BPC-157 vs TB-500: origin, structure and how their research differs

In short: BPC-157 is a synthetic 15-amino-acid peptide described as a fragment of a gastric juice protein. The name TB-500 is used for thymosin beta-4, a 43-amino-acid actin-binding protein, and also for a seven-residue fragment of it. Both have mainly preclinical literature, both are unapproved in Australia, and WADA prohibits both.

BPC-157 and TB-500 are often named together, and sometimes combined in blends, but they are different molecules. This comparison sets out their chemistry, evidence and regulatory status; it is not a guide to choosing between them. Each has a full review: the published research on BPC-157 and what the research on TB-500 covers. Evidence labels follow how to read a peptide study.

Key facts side by side

Property	BPC-157	TB-500 (full-length thymosin beta-4)
Other names	BPC 157, Bepecin, PL 14736 1	Thymosin beta-4, Tβ4, timbetasin 2
Sequence	GEPPPGKPADDAGLV	Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES 3
Length	15 residues	43 residues
End groups	Free amino and carboxylic acid ends	Acetylated amino end (N-acetylserine), free carboxylic acid end
Molecular formula	C62H98N16O22	C212H350N56O78S
Molecular weight	1419.5 g/mol	4963 g/mol
CAS number	137525-51-0	77591-33-4
PubChem CID	9941957	16132341
Origin	Described as a fragment of BPC, a protein isolated from human gastric juice	A protein found in essentially all cells (gene TMSB4X, UniProt P62328)
Evidence base	Mainly rodent and cell studies; three small uncontrolled human reports	Large cell and animal literature on the protein; registered human trials of specific investigational products
WADA status (2026 List)	S0, non-approved substances; prohibited at all times	S2.3, “Thymosin-β4 and its derivatives e.g. TB-500”; prohibited at all times
TGA status	Named as an unapproved peptide product (advisory of 13 April 2026)	TB-500 named as an unapproved peptide product (advisory of 13 April 2026)

Molecular weights are for the free peptide; salt forms such as an acetate weigh more (see acetate vs TFA salts). Certified Research Peptides supplies its TB-500 as full-length thymosin beta-4 acetate, so the TB-500 column describes the full protein. The name is also used for Ac-LKKTETQ, a seven-residue acetylated fragment (C38H68N10O14, 889.0 g/mol, CAS 885340-08-9, PubChem CID 62707662) 4.

What are BPC-157 and TB-500?

BPC-157 is a short synthetic peptide of 15 amino acids from a protein described in human gastric juice 5. TB-500 is a name rather than one defined compound: it is used for thymosin beta-4, a 43-amino-acid protein found in essentially all cells 6, and for Ac-LKKTETQ, a seven-residue acetylated fragment of it 7. BPC-157 shares no sequence with either.

Where does each compound come from?

BPC-157 comes from gastric juice research; thymosin beta-4 is an actin-binding protein made in the body’s cells, and the TB-500 fragment reproduces part of it.

BPC-157. In a 1993 overview, Sikiric and colleagues at the University of Zagreb described a gastric juice protein of relative molecular mass about 40,000, named BPC (body protection compound), and characterised a 15-amino-acid fragment of it, BPC 157 5.

Thymosin beta-4. UniProt records human thymosin beta-4 (gene TMSB4X) as a 44-residue precursor whose first methionine is removed, leaving a 43-residue chain that starts with an acetylated serine 3. A 2010 review by Sosne et al. described it as the major actin-sequestering molecule in eukaryotic cells, found in essentially all cells and body fluids 6. Sequestering means it binds single actin units (building blocks of the cell’s internal scaffold) and stops them joining into filaments 3. The review located the central actin-binding region around residues 17 to 23, LKKTETQ 6.

The name TB-500. Products sold as TB-500 have not all contained the same thing. A Ghent University doping control laboratory identified the acetylated 17 to 23 fragment (Ac-LKKTETQ) in a TB-500 product in 2012 7, and the Hong Kong Jockey Club’s racing laboratory described TB-500 as a veterinary preparation based on that fragment 8. In 2023, a French horse-racing laboratory reported that TB500 products sold online were not consistent with earlier descriptions 9. Sport Integrity Australia uses the name for the full protein, listing “Thymosin Beta-4 (TB-500)” 10. See TB-500 vs thymosin beta-4.

How do their structures differ?

Full-length thymosin beta-4 is almost three times as long as BPC-157 and about 3.5 times heavier, and only thymosin beta-4 carries a chemical cap at its starting end.

• Length and mass. BPC-157 has 15 residues and a molecular weight of 1419.5 g/mol 1. Thymosin beta-4 has 43 residues and a molecular weight of 4963 g/mol 2.
• Composition. BPC-157 contains four prolines, three acidic residues and one lysine. Thymosin beta-4 is rich in charged residues, with nine lysines and eight glutamates in its UniProt sequence 3. Neither contains cysteine, so neither forms disulfide bonds.
• End groups. PubChem records BPC-157 as H-GEPPPGKPADDAGLV-OH, with free ends 1, and thymosin beta-4 with an acetyl group (a two-carbon cap) on its first serine 2.
• Shape. UniProt annotates the whole thymosin beta-4 chain as a disordered region, meaning it has no fixed folded shape on its own 3.

Illustration: two peptide chains of different lengths drawn as beads, one per residue. It does not show the actual structure of either compound.

What has research on each compound measured?

BPC-157 research mostly tests the peptide in rodent injury models; thymosin beta-4 research tests the full protein in cell and animal models; TB-500 papers mostly concern the fragment’s chemistry.

BPC-157. A Europe PMC search on 28 September 2026 returned 224 PubMed-indexed records mentioning BPC-157 in the title or abstract, 174 of them (about 78%) with P. Sikiric of the University of Zagreb as an author 11. A 2025 systematic review of musculoskeletal research included 35 preclinical studies and one clinical study 12.

Thymosin beta-4 and TB-500. The same approach returned 1,104 records mentioning thymosin beta-4 and 30 mentioning TB-500, six of which used the term for something unrelated 13. Judged by their titles, 13 of the relevant TB-500 records are anti-doping analytical papers and seven are reviews. A 2024 Korean anti-doping study stated that the biological effects of the acetylated fragment had not been documented 14.

Study	Compound tested	Study type	Model	What was measured	Reported finding
Staresinic, 2003	BPC-157	Animal and cell	Rats with a transected Achilles tendon; cultured tendon cells	Load to failure, functional index, microscopy	Higher load to failure and functional index values than controls
Malinda, 1999	Thymosin beta-4	Animal and cell	Rat full-thickness skin wound; keratinocyte migration assay	Re-epithelialisation, contraction, collagen, vessel formation	Increased re-epithelialisation and contraction compared with saline controls
Philp, 2003	Thymosin beta-4 and synthetic LKKTETQ	Animal	Skin wounds in diabetic and aged mice	Wound contraction, collagen deposition	LKKTETQ promoted repair in aged mice comparably to the full protein
Esposito, 2012	TB-500 fragment	Analytical	Commercial TB-500 product	Identity of the active ingredient	Identified Ac-LKKTETQ in the product
Rahaman, 2024	TB-500 fragment and its metabolites	Analytical, cell and animal	Human serum and enzymes in vitro; rat urine; fibroblasts	Metabolites, cytotoxicity, wound-closure assay	Ac-LK was the main metabolite; only the metabolite Ac-LKKTE showed significant activity in the closure assay

Have BPC-157 and TB-500 been studied together?

One rat study has compared them directly. Bicer et al. (2026) assigned 32 rats with a cut and repaired Achilles tendon to four groups (control, BPC-157, TB-500 and both combined), then measured tendon strength and scored tissue under the microscope after four weeks. The abstract describes the TB-500 used as synthetic thymosin beta-4 18.

As reported by the authors:

• maximum load to failure was higher than controls in both single-compound groups, significantly so only for TB-500;
• tissue damage scores (Bonar and Movin, where lower means less abnormal tissue) were significantly lower in the TB-500 group, and the Movin score also in the combined group;
• the BPC-157 group’s lower scores did not reach significance, and the combination added nothing over either compound alone.

The authors described the work as an exploratory rat model study 18. No human study comparing the two was found.

How does the evidence base for each differ?

Both evidence bases are mainly preclinical, but BPC-157’s is concentrated in one group, while thymosin beta-4’s is larger and has reached registered human trials.

Concentration. Most BPC-157 papers come from one group 11, and a 2019 review noted that only a handful of groups had studied it in depth 19.

Human data. A 2025 narrative review counted three small pilot studies of BPC-157 in humans 20, and ClinicalTrials.gov lists BPC-157 studies, none with posted results 21. For thymosin beta-4, ClinicalTrials.gov lists 19 records, from phase 1 to phase 3, that test specific investigational products made from the full protein, such as RGN-259 and NL005; nine have posted results. One further trial, NCT07487363, registered in 2026 and recruiting, tests the 17 to 23 fragment under the name TB-500 22. See why most peptide research is preclinical for what preclinical evidence can show.

How are BPC-157 and TB-500 regulated and treated in anti-doping?

Both are unapproved peptide products in Australia and prohibited in sport at all times, under different WADA sections.

TGA. The Therapeutic Goods Administration’s safety advisory of 13 April 2026 names BPC-157 and TB-500 among its examples of unapproved peptide products, meaning goods not included in the Australian Register of Therapeutic Goods, which the TGA has not evaluated for safety, quality or effectiveness 23.

WADA. The 2026 Prohibited List names BPC-157 in section S0 (non-approved substances), where it has been named since the 2022 List 24, and lists “Thymosin-β4 and its derivatives e.g. TB-500” in section S2.3 (growth factors and growth factor modulators), an entry that names both the full protein and TB-500. S0 substances are classed as Specified and S2 substances as non-Specified, a distinction used in sanctioning 25. Sport Integrity Australia lists both among examples of unapproved peptides prohibited in sport 10. Our anti-doping status table covers other research peptides.

How are BPC-157 and TB-500 told apart in the lab?

Mass spectrometry tells them apart. PubChem lists monoisotopic masses of 1418.704 Da for BPC-157, 4960.486 Da for thymosin beta-4 and 888.492 Da for the seven-residue fragment 1, 2, 4, so the same measurement shows which form a product labelled TB-500 contains. HPLC separates the components of a mixture; see how multi-component blends are tested and the BPC-157 and TB-500 blend review.

Anti-doping laboratories have published detection methods for BPC-157 26, 27 and for the TB-500 fragment 8, 14.

Illustration: a mass spectrometer, the instrument that distinguishes peptides by mass.

Frequently asked questions

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

Not always. The name TB-500 is used both for full-length thymosin beta-4, a 43-residue protein 3, and for Ac-LKKTETQ, the acetylated 17 to 23 fragment that Ghent University’s doping control laboratory identified in a TB-500 product in 2012 7. A 2023 analysis found that products sold online as TB500 were not consistent with earlier descriptions 9. Mass spectrometry distinguishes the two. See TB-500 vs thymosin beta-4.

Are BPC-157 and TB-500 related?

No. They share no sequence and come from different parent proteins. BPC-157 was described in 1993 as a fragment of BPC, a protein from human gastric juice 5. TB-500 is either thymosin beta-4, an actin-binding protein found in essentially all cells, or a short fragment of it 6. They are often discussed together, and one 2026 rat study tested both side by side 18.

Which is larger, BPC-157 or TB-500?

It depends on the form of TB-500. Full-length thymosin beta-4 (PubChem CID 16132341) has 43 residues, the formula C212H350N56O78S and a molecular weight of 4963 g/mol, so it is larger than BPC-157 (CID 9941957; 15 residues; 1419.5 g/mol) 2, 1. The seven-residue fragment Ac-LKKTETQ (CID 62707662; 889.0 g/mol) is smaller than both 4.

Have BPC-157 and TB-500 been compared in a study?

One 2026 rat study compared them directly. Bicer et al. assigned 32 rats with a repaired Achilles tendon to control, BPC-157, TB-500 and combined groups, and measured tendon strength and tissue scores after four weeks. They reported some significant differences from controls for TB-500 and the combination, but not for BPC-157 alone 18. No human comparison was found.

Are BPC-157 and TB-500 banned in sport?

Yes. The 2026 WADA Prohibited List names BPC-157 in section S0 (non-approved substances) and lists thymosin beta-4 and its derivatives, including TB-500, in section S2.3 (growth factors and growth factor modulators). Both sections apply at all times, in and out of competition 25. See our anti-doping status table.

References

1. PubChem. BPC-157, compound summary (CID 9941957). National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/9941957, accessed 28 September 2026. [chemical database]
2. PubChem. Timbetasin (thymosin beta-4), compound summary (CID 16132341). National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/16132341, accessed 28 September 2026. [chemical database]
3. UniProt. P62328, thymosin beta-4 (TMSB4X), human. https://www.uniprot.org/uniprotkb/P62328/entry, accessed 28 September 2026. [protein database]
4. PubChem. TB-500, compound summary (CID 62707662). National Center for Biotechnology Information. https://pubchem.ncbi.nlm.nih.gov/compound/62707662, accessed 28 September 2026. [chemical database]
5. Sikirić P, Petek M, Rucman R, et al. A new gastric juice peptide, BPC. An overview of the stomach-stress-organoprotection hypothesis and beneficial effects of BPC. J Physiol Paris. 1993;87(5):313-327. doi:10.1016/0928-4257(93)90038-u. PMID: 8298609. [narrative review]
6. Sosne G, Qiu P, Goldstein AL, et al. Biological activities of thymosin beta4 defined by active sites in short peptide sequences. FASEB J. 2010;24(7):2144-2151. doi:10.1096/fj.09-142307. PMID: 20179146. [narrative review]
7. Esposito S, Deventer K, Goeman J, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential. Drug Test Anal. 2012;4(9):733-738. doi:10.1002/dta.1402. PMID: 22962027. [analytical chemistry study]
8. Ho EN, Kwok WH, Lau MY, et al. 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. J Chromatogr A. 2012;1265:57-69. doi:10.1016/j.chroma.2012.09.043. PMID: 23084823. [analytical method study in horses]
9. Delcourt V, Garcia P, Chabot B, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of misbranded and adulterated drugs. Drug Test Anal. 2023;15(4):458-464. doi:10.1002/dta.3421. PMID: 36482504. [analytical chemistry study of commercial products]
10. Sport Integrity Australia. Peptides explained. https://www.sportintegrity.gov.au/what-we-do/anti-doping/substance-education/peptides, accessed 28 September 2026. [anti-doping agency]
11. Europe PMC. Search of PubMed-indexed records mentioning BPC-157 in the title or abstract, run with and without the author filter “Sikiric P”. https://europepmc.org/search?query=%28TITLE_ABS%3A%22BPC%20157%22%20OR%20TITLE_ABS%3A%22BPC-157%22%20OR%20TITLE_ABS%3A%22BPC157%22%29%20AND%20SRC%3AMED, accessed 28 September 2026. [literature search]
12. Vasireddi N, Hahamyan H, Salata MJ, et al. Emerging Use of BPC-157 in Orthopaedic Sports Medicine: A Systematic Review. HSS J. 2025;21(4):485-495. doi:10.1177/15563316251355551. PMID: 40756949. PMCID: PMC12313605. [systematic review]
13. Europe PMC. Searches of PubMed-indexed records mentioning TB-500 (or TB500) and thymosin beta-4 in the title or abstract. https://europepmc.org/search?query=%28TITLE_ABS%3A%22TB-500%22%20OR%20TITLE_ABS%3A%22TB500%22%29%20AND%20SRC%3AMED, accessed 28 September 2026. [literature search]
14. Rahaman KA, Muresan AR, Min H, et al. Simultaneous quantification of TB-500 and its metabolites in in-vitro experiments and rats by UHPLC-Q-Exactive orbitrap MS/MS and their screening by wound healing activities in-vitro. J Chromatogr B Analyt Technol Biomed Life Sci. 2024;1235:124033. doi:10.1016/j.jchromb.2024.124033. PMID: 38382158. [analytical, cell and rodent study]
15. Staresinic M, Sebecic B, Patrlj L, et al. Gastric pentadecapeptide BPC 157 accelerates healing of transected rat Achilles tendon and in vitro stimulates tendocytes growth. J Orthop Res. 2003;21(6):976-983. doi:10.1016/s0736-0266(03)00110-4. PMID: 14554208. [rodent and cell study]
16. Malinda KM, Sidhu GS, Mani H, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. doi:10.1046/j.1523-1747.1999.00708.x. PMID: 10469335. [rodent and cell study]
17. Philp D, Badamchian M, Scheremeta B, et al. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice. Wound Repair Regen. 2003;11(1):19-24. doi:10.1046/j.1524-475x.2003.11105.x. PMID: 12581423. [mouse and rat study]
18. Biçer O, Adanir O, Güleryüz Y, et al. Effects of BPC-157 and TB-500 on Achilles tendon healing in rats: A histopathological and biomechanical study. Jt Dis Relat Surg. 2026;37(3):822-837. doi:10.52312/jdrs.2026.2951. PMID: 42542926. [rodent study]
19. Gwyer D, Wragg NM, Wilson SL. Gastric pentadecapeptide body protection compound BPC 157 and its role in accelerating musculoskeletal soft tissue healing. Cell Tissue Res. 2019;377(2):153-159. doi:10.1007/s00441-019-03016-8. PMID: 30915550. [narrative review]
20. McGuire FP, Martinez R, Lenz A, et al. Regeneration or Risk? A Narrative Review of BPC-157 for Musculoskeletal Healing. Curr Rev Musculoskelet Med. 2025;18(12):611-619. doi:10.1007/s12178-025-09990-7. PMID: 40789979. PMCID: PMC12446177. [narrative review]
21. ClinicalTrials.gov. Records NCT02637284, NCT07752381 and NCT07803250, found by searching for BPC-157, BPC 157 and PL 14736, accessed 28 September 2026. [trial registry]
22. ClinicalTrials.gov. Search for thymosin beta-4, RGN-259, RGN-352, RGN-137 and TB-500, 20 records including NCT07487363 (TB-500). https://clinicaltrials.gov/search?term=thymosin%20beta%204, accessed 28 September 2026. [trial registry]
23. Therapeutic Goods Administration. Understanding your responsibilities when importing, compounding and supplying unapproved peptide products (safety advisory, 13 April 2026). https://www.tga.gov.au/safety/safety-monitoring-and-information/safety-alerts/understanding-your-responsibilities-when-importing-compounding-and-supplying-unapproved-peptide-products, accessed 28 September 2026. [regulator]
24. World Anti-Doping Agency. WADA publishes 2022 Prohibited List (news release, 30 September 2021). https://www.wada-ama.org/en/news/wada-publishes-2022-prohibited-list, accessed 28 September 2026. [anti-doping agency]
25. World Anti-Doping Agency. The Prohibited List (2026 Prohibited List, in effect from 1 January 2026). https://www.wada-ama.org/en/prohibited-list, accessed 28 September 2026. [anti-doping standard]
26. Cox HD, Miller GD, Eichner D. Detection and in vitro metabolism of the confiscated peptides BPC 157 and MGF R23H. Drug Test Anal. 2017;9(10):1490-1498. doi:10.1002/dta.2152. PMID: 28035768. [analytical method study]
27. Tian T, Jing J, Li Y, et al. Stable Isotope Labeling-Based Nontargeted Strategy for Characterization of the In Vitro Metabolic Profile of a Novel Doping BPC-157 in Doping Control by UHPLC-HRMS. Molecules. 2023;28(21):7345. doi:10.3390/molecules28217345. PMID: 37959764. PMCID: PMC10650108. [analytical method study]