Hexapeptide-33
SFKLRY, a cosmetic hexapeptide. The only papers on its sequence studied the C-terminal amide, an angiogenic peptide, in cells and skin-irritation tests.
Hexapeptide-33 is a synthetic hexapeptide, Ser-Phe-Lys-Leu-Arg-Tyr (PubChem's record, under its INCI name, gives the free acid). The papers found on this sequence studied SFKLRY-NH2, the C-terminal amide, which a 2009 library screen identified as angiogenic in human endothelial cells; a 2012 study found it did not irritate skin at low concentration and mildly irritated it at high concentration. The amide is a different molecule from the free acid PubChem records, and no study names the INCI ingredient. It is not a drug.
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Recommended Dosing
No dosing data yet
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Mechanism of action
Not established for the INCI ingredient. The amide SFKLRY-NH2 induced proliferation, migration and tube formation of human endothelial cells and raised VEGF-A through a G-protein and phospholipase C pathway (2009).
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 169450579). 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
Hexapeptide-33 is a cosmetic peptide ingredient with little or no published literature; this section records what can be checked.
Identity, computed
| Sequence | Ser-Phe-Lys-Leu-Arg-Tyr (SFKLRY) |
| Formula | C39H60N10O9 |
| Average mass | 812.97 g/mol |
| Monoisotopic mass | 812.4545 Da |
| Isoelectric point | 10.45 (net charge +1.97 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 “hexapeptide-33”. EMA medicines list: 0 records for “hexapeptide-33”. 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
SFKLRY-NH2 was identified from a combinatorial library as angiogenic in human umbilical vein endothelial cells (Lee et al., 2009).
A safety study under Korean regulatory guidelines found SFKLRY-NH2 not cytotoxic in skin cell lines and non-irritating at low concentration, mildly irritating at high concentration (Kim et al., 2012).
What we looked for and did not find
No study of the free-acid INCI ingredient, no study in people, no registry record and no drug approval.
| Source | Query | Results, October 28, 2026 | What it was |
|---|---|---|---|
| PubMed | "hexapeptide-33"[tiab] OR SFKLRY[tiab] | 2 | |
| ClinicalTrials.gov | hexapeptide-33 | 0 | |
| Drugs@FDA (openFDA) | hexapeptide-33 | 0 | |
| EMA medicines list | hexapeptide-33 | 0 |
References
- [other] PubChem CID 169450579, Hexapeptide-33: formula C39H60N10O9, molecular weight 813.0. Read October 28, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/169450579
- [pubmed] Lee CH, et al. "Identification of novel synthetic peptide showing angiogenic activity in human endothelial cells." Peptides, 2009;30(2):409-18. PMID: 18992291.
- [pubmed] Kim DH, et al. "The Safety Evaluation of a Potent Angiogenic Activator, Synthetic Peptide (SFKLRY-NH2) for the Skin Application." Toxicol Res, 2012;28(1):51-6. PMID: 24278589.
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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.