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Explore  /  TB-500 (Thymosin Beta-4 fragment)

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TB-500 (Thymosin Beta-4 fragment)

C

lead outcome

Musculoskeletal / tendon / muscle recovery…

grades vary by outcome ↓

Peptide⚠ WADA-banned

also called — TB-500 · "Thymosin Beta-4 fragment" · often marketed (loosely) as Thymosin Beta-4 / Tβ4 / TB4 · thymosin beta-4 · TB-4 · note: TB-500 is a synthetic fragment of thymosin beta-4, not the same molecule

tissue repairwound healingangiogenesisanti-inflammatory (research context)

Research / reference — not for sale. No dosing, reconstitution, or administration is published (intentional). Neutral scientific reference only. Note the identity distinction below — "TB-500" and full-length Thymosin Beta-4 are related but not identical, and it matters for reading the evidence.

In brief

TB-500 is a synthetic actin-binding fragment related to Thymosin Beta-4, studied mainly in animal models for tissue repair, wound healing and inflammation. Importantly, the human clinical data belongs to full-length Tβ4 (mixed-result eye and cardiac trials, no approval), not to the TB-500 fragment — which has no completed human efficacy trials. It is not approved anywhere and is banned in sport.

Legal standing, by region

European Union

Not approved

Not approved for human use; not eligible for magistral/officinal compounding (no Ph. Eur. monograph). Sold only as a non-medicinal "research" chemical, which does not authorise human use.

United States

Not FDA-approved (under review)

Removed from 503A Category 2 in April 2026; on the PCAC agenda for 23 July 2026 (with BPC-157) for possible 503A Bulks-List inclusion; FDA's pre-meeting briefing documents proposed not adding it. Advisory only; no Federal Register rule as of this writing. Full-length Tβ4 sits on a separate drug track (see below).

International

Approved nowhere

Approved nowhere.

⚠ WADA-prohibited in sportSport: WADA-prohibited at all times — Thymosin-β4 and its derivatives (e.g. TB-500) are named under Section S2 of the 2026 Prohibited List; detectable by LC-MS/MS. Athletes should treat it as banned.

Evidence, by outcome

How we grade →

An honest grade per outcome — drawn from the evidence, not any catalogue. Hype and undemonstrated marketing claims grade low.

OutcomeEvidence base · effectGrade

Musculoskeletal / tendon / muscle recovery (the marketed use)

Preclinical; no completed human efficacy trial for the fragment

Animal models only · Suggestive tissue repair

C

Wound healing / corneal repair

Data is on Tβ4, not TB-500; no FDA approval; orphan designation only (neurotrophic keratopathy)

Human trials of full-length Tβ4 — RGN-259 ophthalmic Phase 2/3 (ARISE-1/2); Philp 2003 corneal · Mixed; some benefit, primary endpoints not fully met

C

Cardiac repair

Full-length Tβ4; early-stage

Animal models + an early Tβ4 RCT · Suggestive

C

Marketed "recovery stack" (with BPC-157) for human injury/performance

No human RCT for the injuries the stack targets

None · Not demonstrated

F

Safety & long-term

WADA-banned; long-term/oncologic safety not established

Limited human data for the fragment; theoretical concern from pro-angiogenic activity · Unknown

—

Disclosure

Vallydia sells its own cosmetic serums, and some ingredients graded here belong to the same categories as those products. Grades are drawn from the published evidence by the method we publish, and applied to our own ingredients on the same terms — our copper-peptide serum is graded no more kindly than the peptides it competes with. We disclose the interest so you can weigh it.

Trade names shown here (for example Matrixyl, Argireline, Syn-Ake) are the property of their respective owners and are used only to identify the ingredient under discussion. Their appearance implies no affiliation with, or endorsement by, the proprietor.

Evidence changes

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Identity

Thymosin Beta-4 (Tβ4) is the natural 43-amino-acid actin-sequestering peptide found in nearly every human cell. "TB-500" is a synthetic research/gray-market peptide reproducing Tβ4's actin-binding region (LKKTETQ) — the mechanistically active core. Sources disagree on its exact length (commonly described as a short acetylated fragment; some list ~17 aa), and many suppliers use "TB-500" and "Thymosin Beta-4" interchangeably even though they are not the same molecule. Both are < 43 aa → peptides.

Development & history

Thymosin Beta-4 (Tβ4) was first characterised as a thymic peptide (Goldstein and colleagues) and later recognised as a ubiquitous actin-sequestering peptide involved in cell migration and repair.
The pharmaceutical development has been of full-length Tβ4, chiefly by RegeneRx Biopharmaceuticals (with partners such as ReGenTree / G-treeBNT) — the RGN-259 ophthalmic programme (dry eye, neurotrophic keratopathy; ARISE Phase 2/3, mixed results, orphan designation) and cardiac work — none of which reached approval.
"TB-500" emerged separately as a research/gray-market fragment, used in veterinary settings (notably racehorses) and by athletes for recovery; the fragment itself never had a formal clinical-development programme. It features in several sports-doping cases and is now in the 2026 FDA compounding review.

Mechanism (as proposed)

the LKKTETQ core binds/sequesters G-actin, promoting cell migration, angiogenesis, tissue repair and an anti-inflammatory milieu. Most mechanistic detail comes from full-length Tβ4 biology and animal studies; whether the fragment reproduces these effects in humans is unproven.

Chemical identifiers

Cross-reference identifiers for the authoritative external databases — not a recipe, and nothing about how to use it.

PubChem CID62707662

InChIKeyADKDNDYYIZUVCZ-ZQNQAVPYSA-N

SMILESC[C@H]([C@@H](C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H]([C@@H](C)O)C(=O)N[C@@H](CCC(=O)N)C(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)C)O

via PubChem exact-name match (TB-500) · high confidence

Sources — 5 cited

01Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. (Tβ4 biology review.)

02Philp D, et al. Thymosin β4 and corneal wound healing. 2003.

03RegeneRx / ReGenTree. RGN-259 (Tβ4) ophthalmic ARISE-1/ARISE-2 trials (NCT02597803, NCT02974907); acute MI trial (NCT01311518).

04Thymosin Beta-4 and TB-500 in tissue healing and musculoskeletal repair: a scoping review. Appl Sci. 2026.

05WADA. 2026 Prohibited List, Section S2.

Updated 2026-07-11 (US review status evolving — re-check the July PCAC outcome and any Federal Register rule)

Grades reflect the published evidence, not our interest. No dosing, reconstitution, or administration is published for research compounds — that restraint is deliberate.

Related compounds

Thymosin Alpha-1 (Thymalfasin / Zadaxin)B

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This site provides neutral scientific reference and sells only products lawful in your region. Nothing here is medical advice, a recommendation, or an offer to supply unapproved medicines. No dosing or administration is published for research compounds. Cosmetic peptides per Regulation (EC) 1223/2009. Unapproved injectable peptides are neither sold nor advertised in the EU (Directive 2001/83/EC, Title VIII). © 2026 Vallydia.