# TB-500 research guide

TB-500 is a synthetic seven-amino-acid peptide (Ac-LKKTETQ) that copies the active, actin-binding part of a natural protein, thymosin beta-4. It's studied - mostly in cells and animals - for tissue repair and cell movement. It is not the same as the full thymosin beta-4 protein.

Form Labs materials are research reference materials, not the approved medicines; no Form Labs product is approved for human or veterinary use.

- Parent protein: thymosin beta-4 is 43 amino acids long (Form Labs catalogue record) and was first fully sequenced in 1981 (Low et al., PNAS, 1981).
- Position: TB-500 matches residues 17-23 of that protein, the actin-binding stretch (Van Troys et al., The EMBO Journal, 1996).
- Human data: this guide's 2024 timeline entry lists ClinicalTrials.gov NCT07487363, an early-phase TB-500 safety study, as beginning recruitment, and this guide cites no human results for the fragment.
- Everything below summarises published research. Form Labs supplies TB-500 as laboratory reference material, for research use only.

7: Amino acids in the TB-500 fragment (Ac-LKKTETQ) - a small piece of the 43-amino-acid thymosin beta-4 protein, not the whole thing. (Esposito et al., 2012: https://doi.org/10.1002/dta.1402)

7: Amino acids in the TB-500 fragment, Ac-LKKTETQ - an identity fact, not a product claim. (Esposito et al., 2012: https://doi.org/10.1002/dta.1402)

17-23: The stretch of the 43-amino-acid thymosin beta-4 protein this fragment matches. (Van Troys et al., 1996: https://doi.org/10.1002/j.1460-2075.1996.tb00350.x)

1981: When the parent protein, thymosin beta-4, was first fully sequenced. (Low et al., 1981: https://doi.org/10.1073/pnas.78.2.1162)

0: Published human trials of the TB-500 fragment - the evidence is lab and animal only. (Published research)

## Why is TB-500 studied?

TB-500 is studied because it is a synthetic seven-amino-acid fragment (Ac-LKKTETQ) of thymosin beta-4, a natural protein 43 amino acids long (Form Labs catalogue record). TB-500 copies the seven amino acids that bind actin, a building block that helps cells hold shape and move (Form Labs catalogue record). Most of the well-known research is on the full protein, not on TB-500, and the direct evidence for TB-500 is thin and mostly in cells and animals.

The fragment, not the whole protein.

TB-500 is a shortcut name for one small, active piece of a natural protein called thymosin beta-4. The protein is 43 amino acids long; TB-500 is just the seven that bind actin (a building block that helps cells hold shape and move).

Malinda et al. (Journal of Investigative Dermatology, 1999) reported wound-repair observations for full thymosin beta-4 in rats. Philp et al. (Wound Repair and Regeneration, 2003) studied a TB-500-type short fragment in mice. The parent-protein and fragment findings remain distinct animal records.

## What laboratory observations have TB-500 studies reported?

Van Troys et al. (The EMBO Journal, 1996) identified the actin-binding region of full thymosin beta-4, the parent of TB-500. Philp et al. (Wound Repair and Regeneration, 2003) reported wound-repair observations for a TB-500-type short fragment in mice. Most cited findings concern the parent protein; they do not establish human outcomes for the fragment.

TB-500 fragment and parent records

### Parent-protein region

Van Troys et al. (The EMBO Journal, 1996) identified the actin-binding region of full thymosin beta-4; this is parent-protein research.

### Short-fragment mouse study

Philp et al. (Wound Repair and Regeneration, 2003) reported wound-repair observations for a TB-500-type short fragment in mice; this remains an animal finding.

### Fragment laboratory study

Rahaman et al. (Journal of Chromatography B, 2024) reported no significant increase in wound-healing activity for TB-500 itself in a dish, while a breakdown product differed.

|  |  |
| --- | --- |
| Research code | TB-500 (Ac-LKKTETQ) |
| Class | A synthetic peptide fragment - the actin-binding region (residues 17-23) of the protein thymosin beta-4. |
| Molecule | A short lab-made chain of seven amino acids, N-acetylated (a small chemical cap on one end): Ac-LKKTETQ. Not the full 43-amino-acid thymosin beta-4 protein. |
| Reported half-life | Not established in humans. The published fragment work is mostly analytical (detection) rather than pharmacokinetic. |
| Originator | The fragment was characterised for anti-doping testing (Esposito and colleagues, 2012); the parent protein, thymosin beta-4, was sequenced by Low and colleagues in 1981. |
| Approval status | Not an approved medicine anywhere - a preclinical research compound. On the World Anti-Doping Agency prohibited list. |

## What has TB-500 been studied for?

TB-500 research covers six areas: actin binding, wound healing with the parent protein, wound healing with a TB-500-type short fragment in a mouse model, identity and detection of the fragment, how the fragment breaks down, and human evidence. All of the studies cited in this guide are preclinical, in cells and animals. This guide's 2024 timeline entry lists ClinicalTrials.gov NCT07487363, an early-phase TB-500 safety study, as beginning recruitment, and this guide cites no human results for the fragment.

### Actin binding (identity)

The region of thymosin beta-4 that binds actin - mapped in the lab, and the basis for the fragment.

Van Troys et al., EMBO J, 1996

### Wound healing (parent protein)

Wound repair and skin-cell migration - studied on the full thymosin beta-4 protein in animals.

Malinda et al., J Invest Dermatol, 1999

### Wound healing (the fragment)

Philp et al. (Wound Repair and Regeneration, 2003) reported wound-repair observations for a TB-500-type short fragment in mice; this is an animal finding.

Philp et al., Wound Repair Regen, 2003

### Identity & detection

Making and detecting the Ac-LKKTETQ fragment for anti-doping testing - analytical work, not efficacy.

Esposito et al., 2012; Ho et al., 2012

### Metabolism (the fragment)

How the fragment breaks down; notably, the fragment itself didn't raise wound-healing activity in a dish - a metabolite did.

Rahaman et al., J Chromatogr B, 2024

### Human evidence

There are no published human trials of the fragment; one early-phase safety study is recruiting.

ClinicalTrials.gov NCT07487363

## Published studies

## What did the TB-500 studies find?

The TB-500 record includes parent-protein sequencing (Low et al., PNAS, 1981), actin-binding work (Van Troys et al., The EMBO Journal, 1996), and wound-repair observations for a TB-500-type short fragment in mice (Philp et al., Wound Repair and Regeneration, 2003). Rahaman et al. (Journal of Chromatography B, 2024) reported no significant wound-healing increase for TB-500 itself in a dish.

### The paper that spelled out the parent protein

Low TLK and colleagues - PNAS - 1981

Foundational (parent protein, not the fragment)

This paper worked out the full 43-amino-acid sequence of thymosin beta-4 - the protein that TB-500 is a small piece of.

|  |  |
| --- | --- |
| Studied in | Biochemical work on thymosin beta-4 from cattle. |
| Design | A protein-sequencing study. |
| Measured | The complete amino-acid sequence of thymosin beta-4. |

It established the full sequence of the parent protein (Low TLK and colleagues - PNAS - 1981). TB-500 is just seven of those 43 amino acids - so this is background, not a TB-500 study (Low TLK and colleagues - PNAS - 1981).

https://doi.org/10.1073/pnas.78.2.1162

### Finding the actin-binding part

Van Troys M and colleagues - The EMBO Journal - 1996

Preclinical (in-vitro, parent protein)

This lab study mapped which part of thymosin beta-4 binds actin - and pinpointed the stretch (residues 17-23) that TB-500 copies.

|  |  |
| --- | --- |
| Studied in | Lab experiments with thymosin beta-4 and engineered variants. |
| Design | An in-vitro (test-tube) structure-function study. |
| Measured | Which residues were needed to bind actin. |

It identified the 'LKKTET' region as the actin-binding part - the rationale for making the TB-500 fragment (Van Troys M and colleagues - The EMBO Journal - 1996). It's about the whole protein, not the fragment product (Van Troys M and colleagues - The EMBO Journal - 1996).

https://doi.org/10.1002/j.1460-2075.1996.tb00350.x

### Wound healing with the full protein (in rats)

Malinda KM and colleagues - Journal of Investigative Dermatology - 1999

Preclinical (animal, parent protein)

This study looked at whether the full thymosin beta-4 protein sped up skin-wound healing in rats.

|  |  |
| --- | --- |
| Studied in | Rats (in-vivo) plus cultured skin cells. |
| Design | An animal wound-healing model plus cell experiments. |
| Measured | How quickly wounds re-covered with skin, and how skin cells migrated. |

Full-length thymosin beta-4 was reported to speed wound re-covering in rats (Malinda KM and colleagues - Journal of Investigative Dermatology - 1999). It's about the parent protein, in animals - not the TB-500 fragment or people (Malinda KM and colleagues - Journal of Investigative Dermatology - 1999).

https://doi.org/10.1046/j.1523-1747.1999.00708.x

### The clearest study of the fragment itself

Philp D and colleagues - Wound Repair and Regeneration - 2003

Preclinical (animal, the fragment)

This is the closest genuine study of a TB-500-type short fragment: it tested the seven-amino-acid actin-binding peptide in mice with slow-healing wounds.

|  |  |
| --- | --- |
| Studied in | Mice (diabetic and aged models). |
| Design | An animal wound-healing model comparing the full protein and the short fragment. |
| Measured | How well wounds healed. |

Philp et al. (Wound Repair and Regeneration, 2003) reported that a TB-500-type short fragment reproduced much of the parent protein's wound repair in mice. This remains an animal finding.

https://doi.org/10.1046/j.1524-475X.2003.11105.x

### Making and identifying 'TB-500'

Esposito S and colleagues - Drug Testing and Analysis - 2012

Analytical (the fragment)

This paper made and characterised the exact Ac-LKKTETQ fragment sold as 'TB-500', mainly so anti-doping labs could detect it.

|  |  |
| --- | --- |
| Studied in | Laboratory chemistry. |
| Design | A synthesis and characterisation (analytical) study. |
| Measured | The fragment's structure and how to identify it. |

Esposito et al. (Drug Testing and Analysis, 2012) identified TB-500 as the N-acetylated 17-23 fragment; this is analytical identity research.

https://doi.org/10.1002/dta.1402

### What happens to the fragment - and a surprise

Rahaman KA and colleagues - Journal of Chromatography B - 2024

Preclinical (in-vitro + rat, the fragment)

A recent study measured the TB-500 fragment and its breakdown products, and tested wound-healing activity in a dish.

|  |  |
| --- | --- |
| Studied in | Lab (in-vitro) plus rats. |
| Design | An analytical and in-vitro study of the fragment and its metabolites. |
| Measured | Fragment and metabolite levels, plus in-vitro wound-healing activity. |

Notably, the TB-500 fragment itself didn't significantly raise wound-healing activity in the dish - one of its breakdown products did (Rahaman KA and colleagues - Journal of Chromatography B - 2024). A useful reminder that the fragment's own direct evidence is limited (Rahaman KA and colleagues - Journal of Chromatography B - 2024).

https://doi.org/10.1016/j.jchromb.2024.124033

## What risks have TB-500 studies recorded?

The studies cited in this guide are preclinical, so they do not establish the human safety profile of TB-500. Most of the well-known findings are on full-length thymosin beta-4, not TB-500, and reading them as TB-500 evidence overstates what is known. Form Labs supplies TB-500 only as research material.

### Direct human safety is unknown

Not established

There are no completed human trials of the TB-500 fragment, so its human safety profile isn't established.

### The evidence is mostly about a different molecule

A key caveat

Most of the well-known findings are on full-length thymosin beta-4, not this fragment. Reading them as TB-500 evidence overstates what's actually known about the fragment.

### Banned in sport

Regulatory

TB-500 is on the World Anti-Doping Agency prohibited list, so it isn't permitted for athletes.

### Not an approved medicine

Regulatory

No medicines regulator (the TGA in Australia, the FDA, the EMA) has approved TB-500 for any use. It's supplied here only as a research material.

## What has TB-500 research not established?

The TB-500 guide cites no human results for the fragment, and its timeline record (2024) lists ClinicalTrials.gov NCT07487363 as beginning recruitment. Much of the cited research concerns full thymosin beta-4 rather than the TB-500 fragment. The laboratory and mouse observations do not establish clinical outcomes or long-term safety in people.

- People: there are no published human trials of the fragment; one early-phase safety study is only now recruiting.
- Direct fragment findings remain limited; much of the cited literature concerns the full thymosin beta-4 protein.
- Long-term safety: not established, in animals or people.

## Is TB-500 approved, and where does the research stand?

TB-500 is recorded in this guide's timeline as a preclinical research compound. It begins in 1981 with the sequencing of the parent protein thymosin beta-4 (Low et al., PNAS, 1981) and in 1996 with the mapping of the actin-binding region (Van Troys et al., The EMBO Journal, 1996). A 2024 metabolism study found TB-500 itself underperformed a breakdown product in vitro (Rahaman et al., Journal of Chromatography B, 2024).

- 1981: The parent protein, thymosin beta-4, is fully sequenced.
- 1996: The actin-binding region (residues 17-23) is mapped - the basis for the fragment.
- 1999-2003: Wound-healing studies: the full protein in rats, then the short fragment in mice.
- 2012: The exact Ac-LKKTETQ 'TB-500' fragment is made and characterised for anti-doping testing.
- 2024 ->: A metabolism study finds the fragment itself underperformed a breakdown product in vitro; an early-phase human safety trial begins recruiting.

## What does the TB-500 research mean, and what does it not?

The TB-500 evidence cited in this guide is preclinical: it comes from cells and animals, and animal results often do not carry over to people. Most of the famous thymosin beta-4 findings are on the full 43-amino-acid protein, not on TB-500 (Form Labs catalogue record). A 2024 study found TB-500 itself did not raise wound-healing activity in a dish (Rahaman et al., Journal of Chromatography B, 2024). This guide summarises published research and makes no product claim.

### It's preclinical

The evidence is in cells and animals. Animal results often don't carry over to people, and for this fragment that step is barely tested.

### Most evidence is about the parent protein

The famous thymosin beta-4 findings are on the full 43-amino-acid protein, not this seven-amino-acid fragment. The fragment's own direct research is limited and mostly analytical.

### The fragment underperformed in one recent test

A 2024 study found the TB-500 fragment itself didn't raise wound-healing activity in a dish - a metabolite did. That's a caution against assuming the fragment behaves like the whole protein.

### Where Form Labs fits

This guide is a plain-English summary of published research Form Labs did not run. It's not medical advice, not a product claim, and not use guidance. We supply TB-500 strictly as reference material, with a catalog lot record. Matching current certification is unavailable; published studies do not verify this product lot.

## How is TB-500 handled as reference material?

TB-500 is laboratory reference material, not for human consumption or veterinary use. Storage and lot checks follow the product label and any verified matching certificate of analysis (COA). This guide's catalogue record notes storage at 2-8 C and protection from light. Historical sample reports do not verify current lot identity, purity or release status.

### Research-use boundary

TB-500 is supplied strictly for laboratory research. It is not for human consumption, veterinary, medical, or cosmetic use.

### Storage

Supplied freeze-dried. Keep it at 2-8 C (fridge-cold) and out of light, following the vial label, any verified matching lab report for the batch, and your lab's own written procedures.

## Plain-English definitions.

### Peptide

A short chain of amino acids - the building blocks of proteins.

### Thymosin beta-4

A natural 43-amino-acid protein; TB-500 is a short, seven-amino-acid piece of it.

### Fragment

A shorter piece of a larger peptide or protein.

### Actin

A protein inside cells that helps them hold shape and move.

### N-acetylated

A small chemical cap (the 'Ac') added to one end of the fragment.

### Preclinical

Research in cells and animals, before (or instead of) trials in people.

### In-vitro

In a dish or test tube, outside a living body.

### In-vivo

In a living animal.

### Metabolite

A breakdown product a compound turns into in the body.

### Research use only

Supplied for laboratory research - not for human or animal use, and not a medicine.

## What are the most common questions about TB-500?

TB-500 is a synthetic seven-amino-acid peptide (Ac-LKKTETQ) that copies the actin-binding region of thymosin beta-4 (Form Labs catalogue record) and is studied mostly in cells and animals. The most common questions about TB-500 cover how TB-500 differs from thymosin beta-4 and from BPC-157, how strong the evidence is, whether TB-500 has been tested in people, and its Australian status.

### What is TB-500, in one line?

TB-500 is a synthetic seven-amino-acid peptide (Ac-LKKTETQ) that copies the actin-binding part of the protein thymosin beta-4, studied - mostly in cells and animals - for tissue repair. TB-500 isn't the full protein, and it isn't an approved medicine.

### Is TB-500 the same as thymosin beta-4?

No. Thymosin beta-4 is a full 43-amino-acid protein; TB-500 is just a seven-amino-acid piece of it - the actin-binding region (residues 17-23). Most of the well-known research is on the whole protein, so it shouldn't be read as direct evidence for the shorter TB-500 fragment.

### How strong is the evidence for the TB-500 fragment specifically?

Weaker than it looks. Most of the famous thymosin beta-4 findings (wound healing, blood vessels, heart tissue) are on the full 43-amino-acid protein, not the seven-amino-acid TB-500 fragment. Direct fragment research is thin and largely analytical, and a 2024 study (Rahaman et al.) found the fragment itself didn't raise wound-healing activity in a dish - a breakdown product did.

### What is TB-500 studied for, and in which models?

The parent protein, thymosin beta-4, is studied for cell migration and wound repair (Malinda et al., 1999, in rats) and for the actin-binding region that TB-500 copies (Van Troys et al., 1996). The clearest study of a TB-500-type short fragment is Philp et al. (2003) in mice. All of it is preclinical - cells and animals.

### Has the TB-500 fragment been tested in people?

There are no published human trials of the TB-500 fragment. One early-phase safety study (ClinicalTrials.gov NCT07487363) is recruiting but has no results. Some early human trials exist for the full thymosin beta-4 protein, run years ago, but none led to an approved medicine and none was of the fragment sold as TB-500.

### What does 'Ac-LKKTETQ' mean?

Ac-LKKTETQ is TB-500's sequence: seven amino acids with an acetyl group - the 'Ac' - capping one end. This stretch matches residues 17-23 of thymosin beta-4, the part that binds actin (a protein that helps cells hold their shape and move).

### How is TB-500 different from BPC-157?

TB-500 and BPC-157 are unrelated peptides that both appear in tissue-repair research. TB-500 is a 7-amino-acid fragment of the protein thymosin beta-4; BPC-157 is a 15-amino-acid peptide based on a gastric-juice protein. Different origins and sequences, both preclinical. One 2026 rat study (Biçer et al., Joint Diseases and Related Surgery) included both, and this guide draws no combined claim from it.

### Is TB-500 approved or legal to use?

TB-500 is a Schedule 4 substance in Australia. The October 2026 Poisons Standard (checked 1 October 2026) lists TB-500 in Schedule 4 and in Appendix D, clause 5 - the appendix for poisons whose possession without authority is illegal. The TGA's April 2026 examples of unapproved peptide products name TB-500. Sport Integrity Australia lists thymosin beta-4 (TB-500) as prohibited in sport. Form Labs supplies TB-500 strictly as laboratory research material, not for human or veterinary use.

### What does "for research use only" mean here?

Form Labs supplies peptides strictly as laboratory research materials. This guide is a plain-English summary of published research Form Labs did not run - not medical advice, not a product claim, and not guidance for any human or veterinary use.

## References

- Full amino-acid sequence of the parent protein, thymosin beta-4. Low TLK, Hu SK, Goldstein AL. PNAS, 1981; 78(2): 1162-1166. DOI: 10.1073/pnas.78.2.1162
- In-vitro mapping of the actin-binding region (residues 17-23) of thymosin beta-4. Van Troys M, et al. The EMBO Journal, 1996; 15(2): 201-210. DOI: 10.1002/j.1460-2075.1996.tb00350.x
- Rat study of wound healing with full-length thymosin beta-4. Malinda KM, et al. Journal of Investigative Dermatology, 1999; 113(3): 364-368. DOI: 10.1046/j.1523-1747.1999.00708.x
- Philp D, et al. Wound Repair and Regeneration, 2003; 11(1): 19-24. Mouse wound-repair study of the parent protein and a short actin-binding fragment. DOI: 10.1046/j.1524-475X.2003.11105.x
- Synthesis and characterisation of the Ac-LKKTETQ 'TB-500' fragment for anti-doping detection. Esposito S, et al. Drug Testing and Analysis, 2012; 4(9): 733-738. DOI: 10.1002/dta.1402
- Metabolism study of the TB-500 fragment; the fragment itself did not significantly raise in-vitro wound-healing activity. Rahaman KA, et al. Journal of Chromatography B, 2024; 1235: 124033. DOI: 10.1016/j.jchromb.2024.124033
- Rat Achilles tendon study that included BPC-157 and TB-500 together. Biçer O, et al. Joint Diseases and Related Surgery, 2026; 37(3): 822-837. DOI: 10.52312/jdrs.2026.2951

![One long horizontal bar labelled Full protein with a short solid segment inside it, joined by a thin line to the label Actin binding. The diagram is not to scale.](/assets/content/rb-fragment-within-protein.png)

Van Troys et al. (The EMBO Journal, 1996) identified the parent protein's actin-binding region. Philp et al. (Wound Repair and Regeneration, 2003) reported wound-repair observations for a TB-500-type short fragment in mice; these are separate parent-protein and animal records. The diagram is not to scale.


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