N-Acetyl Semax Peptide
N-Acetyl Semax is a synthetic polypeptide analogous to the naturally occurring adrenocorticotropic hormone (ACTH). The peptide is similar to a fragment from the adrenocorticotropic hormone ACTH (4-7), specifically Met-Glu-His-Phe, combined with a Pro-Gly-Pro extension at the C-terminus.(1) The addition of Pro-Gly-Pro (PGP) to N-Acetyl Semax might enable an enhanced permeability through the blood-brain barrier (BBB) by increasing the peptide’s lipophilicity via improving passive diffusion or uptake via lipid raft-mediated endocytosis, which may potentially allow it to bypass the tight junctions of the BBB. The PGP addition at the C-terminus might also alter the peptide’s interaction with specific BBB transporters or receptors, possibly promoting receptor-mediated transcytosis. Additionally, the acetylation of the peptide might increase its resistance to enzymatic degradation, prolonging its half-life in experimental models.
Overview
N-Acetyl Semax appears to exhibit potential nootropic (memory enhancing) and neuroprotective characteristics, which researchers have proposed may be produced via several routes:
- By potentially interacting with dopamine, serotonin, enkephalin, and brain-derived neurotrophic (BDNF) levels;(2)(3)
- Or by potentially modulating gene expression and increasing the efficacy of the immune system.(4)
Based on studies suggesting that the peptide may inhibit serum enkephalin-degrading enzymes, it is plausible to hypothesize about the interactions between Semax and enkephalins. Researchers suggest Semax’s inhibitory potential on enkephalin-degrading enzymes may lead to an increase in the levels of enkephalins by preventing their degradation. Enkephalins are endogenous opioids that are considered to play roles in nociception and stress response. Further, an increase in enkephalin levels might also influence other neurotransmitter systems due to the complex interplay between the opioid system and neurotransmitters like dopamine and serotonin.(2)
According to studies, Semax may potentially increase the striatal levels of 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite, suggesting a possible enhancement of serotonergic activity. This potential action on serotonin metabolism might amplify serotonin-mediated pathways, possibly influencing central nervous system functioning. On the other hand, Semax does not appear to directly alter dopamine levels or its metabolites. Still, it may modulate the dopaminergic system’s responsiveness, enhancing the dopaminergic agonists’ action.(5)
Chemical Makeup(6)
Molecular Formula: C37H51N9O10S
Molecular Weight: 858.97 g/mol
Other known titles: ACTH (4-7)PGP, HY-P1146
Research and Clinical Studies
N-Acetyl Semax and Nootropic Potential
A study(5) was conducted on experimental rodents to determine the nootropic potential of ACTH hormone and its analogs, such as Semax. After exposure to Semax, all tested rodents were examined for 5-hyrodxyindoleacetic acid (5-HIAA) levels. Based on the results, it was noted that the 5-HIAA levels increased by 25% after just 2 hours following exposure; they increased progressively up to a maximum of 180% after 4 hours. As per Kirill O Eremin et al., “Our results reveal the positive modulatory [action] of Semax on the striatal serotonergic system and the ability of Semax to enhance both the striatal release of dopamine and locomotor behavior elicited by D-amphetamine.”
In another research study,(7) experimental models under excessive stress conditions were exposed to Semax. Upon analyzing behavior 24 hours after peptide exposure, it was noted that they appeared to show signs of enhanced memory and attention. As per the reports, “In the majority of cases, the peptide exhibited positive [actions], and in no case did it produce negative side actions or complications connected with its administration. There is good reason to believe that … potentialities of Semax have not been exhausted and in the future new possibilities … will be revealed.” The study is shared here for educational and research purposes, and studies on the Semax peptide are still being conducted.
N-Acetyl Semax and SSRI Interaction
Selective Serotonin reuptake inhibitors (SSRIs) are a class of antidepressants. In pregnant research models, the compounds may risk passing through the placenta and impacting fetal brain development. In a preclinical research study,(8) experimental rats aged between 1 and 14 days were presented first with an SSRI compound, followed by the Semax peptide. After 4 weeks, it was observed that the rats exposed to SSRIs showcased anxious behavior, especially when exposed to new stimuli. When they were given the Semax peptide, these same rats later reportedly exhibited a reduction in their anxiety levels and potential enhancement in their learning abilities.
N-Acetyl Semax and Separation Anxiety
Young offspring face separation anxiety when they are away from their mothers. Separating for a prolonged period may lead to impaired emotional reactivity. A research study(9) examined young rats facing maternal deprivation. After four weeks of separation from their mothers, these rats reportedly exhibited increased anxiety and excessive physical activity. When the rats were presented with Semax, their reactions improved, indicating reduced anxiety. As per M. A. Volodina et al., these results suggest that “Semax [weakens] the impact of deprivation on animal body weight and [normalizes] the levels of anxiety in rats.”
N-Acetyl Semax and the Cardiovascular System
For this study,(10) rodents were induced with myocardial infarction (MI), which may lead to vascular damage. These rodents were then divided into two groups – one was given Semax peptide for six days, and the second was given a placebo. Following 28 days after the occurrence of myocardial infarction, it was reported by the researchers that the control rodents appeared to exhibit reduced arterial blood pressure and cardiac hypertrophy, both of which may signal impending heart failure. In contrast, the peptide-exposed rodents reportedly exhibited signs of prevention of diastolic blood pressure, which may indicate possible remodeling of the heart ventricle and inhibition of heart failure.
N-Acetyl Semax and Neuroprotection
In a clinical study,(11) research models of ischemic strokes were evaluated for 10 days. Of these, 30% were presented with conventional compounds and the Semax peptide, while the remaining 70% were presented with conventional compounds only. After 10 days, all models were examined via electroencephalogram (EEG). Based on the EEG mapping, the researchers reported that the experimental group exposed to both the peptide and compound exhibited apparently notable improvement in restoring damaged brain activity.
N-Acetyl Semax peptide is available for research and laboratory purposes only. Please review and adhere to our Terms and Conditions before ordering.
References
- T. Kolomin et al., A New Generation of Drugs: Synthetic Peptides based on Natural Regulatory peptides. Neuroscience & Medicine, 2013, 223-252. Published Online December 2013. http://dx.doi.org/10.4236/nm.2013.44035
- Kost NV, Sokolov OIu, Gabaeva MV, Grivennikov IA, Andreeva LA, Miasoedov NF, Zozulia AA. Ingibiruiushchee deĭstvie semaksa i selanka na énkefalindegradiruiushchie fermenty syvorotki krovi cheloveka [Semax and selank inhibit the enkephalin-degrading enzymes from human serum]]. Bioorg Khim. 2001 May-Jun;27(3):180-3. Russian. doi: 10.1023/a:1011373002885. PMID: 11443939. https://pubmed.ncbi.nlm.nih.gov/11443939/
- Shih-Jen Tsai, Semax, an analogue of adrenocorticotropin (4–10), is a potential agent for the treatment of attention-deficit hyperactivity disorder and Rett syndrome, Medical Hypotheses, Volume 68, Issue 5, 2007, Pages 1144-1146. https://doi.org/10.1016/j.mehy.2006.07.017
- Medvedeva, E.V., Dmitrieva, V.G., Povarova, O.V. et al. The peptide semax affects the expression of genes related to the immune and vascular systems in rat brain focal ischemia: genome-wide transcriptional analysis. BMC Genomics 15, 228 (2014). https://doi.org/10.1186/1471-2164-15-228
- Eremin KO, Kudrin VS, Saransaari P, Oja SS, Grivennikov IA, Myasoedov NF, Rayevsky KS. Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents. Neurochem Res. 2005 Dec;30(12):1493-500. doi: 10.1007/s11064-005-8826-8. PMID: 16362768. https://pubmed.ncbi.nlm.nih.gov/16362768/
- National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 9811102, Semax.
- Asmarin IP, Nezavibat’ko VN, Miasoedov NF, Kamenskiĭ AA, Grivennikov IA, Ponomareva-Stepnaia MA, Andreeva LA, Kaplan AIa, Koshelev VB, Riasina TV. Nootropnyĭ analog adrenokortikotropina 4-10-semaks (15-letniĭ opyt razrabotki i izucheniia) [A nootropic adrenocorticotropin analog 4-10-semax (l5 years experience in its design and study)]. Zh Vyssh Nerv Deiat Im I P Pavlova. 1997 Mar-Apr;47(2):420-30. Russian. PMID: 9173745. https://pubmed.ncbi.nlm.nih.gov/9173745/
- Nataliya Yu. Glazova, Daria M. Manchenko, Maria A. Volodina, Svetlana A. Merchieva, Ludmila A. Andreeva, Vladimir S. Kudrin, Nikolai F. Myasoedov, Natalia G. Levitskaya, Semax, synthetic ACTH(4–10) analog, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats, Neuropeptides, Volume 86, 2021, 102114, ISSN 0143-4179. https://doi.org/10.1016/j.npep.2020.102114
- Volodina MA, Sebentsova EA, Glazova NY, Levitskaya NG, Andreeva LA, Manchenko DM, Kamensky AA, Myasoedov NF. Semax attenuates the influence of neonatal maternal deprivation on the behavior of adolescent white rats. Bull Exp Biol Med. 2012 Mar;152(5):560-3. English, Russian. doi: 10.1007/s10517-012-1574-2. PMID: 22803132. https://pubmed.ncbi.nlm.nih.gov/22803132/
- Gavrilova SA, Golubeva AV, Lipina TV, Fominykh ES, Shornikova MV, Postnikov AB, Andrejeva LA, Chentsov IuS, Koshelev VB. [Protective effect of peptide semax (ACTH(4-7)Pro-Gly-Pro) on the rat heart rate after myocardial infarction]. Ross Fiziol Zh Im I M Sechenova. 2006 Nov;92(11):1305-21. Russian. PMID: 17385423. https://pubmed.ncbi.nlm.nih.gov/17385423/
- Gusev EI, Skvortsova VI, Miasoedov NF, Nezavibat’ko VN, Zhuravleva EIu, Vanichkin AV. Effektivnost’ semaksa v ostrom periode polusharnogo ishemicheskogo insul’ta (klinicheskoe i élektrofiziologicheskoe issledovanie) [Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]. Zh Nevrol Psikhiatr Im S S Korsakova. 1997;97(6):26-34. Russian. PMID: 11517472. https://pubmed.ncbi.nlm.nih.gov/11517472/

![N-Acetyl Selank Peptide N-Acetyl Selank is a short, synthetic heptapeptide analogous to the naturally occurring peptide called Tuftsin.(1) Tuftsin is an endogenous tetrapeptide that appears to regulate the immune system. Selank peptide may exhibit immunomodulatory potential; however, it has also been studied in models of anxiety and cognitive decline for its nootropic potential. Apart from the homology with tuftsin, the peptide appears to have a Pro-Gly-Pro fragment at its C-terminus, which may provide an enhancement of Selank's potential to traverse through different tissues and models including the blood-brain barrier (BBB). The BBB is a highly selective, semi-permeable border that separates the circulating blood from the tissues and extracellular fluid in the central nervous system, and is considered to play a crucial role in regulating the passage of substances. Pro-Gly-Pro addition might enhance BBB permeability by potentially impacting the peptide's overall hydrophilicity or lipophilicity, thereby increasing its affinity for the lipid-rich environment of the BBB. Additionally, the Pro-Gly-Pro sequence may interact with specific transport mechanisms or receptors at the BBB, potentially triggering a facilitated transport or receptor-mediated endocytosis. Such processes might allow Selank to bypass the tight junctions that normally restrict the passage of large molecules. Pro-Gly-Pro fragment may also influence the peptide's tertiary structure in a way that makes it more conducive to crossing the BBB. Further, N-Acetyl Selank Amidate has an additional acetyl group attached to the N-terminus. Adding an acetyl group to the N-terminus in N-Acetyl Selank Amidate may improve the peptide's stability through several speculative mechanisms. Acetylation might potentially shield the peptide from rapid enzymatic degradation by exopeptidases, as it might make the N-terminus less accessible or recognizable to these enzymes. Additionally, acetylation may induce changes in the peptide's structure, possibly leading to a more stable conformation that resists denaturation. Overview Studies suggest that the Selank peptide produces possible action in several ways: Firstly, by potentially stimulating the gamma-aminobutyric acid (GABA) receptors system.(2) GABA is considered an inhibitory neurotransmitter in the brain, reducing neuronal excitability, promoting relaxation, and alleviating anxiety. Researchers have posited Selank to potentiate the capacity to induce changes in the expression of genes associated with GABA receptors, transporters, and ion channels. This implies that Selank might potentially influence GABAergic neurotransmission by modulating the availability or functionality of these key components. Furthermore, studies posit that Selank's actions may potentially extend beyond direct actions on GABA receptor gene expression to allosteric modulation of the GABAergic system. This is hinted at by the differential gene expression patterns observed following Selank and GABA exposure, wherein Selank appeared to have uniquely influenced the expression of certain genes. This nuanced action suggests that Selank may modulate the GABAergic system's function in a manner distinct from the straightforward receptor activation induced by GABA. Selank might also initiate longer-lasting alterations in neurotransmitter systems, potentially explaining its prolonged anxiolytic actions in experimental models. Secondly, the peptide may potentially interact with serotonin signaling.(3) Serotonin signaling in the brain is posited to regulate mood and anxiety. Experiments in murine models with blocked serotonin synthesis suggest that Selank may exert the potential to modulate serotonin levels under compromised serotonergic function. Selank was posited to enhance serotonin metabolism in the brainstem via a rapid onset of action on the serotonin system. Specifically, the peptide was suggested to promote increased metabolic activity of serotonin in parts of the brain linked to regulating mood and anxiety. Further, the study posits that Selank's potential to elevate serotonin metabolism indicates a possible mechanism through which Selank might correct disturbances associated with reduced serotonin function. Thirdly, the peptide may act by potentially modulating enkephalin signaling.(4)(5) Studies have posited that Selank may have an inhibitory action on enkephalin-degrading enzymes. This indicates that Selank might slow down the degradation of enkephalins. Enkephalins, as natural ligands of opioid receptors, are considered to play a role in pain perception and modulating mood and stress, implying that Selank’s action on these enzymes might enhance the availability of enkephalins, thereby potentially amplifying their actions. Studies also posit that there may be a tau(1/2) leu-enkephalin increase during Selank exposure in anxiety models. Finally, the peptide may potentially affect brain-derived neurotrophic factor (BDNF) expression.(8) Selank has been suggested to significantly elevate BDNF mRNA levels in the hippocampus, a part of the central nervous system. Selank's potential to enhance BDNF expression, especially in the context of stress and glucocorticoid-induced suppression of BDNF, points towards its potential research implications for ameliorating reduced neuroplasticity. Furthermore, researchers are currently investigating the potential actions of the peptide via genome expression and involvement in the inflammatory process.(7) Chemical Makeup(8) Molecular Formula: C33H57N11O9 Molecular Weight: 751.9 g/mol Other known titles: TP-7, Selanc Research and Clinical Studies Unfortunately, research on N-Acetyl Selank in its acetylated form is still sparse. However, the peptide is expected to have similar impacts as its unacetylated counterpart, Selank, with the addition possibly only affecting the peptide by providing higher stability. Because of this lack of research data, we cite only Selank studies below. N-Acetyl Selank and Anxiolytic Action In 2008, a clinical study(5) was conducted on research models of generalized anxiety disorder (GAD). The research models were divided into two groups – half were presented with allopathic anxiety compounds, and the other half were presented with Selank peptide. After completing this study, the psychometric levels of all models were examined. Based on the results, it was suggested that the Selank peptide appeared to be potentially as impactful as the control compound in reducing the models’ anxiety levels. The peptide-exposed group also exhibited reportedly positive psychostimulant reactions. As per A A Zozulia et al., “The clinical-biological study revealed that [models] with GAD and neurasthenia had the decreased level of tau(1/2) leu-enkephalin [...]. The increase of this parameter and stronger positive correlations with anxiety level were observed during the [exposure to] Selank.” N-Acetyl Selank and Anxiety In this clinical study,(9) research models of standard anxiety and phobia thresholds were examined. The research models were separated into an experimental and control group; the controls were exposed to an allopathic compound, and the experimental group was exposed to Selank peptide. After this study's completion, the results appeared to indicate the peptide's anxiolytic and nootropic potential. N-Acetyl Selank and Mental Cognition Research studies(10) evaluated experimental murine models following exposure to Selank peptide, after which the mice underwent ‘training’ exercises for four days to learn conditioned avoidance response (CAR). Observing the behavior of the models throughout the training period, researchers observed that the learning abilities of murine models appeared to improve as the number of errors reduced over time, compared to control models under the same conditions. These researchers suggested that the peptide may have exhibited nootropic potential. It is posited that such actions on learning and memory might involve several interconnected mechanisms, such as the modulation of neuropeptide systems in the brain, leveraging the potential role these peptides may play in cognitive functions to enhance learning and memory processes. Further, Selank may influence the neural pathways associated with memory consolidation, possibly improving synaptic stability and efficiency, deemed essential for learning. Selank might also facilitate cognitive performance indirectly by reducing anxiety-related parameters, which may often hinder learning efficiency, suggesting a role in the affective components of cognition. The peptide may also have the unique potential to enhance neural plasticity or resilience in underperforming cognitive circuits, thereby improving their functionality. N-Acetyl Selank and Immunomodulation Research models of anxiety and neurasthenia were evaluated in this study(11) following routine exposure to Selank for two weeks. After two weeks, blood samples were collected and analyzed. It was reported that there was a significant rise in the levels of interleukin-6 cytokines and alteration in the Th1 to Th2 cytokine ratio. As per O.N. Uchakina et al., "The cytokine regulating effects revealed in the study suggest that Selank [might act as] a novel immunomodulator in … anxiety-asthenic disorders. Additionally, the adaptogenic properties of Selank may benefit … environmental stressors to prevent infectious diseases.” N-Acetyl Selank and Substance Withdrawal A study(12) in experimental murine models infused the animals with 10% ethanol for 24 weeks. Upon discontinuing alcohol infusion, these murine models exhibited significant alcohol withdrawal symptoms. At this time, the peptide was then given to all affected murine models. 48 hours after the peptide, it was suggested by the researchers that the alcohol withdrawal symptoms were reportedly reduced in all murine models. N-Acetyl Selank and Cholesterol Control In one study,(13) murine models were subjected to a high-fat diet for six consecutive weeks until they gained a standard set weight. At that time, the models were divided into two groups – one exposed to a sodium chloride solution and the rest to the Selank peptide. Upon analysis, it was observed that the peptide group exhibited apparently improved fat metabolism, with a reported reduction of cholesterol levels up to 58%. Most notably, the researchers suggested that Selank may potentially decrease total cholesterol, low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) cholesterol, and triglycerides. This suggests Selank may have either a direct or indirect role in modulating lipid metabolism and may possibly exhibit hypocholesterolemic and/or hypolipidemic action. Furthermore, the study observed apparent improvements in hemostasis parameters, such as increased total fibrinolytic activity and a reduction in platelet aggregation, which might imply amelioration of prothrombotic states. The research also hints at a potential regulatory action of Selank on glucose homeostasis. N-Acetyl Selank peptide is available for research and laboratory purposes only. Please review and adhere to our Terms and Conditions before ordering. References Kozlovskaya MM, Kozlovskii II, Val'dman EA, Seredenin SB. Selank and short peptides of the tuftsin family in the regulation of adaptive behavior in stress. Neurosci Behav Physiol. 2003 Nov;33(9):853-60. https://pubmed.ncbi.nlm.nih.gov/14969422/ Volkova, A., Shadrina, M., Kolomin, T., Andreeva, L., Limborska, S., Myasoedov, N., & Slominsky, P. (2016). Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission. Frontiers in pharmacology, 7, 31. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757669/ Semenova, T. P., kozlovskiĭ, I. I., Zakharova, N. M., & Kozlovskaia, M. M. (2009). Eksperimental'naia i klinicheskaia farmakologiia, 72(4), 6–8. Kost, N. V., Sokolov, O. I.u, Gabaeva, M. V., Grivennikov, I. A., Andreeva, L. A., Miasoedov, N. F., & Zozulia, A. A. (2001). Ingibiruiushchee deĭstvie semaksa i selanka na énkefalindegradiruiushchie fermenty syvorotki krovi cheloveka [Semax and selank inhibit the enkephalin-degrading enzymes from human serum]]. Bioorganicheskaia khimiia, 27(3), 180–183. https://doi.org/10.1023/a:1011373002885 Zozulia, A. A., Neznamov, G. G., Siuniakov, T. S., Kost, N. V., Gabaeva, M. V., Sokolov, O. I.u, Serebriakova, E. V., Siranchieva, O. A., Andriushenko, A. V., Telesheva, E. S., Siuniakov, S. A., Smulevich, A. B., Miasoedov, N. F., & Seredenin, S. B. (2008). Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova, 108(4), 38–48. Inozemtseva, L. S., Karpenko, E. A., Dolotov, O. V., Levitskaya, N. G., Kamensky, A. A., Andreeva, L. A., & Grivennikov, I. A. (2008). Intranasal administration of the peptide Selank regulates BDNF expression in the rat hippocampus in vivo. Doklady biological sciences : proceedings of the Academy of Sciences of the USSR, Biological sciences sections, 421, 241–243. https://doi.org/10.1134/s0012496608040066 T.A Kolomin et al., Transcriptomic Response of Rat Hippocampus and Spleen Cells to Single and Chronic Administration of the Peptide Selank. June 2, 2009. National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 11765600, Selank. https://pubchem.ncbi.nlm.nih.gov/compound/Selank Medvedev VE, Tereshchenko ON, Israelian AIu, Chobanu IK, Kost NV, Sokolov OIu, Miasoedov NF. A comparison of the anxiolytic effect and tolerability of selank and phenazepam in the treatment of anxiety disorders. Zh Nevrol Psikhiatr Im S S Korsakova. 2014;114(7):17-22. Russian. https://pubmed.ncbi.nlm.nih.gov/25176261/ Kozlovskii II, Danchev ND. The optimizing action of the synthetic peptide Selank on a conditioned active avoidance reflex in rats. Neurosci Behav Physiol. 2003 Sep;33(7):639-43. https://pubmed.ncbi.nlm.nih.gov/14552529/ Uchakina ON, Uchakin PN, Miasoedov NF, Andreeva LA, Shcherbenko VE, Mezentseva MV, Gabaeva MV, Sokolov OIu, Zozulia AA, Ershov FI. Immunomodulatory effects of selank in patients with anxiety-asthenic disorders. Zh Nevrol Psikhiatr Im S S Korsakova. 2008;108(5):71-5. Russian. https://pubmed.ncbi.nlm.nih.gov/18577961/ Kolik LG, Nadorova AV, Kozlovskaya MM. Efficacy of peptide anxiolytic selank during modeling of withdrawal syndrome in rats with stable alcoholic motivation. Bull Exp Biol Med. 2014 May;157(1):52-5. https://pubmed.ncbi.nlm.nih.gov/24913576/ N.F. Mjasoedov et al, The Influence of Selank on the Parameters of the Hemostasis System, Lipid Profile, and Blood Sugar Level in the Course of Experimental Metabolic Syndrome. April 14, 2014. Dr. Marinov Dr. Marinov (MD, Ph.D.) is a researcher and chief assistant professor in Preventative Medicine & Public Health. Prior to his professorship, Dr. Marinov practiced preventative, evidence-based medicine with an emphasis on Nutrition and Dietetics. He is widely published in international peer-reviewed scientific journals and specializes in peptide therapy research. Related products](https://medsuk.top/wp-content/uploads/2026/04/N-acetyl-Semax-25mg-600x600-1.jpg)


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