Published · 9 references
Selank vs Semax
Selank and Semax are different molecules: synthetic seven-residue peptides that carry the same three-residue C-terminal extension, on tuftsin in Selank and on an ACTH core in Semax.
Structure at a glance
Selank · 7 residues
Semax · 7 residues
Letters are one-letter amino acid codes.
Drawn from the product database. Each measure's bars share one scale.
| Property | Selank | Semax |
|---|---|---|
| What it is | A synthetic seven-residue peptide: tuftsin, a four-residue fragment of the immunoglobulin G heavy chain, extended at the C-terminus by three residues. | A synthetic seven-residue peptide: the ACTH(4-7) core, extended at the C-terminus by three residues. An analog of the ACTH(4-10) region, not a fragment of it. |
| How they relate | Different molecules built the same way. Both carry the same three-residue C-terminal extension, on different four-residue starting peptides: tuftsin in Selank, the ACTH(4-7) core in Semax. | |
| CAS number | 129954-34-3 | 80714-61-0 |
| Molecular formula | C33H57N11O9 | C37H51N9O10S |
| Molecular weight | 751.88 g/mol | 813.92 g/mol |
| Sequence | TKPRPGP | MEHFPGP |
| Target | No target established for Selank. Its proposed mechanisms are multiple and not fully reconciled. | No target established for Semax. Its proposed mechanisms are multiple, and no single unifying account is settled. |
| Evidence base | In the literature reviewed for Selank: mostly preclinical work, and a handful of small Russian human studies, each with an author from the developing institute. | In the literature reviewed for Semax: mostly preclinical work, and small human studies, most of them Russian-language and largely from the developers' own network. |
| Regulatory status | A medicine containing selank is registered in Russia.[1] No US approval.[2] | A medicine containing semax is registered in Russia.[3] No US approval.[4] |
| Compared head-to-head? | Yes: a 2001 study tested Selank and Semax on enkephalin-degrading enzymes from human serum, in vitro.[5] A 2020 imaging study compared Selank, Semax and placebo in 52 healthy participants.[6] | |
| Handling difference | Selank contains no methionine. Semax contains one, which oxidizes on air exposure. Neither contains a cysteine. | |
How Selank and Semax differ
Selank and Semax are different molecules. Both are synthetic seven-residue peptides, and both carry the same three-residue C-terminal extension. The four residues before that extension come from a different natural molecule in each.
Selank's first four residues are tuftsin, a natural four-residue fragment of the heavy chain of immunoglobulin G, an antibody protein. Semax's first four residues correspond to positions 4 to 7 of adrenocorticotropic hormone (ACTH). Semax is a synthetic analog of the ACTH(4-10) region rather than a fragment of it: ACTH residues 8 to 10 are absent from Semax, replaced by the extension.
Both were developed at the same Russian research institute. Russian research settings also generated most of the human data on the two. For each compound, a large share of the published work comes from a small network of affiliated Russian institutes, much of it in Russian-language journals. In both cases, that limits independent replication.
In the literature reviewed for Selank, most of the work is preclinical, and the human studies are a handful of small Russian studies. An author from the developing institute is on every human study described there. In the literature reviewed for Semax, most studies are also preclinical, and the human studies are small and come largely from the developers' own network.
The two also differ in charge. Selank is strongly cationic, with no acidic side chain. Semax's net charge is close to balanced, and more pH-sensitive across the ordinary working range than a sequence carrying only strong acids and bases.
Selank has no US approval.[2] Nor does Semax.[4] Separate medicines containing selank and semax are registered in Russia.[1][3] Neither material supplied here is one of those medicines: each is a research-grade preparation and holds no marketing authorization.
Have Selank and Semax been compared directly?
Four of the 11 records returned by a PubMed search run in October 2026 were direct comparisons of the two compounds.[7] A 2001 study tested Selank and Semax on enkephalin-degrading enzymes from human serum, in vitro.[5] Results are reported for each compound in that assay. A 2017 study tested Selank and Semax on mouse embryonic stem cells, in vitro.[8] Results are reported for each compound in that assay. Another 2017 study tested Selank and Semax in a rat 6-hydroxydopamine model.[9] Results are reported for each compound in that model. A 2020 imaging study compared Selank, Semax and placebo in 52 healthy participants.[6] Results are reported for each compound in that study. Further records indexed under both compounds have no available abstract and are not described here.
Read more on each compound
Selank
Frequently Asked Questions
Is Selank the same as Semax?+−
Selank and Semax are not the same molecule, though both are synthetic seven-residue peptides that carry the same three-residue C-terminal extension. Selank's first four residues are tuftsin, a fragment of the heavy chain of an antibody protein. Semax's correspond to positions 4 to 7 of ACTH, and Semax is an analog of the ACTH(4-10) region, not a fragment of it.
Were Selank and Semax developed at the same institute?+−
Selank and Semax were both developed at the same Russian research institute. Russian research settings also generated most of the human data on the two. For each compound, a large share of the work comes from a small network of affiliated Russian institutes, and much of it is published in Russian-language journals. This limits independent replication.
Is Selank or Semax approved?+−
Separate medicines containing selank and semax are registered in Russia. Neither material supplied here is one of those medicines: each is a research-grade preparation and holds no marketing authorization. Neither Selank nor Semax has a US approval.
References
- 1Vidal Russian drug reference, entry for Selank (vidal.ru/drugs/selank__21568), retrieved 3 October 2026: current Russian registration dated 15 July 2025. vidal.ru
- 2US Food and Drug Administration, Drugs@FDA, queried via api.fda.gov for selank; no record. Retrieved 3 October 2026. fda.gov
- 3State Register of Medicines (GRLS), Ministry of Health of the Russian Federation, entries for Semax, retrieved 2 October 2026: registrations dated 26 March 2025 and 18 June 2025, listed as valid. grls.rosminzdrav.ru
- 4US Food and Drug Administration, Drugs@FDA. Queried via api.fda.gov/drug/drugsfda.json for semax and semax acetate, 3 October 2026: no record.
- 5Kost NV, Sokolov OYu, Gabaeva MV, Grivennikov IA, Andreeva LA, Myasoedov NF, et al. Semax and selank inhibit the enkephalin-degrading enzymes from human serum. Bioorg Khim. 2001;27(3):180-183. PMID 11443939.
- 6Panikratova YR, Lebedeva IS, Sokolov OY, Rumshiskaya AD, Kupriyanov DA, Kost NV, Myasoedov NF. Functional connectomic approach to studying Selank and Semax effects. Dokl Biol Sci. 2020;490(1):9-11. PMID 32342318. doi:10.1134/S001249662001007X.
- 7PubMed search via NCBI E-utilities, run 3 October 2026; records entered to 2 October 2026. Query: ("selank"[tiab]) AND ("semax"[tiab]) AND ("1800/01/01"[edat] : "2026/10/02"[edat]). 11 records; 4 were direct comparisons, as described above.
- 8Kobylyanskii AG, Zolotarev YA, Andreeva LA, Grivennikov IA, Myasoedov NF. Bull Exp Biol Med. 2017;163(6):731-736. PMID 29063333. doi:10.1007/s10517-017-3891-y.
- 9Slominsky PA, Shadrina MI, Kolomin TA, Stavrovskaya AV, Filatova EV, Andreeva LA, et al. Dokl Biol Sci. 2017;474(1):106-109. PMID 28702721. doi:10.1134/S0012496617030048.
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