Cognitive and neuroactive
Arkham Labs editorial/Published 8 September 2026/Revised 12 September 2026/Corrections policy
Regulatory peptides and small molecules acting on the central nervous system, several of them designed to the same template: take a natural fragment, add Pro-Gly-Pro for protease resistance. Much of the human data exists but was generated and published outside the English-language literature.
Two facts in this family matter more than any grade it carries.
The mechanistic foundation of Dihexa was retracted in April 2025. The structure of P21 is disputed within its own literature — six residues in the founding paper, described differently elsewhere, under two names used interchangeably. Alongside those, N-Acetyl Semax Amidate and N-Acetyl Selank Amidate are both graded Preclinical as a floor: no study of either modified compound exists at any level. Noopept holds Approved Pharma on a Russian prescription registration and is not a peptide; Cerebrolysin holds Mixed Evidence across seven Cochrane reviews of acute ischaemic stroke and is not a defined molecule. The parent compounds, Semax and Selank, are the only two here with indexed human studies.
- Guides in this family
- 8
- Peer-reviewed sources
- 155
- Grades represented
- Preclinical 4 · Early 2 · Approved 1 · Mixed 1
- Cerebrolysin≠Mixed Evidence
- Dihexa◦Preclinical
- N-Acetyl Selank Amidate◦PreclinicalFloor
- N-Acetyl Semax Amidate◦PreclinicalFloor
- Noopept§Approved Pharma
- P21◦Preclinical
- Selank+Early Clinical
- Semax+Early Clinical
Two of the eight are modified variants of other members with no study of the variant itself at any level — the parent compound’s evidence is routinely cited as though it transferred.
For laboratory research use only. Not for human consumption. Nothing here is medical advice.