Neuropeptides are signaling peptides of the nervous system. This class holds seven research compounds: Semax and Selank (short Russian-origin peptides), DSIP, oxytocin, the melanocortin analogs PT-141 and Melanotan 2, and VIP. The product pages describe the receptor each one acts on and what the published studies measured.
What is in this class?
A neuropeptide is a short chain of amino acids that neurons use to signal. This class groups seven of them by the receptor or pathway they act on. Semax, an ACTH(4–10) analog, and Selank, a tuftsin analog, are seven-residue peptides from the Russian literature; most of their studies read gene expression and behavior in rodent models. DSIP, the delta-sleep-inducing peptide, is a nine-residue peptide studied in sleep-architecture and stress models. Oxytocin acts on the OXTR receptor. PT-141 (bremelanotide) and Melanotan 2 are cyclic α-MSH analogs that act on melanocortin receptors, PT-141 more selectively on MC3R and MC4R. VIP, vasoactive intestinal peptide, is a 28-residue peptide with receptors on neurons, gut and immune cells.
What do the studies actually measure?
Receptor binding and downstream signaling first; then expression of markers such as BDNF; then behavior in defined animal tests. Human evidence varies a lot across the class. Oxytocin and bremelanotide have clinical literatures; Semax and Selank have almost no human studies outside Russia, and the one randomised trial of Semax was negative on its primary endpoint. The product pages state this. A 2020 analysis of seized preparations also found these peptides sold with variable content, which is why identity and purity matter more than marketing.
How do the compounds compare?
| Compound | What it is | Sequence / formula | Molecular weight | Sources cited on its page |
|---|---|---|---|---|
| Semax | ACTH(4–10) analog, 7 amino acids | MEHFPGP | 813.9 Da | 14 |
| Selank | tuftsin analog, 7 amino acids | TKPRPGP | 751.9 Da | 7 |
| DSIP | delta-sleep-inducing peptide, 9 amino acids | WAGGDASGE | 848.8 Da | 6 |
| Oxytocin | 9-amino-acid cyclic neuropeptide | CYIQNCPLG-NH₂ | 1,007.2 Da | 11 |
| PT-141 | cyclic α-MSH(4–10) analog (bremelanotide) | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH | 1,025.2 Da | 14 |
| Melanotan 2 | cyclic α-MSH analog, non-selective melanocortin agonist | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ | 1,024.2 Da | 11 |
| VIP | vasoactive intestinal peptide, 28 amino acids | HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH₂ | 3,326.8 g/mol | 16 |
Sequences and molecular weights are the values verified on each product page. "Sources cited" is the count shown on that page on 28 August 2026.
Where do I read more?
Every compound on this page is supplied for laboratory research only. Each product page carries its full reference list.
References
- Filippenkov IB et al. (2024). ACTH-like peptides compensate rat brain gene expression profile disrupted by ischemia. Biomedicines. PMID 39767736
- Vanhee C et al. (2020). The occurrence of putative cognitive enhancing research peptides in seized pharmaceutical preparations. Drug Test Anal. PMID 31667971
- Tukhovskaya EA et al. (2021). DSIP-like KND peptide reduces brain infarction in C57Bl/6 mice and myocardial infarction in SD rats. Biomedicines. PMID 33918965
- Borland JM et al. (2025). Female Syrian hamster analyses of bremelanotide. Neuropharmacology. PMID 39793696
- Fu Y et al. (2026). Divergent effects of peripheral vs. central oxytocin administration on observational fear behavior in mice. Pharmaceuticals (Basel). PMID 41901198
- Anastasio C, Peduto L (2026). Neuronal VIP shapes intestinal stem cell activity and mucosal immunity. Cell Stem Cell. PMID 41795422