Nootropic & CNS — 10 Compounds Compared
Selank, Semax, Dihexa, Cerebrolysin, P21, Oxytocin, DSIP, Pinealon, PE-22-28 and Adamax — the nootropic and central-nervous-system research category compared side by side.
What this category covers
The nootropic and CNS category collects compounds studied for cognition, neuroprotection, neurogenesis, mood and anxiety research, and sleep. It is the most mechanistically scattered category in the library: nearly every entry carries its own distinct compound class, and they are grouped here by research context rather than by a shared pathway.
Read that as a warning about transfer. A regulatory peptide studied in anxiolytic models, a neurotrophic preparation studied in stroke models, and an ion-channel blocker studied in mood research all sit in this category, and a result in one says nothing about the others. The mechanism groups below make the spread explicit.
The other recurring feature here is the mismatch between plasma half-life and reported duration of effect. Several entries report clearance in minutes while the literature discusses effects over much longer windows; where an entry documents that, it says so in its own record rather than resolving it.
Every entry in this category, side by side
All 10 compounds PeptiDex documents under Nootropic & CNS, on the specifications that actually separate one entry from another. Values are reproduced from each entry's own record; follow any name for the full research overview.
| Entry | Compound class | Length (aa) | Molecular weight | Reported half-life |
|---|---|---|---|---|
| Selank | Synthetic heptapeptide (tuftsin analog) | 7 | 751.9 g/mol | ~2-30 minutes (plasma; short, effects outlast) |
| Semax | Synthetic ACTH(4-10) analog (heptapeptide) | 7 | 813.9 g/mol | ~2-5 minutes (plasma) |
| Dihexa | Synthetic angiotensin IV-derived oligopeptide | Not listed | 504.7 g/mol | Not listed |
| Cerebrolysin | Neurotrophic peptide preparation (porcine-brain-derived) | Not listed | Not listed | ~2-4 hours (peptide fraction; mixture) |
| P21 | Neurogenic research peptide (Cerebrolysin/CNTF-related) | Not listed | Not listed | Not listed |
| Oxytocin | Endogenous neurohormone (cyclic nonapeptide) | 9 | 1007.2 g/mol | Approximately a few minutes in circulation |
| Adamax | Experimental nootropic / ampakine-class research compound | Not listed | Not listed | Not listed |
| DSIP | Endogenous neuropeptide (Delta Sleep-Inducing Peptide, nonapeptide) | 9 | 848.8 g/mol | ~7 minutes (serum) |
| Pinealon | Short synthetic peptide bioregulator (tripeptide) | 3 | 418.4 g/mol | Not listed |
| PE-22-28 | Spadin-derived synthetic peptide (TREK-1 channel blocker) | 7 | 773.9 g/mol | Not listed |
Of the 10 compounds above, 7 carry a published molecular weight, 5 have a reported half-life, 6 have a documented residue count and 8 have a published amino-acid sequence. No half-life is recorded for Dihexa, P21, Adamax, Pinealon and 1 others.
A cell reading "Not listed" is a gap in the published record, not an omission on this page. PeptiDex records a specification only where a source documents it. Some entries here are blends or multi-component preparations, which have no single molecular weight to report at all. Where a value has never been established in the published literature the cell says so, rather than carrying an estimate — a plausible-looking number would make the table read as complete while making it wrong.
Mechanisms represented in this category
Every one of the 10 compounds here carries a distinct compound class — this category is grouped by research context, not by a shared mechanism. That is worth knowing before comparing findings across two entries.
Endogenous neurohormone
- Oxytocin — Oxytocin acts through the oxytocin receptor, a G-protein-coupled receptor, mediating uterine contraction and milk let-down in its classical endocrine roles.
Endogenous neuropeptide
- DSIP — DSIP is a neuropeptide historically associated with the promotion of delta-wave (slow-wave) sleep, though its exact receptor and mechanism of action remain poorly defined.
Experimental nootropic / ampakine-class research compound
- Adamax — Ampakines as a class are positive allosteric modulators of AMPA-type glutamate receptors, which can enhance excitatory synaptic transmission.
Neurogenic research peptide
- P21 — P021 is described as an adamantylated, blood-brain-barrier-permeable derivative of a CNTF peptide fragment.
Neurotrophic peptide preparation
- Cerebrolysin — Cerebrolysin is a mixture of low-molecular-weight neuropeptides and free amino acids rather than a single defined peptide.
Short synthetic peptide bioregulator
- Pinealon — Pinealon is a short peptide reported in the Russian bioregulator literature to have neuroprotective and gene-regulatory effects, with proposed activity related to modulation of gene expression in neuronal cells.
Spadin-derived synthetic peptide
- PE-22-28 — PE-22-28 is a shortened, modified analog of spadin designed to block the TREK-1 (two-pore-domain potassium) channel.
Synthetic ACTH analog
- Semax — Semax is an analog of the ACTH(4-10) melanocortin fragment but is described as being devoid of hormonal (corticotropic) activity.
Synthetic angiotensin IV-derived oligopeptide
- Dihexa — Dihexa was designed as an orally active, blood-brain-barrier-penetrant small molecule derived from angiotensin IV.
Synthetic heptapeptide
- Selank — Selank is a stabilized analog of tuftsin (a fragment of the immunoglobulin G heavy chain) and is reported to exert anxiolytic and immunomodulatory effects.
Each line is the opening sentence of that entry's own mechanism record, reproduced verbatim. The full mechanism, the research areas behind it and the evidence level sit on the entry's page.
How the compounds in this category differ
Sharing a category does not make two compounds substitutes. Each note below is the differentiator recorded on that entry — the property that separates it from the others in the table.
Selank
A synthetic heptapeptide studied in anxiolytic and cognitive-research contexts.
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
A 7-amino-acid peptide studied in neuroprotection and cognitive research.
Semax is a melanocortin (ACTH)-derived peptide oriented toward neuroprotection and cognition, whereas Selank derives from tuftsin and is oriented toward anxiolysis.
Dihexa
A synthetic peptide studied in synaptogenesis and cognitive research.
Dihexa is distinguished by its proposed HGF/c-Met-mediated pro-synaptogenic mechanism, unlike the melanocortin (Semax) or tuftsin (Selank) peptides.
Cerebrolysin
A neuropeptide preparation studied in neurological research.
Cerebrolysin is a biologically derived multi-component preparation rather than a single synthetic peptide, distinguishing it from defined molecules like Semax or Dihexa.
P21
A synthetic peptide studied in neurogenesis research.
P21/P021 is distinguished by its CNTF-derived, neurogenesis-focused mechanism, differing from HGF-modulating (Dihexa) or melanocortin (Semax) peptides.
Oxytocin
A naturally occurring nonapeptide studied extensively in social-behavior and neuropeptide research.
Oxytocin is a naturally occurring, FDA-approved hormone, unlike the synthetic research peptides in this class; its behavioral/cognitive applications remain investigational.
Adamax
A synthetic peptide derivative referenced in cognitive and neurological research.
Adamax is distinguished mainly by how little verifiable information exists about it, in contrast to better-characterized peptides in this class.
DSIP
Delta sleep-inducing peptide, a nonapeptide studied in sleep and neurological research.
DSIP is a naturally occurring sleep-associated neuropeptide with an undefined mechanism, distinguishing it from the cognition-focused synthetic peptides in this class.
Pinealon
A short synthetic tripeptide studied in neuroprotection and cellular-aging research.
Pinealon belongs to the ultra-short peptide bioregulator category, unlike the longer or growth-factor-derived peptides elsewhere in this class.
PE-22-28
A synthetic peptide analog of spadin referenced in mood and neuroplasticity research.
PE-22-28 is distinguished by its ion-channel (TREK-1) blocking mechanism aimed at antidepressant effects, unlike the neurotrophic or melanocortin peptides in this class.
Commonly co-studied pairs
Pairings documented on the entries themselves, with the reason each is co-referenced. Cross-referencing research context is not a combination recommendation, and PeptiDex gives no protocol, ratio or dosing guidance.
Within Nootropic & CNS
- Selank + Semax — Sibling Russian heptapeptide co-studied in cognition/anxiety research, with complementary anxiolytic vs. nootropic emphases.
- P21 + Semax — Both are studied as BDNF/neurotrophic-signaling-oriented nootropic research peptides.
- Adamax + Semax — Adamax is a Semax-family analog, so the two are naturally compared in nootropic research discussions.
- DSIP + Pinealon — Both are studied in pineal/CNS-linked regulation, pairing sleep (DSIP) with neuroprotective bioregulator (Pinealon) research.
- PE-22-28 + Semax — Both are studied around BDNF and neurogenesis endpoints in mood/cognition research contexts.
Reaching into other categories
- Cerebrolysin + Epitalon — Both are studied in neuro/longevity research contexts, so they appear together in neuroprotection-oriented research discussions.
- Oxytocin + Kisspeptin-10 — Both are neuropeptides studied around social, reproductive, and limbic signaling, so they appear together in behavioral neuroendocrine research.
- Oxytocin + PT-141 (Bremelanotide) — Both are studied in the context of CNS-mediated sexual and social behavior, a shared research theme.
- DSIP + Epitalon — Both are studied around circadian/pineal and sleep-related neuroendocrine research, so they appear together in sleep and longevity contexts.
1 further pairing is documented on the individual entries. Each note is reproduced from the entry that records the pairing.
What this category is studied for
Research areas drawn from the 10 compounds in this category, deduplicated and ordered by how many entries list them. A further 25 research areas are listed across the individual entries.
Listing a research area records where a compound has been studied. It is not a claim of efficacy, an indication, or a suggestion of human use.
Category questions
How many compounds does PeptiDex list under Nootropic & CNS?
10: Selank, Semax, Dihexa, Cerebrolysin, P21, Oxytocin, Adamax, DSIP, Pinealon and PE-22-28. Each has its own research overview covering compound class, mechanism, studied research areas, specifications and entry-specific questions.
Why do some entries show "Not listed" instead of a molecular weight or half-life?
Because PeptiDex records a specification only where a source documents it. In this category 7 of 10 entries have a published molecular weight and 5 have a reported half-life. Some entries here are blends or multi-component preparations, which have no single molecular weight to report; for the rest, the value has simply not been established in the published literature. An estimate there would look like data and function as a guess, so the gap is shown instead.
What compound classes are represented in this category?
10 distinct classes across the 10 compounds: Synthetic heptapeptide, Synthetic ACTH analog, Synthetic angiotensin IV-derived oligopeptide, Neurotrophic peptide preparation, Neurogenic research peptide, Endogenous neurohormone, Experimental nootropic / ampakine-class research compound, Endogenous neuropeptide, Short synthetic peptide bioregulator and Spadin-derived synthetic peptide. Entries sharing a class are grouped together in the mechanisms section; the comparison table lists each entry's full class verbatim, qualifiers included.
Which entries in this category are studied together?
Selank and Semax are cross-referenced on each other's entries: Sibling Russian heptapeptide co-studied in cognition/anxiety research, with complementary anxiolytic vs. nootropic emphases. The co-studied pairs section lists the rest. Co-reference describes how the literature groups compounds; it is not a combination recommendation and no ratios or protocols are given.
Are the compounds in this category approved for human use?
PeptiDex documents all 10 entries strictly for research and educational purposes and provides no dosing, protocol or human-use guidance. Regulatory status differs from entry to entry and is stated in the regulatory note on each entry's own page. Nothing here is medical advice or a therapeutic claim.
Where should I start in this category?
The comparison table gives the fastest orientation, then the differentiator notes explain why two entries with similar research contexts are not interchangeable. Selank is the entry PeptiDex features here. The glossary defines the vocabulary the entries are written in.
Answers summarise what the catalog records for this category. They are educational context, not medical advice. See the Research Library, the Glossary and each entry's own page for detail.
See also
- Selank vs Semax — the two short Russian-programme peptides most often compared.
- Longevity & Cellular hub — where the peptide-bioregulator research lineage continues.
- Compare Peptides — put any two or three of these entries side by side.
- Glossary — nootropic, agonist, receptor selectivity and half-life.