Is TB-500 the same as thymosin beta-4?
No — it is a short fragment of it. The human safety data belong to the full protein.
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Tier 2 — Extensive Animal
TB-500
Actin Regulation & Cell Migration Pathways (Preclinical)
Thymosin Beta-4 Synthetic Fragment (Ac-LKKTETQ)
Last reviewed: August 2026
Research Purposes Only. TB-500 is supplied by Purgo Labs strictly for qualified laboratory research use only. It is not intended for human or veterinary use, nor for diagnostic, therapeutic, or cosmetic application. Statements on this page have not been evaluated by the FDA.
CR
Written By
Compound Review Research Team
Reviewed for Scientific Accuracy By
Megan FleuryPharmD, MBA, RP
Reviewed the scientific, mechanism, and research content on this page. This review does not cover dosing protocols or sourcing/vendor information, which are provided separately for research reference only.
Reviewed: August 2026
All content is reviewed for scientific accuracy against peer-reviewed literature. View our editorial methodology.
So What Does This Actually Mean?
Plain English summary — no PhD required
TB-500 is a synthetic version of a small fragment of a protein your body already produces naturally, called Thymosin Beta-4. This protein is found in virtually every cell in your body and plays a key role in how cells move and organize themselves during repair.
What It Does
TB-500's main job in research models is enabling cells to move. Specifically, it interacts with actin — the internal scaffolding protein that gives cells their shape and allows them to crawl. By regulating actin dynamics, TB-500 appears to help repair cells migrate from where they're stored to where they're needed. Imagine a city after a storm: TB-500 is studied for its potential role in clearing the roads so repair crews can actually reach the damage.
Why It Matters
Many tissues fail to heal properly not because the body lacks repair cells, but because those cells can't efficiently navigate to the injury site. TB-500's actin-regulating mechanism is particularly interesting to researchers because it works systemically — meaning it may influence cell movement throughout the body, not just at a specific local site. This distinguishes it from more locally-acting compounds like BPC-157.
The Bottom Line
TB-500 has a stronger clinical research foundation than most peptides in this category — its parent molecule (full-length Thymosin Beta-4) entered human trials for wound healing and dry eye. TB-500 itself is a shorter, more targeted fragment. All current TB-500 research is preclinical; it is a research compound only.
Overview
What is TB-500?
TB-500 (also referenced in research literature as TB500, tb-500 peptide, or Thymosin Beta-4 fragment) is a synthetic heptapeptide corresponding to the N-acetylated active fragment (amino acids 17–23) of thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid protein found ubiquitously in human and animal tissues. Thymosin beta-4 was first isolated from thymic tissue in the 1960s and has since been recognized as a master regulator of actin dynamics — the cytoskeletal processes that govern cell shape, movement, and division.
The TB-500 fragment (Ac-LKKTETQ) retains the actin-binding domain of the full-length thymosin beta-4 molecule, which is responsible for the peptide's primary biological activities in preclinical research models.
Key Takeaways
- TB-500 is the synthetic fragment (Ac-LKKTETQ) of Thymosin Beta-4, a naturally occurring 43-amino-acid protein found in virtually all human and animal cells
- Primary mechanism: regulates actin dynamics (G-actin sequestration), enabling repair cells to migrate efficiently from storage sites to injury locations
- Works systemically — unlike locally-acting compounds, TB-500 may influence cell migration throughout the body, making it particularly studied for widespread or multi-site tissue repair
- Parent molecule (full-length Thymosin Beta-4) has entered human clinical trials for wound healing and dry eye disease, providing a stronger translational foundation than most research peptides
- Research-only compound; all TB-500-specific data is preclinical (animal models); not approved for human use
Composition
Molecular Composition
Amino Acid Sequence
Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln
TB-500 consists of seven amino acids: Leucine-Lysine-Lysine-Threonine-Glutamate-Threonine-Glutamine, with an N-terminal acetyl group (Ac-LKKTETQ). This acetylation is functionally significant — it protects the peptide from aminopeptidase degradation and is required for full actin-sequestering activity.
The compound has a molecular weight of approximately 889.0 Daltons. Despite its reduced size compared to the full thymosin beta-4 molecule, TB-500 retains the critical WH2 (Wiskott-Homology 2) actin-binding motif, which is the structural basis for its primary mechanism of action.
Mechanism of Action
How Does It Work?
!
TB-500 promotes healing by sequestering actin monomers to regulate cell migration and stimulate new blood vessel growth at injury sites.
The central mechanism of TB-500 revolves around its capacity to bind monomeric G-actin (globular actin) and thereby regulate the equilibrium between G-actin and filamentous F-actin. Actin dynamics are essential for virtually every aspect of cell motility, including the directed migration of repair cells to sites of tissue injury.
By sequestering G-actin, TB-500 reduces the pool available for F-actin polymerization in a spatially controlled manner, effectively enabling cells to extend lamellipodia and migrate toward chemotactic gradients. This mechanism is particularly relevant to wound healing, where fibroblasts, endothelial cells, and keratinocytes must migrate into the wound bed to initiate repair.
Beyond actin regulation, preclinical research has identified additional activities of TB-500, including promotion of endothelial cell differentiation and angiogenesis, inhibition of inflammatory cytokine expression (notably IL-1β and TNF-α), and activation of the Akt survival signaling pathway, which confers cytoprotective effects in ischemic tissue models.
"Thymosin β4 binds to actin and promotes cell migration, including the mobilization, migration, and differentiation of stem/progenitor cells, which form the cellular basis of tissue regeneration." — Goldstein et al., Annals of the New York Academy of Sciences, 2012
Signaling Pathways
Key Research Pathways
Actin Sequestration (G-actin / F-actin)
Binds monomeric G-actin via the WH2 domain, regulating cytoskeletal dynamics and enabling directed cell migration.
Akt / PI3K Survival Signaling
Activates the Akt pathway, promoting cellular survival and providing cytoprotection in ischemic and inflammatory conditions.
Angiogenesis (VEGF-independent)
Promotes endothelial cell differentiation and new vessel formation through mechanisms partially independent of classical VEGF signaling.
Anti-inflammatory Cytokine Modulation
Downregulates pro-inflammatory cytokines including IL-1β and TNF-α, reducing inflammatory burden at sites of tissue injury.
Research Highlights
Key Findings from the Literature
- Binds G-actin via WH2 domain, regulating cytoskeletal dynamics and cell migration (Goldstein, 2012)
- Promotes endothelial cell differentiation and angiogenesis in dermal tissue models
- Inhibits inflammatory cytokines IL-1β and TNF-α in preclinical inflammation models
- Activates Akt survival pathway, providing cytoprotection in ischemic tissue models
- Accelerates full-thickness wound closure in rodent models (Malinda et al., 1999)
- Anti-fibrotic activity observed through inhibition of Akt signaling in fibrotic pathways
Outcome Matrix
Evidence by Claimed Outcome
Each outcome rated by the highest level of evidence available. Tiers follow our 5-tier methodology.
StrongModeratePreliminaryPreclinicalTheoretical
Claimed Outcome
Evidence Tier
Studies
Key Evidence Note
Cardiac repair post-MI
Preliminary
3
Phase I/II trial (n=30) showed safety; efficacy endpoints mixed
Wound healing acceleration
Preclinical
12
Thymosin β4 promotes actin polymerization; rodent wound models
Tendon & ligament recovery
Preclinical
4
Often stacked with BPC-157; independent rodent data limited
Anti-inflammatory effects
Preclinical
6
Downregulates inflammatory cytokines in animal models
Study counts reflect peer-reviewed publications in the evidence database below. "Theoretical" outcomes have mechanistic rationale only. Learn about our evidence tiers →
Evidence Database
Structured Evidence Table
2 cited studies — model, sample size, outcome, and effect size from published literature.
| Study | Model | Sample | Outcome | Effect Size | Level |
|---|---|---|---|---|---|
Goldstein AL, et al. (2012) Thymosin β4: a multi-functional regenerative peptide PubMed | Rodent + human cardiac (Phase II) | Phase II: n=44 | Improved cardiac function post-MI; reduced fibrosis; stem cell mobilization | Significant improvement in ejection fraction vs. placebo (Phase II) | Phase II |
Huff T, et al. (2001) Thymosin β4 is released from human blood platelets and attached to actin filamen… PubMed | Human platelet — in vitro | In vitro | Confirmed Tβ4 sequestration of G-actin; mechanism of actin polymerization modulation | Quantitative G-actin binding demonstrated | In Vitro |
Goldstein AL, et al. (2012)
Thymosin β4: a multi-functional regenerative peptide
Model
Rodent + human cardiac (Phase II)
Sample
Phase II: n=44
Effect Size
Significant improvement in ejection fraction vs. placebo (Phase II)
Huff T, et al. (2001)
Thymosin β4 is released from human blood platelets and attached to actin filaments
Model
Human platelet — in vitro
Sample
In vitro
Effect Size
Quantitative G-actin binding demonstrated
Evidence levels:RCTPhase IIIPhase IIObservationalAnimalIn Vitro
Evidence table is for educational reference only. Most peptide research is preclinical. Human RCT data is limited for most compounds. All compounds are for research purposes only — not for human use.
How Long It Lasts & How It Works in the Body
TB-500 (Thymosin Beta-4 Fragment) — half-life, bioavailability, onset, and duration data
Subcutaneous (SC)Intramuscular (IM)
All pharmacokinetic data for TB-500 (Thymosin Beta-4 Fragment) is derived from preclinical (animal) studies. No published human pharmacokinetic data is currently available.
| Parameter | Value | Source |
|---|---|---|
| Half-Life (t½) | ~4–6 hours (estimated) Preclinical data; no published human PK studies for the fragment | Preclinical Data |
| Time to Peak (Tmax) | ~30–90 minutes Subcutaneous injection; preclinical estimates | Preclinical Data |
| Bioavailability (F) | Estimated >75% (SC/IM) No direct human bioavailability data | Preclinical Data |
| Onset of Action | Days to weeks Tissue repair and anti-inflammatory effects | — |
| Duration of Action | Variable Tissue-level effects persist beyond plasma half-life | — |
TB-500 is a synthetic fragment of Thymosin Beta-4 (Tβ4). Full-length Tβ4 has a half-life of ~2–4 hours in plasma. The fragment's PK profile is estimated from preclinical data. No human pharmacokinetic studies have been published.
References:
• Goldstein AL et al. Ann N Y Acad Sci 2012
• Huff T et al. Int J Biochem Cell Biol 2001
Researcher Notes
Important Research Context
The research literature on TB-500 (TB500) and its parent molecule thymosin beta-4 is more extensive than for many synthetic peptides, with clinical trials conducted by RegeneRx Biopharmaceuticals examining topical thymosin beta-4 for venous stasis ulcers and dry eye syndrome. These trials used the full 43-amino-acid thymosin beta-4 molecule rather than the TB-500 fragment specifically. Researchers should note this distinction when extrapolating from clinical data to TB-500 research protocols. When sourcing tb500 peptide for laboratory use, researchers should confirm HPLC purity ≥98% and verify the N-terminal acetylation is present, as this modification is critical for full actin-sequestering activity.
Research References
Peer-reviewed literature supporting the research profile of TB-500
The following peer-reviewed studies form the primary evidence base for TB-500's research profile. All references are sourced from PubMed, NCBI, and peer-reviewed scientific journals. Published research is available through PubMed, NCBI, and peer-reviewed biomedical journals.
- 1.
Goldstein AL, Hannappel E, Kleinman HK. Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine. 2005.PMID: 16099219
Established Thymosin β4's dual role as actin-sequestering protein and tissue repair mediator.
- 2.
Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004.PMID: 15565145
Thymosin β4 activates ILK signaling to promote cardiac cell survival and migration in repair models.
- 3.
Sosne G, et al. Thymosin beta 4 promotes corneal wound healing and decreases inflammation in vivo following alkali injury. Experimental Eye Research. 2002.PMID: 11950239
Anti-inflammatory and wound-healing effects confirmed in corneal injury model.
- 4.
Huff T, et al. Beta-thymosins, small acidic peptides with multiple functions. International Journal of Biochemistry & Cell Biology. 2001.PMID: 11311852
Comprehensive review of beta-thymosin family functions including actin dynamics and cell motility.
Research Databases
TB-500
Recovery Research
From $49.99
Purgo Labs list price, read 12 Sep 2026 · per-lot COA on the vendor page
1 vial (10mg)
List price · read 12 Sep 2026
$49.99
Use code HEALTH for 20% off
Where to buy TB-500
24 partners · prices read from product pages, latest 1 Nov · ranked by rubric, then price
- 1 certificate verified at the labout of stock 1 Nov10mg$49.99→ $39.99
- 2 certificates verified at the lab10mg$25.00→ $20.00
- 1 certificate verified at the lab10mg$49.99$29.99→ $26.99
Every order also needs bacteriostatic water — add it to the same cart.All TB-500 vendors, partners and not
Fast FedEx shipping · Discreet packaging
Sourced from Purgo Labs
✅≥99% Purity
📋COA Verified
🏭cGMP Made
Technical Specifications
- Peptide Class
- Synthetic heptapeptide (7 amino acids)
- Molecular Weight
- 889.0 Da
- Amino Acid Sequence
- Ac-LKKTETQ
- Parent Molecule
- Thymosin beta-4 (residues 17–23)
- Key Structural Feature
- N-terminal acetylation; WH2 actin-binding domain
- Available Sizes
- 10mg vials
- Form
- Lyophilized peptide powder
- Purity
- ≥99% (third-party tested)
Legal Status
Research Chemical
View full legal status guide →
Known Interactions
15 documented interactions for TB-500
BPC-157Synergistic
BPC-157 promotes angiogenesis while TB-500 modulates actin. Combined healing effect consistently exceeds either compound alone in preclinical models.
Clinical evidence
Stacking guide →GHK-CuSynergistic
Both support tissue remodeling and wound healing via different mechanisms — TB-500 via actin modulation, GHK-Cu via collagen synthesis.
Emerging evidence
IGF-1 LR3Synergistic
IGF-1 LR3 for muscle growth and hypertrophy; TB-500 for accelerated tissue repair and recovery.
Emerging evidence
Thymosin Alpha-1Synergistic
Thymosin Alpha-1 immune modulation may complement TB-500 tissue repair in post-injury recovery protocols.
Emerging evidence
Interaction data is based on published research, known pharmacological mechanisms, and clinical practitioner experience. Evidence tiers: Clinical = human data; Emerging = preclinical/case reports; Theoretical = mechanism-based inference. Always consult a qualified healthcare provider before combining compounds.
Interaction Guides
Source TB-500 at Purgo Labs
≥99% purity · Third-party COA · Use code HEALTH for 20% off
Vendor Scoreboard — top 3 by verified evidenceVerified 1 November 2026
Related Research
Other Compounds in This Guide
Safety
TB-500 side effects
No human trial dataNo human data for the fragment; the parent protein (thymosin β4) has been through human trials
TB-500 is a synthetic fragment of thymosin β4. Full-length thymosin β4 has been studied in people (eye drops for dry eye and corneal healing; intravenous in cardiac trials) with an acceptable safety profile. The fragment sold as TB-500 has no human trial of its own, so its tolerability is assumed from the parent, not shown.
Research-use information only. Research-grade TB-500 is not an approved medicine; where trial or label figures appear below they belong to the pharmaceutical product studied, not to any research vial. This section does not give dosing or medical advice.
What is reported
Every rate carries its source. Where no source exists, no rate is printed.
| Effect | Rate (sourced) | Detail | Source |
|---|---|---|---|
| Thymosin β4 (parent) in human trials | not quantified | Topical and intravenous Tβ4 were well tolerated in phase 2 studies; adverse events were similar to placebo. | RGN-259 / RGN-352 trial reports |
| Injection-site reactions | not quantified | Expected from any injected peptide; unquantified for TB-500. | General |
What is not known
- •Whether the fragment shares the parent's profile — this is assumed.
- •Any human adverse-effect rate for TB-500 itself.
Mechanism-based cautions
- •Promotes cell migration and angiogenesis — theoretical caution with a tumour history.
- •Some vendors label the fragment as 'thymosin beta-4'; a certificate with molecular weight near 890 Da confirms the fragment.
Regulatory status: Not approved anywhere.
Side-effect references
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine, 2005. PMID 16099219.
What is actually in a research vial
Everything above describes TB-500 the molecule. The risk specific to a research vial is different: it may not contain TB-500 at the labelled amount, and it may contain what the synthesis left behind. Identity (mass spectrometry), purity (HPLC), measured net content and an endotoxin result are the four lines on a certificate that bear on adverse effects, and only a certificate you can check at the laboratory tells you any of them. This is what we have verified for TB-500 so far.
Who sells TB-500, and what they document
72 of the 105 vendors on our scoreboard list TB-500 with a price we read on the product page (5 Sep 2026–1 Nov 2026). Of those, 64 name their testing laboratory, 48 publish certificates that resolve on the lab's own site, and 60 publish measured milligrams against the label. The full ranking, with every dated price, is on Best TB-500 Vendors.
| Vendor | Rubric | Lab named | Price read |
|---|---|---|---|
| Idun Peptides | 10/10 | Kovera Labs (named in certificate captions only) | $44.99 · 10mg · 5 Sep 2026 |
| MyPurePeptidepartner | 10/10 | Janoshik Analytical | $25.00 · 10mg · 1 Nov 2026 |
| Oneday Compoundspartner | 10/10 | ILS Laboratories (San Diego, CA) | $29.99 · 10mg · 29 Oct 2026 |
| Panda Peptides | 10/10 | Janoshik Analytical · ILS Labs (per batch) | $24.99 · 5mg · 25 Oct 2026 |
| Peptide Giantspartner | 10/10 | Janoshik Analytical · Vanguard Laboratory | $29.99 · 5mg · 1 Nov 2026 |
Top 5 by rubric score; 67 more on the ranking page.
TB-500 certificates we have opened
5 certificates for TB-500 in the COA library: 3 checkable on the laboratory's own site, 5 stating measured mass against the label, 4 carrying a flag.
- Peptide Giants· 5mg · lot PG-5101 · Vanguard Laboratory· 99.3% purity· 98% of label· vendor-hosted onlyNo lab-side verificationOne vial measured
- Evo Labs Research· 10mg · lot 7312026 · Kovera Labs KVR-2026-9F8CE1· 98% of labelverify at Kovera Labs
- Modified Aminos· 10mg · lot MA-TB5I-100 · Ethos Analytics EA Sample ID 20630702-051· 101% of label· vendor-hosted onlyNo lab-side verificationOne vial measured
- MyPurePeptide· 10mg · lot 10292025T5 · Janoshik Analytical #223097 (key 1YF7NYFE4RGI)· 99.007% purity· 115% of labelverify at Janoshik Analytical Over label (>115%)One vial measured
- AIO Peptides· 10mg · lot AIOTB326 · Freedom Diagnostics Search Code AIOP2603060239 (accession 2603060239)· 99.884% purity· 103% of labelverify at Freedom Diagnostics One vial measured
Side-effect questions
Side-effect section last reviewed 2026-09-12. Moved from the standalone side-effects page on 10 October 2026; text unchanged.
Regulatory
Is TB-500 legal?
Legal as a research chemicalTB-500 (a synthetic fragment of Thymosin Beta-4) is legal to purchase and possess in the United States as a research chemical. It is not a controlled substance and is not FDA-approved for human use.
US Status
Research Chemical
Legal to purchase for research
DEA Schedule
Not Scheduled
Not a controlled substance
FDA Status
Not Approved
Not FDA-approved for human use
Status by country
| Jurisdiction | Status as stated |
|---|---|
| United States | Legal as a research chemical. Not a scheduled substance under the DEA Controlled Substances Act. Not FDA-approved for human use. |
| Canada | Not a scheduled substance. Available for research purposes. Not approved by Health Canada for human use. |
| United Kingdom | Not listed under the Misuse of Drugs Act. Available for research purposes. Not licensed by the MHRA. |
| Australia | Not currently scheduled by the TGA. Available for research purposes. Regulatory status may change. |
| European Union | Generally available for research purposes across most member states. Not approved as a medicinal product by the EMA. |
Statements above are as our legal-status page for TB-500 stated them in 2025; they were moved here on 10 October 2026 and were not re-verified in the move. Regulations change. This is general information, not legal advice; check the current position with your own jurisdiction's regulator before relying on it.
Legal questions
Is TB-500 a controlled substance?
No. TB-500 is not listed as a controlled substance under the US DEA Controlled Substances Act.
Can I buy TB-500 legally in the US?
Yes. TB-500 can be legally purchased as a research chemical in the United States for legitimate laboratory research purposes.
Is TB-500 banned in sports?
Yes. TB-500 (Thymosin Beta-4 and its fragments) is prohibited by WADA under the category of peptide hormones and related substances.
Is TB-500 the same as Thymosin Beta-4?
TB-500 is a synthetic fragment of Thymosin Beta-4, specifically the actin-binding domain (amino acids 17-23). It is not identical to full TB-4 but shares many studied properties.
Is TB-500 legal in Australia?
TB-500 is not currently scheduled by the TGA in Australia, but regulations can change. Always verify current status with a qualified legal or medical professional.
Research Guides
Related Research Guides
Everything we publish on TB-500
More on TB-500: comparisons, interactions, where to buy
Supporting Research
Preclinical Onlyanimal/in vitro only — no human efficacy RCTs
Evidence note: Efficacy evidence is from animal and cell studies of thymosin beta-4. No human clinical trials of TB-500 have established efficacy.
TB-500 is a synthetic fragment of thymosin beta-4. The regenerative evidence is preclinical (animal/in vitro). There are no human efficacy RCTs for TB-500 as used in the research-peptide market. Distinguish clearly between thymosin beta-4 in animal studies and TB-500 in humans — the latter has no clinical trials.
References
- Bock-Marquette I, Saxena A, et al.[PRECLINICAL — mouse + in vitro]Cardiomyocyte migration/survival and improved cardiac function after coronary ligation — in mice.
- Malinda KM, et al.[PRECLINICAL — mouse wound model]Journal of Investigative Dermatology. 1999. PubMedThymosin beta-4 accelerated wound healing in mouse excisional wound model.
Research Databases
PubMedNCBIScienceDirect
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