Thymosin Alpha-1 (Thymic Peptide)

Thymosin Alpha-1 is a 28-amino-acid peptide originally isolated from the thymus gland, the organ central to immune-cell development. It is N-terminally acetylated, carries CAS number 62304-98-7, and has the molecular formula C129H215N33O55 with a molecular weight of 3108.3 g/mol.

Under the name thymalfasin (Zadaxin), this molecule is used clinically in some countries. It is studied as an immune-modulating peptide and is supplied here as a research compound in lyophilized powder form for laboratory reconstitution.

Thymosin alpha-1 is approved as a prescription medicine in a number of countries outside the United States under the name thymalfasin. It holds no approved indication in the United States, and the material listed here is a research-grade reference peptide, not that product.

Thymosin Alpha-1 was identified in the 1970s through the work of Allan Goldstein and colleagues on thymic peptides. A 2001 monograph by Ancell and colleagues in the American Journal of Health-System Pharmacy summarized the early profile of thymosin alpha-1 (PubMed 11381492).

A 2016 review by King and Tuthill in Vitamins and Hormones surveyed immune modulation with thymosin alpha-1 treatment (PubMed 27450734), and a 2025 review in the International Journal of Molecular Sciences examined it in the context of aging (PubMed 41373628). It has a more developed clinical record than most peptides in this encyclopedia.

In research models, Thymosin Alpha-1 is studied for effects on immune-cell function, particularly T-cell maturation and the activity of dendritic cells, with proposed signaling through Toll-like receptors. This immune-modulating profile is the focus of most of its research literature.

It is biochemically distinct from the beta-thymosin family that includes TB-500, despite the shared thymosin name. For current findings, search PubMed directly.

Lyophilized Thymosin Alpha-1 is generally stored at -20°C for long-term holding, with stability reported around 24 months. Refrigeration at 2°C to 8°C suits shorter windows, away from light and moisture.

The lot-specific Certificate of Analysis is the authoritative reference for a given batch.

Reconstitution means returning a lyophilized compound to solution. This page gives no preparation procedure: solvent, concentration and handling steps belong to the methodology of the study being reproduced, not to a compound reference. Thymosin Alpha-1 is handled as aqueous-soluble material.

Lyophilized material is hygroscopic, so a sealed container is allowed to reach ambient temperature before it is opened. Solubility and water-content figures for a given lot appear on its Certificate of Analysis.

Identity and purity of research-grade Thymosin Alpha-1 are established analytically, by HPLC with mass spectrometric confirmation of the expected mass. Verified purity is documented per lot on the Certificate of Analysis. The N-terminal acetylation should be reflected in the identity confirmation.

Check HPLC purity, mass-spec identity, and net peptide content on the Certificate of Analysis. peptides.com publishes lot-specific lab reports for verification.

Thymosin Alpha-1 is grouped with immune-context and regenerative research peptides:

• TB-500.
  A beta-thymosin family peptide studied in repair models. 
• BPC-157.
  A repair-context research peptide. 
• Epitalon.
  A tetrapeptide studied in longevity-context research.

Ancell CD, Phipps J, et al. (2001). Thymosin alpha-1. American Journal of Health-System Pharmacy.
PubMed 11381492

King R, Tuthill C (2016). Immune Modulation with Thymosin Alpha 1 Treatment. Vitamins and Hormones.
PubMed 27450734

Simonova MA, Ivanov I, et al. (2025). Aging and Thymosin Alpha-1. International Journal of Molecular Sciences.
PubMed 41373628

peptides.com carries Thymosin Alpha-1 in research-grade lyophilized vials. Each ships with a batch-specific Certificate of Analysis.

• Browse all Thymosin Alpha-1 research products
• Catalyst Compounds Thymosin Alpha-1
• Collections: Research Vials. Documentation: COA and Lab Testing.

These products are sold for Research Use Only and are not intended for human consumption.