 gene, its target genes and co-repressor genes under the action of Selank and its fragments have been studied in detail before (Kolomin et al., 2011b). In order to understand more precisely the effects of Selank and its putative pharmacophore Gly-Pro on the expression of inflammation-related genes, we evaluated the expression dynamics of C3, Casp1, Il2rg and Xcr1 genes that respond positively to Selank and its fragments in mouse spleen at 30 min, 90 min, 6 h, 3 h and 24 h after administration. [1]

---

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) derived from tuftsin (Thr-Lys-Pro-Arg). It has been developed as a nootropic and anxiolytic agent and is approved for medical use in Russia (brand name Selank). Selank has shown potential for treating anxiety disorders and improving cognitive function. The diacetate salt enhances stability. Selank is not approved by FDA or EMA for use in other countries. Purity ≥98% for research grade.

C37H65N11O13

871.98

871.4763311

Selank;129954-34-3

155804769

H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH.2CH3CO2H; Thr-Lys-Pro-Arg-Pro-Gly-Pro; L-threonyl-L-lysyl-L-prolyl-L-arginyl-L-prolyl-glycyl-L-proline acetic acid

TKPRPGP

White to off-white solid at room temperature

11

16

19

61

1390

7

C[C@H]([C@@H](C(=O)N[C@@H](CCCCN)C(=O)N1CCC[C@H]1C(=O)N[C@@H](CCCN=C(N)N)C(=O)N2CCC[C@H]2C(=O)NCC(=O)N3CCC[C@H]3C(=O)O)N)O.CC(=O)O.CC(=O)O

VHEHIIUPYDNNTE-UXAXJNOXSA-N

InChI=1S/C33H57N11O9.2C2H4O2/c1-19(45)26(35)29(49)41-20(8-2-3-13-34)30(50)44-17-6-11-23(44)28(48)40-21(9-4-14-38-33(36)37)31(51)43-16-5-10-22(43)27(47)39-18-25(46)42-15-7-12-24(42)32(52)53;2*1-2(3)4/h19-24,26,45H,2-18,34-35H2,1H3,(H,39,47)(H,40,48)(H,41,49)(H,52,53)(H4,36,37,38);2*1H3,(H,3,4)/t19-,20+,21+,22+,23+,24+,26+;;/m1../s1

acetic acid;(2S)-1-[2-[[(2S)-1-[(2S)-2-[[(2S)-1-[(2S)-6-amino-2-[[(2S,3R)-2-amino-3-hydroxybutanoyl]amino]hexanoyl]pyrrolidine-2-carbonyl]amino]-5-(diaminomethylideneamino)pentanoyl]pyrrolidine-2-carbonyl]amino]acetyl]pyrrolidine-2-carboxylic acid

Selank (diacetate); TP-7 (diacetate); SELANC DIACETATE; SELANK DIACETATE; TP-7 DIACETATE;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O :~250 mg/mL (~286.70 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

---

Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

View More

Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

---

Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

View More

Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

---

Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

---

 (Please use freshly prepared in vivo formulations for optimal results.)