Acetyl Tetrapeptide-11
Ac-PPYL, a cosmetic tetrapeptide sold for skin firmness. Its one paper tests it in skin cells in combination with other peptides.
Acetyl tetrapeptide-11 is a synthetic tetrapeptide, Ac-Pro-Pro-Tyr-Leu (PubChem lists it under its INCI name). It is sold as an anti-ageing skin-care ingredient. The one paper found is a 2021 cell study in which combinations including Ac-PPYL, with Pal-KTTKS and niacinamide or with Pal-KT, produced synergistic responses in keratinocytes and fibroblasts. No study in people was found. It is not a drug.
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Recommended Dosing
No dosing data yet
This page has no dosing data yet.
Mechanism of action
Not established on its own. In a 2021 cell study, Ac-PPYL with Pal-KTTKS and niacinamide activated NRF2-mediated oxidative-stress responses, and with Pal-KT it restored cellular adenosine triphosphate; the effects were measured for the combinations.
Primary uses
- Cosmetic skin-care formulations
Typical dosing
No published study states an amount of this ingredient used on skin, and a supplier's use level is not a source on this site, so none is given.
Regulatory status
Not a drug: PubChem lists it under its INCI name as a cosmetic ingredient (CID 91936941). Drugs@FDA and the EMA medicines list hold no record for it (searched October 28, 2026).
Status as of this entry's last review, October 28, 2026. Approvals, compounding rules and sport rules change; the regulatory tracker is checked more often.
What we checked
Acetyl Tetrapeptide-11 is a cosmetic peptide ingredient with little or no published literature; this section records what can be checked.
Identity, computed
| Sequence | Ac-Pro-Pro-Tyr-Leu (Ac-PPYL) |
| Formula | C27H38N4O7 |
| Average mass | 530.62 g/mol |
| Monoisotopic mass | 530.274 Da |
| Isoelectric point | 0.0 (net charge -1.0 at pH 7) |
The sequence is the one PubChem's record gives for the INCI ingredient; the values below are computed and agree with PubChem's formula.
Regulatory status, read October 28, 2026
Drugs@FDA: 0 records for “acetyl tetrapeptide-11”. EMA medicines list: 0 records for “acetyl tetrapeptide-11”. Run for semaglutide, the same queries return 6 and 5 records (and the registry search 80 trials), so a zero here is an absence, not a broken search. Not named on the WADA 2026 and 2027 Prohibited Lists. As a substance with no current approval for human therapeutic use, it falls under section S0 (non-approved substances), which is prohibited at all times; the lists were read on October 28, 2026.
What the studies show
In keratinocyte and fibroblast cell lines, combinations containing Ac-PPYL produced synergistic gene-expression and energy (adenosine triphosphate) responses compared with the single peptides (Flagler et al., 2021).
What we looked for and did not find
No study in people, no registry record and no drug approval.
| Source | Query | Results, October 28, 2026 | What it was |
|---|---|---|---|
| PubMed | ("tetrapeptide-11"[tiab] AND acetyl[tiab]) OR "Ac-PPYL"[tiab] | 1 | the hyphenated name is matched word by word |
| ClinicalTrials.gov | acetyl tetrapeptide-11 | 0 | |
| Drugs@FDA (openFDA) | acetyl tetrapeptide-11 | 0 | |
| EMA medicines list | acetyl tetrapeptide-11 | 0 |
References
- [other] PubChem CID 91936941, Acetyl Tetrapeptide-11: formula C27H38N4O7, molecular weight 530.6. Read October 28, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/91936941
- [pubmed] Flagler MJ, et al. "Combinations of peptides synergistically activate the regenerative capacity of skin cells in vitro." Int J Cosmet Sci, 2021;43(5):518-529. PMID: 34272744.
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This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.