Thymosin Alpha-1: Research, Handling and Batch Documentation

Identity and research status

Also referred to as

Ta1, Thymalfasin, Zadaxin

Sequence

Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH

One-Letter Sequence

Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN

Length

28 amino acids

Molecular Formula

C129H215N33O55

Molecular Weight

3,108.3 g/mol

CAS Number

62304-98-7

PubChem CID

16130571

INN

Thymalfasin

Parent Protein

Prothymosin alpha, UniProt P06454, residues 1 to 28 of the mature chain

N-Terminus

Acetylated serine

Cysteine Residues

None, so no disulfide bond

Net Charge

Strongly acidic, 9 Glu and 4 Asp against 4 Lys

CAS number

62304-98-7

Mechanism, in brief

Thymosin Alpha-1 has no dedicated receptor of its own. The best-characterised route of action is agonism at Toll-like receptors on antigen-presenting cells. In fungus-pulsed murine dendritic cells, the peptide drove functional maturation and interleukin-12 production through a p38 MAPK and NF-kB dependent pathway that required MyD88, and mice deficient in the relevant Toll-like receptors lost the effect (Romani et al., Blood 2004). A follow-up study in murine cytomegalovirus infection localised the activity to plasmacytoid dendritic cells and traced it through TLR9, MyD88 and IRF7 to an interferon-alpha and interferon-gamma dependent effector arm (Bozza et al., International Immunology 2007).

1. Pattern-recognition engagement. Binds Toll-like receptor 9 on plasmacytoid dendritic cells and Toll-like receptor 2 on myeloid antigen-presenting cells, acting as an agonist rather than binding a dedicated peptide receptor.
2. MyD88-dependent transduction. Signal proceeds through MyD88 to p38 MAPK, NF-kB and IRF7. MyD88-null and TLR9-null mice lose the antifungal and antiviral protection seen in wild-type animals.
3. Dendritic cell maturation. Upregulates MHC class I and II and drives interleukin-12 and type I interferon production, converting resting dendritic cells into competent T cell primers.
4. T cell differentiation. Shifts naive T cells toward a Th1 phenotype, raises interleukin-2 and interferon-gamma, and increases circulating mature CD4-positive and CD8-positive counts in lymphopenic settings.
5. Tolerogenic counterweight. Induces indoleamine 2,3-dioxygenase in dendritic cells, which supports regulatory T cell function and explains the damping seen with bacterial TLR2 and TLR4 agonists.

The full research write-up, including the findings behind each claim and the model each came from, is on the Thymosin Alpha-1 10mg 10mg page.

Vial sizes available

Every size of Thymosin Alpha-1 Volta lists, in stock or not. Each is a separate catalogue page with its own batch number and specification table.

• Thymosin Alpha-1 10mg 10mgBatch #: VPTA10100
  Restocking

Purity and batch documentation

Volta's release specification is >99% (HPLC). That is a threshold we set. >99% is the specification every batch is released to. The figure on a certificate is what a laboratory measured for one lot.

No third-party certificate has been published for Thymosin Alpha-1yet. The certificates Volta does publish, with the laboratory's own verification link on each, are in the certificate archive.

Research on Thymosin Alpha-1

Handling and stability

Regulatory context

United States

Not FDA-approved. FDA orphan drug designation for hepatitis B. Available through compounding pharmacies.

Canada

Not approved by Health Canada.

United Kingdom

Not MHRA-approved.

• the legal status of research peptides in Canada
• Health Canada's regulatory position

Primary sources

1. Goldstein AL, Low TL, McAdoo M, et al.. Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide. Proceedings of the National Academy of Sciences of the USA (1977). doi:10.1073/pnas.74.2.725
2. Sarandeses CS, Covelo G, Diaz-Jullien C, Freire M. Prothymosin alpha is processed to thymosin alpha 1 and thymosin alpha 11 by a lysosomal asparaginyl endopeptidase. Journal of Biological Chemistry (2003). doi:10.1074/jbc.M213005200
3. Romani L, Bistoni F, Gaziano R, et al.. Thymosin alpha 1 activates dendritic cells for antifungal Th1 resistance through toll-like receptor signaling. Blood (2004). doi:10.1182/blood-2003-11-4036
4. Bozza S, Gaziano R, Bonifazi P, et al.. Thymosin alpha1 activates the TLR9/MyD88/IRF7-dependent murine cytomegalovirus sensing for induction of anti-viral responses in vivo. International Immunology (2007). doi:10.1093/intimm/dxm097
5. Giacomini E, Severa M, Cruciani M, et al.. Dual effect of Thymosin alpha 1 on human monocyte-derived dendritic cell in vitro stimulated with viral and bacterial toll-like receptor agonists. Expert Opinion on Biological Therapy (2015). doi:10.1517/14712598.2015.1019460
6. Chien RN, Liaw YF, Chen TC, Yeh CT, Sheen IS. Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial. Hepatology (1998). doi:10.1002/hep.510270527
7. You J, Zhuang L, Cheng HY, et al.. A randomized, controlled, clinical study of thymosin alpha-1 versus interferon-alpha in patients with chronic hepatitis B lacking HBeAg in China. Journal of the Chinese Medical Association (2005). doi:10.1016/s1726-4901(09)70137-6
8. Peng D, Xing HY, Li C, et al.. The clinical efficacy and adverse effects of entecavir plus thymosin alpha-1 combination therapy versus entecavir monotherapy in HBV-related cirrhosis: a systematic review and meta-analysis. BMC Gastroenterology (2020). doi:10.1186/s12876-020-01477-8
9. Wu J, Zhou L, Liu J, et al.. The efficacy of thymosin alpha 1 for severe sepsis (ETASS): a multicenter, single-blind, randomized and controlled trial. Critical Care (2013). doi:10.1186/cc11932
10. Wu J, Pei F, Zhou L, et al.. The efficacy and safety of thymosin alpha1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. BMJ (2025). doi:10.1136/bmj-2024-082583
11. Gu B, Zhou Y, Nie Y, et al.. Efficacy of thymosin alpha1 for sepsis: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Cellular and Infection Microbiology (2025). doi:10.3389/fcimb.2025.1673959
12. Carraro G, Naso A, Montomoli E, et al.. Thymosin-alpha 1 enhances the immunogenicity of an adjuvated pandemic H1N1v influenza vaccine in hemodialyzed patients: a pilot study. Vaccine (2012). doi:10.1016/j.vaccine.2011.12.014
13. Tuthill CW, Awad A, Parrigon M, Ershler WB. A pilot trial of thymalfasin to prevent COVID-19 infection and morbidities in renal dialysis patients: preliminary report. International Immunopharmacology (2023). doi:10.1016/j.intimp.2023.109950
14. Maio M, Mackiewicz A, Testori A, et al.. Large randomized study of thymosin alpha 1, interferon alfa, or both in combination with dacarbazine in patients with metastatic melanoma. Journal of Clinical Oncology (2010). doi:10.1200/JCO.2009.25.5208
15. Liu Y, Pan Y, Hu Z, et al.. Thymosin alpha 1 reduces the mortality of severe coronavirus disease 2019 by restoration of lymphocytopenia and reversion of exhausted T cells. Clinical Infectious Diseases (2020). doi:10.1093/cid/ciaa630
16. Shehadeh F, Benitez G, Mylona EK, et al.. A pilot trial of thymalfasin (thymosin-alpha-1) to treat hospitalized patients with hypoxemia and lymphocytopenia due to coronavirus disease 2019 infection. Journal of Infectious Diseases (2023). doi:10.1093/infdis/jiac362
17. Grottesi A, Sette M, Palamara T, et al.. The conformation of peptide thymosin alpha 1 in solution and in a membrane-like environment by circular dichroism and NMR spectroscopy. Peptides (1998). doi:10.1016/s0196-9781(98)00132-6
18. Ancell CD, Phipps J, Young L. Thymosin alpha-1. American Journal of Health-System Pharmacy (2001). doi:10.1093/ajhp/58.10.886
19. Camerini R, Garaci E. Historical review of thymosin alpha 1 in infectious diseases. Expert Opinion on Biological Therapy (2015). doi:10.1517/14712598.2015.1033393
20. National Center for Biotechnology Information. Thymalfasin (Compound Summary, CID 16130571). PubChem (2026)
21. UniProt Consortium. Prothymosin alpha (PTMA_HUMAN, P06454). UniProtKB (2026)
22. ClinicalTrials.gov. Thymalfasin as an enhancer of vaccine response among older adults receiving booster doses of COVID-19 vaccine (NCT06821100). ClinicalTrials.gov (2024)