Thymosin alpha-1
Also known as: Tα1 · thymalfasin
A 28-residue thymic peptide with immunomodulatory activity, approved in some jurisdictions as thymalfasin.
Development status: Approved as a medicine in one or more jurisdictions
Identifiers and molecular characteristics
- CAS number
- Not verified
- Molecular formula
- Not verified
- Molecular mass
- Not verified
- Amino-acid sequence
- Not verified
- PubChem CID
- Not verified
Identifiers are published only with a source and a check date. Fields marked “not verified” have not yet been confirmed against a primary source — we show the gap rather than an unchecked figure. Always confirm against the certificate of analysis for the specific lot you hold.
Biological targets
- Toll-like receptor signalling (reported)
- T-cell maturation pathways
Mechanism of action
Reported to influence T-cell differentiation and innate immune signalling. Distinct from thymosin beta-4 despite the shared family name — the thymosins are a nomenclature grouping, not a structural family.
Research evidence and its limits
Clinical trials in hepatitis and as a vaccine adjuvant, with approval in several countries.
Safety considerations
Where this compound is an approved medicine, the authoritative safety source is the product labelling issued by the relevant regulator — not this page. Research-grade material is not pharmaceutical product and carries none of those assurances. Supplied and discussed here strictly as a laboratory research material. Not a medicine, not for human or veterinary administration, and nothing on this page should be read as a dosing, treatment or safety recommendation.
Analytical identification and quality testing
Identity by high-resolution mass spectrometry against the expected mass, purity by RP-HPLC with UV detection. Tandem MS sequencing or peptide mapping gives stronger identity evidence than mass alone.
Regulatory status
Approved in a number of jurisdictions. Not FDA-approved.
Frequently asked questions
Is thymosin alpha-1 related to thymosin beta-4?
Only by name and tissue of origin. They are structurally unrelated peptides with different biology. The "thymosin" label is historical nomenclature from fractionation of thymic extracts, not a structural classification.
References
Related compounds
TB-500 (thymosin beta-4 fragment)
A synthetic peptide corresponding to an active region of thymosin beta-4. Frequently conflated with full-length thymosin beta-4, which is a different and longer molecule — the two should not be treated as interchangeable.
LL-37
The only human cathelicidin, released by proteolytic processing of the precursor hCAP18. A central molecule in innate immunity and in antimicrobial peptide research.
Entry last reviewed 2026-10-11. Regulatory status and scientific understanding change; verify against primary sources before relying on anything here.