Selank vs Semax
Selank (Synthetic heptapeptide (tuftsin analog)) and Semax (Synthetic ACTH(4-10) analog (heptapeptide)) are documented as co-studied in the PeptiDex library. This page puts the two entries side by side on class, molecular weight, half-life, origin, mechanism and studied research areas — every value taken from the entry it belongs to.
Why these two are co-studied
Cross-referenced for research context — not a usage or combination recommendation.
At a glance
| Attribute | Selank | Semax |
|---|---|---|
| Compound class | Synthetic heptapeptide (tuftsin analog) | Synthetic ACTH(4-10) analog (heptapeptide) |
| Research category | Cognitive & Nootropic | Cognitive & Nootropic |
| Length (amino acids) | 7 amino acids | 7 amino acids |
| Molecular weight | 751.9 g/mol | 813.9 g/mol |
| Half-life | ~2-30 minutes (plasma; short, effects outlast) | ~2-5 minutes (plasma) |
| Origin | Selank was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a synthetic analog of the endogenous immunomodulatory peptide tuftsin. It is marketed in Russia as an anxiolytic. | Semax was developed in Russia (Institute of Molecular Genetics, Russian Academy of Sciences) as a synthetic analog of a fragment of adrenocorticotropic hormone (ACTH 4-10) with an added Pro-Gly-Pro tail for stability. It is marketed in Russia and some neighboring countries. |
“Not documented” means the PeptiDex entry records no value for that field. Nothing on this page is estimated, and no figure is carried over from one compound to the other.
How Selank works
Selank is a stabilized analog of tuftsin (a fragment of the immunoglobulin G heavy chain) and is reported to exert anxiolytic and immunomodulatory effects. Research suggests it influences the expression of genes and levels of monoamines and can modulate the balance of certain cytokines and enkephalin-degrading enzymes. It has been studied for effects on brain-derived neurotrophic factor (BDNF) and GABAergic/serotonergic signaling, though the full mechanism is not completely characterized.
How Semax works
Semax is an analog of the ACTH(4-10) melanocortin fragment but is described as being devoid of hormonal (corticotropic) activity. Research reports that it influences brain-derived neurotrophic factor (BDNF) and its receptor TrkB, modulates the expression of neurotrophin-related and immune genes, and may affect monoaminergic systems. It has been studied for neuroprotective and nootropic effects, potentially via effects on the melanocortin system.
Mechanistic descriptions reflect published research-literature understanding and are quoted from each compound's own entry. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
Where each one appears in the literature
The research contexts each entry documents. Listing a research area is not a claim of efficacy or a therapeutic indication, and the two lists are not scored against each other.
Selank
Semax
What sets each apart
Selank
Unlike Semax (an ACTH fragment focused on neuroprotection and cognition), Selank derives from tuftsin and is primarily positioned as an anxiolytic with immunomodulatory activity.
Semax
Semax is a melanocortin (ACTH)-derived peptide oriented toward neuroprotection and cognition, whereas Selank derives from tuftsin and is oriented toward anxiolysis.
Frequently asked questions
How does Selank differ from Semax?
Both are Russian-developed heptapeptides carrying a stabilizing Pro-Gly-Pro tail, but they derive from different parents and are studied for different endpoints. Selank is built from tuftsin and is studied primarily in anxiety and stress models, while Semax is derived from an ACTH(4-7) fragment and is studied mainly for cognition, attention, and neuroprotection.
What is Selank and what is it studied for?
Selank is a synthetic heptapeptide analog of the endogenous immunomodulatory tetrapeptide tuftsin, developed at the Russian Academy of Sciences. It is studied in research models of anxiety, stress adaptation, and cognition, where it is reported to modulate GABAergic and monoaminergic signaling and to influence brain-derived neurotrophic factor expression.
Why is Selank often administered intranasally in research?
Intranasal delivery is the route used in the original Russian protocols because it allows both systemic absorption and direct nose-to-brain transport via olfactory and trigeminal pathways, partly bypassing the blood-brain barrier. This is relevant because Selank has a very short plasma half-life, so direct CNS access is a research design consideration.
How does Semax differ from Selank?
Both are Russian heptapeptides with a Pro-Gly-Pro stabilizing tail, but Semax derives from ACTH(4-7) and is studied mainly for cognition, focus, and neuroprotection, whereas Selank derives from tuftsin and is studied primarily for anxiety and stress modulation.
What is Semax and what is it studied for?
Semax is a synthetic heptapeptide that adds a stabilizing Pro-Gly-Pro tail to the ACTH(4-7) fragment, developed at the Russian Academy of Sciences. It is studied in research models of cognition, attention, memory, and neuroprotection, where it is reported to upregulate BDNF and NGF messenger RNA in the hippocampus and cortex.
How does Semax achieve long effects despite a very short half-life?
The parent peptide has a plasma half-life of only about 2-5 minutes, yet its transcriptional effects on neurotrophic factors are measured over hours. The Pro-Gly-Pro tail slows peptidase cleavage relative to the native ACTH(4-7) fragment, allowing enough exposure to drive downstream BDNF/NGF signaling that outlasts the peptide itself.
Answers are the ones published on each compound's own PeptiDex entry. They are educational summaries of research-literature context and are not medical advice.