Structure · schematic
Peptide chain of 28 amino acids · Thymuspeptid
Sequence
Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN
Schematic representation of the amino acid chain — not a chemical structural formula. Each node represents one amino acid (shown truncated).
Research areas*
* Contexts in which the peptide has been scientifically studied — not assured or recommended effects.
Mechanism of action
- Thymosin alpha-1 (Tα1) is a 28-amino-acid peptide originally isolated as fraction 5 from the thymus.
- It is a natural cleavage product of prothymosin alpha and is produced mainly in thymic epithelial cells.
- Tα1 modulates T-cell maturation and function: it promotes the Th1 response, increases the activity of natural killer cells (NK cells) and stimulates the production of IL-2, interferon-gamma and interferon-alpha.
- Its molecular site of action includes Toll-like receptors (TLR2 and TLR9) on dendritic cells, which explains its activation of the adaptive immune response.
Research status
- Among peptides not approved in the EU, thymosin alpha-1 has a comparatively strong clinical evidence base.
- In China and several other countries, Zadaxin (thymalfasin) is approved for the treatment of chronic hepatitis B and C and as an adjuvant in malignant disease.
- Several randomised controlled studies have investigated Tα1 in hepatitis B (reduced viral load, improved HBeAg seroconversion) and sepsis-associated immune deficiencies.
- During the COVID-19 pandemic, thymosin alpha-1 was used in China as a supportive treatment; retrospective analyses showed reduced mortality in severely ill patients in some studies, though methodological limitations exist.
Evidence level
Cited studies
Known risks
- 01Generally well tolerated in clinical studies — no serious safety signal known
- 02Local injection-site reactions (pain, redness) the most commonly described side effect
- 03Theoretical risk of immune stimulation in pre-existing autoimmune conditions
- 04Long-term data for continuous use outside clinical studies are lacking
- 05Quality control not guaranteed from unapproved sources
Frequently asked questions
What is Thymosin Alpha-1?
Thymosin alpha-1 (Tα1) is a 28-amino-acid peptide originally isolated as fraction 5 from the thymus.
What type of peptide is Thymosin Alpha-1?
Thymosin Alpha-1 belongs to the Thymic peptide class.
Is Thymosin Alpha-1 legal in Germany?
Thymosin Alpha-1 is not approved as a medicine in Germany. Obtaining it outside clinical studies is legally problematic.
Where can I buy Thymosin Alpha-1?
Peptica sells nothing and names no sources. Thymosin Alpha-1 is "not approved" in Germany; obtaining unapproved substances outside clinical studies is illegal and carries quality and safety risks.
Is Thymosin Alpha-1 banned in sport (WADA)?
Thymosin Alpha-1 is currently not on the WADA Prohibited List.
What are the known risks of Thymosin Alpha-1?
Documented risks include: Generally well tolerated in clinical studies — no serious safety signal known; Local injection-site reactions (pain, redness) the most commonly described side effect. This is not a complete safety assessment and not medical advice — see the risks section for the full list.
How well researched is Thymosin Alpha-1?
The evidence is classified as “early clinical studies”. 3 studies are cited on this page.
What is the molecular weight of Thymosin Alpha-1?
Thymosin Alpha-1 has a molar mass of about 3108.3 Da, with a plasma half-life of ~2 hours.
Which peptides are related to Thymosin Alpha-1?
Closely related entries: Epithalon, LL-37. A direct side-by-side comparison is available via the compare function.
Related entries
Legal status
Germany
not approvedAustria
not approvedSwitzerland
not approvedEU
not approvedUSA
not approvedCanada
not approvedLegal status varies by country and can change. This is not legal advice.
Sources & methodology
- 3 peer-reviewed studies cited, linked to PubMed where available.
- Molecular data verified against PubChem and primary literature. PubChem CID 16130571
- Editorial standard: no dosage guidance, no sources, evidence level stated explicitly.
Last editorially reviewed: 28 May 2026
Legal assessment
Thymalfasin (Zadaxin) is not approved as a medicine in the EU, Germany, Austria or Switzerland. It is approved in China, Italy and about 35 other countries for hepatitis indications. Not on the WADA list. Importing it without a medical prescription and approval is legally problematic in Germany (AMG).
Important notice
This site is intended solely for factual, scientifically oriented information about peptides. It does not constitute medical advice, does not replace a consultation with a doctor and contains no recommendations for use in humans.
This site does not sell any substances and names no sources for unapproved substances. For medical questions, please consult qualified medical professionals.
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