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Peptency Academy · Compound

TB-500: two molecules, one name

The Peptency catalog record uses TB-500 for the 43 residue thymosin beta 4. Source sentenceslug tb-500: sequenceLength 43, sequence Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES, cas 77591-33-41 Peptency catalog record, TB-500 Thymosin beta 4 is also called timbetasin and weighs about 4963 Da. Source sentenceSynonyms include 'Timbetasin'; MolecularWeight 49632 PubChem CID 16132341 Most analytical and regulatory sources use TB-500 for the 7 residue fragment Ac-LKKTETQ. Source sentencedetection and the identification of the N-terminal acetylated 17-23 fragment of human thymosin beta 4 (Ac-LKKTETQ) in TB-5003 Drug Test Anal 20124 J Chromatogr B Analyt Technol Biomed Life Sci 20245 J Chromatogr A 20126 FDA, bulk drug substances Category 2 page, content current as of 22 April 20267 ClinicalTrials.gov NCT07487363 The fragment weighs about 889 Da. Source sentenceMolecularWeight 889.0; MolecularFormula C38H68N10O148 PubChem CID 62707662

Version 1Edited Evidence through 31 sources

Regulatory content shown for: United States and the Americas.

Two molecules, one name

  • Catalog recordThymosin beta 443 residuesabout 4963 DaSource sentenceSynonyms include 'Timbetasin'; MolecularWeight 49632 PubChem CID 16132341
  • Most analytical and regulatory sourcesAc-LKKTETQ7 residuesabout 889 DaSource sentenceMolecularWeight 889.0; MolecularFormula C38H68N10O148 PubChem CID 62707662

Known, not known, contested

Known

Not known

  • No published human study of the fragment Ac-LKKTETQ was found in PubMed as of 12 Oct 2026; one registered trial (NCT07487363) is recruiting. Source sentence38 records screened on 12 Oct 2026; none reports a human study of the fragment14 PubMed search for TB-500, TB500 or LKKTETQ, 12 October 20267 ClinicalTrials.gov NCT07487363
  • Whether the fragment shares the activities studied for the full protein is not documented: a 2024 metabolism paper states "the biological effects of TB-500, however, have not been documented". Source sentenceThe biological effects of TB-500, however, have not been documented.4 J Chromatogr B Analyt Technol Biomed Life Sci 2024
  • Which molecule a vial labelled TB-500 contains cannot be read from the name. The molecule line for Peptency lots is pending the lot results. Source sentenceVR23: TB-500 catalog molecule line from the lab results already held per lot, state open15 Drug Test Anal 2023

Contested

  • Most analytical and regulatory sources use "TB-500" for the 7 residue fragment, while the catalog record uses it for the 43 residue protein. Source sentenceTB-500 (Ac-LKKTETQ), derived from the active site of thymosin β4 (Tβ4)4 J Chromatogr B Analyt Technol Biomed Life Sci 20243 Drug Test Anal 20125 J Chromatogr A 20121 Peptency catalog record, TB-500
  • Some papers use the same name for the full protein: a 2026 rat study calls its material "synthetic thymosin beta-4 (TB-500)" and its abstract gives no sequence or mass. Source sentencesynthetic thymosin beta-4 (TB-500)16 Jt Dis Relat Surg 2026
  • A 2025 materials paper uses "TB500" for a peptide with the sequence LKKTETQ inside a larger conjugate. Source sentenceincorporates TB500, a biologically active peptide with the amino acid sequence LKKTETQ17 ACS Appl Mater Interfaces 2025
  • Products sold online as TB500 and TB1000 were found "not systematically consistent" with their descriptions. Source sentenceWe confirm that the content of TB500/TB1000 products is not systematically consistent with it's former descriptions15 Drug Test Anal 2023

Chemistry: thymosin beta 4, the catalog record

Sequence
Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES
Length
43 residues
Modifications
N-terminal acetylation (Ser1)
Formula
C212H350N56O78S
Monoisotopic mass
4960.4863 Da
Average mass
4963 Da
CAS
77591-33-4
PubChem CID
16132341
InChIKey
UGPMCIBIHRSCBV-XNBOLLIBSA-N
Synonyms
thymosin beta 4, thymosin beta-4, Tβ4, Tbeta4, timbetasin
Salt form
No salt form stated in the record
Checked 12 October 2026 2 PubChem CID 16132341

Chemistry: the fragment Ac-LKKTETQ

  • Ac-LKKTETQ, the 7 residue fragment: formula C38H68N10O14, monoisotopic mass 888.4916 Da, average mass 889.0 Da, PubChem CID 62707662, InChIKey ADKDNDYYIZUVCZ-ZQNQAVPYSA-N. PubChem lists CAS 885340-08-9 among its synonyms; that number is not confirmed against the CAS Registry for this page. Source sentenceMolecularFormula C38H68N10O14; MonoisotopicMass 888.49164688; MolecularWeight 889.0; InChIKey ADKDNDYYIZUVCZ-ZQNQAVPYSA-N; synonyms include 885340-08-98 PubChem CID 62707662
  • PubChem lists "Thymosin beta4 Acetate" and "TB 500 acetate" as synonyms. The masses on this page are for the peptides without a counterion. Source sentenceSynonyms: 'Thymosin beta4 Acetate' (CID 16132341); 'TB 500 acetate' (CID 62707662)2 PubChem CID 161323418 PubChem CID 62707662

Sequence

Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES

LKKTETQ residues 17 to 23Residues 17 to 23 of thymosin beta 4 are the same seven amino acids as the fragment. Only the fragment carries an acetyl group on Leu17.

Which molecule is in a vial labelled TB-500?

  • Read the mass result on the certificate of analysis. A deconvoluted intact mass near 4960.5 Da (monoisotopic) fits thymosin beta 4. A singly protonated ion near m/z 889.50 fits Ac-LKKTETQ. A label that says only "TB-500" fits either. Source sentenceMonoisotopicMass 4960.4863169 (CID 16132341); 888.49164688 (CID 62707662); [M+H]+ computed as monoisotopic mass plus 1.007282 PubChem CID 161323418 PubChem CID 62707662
  • Monoisotopic masses: 4960.49 Da for thymosin beta 4 and 888.49 Da for Ac-LKKTETQ. Source sentenceMonoisotopicMass 4960.4863169 (CID 16132341); 888.49164688 (CID 62707662)2 PubChem CID 161323418 PubChem CID 62707662
  • The fragment was identified in a product sold as TB-500 by liquid chromatography with high resolution mass spectrometry (Orbitrap), and a reference standard was synthesised. Source sentenceThis work describes the detection and the identification of the N-terminal acetylated 17-23 fragment of human thymosin beta 4 (Ac-LKKTETQ) in TB-500 by means of high-performance liquid chromatography/high resolution mass spectrometry using an Orbitrap Exactive benchtop mass spectrometer.3 Drug Test Anal 2012
  • Doping control laboratories have published LC-MS methods for the fragment and its metabolites in equine urine and plasma, and in rat urine. Source sentencedescribes a method for the simultaneous detection of N-acetylated LKKTETQ and its metabolites in equine urine and plasma samples5 J Chromatogr A 20124 J Chromatogr B Analyt Technol Biomed Life Sci 2024
  • Ac-LK and Ac-LKK are reported metabolites of the fragment in rats. Source sentenceAc-LK was the primary metabolite with the highest concentration in rats at 0-6 h intervals. Also, the metabolite Ac-LKK was a long-term metabolite of TB-5004 J Chromatogr B Analyt Technol Biomed Life Sci 2024
  • Products bought online as TB500 and TB1000 were not consistent with their descriptions (analytical finding, 2023). Source sentencethe content of TB500/TB1000 products is not systematically consistent with it's former descriptions15 Drug Test Anal 2023
  • Equine doping laboratories report products online that claim either the acetylated fragment or the full protein (2024). Source sentenceproducts available online claiming to contain a synthetic acetylated fragment of TB4 or TB4 itself18 Drug Test Anal 2025
  • Thymosin beta 4 measured in stored horse plasma rises when plasma is not separated from blood cells, which matters for detection methods. Source sentencethe TB4 concentration increases significantly and rapidly in plasma stored at 4°C when not separated from blood cells due to cell lysis18 Drug Test Anal 2025

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

Not always. Most analytical and regulatory sources use TB-500 for the 7 residue fragment Ac-LKKTETQ, residues 17 to 23 of thymosin beta 4, while the Peptency catalog record uses the name for the full 43 residue protein. Source sentencedetection and the identification of the N-terminal acetylated 17-23 fragment of human thymosin beta 4 (Ac-LKKTETQ) in TB-5003 Drug Test Anal 20124 J Chromatogr B Analyt Technol Biomed Life Sci 20245 J Chromatogr A 20126 FDA, bulk drug substances Category 2 page, content current as of 22 April 20267 ClinicalTrials.gov NCT074873631 Peptency catalog record, TB-5002 PubChem CID 16132341

What is the molecular weight of TB-500?

It depends on the molecule. Thymosin beta 4 (C212H350N56O78S) has an average mass of about 4963 Da and a monoisotopic mass of 4960.49 Da; Ac-LKKTETQ (C38H68N10O14) has about 889.0 Da and 888.49 Da (PubChem CIDs 16132341 and 62707662). Source sentenceMonoisotopicMass 4960.4863169 (CID 16132341); 888.49164688 (CID 62707662)2 PubChem CID 161323418 PubChem CID 62707662

What is Ac-LKKTETQ?

It is the N-terminally acetylated 17 to 23 fragment of human thymosin beta 4, identified in a product sold as TB-500 by high resolution mass spectrometry. A 2024 metabolism study uses the name TB-500 for this fragment. Source sentencethe N-terminal acetylated 17-23 fragment of human thymosin beta 4 (Ac-LKKTETQ)3 Drug Test Anal 20125 J Chromatogr A 20124 J Chromatogr B Analyt Technol Biomed Life Sci 20241 Peptency catalog record, TB-500

How does a lab tell the two TB-500 molecules apart?

By mass spectrometry: the two differ by about 4074 Da, so an intact mass result places a sample on one side or the other. Published LC-MS methods exist for the fragment and its metabolites. Source sentenceMolecularWeight 4963 (CID 16132341) against 889.0 (CID 62707662); difference computed2 PubChem CID 161323418 PubChem CID 627076625 J Chromatogr A 20124 J Chromatogr B Analyt Technol Biomed Life Sci 2024

Evidence map: thymosin beta 4 (1 to 43)

Primary studies of thymosin beta 4 (1 to 43), by model and by what was measured. Reviews are not counted. An empty cell means: not mapped yet.
ModelChemistry and analyticalPharmacokineticsReceptor binding and signallingTissue histologyBiomarkersClinical endpoint
Analytical only (no biological model)Not mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yet
In vitro or ex vivoNot mapped yetNot mapped yetReceptor binding and signalling2Not mapped yetNot mapped yetNot mapped yet
RodentNot mapped yetNot mapped yetNot mapped yetTissue histology1Not mapped yetNot mapped yet
Other animalNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yet
Human, uncontrolledNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yetNot mapped yet
Human, randomisedNot mapped yetPharmacokinetics1Not mapped yetNot mapped yetNot mapped yetClinical endpoint3

6 studies countedEvidence level facet: L4. A design scale, not a measure of strength or quality.

Counts only the exact match studies reviewed for this page on 12 October 2026. Empty cells were not searched exhaustively and are marked not mapped yet. Related forms (recombinant protein, endogenous equine protein, material without a stated sequence) are in the study list and are not counted.

Evidence map: Ac-LKKTETQ (thymosin beta 4, 17 to 23)

Primary studies of Ac-LKKTETQ (thymosin beta 4, 17 to 23), by model and by what was measured. Reviews are not counted. An empty cell means: no published study found as of 12 October 2026.
ModelChemistry and analyticalPharmacokineticsReceptor binding and signallingTissue histologyBiomarkersClinical endpoint
Analytical only (no biological model)Chemistry and analytical1No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026
In vitro or ex vivoChemistry and analytical2Pharmacokinetics2Receptor binding and signalling1No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026
RodentNo published study found as of 12 October 2026Pharmacokinetics1No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026
Other animalChemistry and analytical1Pharmacokinetics1No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026
Human, uncontrolledNo published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found
Human, randomisedNo published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found as of 12 October 2026No published study found

3 studies countedEvidence level facet: L2. A design scale, not a measure of strength or quality.

Built from a screen of all 38 PubMed records naming TB-500, TB500 or LKKTETQ in title or abstract on 12 October 2026. One registered trial of the fragment, NCT07487363, is recruiting and has no published results.

Who produced this evidence

Studies

  1. Analytical only (no biological model)Drug Test Anal 2012

    Identity of the peptide in a product sold as TB-500 by LC-HRMS (Orbitrap); synthesis of a reference standard

    Design
    Analytical chemistry: synthesis by solid phase peptide synthesis, identification in a commercial product
    Population or model
    none (chemistry and analytical)
    Molecule
    Ac-LKKTETQ (thymosin beta 4, 17 to 23) different molecule

    PubMed 22962027DOI

  2. RodentJ Chromatogr B Analyt Technol Biomed Life Sci 2024

    Metabolites of Ac-LKKTETQ in human serum in vitro, enzyme systems and rat urine; cytotoxicity and scratch assays in fibroblasts

    Design
    Analytical method development plus in vitro metabolism and rat urine metabolite study
    Population or model
    human serum and enzyme systems in vitro; rat; fibroblast cell assays
    Molecule
    Ac-LKKTETQ (thymosin beta 4, 17 to 23) different molecule

    Authors declare no competing interests

    PubMed 38382158DOI

  3. Other animalJ Chromatogr A 2012

    Detection of N-acetylated LKKTETQ and its metabolites in equine urine and plasma by LC-MS

    Design
    Analytical method development with in vitro metabolite identification and equine samples collected after a TB-500 product was given
    Population or model
    horse (other animal); in vitro metabolism
    Molecule
    Ac-LKKTETQ (thymosin beta 4, 17 to 23) different molecule

    PubMed 23084823DOI

  4. RodentJ Invest Dermatol 1999

    Re-epithelialisation, contraction, collagen deposition and vessel formation in rat skin wounds; keratinocyte migration (Boyden chamber)

    Design
    Animal study plus cell migration assay
    Population or model
    rat full thickness skin wound model; keratinocytes in vitro
    Molecule
    thymosin beta 4 (1 to 43) exact

    PubMed 10469335DOI

  5. In vitro or ex vivoFASEB J 2003

    Endothelial cell migration, adhesion and vessel sprouting for the full protein and for peptides containing or lacking the seven residue actin binding motif

    Design
    In vitro and ex vivo comparison of the full protein, proteolytic fragments and synthetic peptides
    Population or model
    human umbilical vein endothelial cells; chick aortic arch explants
    Molecule
    thymosin beta 4 (1 to 43) exact

    Molecule note: Full protein exact; the synthetic motif peptides are a related form of the fragment (acetylation not stated).

    PubMed 14500546DOI

  6. Human, randomisedCornea 2015

    Adverse events (registry primary outcome); corneal fluorescein staining and a symptom questionnaire (registry secondary outcomes)

    Design
    Randomised, double masked, vehicle controlled, phase 2
    Population or model
    adults with severe dry eye
    Molecule
    thymosin beta 4 (1 to 43) exact
    n
    9
    Comparator
    vehicle
    Blinding
    double masked (registry: triple)
    Duration
    56 days including 28 day follow up
    Funding
    PubMed publication type: Research Support, Non-U.S. Gov't; registry sponsor Michigan Cornea Consultants

    Molecule note: Eye drop formulation RGN-259 containing thymosin beta 4.

    PubMed 25826322DOI

  7. Human, randomisedInt J Mol Sci 2022

    Closure of persistent epithelial defects at day 29 (registry primary outcome); comfort scores

    Design
    Randomised, placebo controlled, double masked, phase 3 (SEER-1)
    Population or model
    adults with stage 2 or 3 neurotrophic keratopathy
    Molecule
    thymosin beta 4 (1 to 43) exact
    n
    18
    Comparator
    placebo
    Blinding
    double masked (registry: quadruple)
    Funding
    Sponsor ReGenTree LLC (registry)

    Two authors employed by ReGenTree LLC, which develops RGN-259; one by its parent company (declared). Molecule note: RGN-259 eye drop formulation containing thymosin beta 4.

    PubMed 36613994DOI

  8. Human, randomisedAnn N Y Acad Sci 2010

    Safety and tolerability (registry primary outcome); ulcer closure

    Design
    Randomised, double blind, placebo controlled, sequential cohorts, phase 2
    Population or model
    adults with venous stasis ulcers
    Molecule
    thymosin beta 4 (1 to 43) exact
    n
    73
    Comparator
    placebo
    Blinding
    double blind (registry: quadruple)
    Duration
    84 days (registry title)
    Funding
    Registry sponsor RegeneRx Biopharmaceuticals

    Molecule note: Abstract describes a synthetic copy of the naturally occurring 43 amino acid peptide.

    PubMed 20536470DOI

  9. Human, randomisedAnn N Y Acad Sci 2010

    Adverse events and pharmacokinetic parameters

    Design
    Randomised, placebo controlled, single and multiple ascending cohorts, phase 1
    Population or model
    healthy volunteers
    Molecule
    thymosin beta 4 (1 to 43) exact
    n
    40
    Comparator
    placebo
    Duration
    single exposure, then 14 days

    Molecule note: Abstract states synthetic thymosin beta 4.

    PubMed 20536472DOI

  10. Human, randomisedCardiovasc Res 2025

    Infarct area by imaging at 90 days in the trial

    Design
    Mouse and cell work plus a randomised, placebo controlled, double blind trial
    Population or model
    mouse; cardiomyocyte lines; human randomised: adults after ST elevation myocardial infarction
    Molecule
    recombinant thymosin beta 4 (NL005) related form
    n
    96
    Comparator
    placebo
    Blinding
    double blind

    Three authors employed by Beijing Northland Biotechnology (declared). Molecule note: Recombinant human thymosin beta 4 (NL005); N terminal acetylation not stated in abstract.

    PubMed 41229390DOI

  11. Human, randomisedJ Cell Mol Med 2021

    Safety, tolerability, pharmacokinetics and anti drug antibodies

    Design
    Randomised, double blind, phase 1
    Population or model
    healthy volunteers
    Molecule
    recombinant thymosin beta 4 (NL005) related form
    n
    84

    Three authors are employees of the sponsor (declared). Molecule note: Recombinant human thymosin beta 4 (NL005).

    PubMed 34346165DOI

  12. RodentJt Dis Relat Surg 2026

    Load to failure, histology scores and collagen type I and III staining

    Design
    Randomised animal study, four groups
    Population or model
    rat (Sprague-Dawley), Achilles tendon transection model
    Molecule
    not stated in the abstract (no sequence or mass given) related form
    n
    32

    Molecule note: Abstract calls the material synthetic thymosin beta-4 (TB-500) and gives no sequence or mass, so the molecule cannot be assigned.

    PubMed 42542926DOI

  13. In vitro or ex vivoACS Appl Mater Interfaces 2025

    Gelation, cell migration and corneal epithelium in a hydrogel built from a Nap-YpYY-TB500 precursor

    Design
    Materials study with cell assays and an animal model
    Population or model
    human corneal cells in vitro; alkali burn model
    Molecule
    a peptide with the sequence LKKTETQ inside a larger conjugate related form

    Molecule note: Uses the name TB500 for a peptide with the sequence LKKTETQ inside a larger conjugate.

    PubMed 41359360DOI

  14. Analytical only (no biological model)Drug Test Anal 2023

    Content of products sold online as TB500, TB1000 and SGF1000

    Design
    Analytical study of products bought online (short communication)
    Population or model
    none (product analysis)
    Molecule
    product sold as TB-500 (content not confirmed) related form

    Molecule note: Products named TB500 and TB1000; content found inconsistent with descriptions, so not counted for either molecule.

    PubMed 36482504DOI

  15. Other animalDrug Test Anal 2025

    Endogenous thymosin beta 4 concentration in racing horse blood; effect of sample storage; a synthesis impurity marker

    Design
    Population study of endogenous levels plus detection strategy
    Population or model
    horse (other animal)
    Molecule
    endogenous equine thymosin beta 4 related form

    Molecule note: Endogenous equine thymosin beta 4; sequence identity with the catalog molecule not checked for this page.

    PubMed 39314109DOI

Mechanism studied

  • Thymosin beta 4 is described as the main G-actin sequestering peptide, and a seven amino acid actin binding motif was studied in cell assays. Source sentenceIt is the most abundant member of the beta-thymosin family in mammalian tissue and is regarded as the main G-actin sequestering peptide.20 FASEB J 2003

Status matrix

United States: FDA records

US

Sport anti-doping lists

International

  • The WADA 2026 Prohibited List names "Thymosin-ß4 and its derivatives e.g. TB-500" in class S2.3, so the class covers both molecules. Source sentenceS2.3. GROWTH FACTORS AND GROWTH FACTOR MODULATORS ... Thymosin-ß4 and its derivatives e.g. TB-50026 WADA Prohibited List 2026
  • An equine doping study states that thymosin beta 4 is forbidden by the IFHA, the FEI and WADA. Source sentenceforbidden by the IFHA, the FEI, and the WADA18 Drug Test Anal 2025

Elsewhere: New Zealand

New Zealand

  • New Zealand's Medsafe advisory of 21 May 2026 lists TB-500 and thymosin among products advertised by online sellers. Source sentenceTB‑500 and thymosin28 Medsafe, 21 May 2026

Registered trials

  • NCT07487363Phase 1/2

    Status
    Recruiting (start 5 Feb 2026, estimated primary completion 14 Feb 2027)
    Sponsor
    Hudson Biotech
    Site countries
    China (global context)
    Primary endpoint
    safety: adverse events
    Primary endpoint met
    not reported
    Last synced
    12 October 2026

  • NCT01393132Phase 2

    Status
    Completed (Dec 2012), results posted
    Sponsor
    Michigan Cornea Consultants
    Site countries
    US
    Primary endpoint
    safety
    Primary endpoint met
    not reported
    Last synced
    12 October 2026

  • NCT02600429Phase 3

    Status
    Terminated (business decision)
    Sponsor
    ReGenTree
    Site countries
    US
    Primary endpoint
    epithelial defect closure at day 29
    Primary endpoint met
    not met
    Last synced
    12 October 2026

  • NCT05555589Phase 3

    Status
    Recruiting per registry (last update 23 Dec 2025; estimated completion 30 May 2026 has passed)
    Sponsor
    ReGenTree
    Site countries
    Italy, Poland, Spain, US
    Primary endpoint
    epithelial defect closure at day 29
    Primary endpoint met
    not reported
    Last synced
    12 October 2026
  • ClinicalTrials.gov on 12 Oct 2026: 18 records for "thymosin beta 4" (one of them the fragment trial) and 1 record for "TB-500". Source sentencetotalCount 18; totalCount 1 (NCT07487363)31 ClinicalTrials.gov search, 12 October 2026

Timeline

  1. Rat skin wound model and keratinocyte migration study of thymosin beta 4 Source sentenceJ Invest Dermatol 1999: Re-epithelialisation, contraction, collagen deposition and vessel formation in rat skin wounds; keratinocyte migration (Boyden chamber)19 J Invest Dermatol 1999
  2. Seven residue actin binding motif compared with the full protein in endothelial assays Source sentenceFASEB J 2003: Endothelial cell migration, adhesion and vessel sprouting for the full protein and for peptides containing or lacking the seven residue actin binding motif20 FASEB J 2003
  3. Healthy volunteer randomised study of synthetic thymosin beta 4 published Source sentenceAnn N Y Acad Sci 2010: Adverse events and pharmacokinetic parameters13 Ann N Y Acad Sci 2010
  4. Ac-LKKTETQ identified in a product sold as TB-500 by LC-HRMS Source sentenceDrug Test Anal 2012: Identity of the peptide in a product sold as TB-500 by LC-HRMS (Orbitrap); synthesis of a reference standard3 Drug Test Anal 2012
  5. LC-MS method for the fragment in horse urine and plasma Source sentenceJ Chromatogr A 2012: Detection of N-acetylated LKKTETQ and its metabolites in equine urine and plasma by LC-MS5 J Chromatogr A 2012
  6. Online TB500 and TB1000 products analysed Source sentenceDrug Test Anal 2023: Content of products sold online as TB500, TB1000 and SGF100015 Drug Test Anal 2023
  7. SEER-2 phase 3 starts at sites in the US, Italy, Poland and Spain Source sentenceStudy start 2023-04; locations United States, Italy, Poland, Spain30 ClinicalTrials.gov NCT05555589
  8. Metabolism of Ac-LKKTETQ in human serum in vitro and in rats Source sentenceJ Chromatogr B Analyt Technol Biomed Life Sci 2024: Metabolites of Ac-LKKTETQ in human serum in vitro, enzyme systems and rat urine; cytotoxicity and scratch assays in fibroblasts4 J Chromatogr B Analyt Technol Biomed Life Sci 2024
  9. Endogenous thymosin beta 4 population study in racing horses Source sentenceDrug Test Anal 2025: Endogenous thymosin beta 4 concentration in racing horse blood; effect of sample storage; a synthesis impurity marker18 Drug Test Anal 2025
  10. WADA 2026 list in force, S2.3 names thymosin beta 4 and derivatives Source sentenceS2.3 ... Thymosin-ß4 and its derivatives e.g. TB-50026 WADA Prohibited List 2026
  11. A registered human trial of the fragment starts recruiting in China Source sentenceStudy start 2026-02-05; overall status Recruiting7 ClinicalTrials.gov NCT07487363
  12. Medsafe advisory names TB-500 Source sentence21 May 2026 ... TB‑500 and thymosin28 Medsafe, 21 May 2026

Integrity notes

Chemistry and records

TB-500: sequence, mass, CAS and regulatory record in the research library →

Sources

  1. 1Peptency catalog record, TB-500 accessed 12 Oct 2026
  2. 2PubChem CID 16132341 accessed 12 Oct 2026
  3. 3Drug Test Anal 2012 accessed 12 Oct 2026
  4. 4J Chromatogr B Analyt Technol Biomed Life Sci 2024 accessed 12 Oct 2026
  5. 5J Chromatogr A 2012 accessed 12 Oct 2026
  6. 6FDA, bulk drug substances Category 2 page, content current as of 22 April 2026 accessed 12 Oct 2026
  7. 7ClinicalTrials.gov NCT07487363 accessed 12 Oct 2026
  8. 8PubChem CID 62707662 accessed 12 Oct 2026
  9. 9PubMed search for randomised trials of thymosin beta 4, 12 October 2026 accessed 12 Oct 2026
  10. 10Cornea 2015 accessed 12 Oct 2026
  11. 11Int J Mol Sci 2022 accessed 12 Oct 2026
  12. 12Ann N Y Acad Sci 2010 accessed 12 Oct 2026
  13. 13Ann N Y Acad Sci 2010 accessed 12 Oct 2026
  14. 14PubMed search for TB-500, TB500 or LKKTETQ, 12 October 2026 accessed 12 Oct 2026
  15. 15Drug Test Anal 2023 accessed 12 Oct 2026
  16. 16Jt Dis Relat Surg 2026 accessed 12 Oct 2026
  17. 17ACS Appl Mater Interfaces 2025 accessed 12 Oct 2026
  18. 18Drug Test Anal 2025 accessed 12 Oct 2026
  19. 19J Invest Dermatol 1999 accessed 12 Oct 2026
  20. 20FASEB J 2003 accessed 12 Oct 2026
  21. 21ClinicalTrials.gov NCT00832091 accessed 12 Oct 2026
  22. 22ClinicalTrials.gov NCT02600429 accessed 12 Oct 2026
  23. 23Cardiovasc Res 2025 accessed 12 Oct 2026
  24. 24J Cell Mol Med 2021 accessed 12 Oct 2026
  25. 25openFDA Drugs@FDA query for thymosin, 12 October 2026 accessed 12 Oct 2026
  26. 26WADA Prohibited List 2026 accessed 12 Oct 2026
  27. 27Federal Register 2026-07361, 16 April 2026 accessed 12 Oct 2026
  28. 28Medsafe, 21 May 2026 accessed 12 Oct 2026
  29. 29ClinicalTrials.gov NCT01393132 accessed 12 Oct 2026
  30. 30ClinicalTrials.gov NCT05555589 accessed 12 Oct 2026
  31. 31ClinicalTrials.gov search, 12 October 2026 accessed 12 Oct 2026

About this page

Research-use information. This library summarises published literature and regulator records. It is not guidance for use, not medical advice, and not a statement that any material is suitable for use in people or animals.

Reviewed by the Peptency editorial process. Version 1, last edited 12 October 2026, 31 sources.

Cite this page: Peptency Academy. TB-500: two molecules, one name. Version 1./us/academy/compounds/tb-500/