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What Is Thymosin Alpha-1 (Tα1)?

Research overview · Published July 2026 · For research use only

Thymosin Alpha-1 (Tα1), also called thymalfasin, is a 28-amino-acid peptide identical to a naturally occurring thymic peptide, studied for immune-modulating activity. Its regulatory status differs by country — see the note below.

The short answer

Thymosin Alpha-1 is a fragment of the larger prothymosin-α protein, produced in the thymus and involved in immune regulation. As a synthetic peptide (thymalfasin) it is one of the more clinically studied peptides in this catalog and is an approved medicine in a number of countries, though not the United States.

Composition and specifications

CompoundThymosin Alpha-1 (Tα1)
ClassImmune-modulating peptide (28 aa)
Also known asThymalfasin · CAS 62304-98-7
Sequence / length28 amino acids (N-terminally acetylated)
CAS number62304-98-7
Molecular weight3108.3 g/mol
Purity (typical)≥98.0%
AppearanceWhite lyophilized powder; water-soluble

Values above reflect the compound's published specification. As with any research material, the definitive confirmation of identity and purity for a given lot is the mass-spectrometry and HPLC data on its Certificate of Analysis.

How it is described mechanistically

Thymosin Alpha-1 is characterized in research as an immunomodulator that influences T-cell maturation and function and toll-like-receptor-associated signaling. These descriptions come from a substantial immunology literature, including clinical studies conducted in countries where the drug product is approved.

What has research examined?

Thymosin Alpha-1 has one of the deeper evidence bases in this catalog. Areas examined include:

Approval abroad does not make US research-grade material a medicine; the research-grade compound is supplied for laboratory use only.

Research use only. Thymosin Alpha-1 is intended for laboratory and experimental use by qualified researchers — not for human or veterinary administration, diagnosis, or treatment. Nothing on this page is medical advice.

How is it characterized and tested?

Two questions matter most about any peptide sample in a research context: is it the right molecule, and how pure is it. Those are answered by analytical testing — commonly mass spectrometry for identity and HPLC for purity — with both reported on a batch-specific Certificate of Analysis (COA). An independent, published COA lets a researcher confirm identity and purity before beginning work. See peptide handling and storage for how samples are kept stable once received.

Primary literature: browse peer-reviewed studies on Thymosin Alpha-1 at PubMed.

Common questions

Is Thymosin Alpha-1 FDA-approved?

A thymalfasin drug product is approved in a number of countries but is not FDA-approved in the United States. The research-grade material offered here is supplied for laboratory research use only.

How is Thymosin Alpha-1 different from Thymosin Beta-4?

They are different peptides in the thymosin family. Alpha-1 (28 aa) is studied mainly for immune modulation; Beta-4 (43 aa) is studied mainly as an actin-sequestering, tissue-repair-associated peptide.

What is Thymosin Alpha-1 studied for?

Primarily immune-modulation and T-cell signaling, with a clinical literature from countries where the drug product is approved.