TB-500 / thymosin-related fragments
Names used online for synthetic products associated with thymosin beta-4 research.
Editorial review: August 13, 2026Evidence snapshot
This drawer marks papers. It is not a plan, a dose, or a source. A paper is a bounded report. It is not a protocol. Grades name the object. They are not a safety rating.
Identity lock. On this site, TB-500 means the N-acetyl heptapeptide fragment Ac-LKKTETQ (actin-binding region of thymosin β4; fragment CAS 885340-08-9), not full-length thymosin β4. Full-length Tβ4 is a different molecule — do not use full Tβ4 CAS 77591-33-4 as this fragment’s identity. Many papers study full Tβ4, unacetylated LKKTETQ, or commercial “TB-500” only as a doping analyte. Tag each paper. Do not treat a full-Tβ4 dry-eye or venous-ulcer trial as evidence for the Ac-LKKTETQ fragment. The fragment has no approved indication. Off-label does not apply.
Bottom line
Most clinical and much preclinical “healing” literature is full-length thymosin β4, not Ac-LKKTETQ. Papers that specify the commercial TB-500 fragment (Ac-LKKTETQ) are largely analytical, doping-control, metabolism, or in-vitro/rat screening work. A mouse wound paper shows activity of the unacetylated heptapeptide LKKTETQ alongside full Tβ4 — still not a human fragment trial. Honest line: controlled human efficacy for the Ac-LKKTETQ fragment is not established in this set.
Papers
Fragment Ac-LKKTETQ / commercial “TB-500” (identity and analytics)
PMID 22962027 — Esposito 2012
Tested: chemical identification of N-terminal acetylated Tβ4 fragment Ac-LKKTETQ in a product labeled TB-500, with synthetic confirmation (doping-suspected preparation).
Does not show: human therapeutic efficacy. Establishes what that commercial object contained in the analyzed sample.
PMID 23084823 — Ho 2012
Tested: LC-MS doping-control methods for TB-500 described as a synthetic N-acetylated LKKTETQ segment of Tβ4 in equine urine and plasma.
Does not show: a human healing trial. Detection method paper.
PMID 38382158 — Rahaman 2024
Tested: quantification of TB-500 (Ac-LKKTETQ) and metabolites in in-vitro systems and in rats; in-vitro wound-healing activity screening of parent versus metabolites. Authors note biological effects of TB-500 itself had been poorly documented relative to unacetylated LKKTETQ.
Does not show: a controlled human fragment trial.
PMID 36482504 — Delcourt 2023
Tested: analytical characterization of misbranded/adulterated products marketed as TB500/TB1000 (and related), not a clinical intervention.
Does not show: efficacy. Underscores identity and labeling risk.
Related short peptide (LKKTETQ — not the same as Ac-LKKTETQ)
PMID 12581423 — Philp 2003
Tested: full-length thymosin β4 and a synthetic seven-amino-acid actin-binding peptide LKKTETQ (acetylation not the named object here) in dermal wound models in diabetic and aged mice.
Does not show: a human result, or that commercial Ac-LKKTETQ TB-500 is the same tested article as unacetylated LKKTETQ.
PMID 20179146 — Sosne 2010
Tested: review of biological activities of Tβ4 mapped to short active-site peptide sequences (including actin-binding domain peptides).
Does not show: a controlled human Ac-LKKTETQ drug trial.
Full-length thymosin β4 (different object — do not grade as TB-500 fragment)
PMID 26056426 — Sosne 2015
Tested: thymosin β4 ophthalmic solution versus placebo in a randomized Phase II dry-eye trial (full Tβ4).
Does not show: an Ac-LKKTETQ fragment result, or a systemic “TB-500” claim.
PMID 17495250 — Guarnera 2007
Tested: clinical remarks on a European prospective randomized topical thymosin β4 study in venous ulcers (full Tβ4).
Does not show: fragment Ac-LKKTETQ efficacy.
Context, not a grade
Additional doping-screen papers that list TB-500 among small peptides (e.g. multi-analyte urine methods) are detection context only. They do not establish healing in people.
What is not established
Controlled human efficacy for Ac-LKKTETQ / TB-500 fragment. Equivalence of fragment, unacetylated LKKTETQ, and full-length Tβ4. Any approved fragment indication. Product identity between a kit labeled TB-500 and either full Tβ4 drug candidates or laboratory reference standards. Full-Tβ4 ophthalmic or ulcer papers do not fill the fragment gap.
Selected sources
22962027 23084823 38382158 36482504 12581423 20179146 26056426 17495250
Reported experiences
Recovery, mobility, soft-tissue comfort
Reported topics are not established benefits.Risks and unknowns
Unknown identity and purity, injection risks, limited human safety data
Compare experiences with care.
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