Thymosin Alpha-1
Stocked in 5mg, 10mg at MontanaPep in Great Falls, Montana. Sold for laboratory research use only.
| Size | Catalog no. | Price per vial |
|---|---|---|
| 5mg | TA5 | $30 |
| 10mg | TA10 | $40 |
Classification
Endogenous 28-residue thymic peptide; approved as a medicine outside the US
Structure and chemistry
Thymosin alpha-1 (T-alpha-1, generic name thymalfasin) is a 28-amino-acid peptide with an acetylated N-terminus (N-alpha-acetylserine) and a molecular weight of roughly 3,108 Da. It contains no disulfide bonds and is highly acidic and heat-stable. In the body it is produced by cleavage of the 113-amino-acid nuclear precursor protein prothymosin alpha. The synthetic form is structurally identical to the natural peptide and is made by solid-phase synthesis.
What the published research shows
The evidence base is genuinely large but the results are mixed, and this matters more than the volume. Early animal and small human studies supported immune-restoring activity, and it holds marketing approval in many countries for chronic hepatitis B. However, the largest and highest-quality trial to date — the 1,106-patient TESTS phase 3 sepsis trial published in the BMJ in 2025 — found no clear mortality benefit. A 2025 meta-analysis found an overall mortality benefit that disappeared when the analysis was restricted to high-quality and multicentre trials.
Mechanism of action
An immune modulator rather than a general immune stimulant. It acts largely through Toll-like receptor signalling (notably TLR2 and TLR9) on dendritic cells and monocytes, promoting dendritic cell maturation, T-cell differentiation toward a Th1 profile, increased MHC class I expression, and enhanced natural killer cell activity. It is described as restoring balance in a dysregulated immune system rather than uniformly amplifying immune responses.
Development history
Not designed as a drug — it was isolated from thymus tissue during research into how the thymus gland directs T-cell development. Allan L. Goldstein and colleagues first prepared “thymosin fraction 5,” a partially purified calf-thymus extract with immune-restoring activity, then systematically fractionated it to identify the most biologically active single component.
Current regulatory status
Thymosin alpha-1 is marketed as Zadaxin (thymalfasin) by SciClone Pharmaceuticals and holds marketing approval in roughly 35 countries — including China and Italy — principally for chronic hepatitis B and as an immune adjuvant. It has never been approved by the FDA for any indication in the United States. Catalog material sold as Thymosin Alpha-1 is a research-grade item and is not the approved foreign drug product.
Analytical testing
Identity, chromatographic purity, and net peptide content should be assessed separately on a COA. Confirming the N-terminal acetylation by mass spectrometry matters, since an unacetylated 28-mer is a different molecule from thymosin alpha-1.
Ordering from Great Falls
MontanaPep, also known as Montana Peptides, is an independently owned supplier based at 715 13th Ave S, Great Falls, Montana. Local pickup is available by arrangement, and we ship to research addresses across Montana including Billings, Missoula, Bozeman, Helena, Butte, Kalispell and Havre. Call (406) 799-0812 or email customerservice@montanapep.com.