TB-500

Overview

TB-500 is a synthetic seven-amino-acid peptide with sequence Ac-LKKTETQ. It corresponds to a small active region of thymosin beta-4 (Tβ4): the part (residues 17 to 23) responsible for binding actin, the building material of the cytoskeleton. The 'Ac' denotes an acetyl group at the N-terminus, a chemical addition that makes the fragment more stable.

One common confusion needs to be addressed up front. In the research-peptide market, 'TB-500' and 'thymosin beta-4' are often used interchangeably as if they were the same compound. They are not. Tβ4 is the full endogenous protein of 43 amino acids (about 4,963 Da). TB-500 is a fragment of only seven amino acids (about 889 Da), roughly one-fifth of the mass. The great majority of research circulating under the name 'TB-500' was in fact performed with the full Tβ4 protein. Findings from one cannot simply be attributed to the other.

For the full scientific context, from mechanism to clinical trials and evidence, see the thymosin beta-4 profile in this database. This page describes specifically what is known about the TB-500 fragment itself.

This profile summarises the current state of research. It does not constitute efficacy claims or product recommendations.

Mechanism of action

The LKKTETQ segment is the part of Tβ4 that binds actin. On that basis, TB-500 is presumed to mimic part of the actin-related effects of the full protein: influencing cell motility and supporting tissue repair. Whether the fragment retains all functions of the full protein is uncertain, however. Tβ4 contains additional active regions that are absent in TB-500, including a separate fragment (Ac-SDKP) linked to inflammation and fibrosis dampening. The fragment is by definition more limited than the whole protein.

Research findings

• First publication described TB-500 as a veterinary preparation and developed an assay to detect it in equine urine and plasma (doping control)
• A more recent study quantified TB-500 and its metabolites in rats and in laboratory models, with an initial exploration of wound-healing activity in vitro
• No human study of the fragment itself has been identified; there are no human outcome data
• Broader findings on wound healing, cardiac repair and angiogenesis often attributed to TB-500 actually come from research with the full Tβ4 protein (see Tβ4 profile)

Research context

TB-500 is primarily known as a market name rather than as an independently studied substance. The fragment is derived from the active region of Tβ4, but its stand-alone scientific basis is limited.

The fragment is also prohibited for athletes by the World Anti-Doping Agency (WADA), and originally surfaced as a preparation in equine sports.

Anyone evaluating the efficacy of TB-500 runs into a core problem: nearly all supporting evidence concerns a different, larger molecule. Making that distinction honestly is more important than glossing over it.

Open questions

• Direct human clinical data on the TB-500 fragment are absent; no human trial of the fragment itself has been identified
• The extent to which the fragment retains the efficacy of the full protein has not been established; comparative studies under equal conditions are lacking
• Long-term safety profile is not established
• Optimal dosing and routes of administration are unclear

Research outlook

Published outcomes from a human study of the fragment itself

Direct comparison between the TB-500 fragment and full-length Tβ4 under standardised conditions

Characterisation of the mechanism of the fragment itself, distinct from the full protein

Scientific interest

Synthetic fragment of the actin-binding region of Tβ4, a tool for studying cell-migration effects without the full protein

The full parent protein (Tβ4) is much further along in clinical research (see that profile)

Illustrates a broader theme: the difference between a market name and an independently substantiated research substance

Specifications

References

1. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry · Ho ENM, Kwok WH, Lau MY et al. · Journal of Chromatography A · 2012
2. Simultaneous quantification of TB-500 and its metabolites in rat plasma and screening by wound healing activities in-vitro · Rahaman KA, Hakim M, Muresan AR et al. · Journal of Chromatography B · 2024

Availability

In stock · Batch PEP-TB5-2026-01 · HPLC 98.65 % · released 31 Aug 2026

• TB-500 5 mg · product page with price and batch CoA