TB-500
Research highlights
- ✓A synthetic peptide related to thymosin beta-4, a naturally occurring actin-binding protein
- ✓Thymosin beta-4 occurs in many mammalian cell types and tissues
- ✓Studied in vitro and in rodent models, largely around actin dynamics
- ✓Published work is largely preclinical; human data remains limited
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What is TB-500?
A synthetic peptide related to thymosin beta-4, a 43-amino-acid actin-binding protein that occurs naturally in mammalian cells. Suppliers generally describe TB-500 as corresponding to the actin-binding region of that protein rather than the full-length sequence, so the exact material can vary by source.
Does TB-500 appear on anti-doping lists?
Yes. Thymosin beta-4 and related peptides appear on the World Anti-Doping Agency's Prohibited List. That is worth knowing for anyone working with athlete samples or in a sport-adjacent setting. WADA revises the list annually, so check the current version directly.
TB-500, explained
The short version: TB-500 is a synthetic copy of a seven-amino-acid stretch of thymosin beta-4, the part of the protein that binds actin. It started life as a veterinary product, and doping labs have published more on it than anyone testing it for healing.
What it is
Thymosin beta-4 is a 43-amino-acid protein. Its best-known job is holding on to actin, the building block of the scaffolding that lets cells change shape and crawl. Positions 17 to 23 of the protein, the sequence LKKTETQ, form the site responsible for that actin binding, and lab work ties the same stretch to cell migration and wound repair.
TB-500 is that short sequence, made in a lab with an acetyl group added to its front end. It is a fragment, not the whole thymosin beta-4 protein, and the two should not be treated as interchangeable.
What has been studied
Most of the published work is about catching it. In 2012 the Hong Kong Jockey Club's racing laboratory described TB-500 as a veterinary preparation and developed a test that picked up the fragment and its breakdown products in horse urine and plasma after a single injection.
A 2024 study from the Korea Institute of Science and Technology's doping control centre followed how TB-500 is broken down in human serum, enzyme systems and rats. It opened by noting that the biological effects of TB-500 itself have not been documented. When the team tested the parent peptide and its pieces on fibroblasts in a scratch-wound assay, only one breakdown product, Ac-LKKTE, sped up wound closure. They suggested earlier healing claims for TB-500 may really belong to that metabolite.
Where the evidence stops
We could not find a single human trial of TB-500. Studies on the full thymosin beta-4 protein don't carry over to a seven-amino-acid piece of it, and even the lab data on the fragment is thin and partly contradictory. WADA's 2026 list bans thymosin beta-4 and its derivatives, naming TB-500, under S2 at all times.
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 fragment that horse-racing labs know well and healing research barely knows at all.
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 TB-500
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Small checkout glitch, but after following up it was quickly sorted out and everything went smoothly from there. Good customer service - thank you.
Tonia K. · 30 Sep 2026
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