How we scored it
Ser-Pro-Leu-Gln-NH2: four proteinogenic residues; formula C19H34N6O6 (442.5) matches the C-terminal amide; amide treated as natural; 442.5/442.5 = 1.0.
What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.
Where it comes from
Dominant route: chemical peptide synthesis from fermentation-derived L-amino acids; protecting groups, resins and coupling agents leave no mass. No alternative route is commercially significant.
In plain English
A short peptide of four amino acids (glutamine, leucine, proline and serine) used to condition skin. It is assembled in the laboratory from amino acids that are themselves produced by fermentation or protein hydrolysis.
CosIng definition: Tetrapeptide-26 is the synthetic peptide consisting of glutamine, leucine, proline and serine
Structure
(2S)-2-[[(2S)-2-[[(2S)-1-[(2S)-2-amino-3-hydroxypropanoyl]pyrrolidine-2-carbonyl]amino]-4-methylpentanoyl]amino]pentanediamide
References
- 1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
- 2Tetrapeptide-26. PubChem CID 73507321. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
- 3TETRAPEPTIDE-26. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
- 4TETRAPEPTIDE-26. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=TETRAPEPTIDE-26