TB-500 Capsules 500mcg
TB-500 (Ac-LKKTETQ) is a synthetic, N-acetylated heptapeptide corresponding to amino acids 17 23 of thymosin beta-4 (T 4), a 43-amino-acid actin-sequestering protein expressed in nearly every mammalian cell.
$160.00
Research goals: Recovery & Healing
Description
TB-500 (Ac-LKKTETQ) is a synthetic, N-acetylated heptapeptide corresponding to amino acids 17–23 of thymosin beta-4 (Tβ4), a 43-amino-acid actin-sequestering protein expressed in nearly every mammalian cell. The 17–23 sequence contains the actin-binding motif of Tβ4 that drives the parent protein’s effects on cell migration, angiogenesis, and tissue repair. TB-500 is the form used in equine veterinary medicine and in research; it is on the World Anti-Doping Agency prohibited list. Most peer-reviewed clinical research has been conducted on full-length Tβ4 (development codes RGN-259 ophthalmic and RGN-352 injectable), which informs the mechanism of action discussed below.
The strongest peer-reviewed human finding for the Tβ4 family comes from a Phase 3 randomized, placebo-controlled, double-masked trial of 0.1% topical Tβ4 (RGN-259) in patients with neurotrophic keratopathy: RGN-259-treated patients showed significantly faster corneal epithelial healing and improvements in ocular comfort versus placebo, with no significant adverse events (Sosne et al., Int J Mol Sci 2022).2
Important Note on the Evidence Base
The commercial product sold as “TB-500” is the N-acetylated 17–23 fragment of thymosin beta-4 (Ac-LKKTETQ) — not the full-length 43-amino-acid Tβ4 protein. The peer-reviewed clinical trials referenced below were conducted with full-length Tβ4 (RGN-259 topical for ophthalmic indications; RGN-352 injectable for cardiac repair). As of 2026, no published randomized controlled trial in humans has tested the injected TB-500 heptapeptide fragment for any musculoskeletal, cardiac, or systemic indication. The mechanistic work in animal models and the foundational cardiac biology paper from Bock-Marquette et al. likewise used full-length Tβ4. Whether the heptapeptide fragment fully recapitulates the parent protein’s tissue-repair effects in vivo is a real, unresolved question. This product is for laboratory research only; it is not approved by the FDA or EMA.
Published Research on Thymosin Beta-4 / TB-500
Foundational Cardiac Repair Mechanism — Bock-Marquette et al., Nature (2004)
This foundational paper demonstrated that the G-actin-sequestering peptide Tβ4 promotes myocardial and endothelial cell migration in the embryonic heart and retains this property in postnatal cardiomyocytes. Cell-survival assays showed enhanced viability of embryonic and postnatal cardiomyocytes in culture. Mechanistically, the authors showed that Tβ4 forms a functional complex with PINCH and integrin-linked kinase (ILK), activating the survival kinase Akt. After coronary artery ligation in mice, intraperitoneal Tβ4 treatment upregulated cardiac ILK and Akt activity, enhanced early myocyte survival, and improved cardiac function — establishing the mechanistic basis for the cardiac development program subsequently pursued by RegeneRx.1
RGN-259 Phase 3 Trial in Neurotrophic Keratopathy — Sosne et al., International Journal of Molecular Sciences (2022)
This Phase 3 randomized, placebo-controlled, double-masked clinical trial evaluated topical 0.1% RGN-259 (full-length recombinant Tβ4 ophthalmic solution) in patients with neurotrophic keratopathy — a difficult-to-treat condition characterized by impaired corneal sensation and persistent epithelial defects. RGN-259 treatment promoted rapid healing of epithelial defects, improved Mackie classification disease stage at days 29, 36, and 43, and showed significant improvements in ocular discomfort, foreign body sensation, and dryness. No significant adverse effects were reported. The authors conclude RGN-259 is safe and effective for this challenging patient population.2
Actin-Sequestering Protein Review — Goldstein, Hannappel & Kleinman, Trends in Molecular Medicine (2005)
This authoritative review by the original discoverers of thymosin beta-4 frames Tβ4 as a moonlighting actin-sequestering protein with broad tissue-repair activity beyond its primary cytoskeletal function. The review covers Tβ4’s roles in dermal wound healing, corneal repair, hair follicle regeneration, cardiac repair after injury, and anti-inflammatory effects, and discusses the structure-activity relationship between the actin-binding motif (residues 17–23, the basis of TB-500) and the full-length protein’s broader activity. The review remains the most-cited single source for Tβ4’s pleiotropic biology.3
Cardioprotection by Systemic Administration — Postrach et al., Frontiers in Pharmacology (2014)
This study tested two Tβ4 administration regimens (short-term during the first 3 days post-injury, and long-term every third day until study end) in a rat model of chronic myocardial ischemia. Long-term repeated administration produced clinically measurable improvements in cardiac function, while short-term administration did not, suggesting that repeated administration may be required for clinical benefit post-MI. Plasma biomarkers of cardiac function and myocardial injury were sensitive pharmacodynamic biomarkers of Tβ4 effects, supporting their use in subsequent clinical studies. The work informed the administration strategy for the RGN-352 cardiac development program.4
About the Compound
TB-500 is the N-acetylated heptapeptide corresponding to the actin-binding motif (residues 17–23) of thymosin beta-4. The acetylation of the N-terminal leucine protects the peptide from aminopeptidase degradation, extending its plasma half-life relative to the unmodified fragment. Tβ4’s biological mechanism centers on G-actin sequestration: by binding monomeric actin, it regulates the available pool for filament polymerization, which in turn modulates cell shape, migration, and division. Beyond actin, the parent protein activates the PINCH–ILK–Akt survival pathway in cardiomyocytes, upregulates laminin-5 expression in corneal epithelium, and exhibits anti-apoptotic and anti-inflammatory effects across multiple tissue types.
- Compound class: synthetic N-acetylated heptapeptide; thymosin beta-4 (17–23) fragment
- Sequence: Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ); INN: fequesetide (unacetylated form)
- Synonyms: TB-500, TB500, Tβ4 17–23 acetate
- CAS Number: 885340-08-9
- Molecular Formula: C38H68N10O14
- Molecular Weight: 889.02 g/mol
- Mechanism: actin-sequestering motif of Tβ4; modulates cell migration, angiogenesis, and tissue repair signaling
- Regulatory status: not approved by the FDA or EMA. Prohibited by the World Anti-Doping Agency in competition. Prescription medicine in some jurisdictions (Australia, New Zealand)
Product Specifications
- Format: capsules
- Strength: 500 mcg per capsule
- Count: 60 capsules per bottle
- Purity: ≥99% (HPLC verified)
- Container: sealed amber bottle
- Certificate of Analysis: lot-specific COA available
See the FDA Disclosure, Storage Instructions, and RUO tabs for handling, storage, and regulatory information.
References
- Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. doi:10.1038/nature03000
- Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. 0.1% RGN-259 (Thymosin β4) ophthalmic solution promotes healing and improves comfort in neurotrophic keratopathy patients in a randomized, placebo-controlled, double-masked Phase III clinical trial. Int J Mol Sci. 2022;24(1):554. doi:10.3390/ijms24010554
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421-429. doi:10.1016/j.molmed.2005.07.004
- Postrach J, Schmidt M, Thörmer J, et al. Cardioprotection by systemic administration of thymosin beta four following ischemic myocardial injury. Front Pharmacol. 2014;5:36. doi:10.3389/fphar.2014.00036
Preparation and storage
Research-only handling information. TB-500 is sold strictly for in vitro laboratory research. The handling and storage guidance below reflects standard practice in published peptide research literature. TB-500 is not a drug, supplement, or food product, and is not for human consumption, veterinary use, or medical applications.
Format
- Form: Capsules
- Available strengths: 60ct
- Verified purity: >99% (HPLC, LC–MS)
- Documentation: Batch-specific Certificate of Analysis (COA) included
Handling for Research Use
TB-500 capsules ship as a pre-encapsulated, dry oral-research format. No reconstitution is required. The capsules can be opened for analytical or assay work that requires the dry powder.
Storage & Handling
- Upon receipt: Store in a cool, dry place away from direct light.
- Short-term storage: Room temperature in a sealed container is acceptable for several months.
- Long-term storage: Refrigeration at 4 °C (39 °F) extends shelf stability. Capsules do not require freezing.
- Humidity: Keep the original desiccant-sealed container closed when not in use. Excess moisture can compromise capsule integrity.
- Light exposure: Minimize exposure to direct light during handling.
Important Notice
All Omnix Peptides products are sold for laboratory, research, or analytical purposes only. They are not for human consumption, veterinary use, or medical applications. Researchers and laboratory professionals must follow all applicable institutional, local, state, and federal regulations governing the handling of research compounds.
Citations
Citations and reference data. Omnix Peptides supplies research-grade compounds for use by qualified laboratory professionals. The references below cite published preclinical research conducted in animal models and in vitro systems. They are not intended to represent clinical evidence in humans, and TB-500 has not been approved by the FDA, EMA, or any other regulatory authority for any indication.
Compound Reference Data
- Compound: TB-500
- CAS Number: 885340-08-9
- Molecular Formula: C38H68N10O14
- Molecular Weight: 889.02 g/mol
- Sequence: Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ); INN: fequesetide (unacetylated form)
- Synonyms: —
Selected Published Studies
The following peer-reviewed studies were conducted using animal models or in vitro cell-culture systems. They are listed here as a reference for researchers investigating TB-500. None of these studies should be interpreted as recommending TB-500 for human use, treatment, or any clinical purpose.
- Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. doi:10.1038/nature03000
- Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. 0.1% RGN-259 (Thymosin β4) ophthalmic solution promotes healing and improves comfort in neurotrophic keratopathy patients in a randomized, placebo-controlled, double-masked Phase III clinical trial. Int J Mol Sci. 2022;24(1):554. doi:10.3390/ijms24010554
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421-429. doi:10.1016/j.molmed.2005.07.004
- Postrach J, Schmidt M, Thörmer J, et al. Cardioprotection by systemic dosing of thymosin beta four following ischemic myocardial injury. Front Pharmacol. 2014;5:36. doi:10.3389/fphar.2014.00036
Evidence-Base Disclosure
The published evidence base for TB-500 consists predominantly of preclinical research — animal models (often rats or mice) and in vitro cell-culture experiments. Where Phase I or Phase II human trials exist, they are noted in the compound page summary. Researchers should interpret the cited literature within the experimental context of each individual study.
Frequently asked questions
Frequently asked questions about the TB-500 Capsules. Questions on this page cover handling, storage, documentation, and ordering. TB-500 is sold for laboratory, research, or analytical purposes only — not for human consumption, veterinary use, or medical applications.
Why does Omnix offer TB-500 in a capsule format?
Capsule format is used in oral-research and analytical contexts where dry, pre-measured administration is preferred over a reconstituted solution. The capsules contain the same research-grade compound supplied in the vial format and are tested to the same purity specification.
Do the TB-500 capsules require refrigeration?
Capsules are stable at room temperature for several months when kept in a cool, dry place away from direct light. Refrigeration at 4 °C (39 °F) extends shelf stability and is recommended for long-term storage. Capsules do not require freezing.
Can the capsules be opened to access the dry powder?
Yes. The capsule shell can be opened for analytical or assay work that requires direct handling of the dry powder. Once opened, the powder should be used immediately or transferred to a sealed, light-protected container.
Is TB-500 approved by the FDA?
No. TB-500 is not approved by the FDA, EMA, or any other regulatory authority for any indication. TB-500 is sold by Omnix Peptides strictly for laboratory, research, or analytical purposes. It is not for human consumption, veterinary use, or medical applications.
What is included with each TB-500 Capsules?
Each order includes the sealed product container and a batch-specific Certificate of Analysis (COA) verifying identity and purity by HPLC and LC–MS. The full COA library for Omnix Peptides is available at /coa-lab-reports/.
What is a Certificate of Analysis (COA), and how do I read it?
A COA is a batch-specific lab report that documents the identity, purity, and quality control results for the production lot you receive. The COA lists the compound name, CAS number, lot number, analytical methods used (HPLC, LC–MS), and the measured purity percentage. Every Omnix order includes the COA for the lot shipped.
What is the CAS number for TB-500?
The CAS number for TB-500 is 885340-08-9. Researchers can use this identifier to locate published literature in PubMed and other scientific databases.
How does Omnix Peptides ship orders?
Orders ship from a US-based facility with tracked domestic shipping. Free shipping is offered on orders over $99. Lyophilized vials and capsules ship at ambient temperature; sprays ship insulated when seasonal conditions require it. Tracking information is provided by email after the order ships.
What if my product arrives damaged or the seal is broken?
Contact Omnix Peptides within 48 hours of delivery. Product damaged in transit or arriving with a compromised seal will be replaced at no cost. See the Shipping & Return Policy at /shipping-return-policy/ for full terms.
Where can I find published research on TB-500?
Peer-reviewed studies relevant to TB-500 are listed in the Citations tab on this product page. The same studies can be located independently on PubMed using the CAS number (885340-08-9) or the compound name.
Customer reviews
Certificate of Analysis
Certificate of Analysis (COA) for this batch is available on request. Email orders@omnixpeptides.com with your order number to receive a copy. COAs include HPLC purity analysis performed by an independent third-party laboratory.
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