Thymosin Alpha-1
Research highlights
- ✓Naturally derived from thymic tissue — central immune regulatory peptide
- ✓May enhance T-cell and dendritic-cell function in research models
- ✓Studied extensively in oncology, hepatitis and immunodeficiency contexts
- ✓One of the most published immunomodulatory peptides in scientific literature
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What is Thymosin Alpha-1?
Thymosin Alpha-1 is a peptide fragment of prothymosin alpha, originally isolated from thymic tissue. It modulates immune response and has been studied in antiviral and antitumour contexts with an extensive published safety profile.
What purity is guaranteed?
Where we hold an independent Janoshik report for a compound we publish it in full - batch number, purity and a verification key you can check against the lab yourself. Where we do not hold one the product is marked research grade and we say so, rather than claim a report we cannot produce.
Thymosin Alpha-1, explained
The short version: Thymosin alpha-1 is a 28-amino-acid peptide from the thymus that acts on the immune system. Its synthetic form, thymalfasin (Zadaxin), is an approved medicine in more than 35 countries, but not in the US.
What it is
Thymosin alpha-1 was isolated in the 1970s from thymosin fraction 5, an extract of calf thymus, and the synthetic copy is called thymalfasin.
The shared name causes confusion. It has nothing to do with thymosin beta-4, the protein that TB-500 is cut from. A 2020 review describes the two as having very different chemistry and immune roles: alpha-1 enhances immune responses, while beta-4 binds actin inside cells.
What the trials found
According to that review in the World Journal of Virology (Dominari and colleagues), thymalfasin is approved in more than 35 countries for hepatitis B and C and as an immune enhancer in some other conditions. In the US, the FDA has granted it orphan drug designations, including for malignant melanoma and liver cancer, but no approval. Its hepatitis use has largely given way to direct-acting antivirals.
The largest recent test was in sepsis. TESTS, a phase 3 trial at 22 hospitals in China published in the BMJ in 2025, randomised 1,106 adults to thymosin alpha-1 or placebo. Deaths at 28 days were 23.4% and 24.1%, and the authors found no clear evidence of benefit, despite an earlier smaller trial that had looked promising.
Where the evidence stops
Thymalfasin's approvals cover a licensed product, for named conditions, in named countries. They are not a verdict on research-grade powder. The one big modern trial was negative, and the FDA's compounding page notes possible immune reactions and impurity complexities with compounded thymosin alpha-1.
Handling and storage
It arrives as a freeze-dried powder. Once bacteriostatic water goes in, it belongs in the fridge. Our reconstitution and storage guide covers the details, and the calculator does the maths.
A real medicine in much of the world, a failed bet in sepsis, and no relation to TB-500.
Sources (checked 7 October 2026)
For research use only. Not for human consumption. Nothing on this page is medical advice.
Reviews from people who ordered Thymosin Alpha-1
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★★★★★
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Rosemary V. · 8 Oct 2026
★★★★★
It was my 1st order. Everything went smooth, fantastic, fabulous!!!!! Received my vials 3days after placing the order. Asked lots of questions and received answers within minutes. Great awesome service!!! Will definitely order again. Thanks so much. Keep it up.
Lila J. · 8 Oct 2026
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Louise G. · 7 Oct 2026
★ 4.8 across all 19 JP Research reviews, good and bad. See them. Every reviewer gets R100 store credit, whatever they rate.
