Nootropic was coined by Corneliu Giurgea in 1972 to describe piracetam and compounds like it. His definition was specific: enhancement of learning and memory, resistance of learned behaviours to disruptive conditions, protection of the brain against physical or chemical injury, improvement of tonic cortical control mechanisms, and — the criterion most often ignored — an absence of the sedative, stimulant or toxic effects typical of psychotropic drugs.
Why the definition matters in a catalog
Almost nothing marketed as a nootropic today satisfies all five criteria, and the word carries no regulatory or mechanistic meaning. In peptide research it functions as a shelving category, grouping molecules with entirely different targets: melanocortin-derived ACTH fragments such as Semax, the tuftsin analogue Selank, angiotensin-IV-derived Dihexa, and the ampakine-adjacent and racetam small molecules. Their proposed mechanisms range from BDNF expression and HGF/c-Met signalling to GABAergic modulation.
Because the category is heterogeneous and much of the peptide literature is Russian-language rodent work plus small clinical series, comparative claims should be framed by study type rather than by category. None of this material is approved in the US; it is supplied research use only.
Related terms and material
neurotrophin · intranasal. Reference material: nootropic peptides, Semax, Selank. Further reading: peptides for focus and memory research.