Thymosin Alpha-1

Product Details

Thymosin Alpha – 1 (Thymalfasin, Zadaxin) — Research Grade Peptide, ≥98% Purity (HPLC)

Immunomodulatory thymic peptide. TLR signaling agonist. Lyophilized powder. Lot-specific COA included.

Thymosin Alpha – 1 (Tα1), also known as thymalfasin, is a synthetic 28-amino-acid peptide corresponding to the N-terminally acetylated form of the naturally occurring thymic hormone first isolated by Allan Goldstein and colleagues in 1977. It is not the same as Thymosin Beta-4 or its fragment TB-500 — the two share only a name, not a structure or mechanism.

The peptide’s research profile centers on Toll-like receptor (TLR) signaling. Tα1 primes dendritic cells for T-helper type 1 (Th1) resistance through TLR9/MyD88-dependent signaling, activates plasmacytoid dendritic cells via the TLR9/MyD88-dependent viral recognition pathway, and binds apoptotic bodies to trigger TLR7 signaling in dendritic cells. Through these pathways, Tα1 promotes T-cell maturation and Th1 polarization, enhances natural killer cell activity, and modulates tumor-associated macrophages and myeloid-derived suppressor cells.

The clinical evidence base is the strongest of any immunomodulatory peptide in this catalog, and it cuts both ways. In chronic hepatitis B, 26 weeks of Tα1 therapy produced a 40.6% complete virological response (clearance of both HBV DNA and HBeAg) versus 9.4% in untreated controls (P = .004). In the 2025 TESTS Phase III trial of 1,089 sepsis patients, however, Tα1 produced a 28-day mortality of 23.4% versus 24.1% on placebo (hazard ratio 0.99, 95% CI 0.77 to 1.27) — no clear evidence of benefit.

Supplied as a sterile-filtered, lyophilized powder for in vitro and preclinical research applications. Each lot is independently verified for purity and identity and ships with a Certificate of Analysis.

Specifications

Note: Thymosin Alpha-1 is supplied in both free base and acetate salt forms. FDA reviewed both forms (thymosin alpha-1 free base and thymosin alpha-1 acetate) for the 503A Bulks List. Verify the exact form, molecular weight, and purity against the Certificate of Analysis supplied with your lot. The compound should not be confused with Thymosin Beta-4 (TB-500), which has a different sequence and a different mechanism.

Research applications

Thymosin Alpha-1 is used in laboratory settings to investigate:

• TLR9/MyD88-dependent dendritic cell priming — activation of plasmacytoid dendritic cells via TLR9 signaling for antiviral T-helper type 1 resistance in vivo

• TLR7 signaling and chemotherapy-induced immunity — Tα1 binds apoptotic bodies and protects AB-borne miR146a-5p from degradation in dendritic cells, triggering TLR7 signaling and driving DC activation to prime tumor-specific T cells

• CD8⁺ T-cell activation and exhaustion reversal — Tα1 promotes functional activation of CD8⁺ T-cells and mitigates exhaustion marker expression following chronic stimulation in vitro

• HIV latency and IL-15 pathway research — Tα1-induced secretion of the IL-15/RA complex by THP-1-derived dendritic cells restrains HIV latency in vitro, enhancing CD8+ T cell function and suppressing reservoir size

• Hepatitis B and C virological response — 26 weeks of Tα1 therapy produced 40.6% complete virological response versus 9.4% in controls (P = .004) in chronic hepatitis B

• Sepsis and critical illness research — the TESTS Phase III trial (N = 1,089) found no reduction in 28-day mortality (23.4% vs 24.1%, HR 0.99)

• Cancer immunotherapy adjunct research — Tα1 may remodel immunosuppressive “cold” tumors toward immune-responsive states and enhance responses to chemotherapy, radiotherapy, and immune checkpoint blockade

• Analytical method development — LC-MS/MS quantification and reference standard preparation for thymic peptide analysis in biological matrices

Handling and storage

Reconstitute under aseptic conditions using sterile water or an appropriate aqueous buffer. Thymosin Alpha-1 is soluble in water. Aliquot immediately after reconstitution to avoid repeated freeze-thaw cycles. Lyophilized powder is stable for up to 2 years at −20 °C under sealed, desiccated, light-protected conditions. Reconstituted solutions should be stored at 2–8 °C and used within 14–21 days. Do not freeze reconstituted solution.

For laboratory use by qualified personnel only. Thymosin Alpha-1 peptide