This page compares what is documented about Selank and Semax, rather than ranking them by effect. What each molecule is, the sizes and prices actually carried, what the certificate covers, and how the two differ on the bench. Everything here is research-use-only material and we do not publish outcome, dosing or administration content for any compound in the catalogue.
What is Selank and what is Semax?
Selank. Selank is a tuftsin-family heptapeptide developed at the Russian Academy of Sciences, studied in neurochemistry models of BDNF expression and enkephalin degradation.
Semax. Semax, an ACTH(4-7) analogue with a PGP tail, has three decades of neurochemistry literature behind it — BDNF expression work in cellular models above all.
How do Selank and Semax compare on price and size?
| Selank | Semax | |
|---|---|---|
| Sizes carried | 5 mg, 10 mg | 5 mg, 10 mg |
| From | $39.00 | $34.00 |
| Best price per unit | $4.40 / mg | $3.90 / mg |
| Availability | Backordered — waitlist | Backordered — waitlist |
| Certificate | Lot certificate on the product page | Lot certificate on the product page |
| Molecular formula | C33H57N11O9 | C37H51N9O10S |
| Molar mass | 751.9 g/mol | 813.9 g/mol |
| Source | PubChem CID 11765600 | PubChem CID 9811102 |
| Research area | neuropeptide research | neurotrophin research |
At their best sizes Semax works out at $3.90 per mg against $4.40 for Selank — 13% more for the mg. Vial prices start at $39.00 and $34.00 respectively, which is the number most people compare and the one that says least, because the two are not sold in the same sizes. Full sizes, tier pricing and the lot certificate sit on the Selank page and the Semax page.
What is each one studied for?
What the published literature investigates, which is a different question from what either will do, and the only one of the two a supplier can answer.
Selank is studied in neuropeptide research. Tuftsin-family peptides keep a niche but persistent presence in the neurochemistry literature, Selank foremost among them.
Semax is studied in neurotrophin research. ACTH-fragment neuropeptides remain a steady research area, with Semax the most-published compound of the class.
Studied in the same area does not make two compounds interchangeable, and the research library holds the per-compound documentation.
Semax vs Selank: how they differ on the bench
Semax. Semax's PGP tail is the stability engineering; without it the ACTH fragment degrades in minutes. Identity testing confirms the full modified sequence.
Selank. Short neuropeptides like Selank are where net-content testing earns its keep — small absolute masses leave no room for a short-filled vial.
What actually differs between Semax and Selank
Worth doing the arithmetic before comparing sizes: Semax is 813.9 g/mol and Selank is 751.9 g/mol, a factor of 1.1. A milligram of Selank therefore contains roughly 1.1 times as many molecules as a milligram of Semax, so two vials of the same labelled mass hold quite different amounts of substance. Equal milligrams are not equal moles, which is what the molarity calculator exists to convert, and it is the reason a price-per-milligram comparison and a price-per-mole comparison can point at different vials.
Identity is the other analytical axis, and it is settled per lot rather than per compound. Selank. Catalogued as Selank, and the certificate's identity test resolves to that. Semax. Catalogued as Semax, and the certificate's identity test resolves to that.
Both are released against a certificate reporting identity, purity by the stated method and net peptide content, readable before anything is bought.
Which is better, Semax or Selank?
Neither Semax nor Selank is ranked against the other here, and the refusal is deliberate. Better, safer and stronger are questions about effects in a living system, and we sell neither compound for use in one — why none of these pages ranks two compounds sets out the reasoning in full.
What it does instead, for these two:
- Semax is the cheaper of the two per mg, at $3.90 against $4.40.
- Semax is the heavier molecule by a factor of 1.1, so equal milligrams are not equal moles.
- Both are carried in 2 sizes, and each lot carries its own certificate.
Every one of those is checkable before you buy.
Common questions
What is the difference between Semax and Selank?
Different molecules before anything else: Semax is C37H51N9O10S and Selank is C33H57N11O9. Semax, an ACTH(4-7) analogue with a PGP tail, has three decades of neurochemistry literature behind it — BDNF expression work in cellular models above all. Selank is a tuftsin-family heptapeptide developed at the Russian Academy of Sciences, studied in neurochemistry models of BDNF expression and enkephalin degradation.
Which one should I choose?
Selank is carried in 5 mg, 10 mg and Semax in 5 mg, 10 mg, each lot with its own certificate. Which of those suits the work is yours to decide; everything here is research-use-only rather than guidance for use in a human or an animal.
Do both Selank and Semax come with a certificate of analysis?
Neither is in stock at the moment, so in each case the certificate is the one attached to the lot that arrives. A certificate belongs to a lot, not to a product. It is linked from the product page, and reports identity, purity by the stated method, and net peptide content for the material actually in that lot.
Which is cheaper, Semax or Selank?
Per mg, Semax at $3.90 against $4.40, taking each one's best size. By vial they start at $39.00 for Selank and $34.00 for Semax, which is the comparison most people make and the one that says least, because the two are not sold in the same sizes.
Is a milligram of Selank the same as a milligram of Semax?
By mass yes, by amount of substance no. Semax is 813.9 g/mol and Selank is 751.9 g/mol, a factor of 1.1, so a milligram of Selank holds roughly 1.1 times as many molecules. Two vials with the same number on the label are not the same amount of substance, which is what the molarity calculator converts.
FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. NOT FOR PERSONAL, MEDICAL, DIAGNOSTIC, THERAPEUTIC, OR RECREATIONAL USE.