Frag 17-23
Tβ4 residues 17–23 (LKKTETQ / Ac-LKKTETQ) — ≠ hGH Frag 176-191 ≠ thymosin α1.
Editorial review:Evidence 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. Frag 17-23 is the thymosin β4 (Tβ4) actin-binding heptapeptide spanning residues 17–23: sequence LKKTETQ. The common research/acetylated form is Ac-LKKTETQ, widely overlapping the object sold/discussed as TB-500; INN-related monomer fequesetide maps to non-acetylated LKKTETQ. PubChem: fequesetide / LKKTETQ CID 10169788 (C36H66N10O13 / MW 847.0; CAS 476014-70-7); Ac-LKKTETQ / TB-500 CID 62707662 (C38H68N10O14 / MW 889.0; CAS 885340-08-9). ≠ full-length Tβ4 (43 aa) ≠ thymosin alpha-1 / thymalfasin ≠ Thymalin ≠ hGH Frag 176-191 / AOD-9604. Align Ac-LKKTETQ with the site TB-500 fragment lock — do not overwrite hgh-frag-176-191.md or tb-500.md from this drawer. Human clinical RCTs specific to the isolated 17–23 fragment are essentially absent. This drawer marks papers. It is not use advice.
Bottom line
Strongest object-matched literature is structural/actin-binding mapping for Tβ4’s 17–23 region, angiogenesis assays with the actin-binding site peptide, and analytical identification of acetylated 17–23 in TB-500 products. Refuse wound-healing or recovery glow that treats Frag 17-23 as proven human therapy or as identical to full Tβ4 clinical programs.
Papers
Identity / analytical — TB-500 contains Ac-17-23
PMID 22962027 — Esposito 2012
Tested: synthesis and characterization of the N-terminal acetylated 17–23 fragment of thymosin β4 identified in TB-500 (product suspected to possess doping potential).
Does not show: human clinical efficacy of Frag 17-23, or approval as a medicine.
Actin-binding domain biology (fragment / site papers)
PMID 14500546 — Philp 2003
Tested: the actin binding site on thymosin β4 promoting angiogenesis (peptide-site framing tied to the 17–23 region biology).
Does not show: a controlled human wound or sports-recovery RCT for isolated Frag 17-23.
PMID 8617195 — Van Troys 1996
Tested: mutational mapping of the actin binding site of thymosin β4.
Does not show: human therapeutic outcomes for a marketed fragment.
PMID 28028989 — Kuzan 2016
Tested: review of thymosin β as an actin-binding protein with varied functions.
Does not show: Frag 17-23 human clinical approval; full Tβ4 review ≠ fragment RCT.
PMID 7945275 — Safer 1994
Tested: beta-thymosins as actin-binding peptides (foundational class biology).
Does not show: consumer peptide efficacy claims.
Related cellular models (keep object-tagged)
PMID 34170491 — Yoon 2021
Tested: effects of thymosin β4–derived peptides on migration and invasion of ovarian cancer cells (includes derived-peptide framing).
Does not show: a human oncology or healing indication for Frag 17-23; oncology migration assays are not sports-medicine proof.
What is not established
Human clinical efficacy for isolated Frag 17-23 / Ac-LKKTETQ. Equivalence to full-length Tβ4, thymosin alpha-1, or hGH fragment 176-191. That actin-binding/angiogenesis assays equal recovery outcomes in people. Product integrity of unlabeled “Frag 17-23” vs analytically confirmed Ac-LKKTETQ. This drawer does not provide use advice, schedules, or sourcing.
Selected sources
Reported experiences
Reported topics are not established benefits.Risks and unknowns
Compare experiences with care.
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