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TB-4 Frag

Fragment of thymosin beta-4 for targeted healing benefits

TB-4 Frag molecular structure

Overview

TB-4 Fragment represents a specific peptide sequence derived from the full-length thymosin beta-4 (Tβ4) molecule. Research has explored whether smaller fragments of Tβ4 retain the regenerative and healing properties of the parent peptide while offering advantages in synthesis, stability, or cost. Various TB-4 fragments have been studied, with some retaining actin-binding capabilities and wound-healing properties. The most commonly referenced fragment includes the actin-binding domain responsible for Tβ4's effects on cell migration and tissue repair. Studies examining fragments suggest some biological activity is preserved, though typically at reduced potency compared to full-length TB-500/Tβ4. The appeal of fragments lies in potentially lower cost and simpler synthesis while maintaining therapeutic relevance. However, research on TB-4 fragments is considerably more limited than on full-length thymosin beta-4, and the optimal fragment sequence for different applications remains under investigation. Users should be aware that fragment products may vary in their specific sequences and biological activity.

Last reviewed: 2026-08-18

Identity & Aliases

Also known as

TB4 fragmentThymosin beta-4 fragmentTB-500LKKTETQ (actin-binding motif)Thymosin β4 (full-length parent)

Full composition (formula, molecular weight, sequence) in Quick Facts →

Research Areas

Tissue repair and regenerationWound healingAngiogenesisCardiac repair after myocardial infarctionOphthalmic wound healing

Available Evidence

Human

Full-length thymosin beta-4 has been studied in clinical trials (e.g., a phase 2 randomized trial of systemic TB4 after ST-elevation myocardial infarction, NCT01311518, and ophthalmic trials for corneal wound healing). No FDA approval exists; the C-terminal fragment sold as 'TB-500'/'TB-4 frag' has essentially no published human trial data of its own.

Animal

Animal models show thymosin beta-4 accelerates dermal wound healing, promotes angiogenesis, and improves cardiac function after myocardial infarction; the actin-binding motif LKKTETQ is implicated in cell migration and repair.

In Vitro

In vitro studies demonstrate TB4-mediated actin sequestration, cell migration and endothelial tube formation.

Uncertain

Athletic-recovery and broad 'healing' claims for TB-500-style fragments are not supported by clinical evidence; fragment-specific pharmacology is poorly characterized.

Key Studies & Findings

2 studies
Preclinical2004

Thymosin beta4 activated integrin-linked kinase and promoted cardiac cell migration, survival and cardiac repair in animal models.

Benefits & Effects

4 documented

Multi-tissue regeneration

anecdotalHealing

Wound healing support

anecdotalHealing

Cardiac repair potential

anecdotalCardiovascular

Dermal healing

anecdotalSkin Health

Side Effects & Safety

2 reported

No adverse events in Phase II trials

MildRare Reversible

Generally well-tolerated

MildRare Reversible

Limitations & Open Questions

Published clinical data apply to full-length thymosin beta-4, not to the commercially sold fragment; the fragment has no dedicated human trials; dosing, stability and safety of 'TB-500' products are unregulated and poorly documented.

Pharmacology

The 43-amino-acid thymosin beta-4 sequesters actin monomers (via the LKKTETQ actin-binding motif) and promotes cell migration, angiogenesis and wound healing. The fragment marketed as TB-500 contains the actin-binding domain. Pharmacokinetics of the fragment in humans are not published.

Reported Research Dosing

Reported values from research literature and community protocols. Educational reference only — not a dosing recommendation or medical advice.

dosage not established

Route: SC/Topical
Half-life: Variable (fragment)

Frequently Asked Questions

Is TB-500 (TB-4 frag) FDA-approved?

No. It is an unapproved research compound; only investigational trials of full-length thymosin beta-4 exist.

Is the fragment the same as thymosin beta-4?

No — it is a shortened version containing the actin-binding motif; most clinical evidence comes from the full-length peptide.

Related Resources

Quick Facts

Molecular Weight

844.0

Mechanism

Different fragments of Thymosin Beta-4 for enhanced tissue repair

Safety Information

Research compound. ANGIOGENESIS CONCERN - Avoid with cancer history. WADA BANNED. Phase III trials ongoing (dry eye).

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